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Da Silva F, Linhares JMM, Lira M. What intrinsic factors affect the central corneal thickness? Ophthalmic Physiol Opt 2025; 45:315-332. [PMID: 39495112 DOI: 10.1111/opo.13414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 10/15/2024] [Accepted: 10/22/2024] [Indexed: 11/05/2024]
Abstract
The cornea is one of the tissues responsible for covering and protecting the inner structures of the eye. Central corneal thickness (CCT) is defined as the distance between the anterior epithelial surface and the posterior surface of the endothelial layer. This parameter plays a very important role regarding intraocular pressure (IOP) measurement, evaluation of corneal uniformity, selection of a suitable technique for corneal refractive surgery and the planning of surgical procedures to overcome corneal disease. This comprehensive review elucidates the multifaceted factors influencing the central corneal thickness. Recognising the impact of these factors not only enhances our understanding of corneal dynamics but also contributes significantly to the refinement of diagnostic and therapeutic strategies in ophthalmology.
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Affiliation(s)
- Filipe Da Silva
- Physics Centre of Minho and Porto Universities (CF-UM-UP), School of Sciences, University of Minho, Braga, Portugal
| | - João M M Linhares
- Physics Centre of Minho and Porto Universities (CF-UM-UP), School of Sciences, University of Minho, Braga, Portugal
| | - Madalena Lira
- Physics Centre of Minho and Porto Universities (CF-UM-UP), School of Sciences, University of Minho, Braga, Portugal
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Ghosh A, Bera AK, Singh V, Basu S, Pati F. Bioprinting of anisotropic functional corneal stroma using mechanically robust multi-material bioink based on decellularized cornea matrix. BIOMATERIALS ADVANCES 2024; 165:214007. [PMID: 39216318 DOI: 10.1016/j.bioadv.2024.214007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2024] [Revised: 07/08/2024] [Accepted: 08/23/2024] [Indexed: 09/04/2024]
Abstract
Corneal scarring is a common cause of blindness, affecting millions globally each year. A huge gap between the demand and supply of donor tissue currently limits corneal transplantation, the only definitive therapy for patients with corneal scarring. To overcome this challenge, researchers have harnessed the efficacy of 3D bioprinting to fabricate artificial corneal stromal constructs. With all the different bioinks available, the decellularized corneal matrix-based bioprinted construct can fulfill the required biological functionality but is limited by the lack of mechanical stiffness. Additionally, from a biophysical standpoint, it is necessary for an ideal corneal substitute to mimic the anisotropy of the cornea from the central optic zone to the surrounding periphery. In this study, we enhanced the mechanical robustness of decellularized cornea matrix (DCM) hydrogel by blending it with another natural polymer, sonicated silk fibroin solution in a defined ratio. Although hybrid hydrogel has an increased complex modulus than DCM hydrogel, it has a lower in vitro degradation rate and increased opaqueness due to the presence of crystalline beta-sheet conformation within the hydrogel. Therefore, we used this multi-material bioink-based approach to fabricate a corneal stromal equivalent where the outer peripheral corneal rim was printed with a mechanically robust polymeric blend of DCM and sonicated silk fibroin and the central optic zone was printed with only DCM. The bioprinted corneal stroma thus maintained its structural integrity and did not break when lifted with forceps. The two different bioinks were encapsulated with human limbus-derived mesenchymal stem cells (hLMSC) individually and 3D bioprinted in different patterns (concentric and parallel) to attain a native-like structure in terms of architecture and transparency. Thus, the bilayer cornea constructs maintained high cell viability and expressed keratocyte core proteins indicating optimal functionality. This approach helped to gain insight into bioprinting corneas with heterogeneous mechanical property without disturbing the structural clarity of the central optic zone.
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Affiliation(s)
- Anwesha Ghosh
- Department of Biomedical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy 502284, Telangana, India
| | - Ashis Kumar Bera
- Department of Biomedical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy 502284, Telangana, India
| | - Vivek Singh
- Centre Ocular Regeneration, Prof. Brien Holden Eye Research Centre L.V. Prasad Eye Institute, Hyderabad 500034, Telangana, India
| | - Sayan Basu
- Centre Ocular Regeneration, Prof. Brien Holden Eye Research Centre L.V. Prasad Eye Institute, Hyderabad 500034, Telangana, India
| | - Falguni Pati
- Department of Biomedical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy 502284, Telangana, India.
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Antonov AA, Volzhanin AV, Klinicheva EA, Karpilova MA. [Influence of corneal curvature and peripheral thickness on tonometry readings]. Vestn Oftalmol 2024; 140:43-50. [PMID: 38739130 DOI: 10.17116/oftalma202414002243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2024]
Abstract
PURPOSE This study investigates the influence of peripheral corneal thickness (PCT) and its curvature on tonometry readings. MATERIAL AND METHODS The study included 49 patients (49 eyes) who were indicated for glaucoma surgery. Using bidirectional applanation tonometry, the following parameters were obtained: IOPcc, IOPg - intraocular pressure (IOP) corrected for corneal compensation, taken as the most reliable indicator; IOP converted to Goldmann measurement, taken as the result of applanation tonometry, ΔIOP (IOPcc-IOPg), CH and CRF (corneal hysteresis and corneal resistance factor). During corneal topography, the corneal thickness was studied in the center, PCT at 1.5; 2, 3, 4 and 5 mm from the center in four meridians, as well as ΔPCT (PCT 3 mm - PCT 1.5 mm), the curvature of the anterior and posterior surfaces of the cornea and the depth of the anterior chamber. Aberrometry was used to obtain refractometry data and the curvature of the anterior surface of the cornea. The influence of the studied parameters on ΔIOP was evaluated. RESULTS ΔIOP correlated with CRF (r= -0.652), CH (r= -0.873), central corneal thickness (r= -0.293), PCT at all distances except 5 mm (r= -0.297; -0.287; -0.302; -0.303), with the strong and weak meridians of the anterior surface of the cornea (r=0.328; r=0.315), with the strong and weak meridians of the posterior surface, as well as the average curvature of the posterior surface (r=0.307; r=0.332; r=0.328). After step-by-step selection of the above parameters for creating a linear regression model for ΔIOP calculation, CH, CRF and PCT1.5mm remained in the model. The model describes ΔIOP with high accuracy (R2=0.974). CONCLUSION Biomechanical parameters of the cornea are the leading factor of applanation tonometry error. Individual linear dimensions of the cornea (thickness, curvature) have a lesser effect.
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Affiliation(s)
- A A Antonov
- Krasnov Research Institute of Eye Diseases, Moscow, Russia
| | - A V Volzhanin
- Krasnov Research Institute of Eye Diseases, Moscow, Russia
| | - E A Klinicheva
- Krasnov Research Institute of Eye Diseases, Moscow, Russia
| | - M A Karpilova
- Krasnov Research Institute of Eye Diseases, Moscow, Russia
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Yang Y, Zhong J, Cui D, Jensen LD. Up-to-date molecular medicine strategies for management of ocular surface neovascularization. Adv Drug Deliv Rev 2023; 201:115084. [PMID: 37689278 DOI: 10.1016/j.addr.2023.115084] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 08/30/2023] [Accepted: 09/04/2023] [Indexed: 09/11/2023]
Abstract
Ocular surface neovascularization and its resulting pathological changes significantly alter corneal refraction and obstruct the light path to the retina, and hence is a major cause of vision loss. Various factors such as infection, irritation, trauma, dry eye, and ocular surface surgery trigger neovascularization via angiogenesis and lymphangiogenesis dependent on VEGF-related and alternative mechanisms. Recent advances in antiangiogenic drugs, nanotechnology, gene therapy, surgical equipment and techniques, animal models, and drug delivery strategies have provided a range of novel therapeutic options for the treatment of ocular surface neovascularization. In this review article, we comprehensively discuss the etiology and mechanisms of corneal neovascularization and other types of ocular surface neovascularization, as well as emerging animal models and drug delivery strategies that facilitate its management.
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Affiliation(s)
- Yunlong Yang
- Department of Cellular and Genetic Medicine, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China.
| | - Junmu Zhong
- Department of Ophthalmology, Longyan First Hospital Affiliated to Fujian Medical University, Longyan 364000, Fujian Province, China
| | - Dongmei Cui
- Shenzhen Eye Hospital, Jinan University, Shenzhen Eye Institute, Shenzhen 518040, Guangdong Province, China
| | - Lasse D Jensen
- Department of Health, Medicine and Caring Sciences, Division of Diagnostics and Specialist Medicine, Unit of Cardiovascular Medicine, Linköping University, Linköping, Sweden.
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Towler J, Consejo A, Zhou D, Romano V, Levis H, Boote C, Elsheikh A, Geraghty B, Abass A. Typical localised element-specific finite element anterior eye model. Heliyon 2023; 9:e13944. [PMID: 37101628 PMCID: PMC10123217 DOI: 10.1016/j.heliyon.2023.e13944] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 11/19/2022] [Accepted: 02/15/2023] [Indexed: 03/07/2023] Open
Abstract
Purpose The study presents an averaged anterior eye geometry model combined with a localised material model that is straightforward, appropriate and amenable for implementation in finite element (FE) modelling. Methods Both right and left eye profile data of 118 subjects (63 females and 55 males) aged 22-67 years (38.5 ± 7.6) were used to build an averaged geometry model. Parametric representation of the averaged geometry model was achieved through two polynomials dividing the eye into three smoothly connected volumes. This study utilised the collagen microstructure x-ray data of 6 ex-vivo healthy human eyes, 3 right eyes and 3 left eyes in pairs from 3 donors, 1 male and 2 females aged between 60 and 80 years, to build a localised element-specific material model for the eye. Results Fitting the cornea and the posterior sclera sections to a 5th-order Zernike polynomial resulted in 21 coefficients. The averaged anterior eye geometry model recorded a limbus tangent angle of 37° at a radius of 6.6 mm from the corneal apex. In terms of material models, the difference between the stresses generated in the inflation simulation up to 15 mmHg in the ring-segmented material model and localised element-specific material model were significantly different (p < 0.001) with the ring-segmented material model recording average Von-Mises stress 0.0168 ± 0.0046 MPa and the localised element-specific material model recording average Von-Mises stress 0.0144 ± 0.0025 MPa. Conclusions The study illustrates an averaged geometry model of the anterior human eye that is easy to generate through two parametric equations. This model is combined with a localised material model that can be used either parametrically through a Zernike fitted polynomial or non-parametrically as a function of the azimuth angle and the elevation angle of the eye globe. Both averaged geometry and localised material models were built in a way that makes them easy to implement in FE analysis without additional computation cost compared to the limbal discontinuity so-called idealised eye geometry model or ring-segmented material model.
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Affiliation(s)
- Joseph Towler
- Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK
| | | | - Dong Zhou
- Department of Civil Engineering and Industrial Design, School of Engineering, University of Liverpool, Liverpool, UK
| | - Vito Romano
- Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK
- Department of Medical and Surgical Specialities, Radiological Sciences, And Public Health, Ophthalmology Clinic, University of Brescia, Italy
| | - Hannah Levis
- Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK
| | - Craig Boote
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK
| | - Ahmed Elsheikh
- Department of Civil Engineering and Industrial Design, School of Engineering, University of Liverpool, Liverpool, UK
- Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing, China
- NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
| | - Brendan Geraghty
- Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK
| | - Ahmed Abass
- Department of Mechanical, Materials and Aerospace Engineering, School of Engineering, University of Liverpool, Liverpool, UK
- Department of Production Engineering and Mechanical Design, Faculty of Engineering, Port Said University, Egypt
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Aguilella-Arzo M, Compañ V. A three-dimensional model to describe complete human corneal oxygenation during contact lens wear. J Biomed Mater Res B Appl Biomater 2023; 111:610-621. [PMID: 36214217 PMCID: PMC10092785 DOI: 10.1002/jbm.b.35180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 09/13/2022] [Accepted: 09/21/2022] [Indexed: 01/21/2023]
Abstract
We perform a novel 3D study to quantify the corneal oxygen consumption and diffusion in each part of the cornea with different contact lens materials. The oxygen profile is calculated as a function of oxygen tension at the cornea-tear interface and the oxygen transmissibility of the lens, with values used in previous studies. We aim to determine the influence of a detailed geometry of the cornea in their modeling compared to previous low dimensional models used in the literature. To this end, a 3-D study based on an axisymmetric volume element analysis model was applied to different contact lenses currently on the market. We have obtained that the model provides a valuable tool for understanding the flux and cornea oxygen profiles through the epithelium, stroma, and endothelium. The most important results are related to the dependence of the oxygen flux through the cornea-lens system on the contact lens thickness and geometry. Both parameters play an important role in the corneal flux and oxygen tension distribution. The decline in oxygen consumption experienced by the cornea takes place just inside the epithelium, where the oxygen tension falls to between 95 and 16 mmHg under open eye conditions, and 30 to 0.3 mmHg under closed eye conditions, depending on the contact lens worn. This helps to understand the physiological response of the corneal tissue under conditions of daily and overnight contact lens wear, and the importance of detailed geometry of the cornea in the modeling of diffusion for oxygen and other species.
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Affiliation(s)
| | - Vicente Compañ
- Departamento de Termodinámica Aplicada. Escuela Técnica Superior de Ingenieros Industriales (ETSII), Universitat Politècnica de València, Valencia, Spain
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Balters L, Reichl S. 3D bioprinting of corneal models: A review of the current state and future outlook. J Tissue Eng 2023; 14:20417314231197793. [PMID: 37719307 PMCID: PMC10504850 DOI: 10.1177/20417314231197793] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 08/13/2023] [Indexed: 09/19/2023] Open
Abstract
The cornea is the outermost layer of the eye and serves to protect the eye and enable vision by refracting light. The need for cornea organ donors remains high, and the demand for an artificial alternative continues to grow. 3D bioprinting is a promising new method to create artificial organs and tissues. 3D bioprinting offers the precise spatial arrangement of biomaterials and cells to create 3D constructs. As the cornea is an avascular tissue which makes it more attractive for 3D bioprinting, it could be one of the first tissues to be made fully functional via 3D bioprinting. This review discusses the most common 3D bioprinting technologies and biomaterials used for 3D bioprinting corneal models. Additionally, the current state of 3D bioprinted corneal models, especially specific characteristics such as light transmission, biomechanics, and marker expression, and in vivo studies are discussed. Finally, the current challenges and future prospects are presented.
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Affiliation(s)
- Leon Balters
- Institute of Pharmaceutical Technology and Biopharmaceutics, Technische Universität Braunschweig, Braunschweig, Germany
| | - Stephan Reichl
- Institute of Pharmaceutical Technology and Biopharmaceutics, Technische Universität Braunschweig, Braunschweig, Germany
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Ying PX, Fu M, Huang C, Li ZH, Mao QY, Fu S, Jia XH, Cao YC, Hong LB, Cai LY, Guo X, Liu RB, Meng FK, Yi GG. Profile of biological characterizations and clinical application of corneal stem/progenitor cells. World J Stem Cells 2022; 14:777-797. [PMID: 36483848 PMCID: PMC9724387 DOI: 10.4252/wjsc.v14.i11.777] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Revised: 11/08/2022] [Accepted: 11/23/2022] [Indexed: 12/13/2022] Open
Abstract
Corneal stem/progenitor cells are typical adult stem/progenitor cells. The human cornea covers the front of the eyeball, which protects the eye from the outside environment while allowing vision. The location and function demand the cornea to maintain its transparency and to continuously renew its epithelial surface by replacing injured or aged cells through a rapid turnover process in which corneal stem/progenitor cells play an important role. Corneal stem/progenitor cells include mainly corneal epithelial stem cells, corneal endothelial cell progenitors and corneal stromal stem cells. Since the discovery of corneal epithelial stem cells (also known as limbal stem cells) in 1971, an increasing number of markers for corneal stem/progenitor cells have been proposed, but there is no consensus regarding the definitive markers for them. Therefore, the identification, isolation and cultivation of these cells remain challenging without a unified approach. In this review, we systematically introduce the profile of biological characterizations, such as anatomy, characteristics, isolation, cultivation and molecular markers, and clinical applications of the three categories of corneal stem/progenitor cells.
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Affiliation(s)
- Pei-Xi Ying
- Department of Ophthalmology, Zhujiang Hospital, The Second Clinical School, Southern Medical University, Guangzhou 510280, Guangdong Province, China
| | - Min Fu
- Department of Ophthalmology, Zhujiang Hospital, Southern Medical University, Guangzhou 510280, Guangdong Province, China
| | - Chang Huang
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai 200030, China
- NHC Key Laboratory of Myopia, Fudan University, Shanghai 200030, China
- Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai 200030, China
| | - Zhi-Hong Li
- Department of Cardiology, State Key Laboratory of Organ Failure Research, Guangdong Provincial Key Lab of Shock and Microcirculation, Nanfang Hospital, Southern Medical University, Guangzhou 510550, Guangdong Province, China
| | - Qing-Yi Mao
- The Second Clinical School, Southern Medical University, Guangzhou 510515, Guangdong Province, China
| | - Sheng Fu
- Hengyang Medical School, The University of South China, Hengyang 421001, Hunan Province, China
| | - Xu-Hui Jia
- The Second Clinical School, Southern Medical University, Guangzhou 510515, Guangdong Province, China
| | - Yu-Chen Cao
- The Second Clinical School, Southern Medical University, Guangzhou 510515, Guangdong Province, China
| | - Li-Bing Hong
- The Second Clinical School, Southern Medical University, Guangzhou 510515, Guangdong Province, China
| | - Li-Yang Cai
- The Second Clinical School, Southern Medical University, Guangzhou 510515, Guangdong Province, China
| | - Xi Guo
- Medical College of Rehabilitation, Southern Medical University, Guangzhou 510515, Guangdong Province, China
| | - Ru-Bing Liu
- The Second Clinical School, Southern Medical University, Guangzhou 510515, Guangdong Province, China
| | - Fan-ke Meng
- Emergency Department, Zhujiang Hospital, Southern Medical University, Guangzhou 510280, Guangdong Province, China
| | - Guo-Guo Yi
- Department of Ophthalmology, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou 510655, Guangdong Province, China
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Muacevic A, Adler JR. A Study Linking Axial Length, Corneal Curvature, and Eye Axis With Demographic Characteristics in the Emmetropic Eyes of Bangladeshi People. Cureus 2022; 14:e29925. [PMID: 36225244 PMCID: PMC9536359 DOI: 10.7759/cureus.29925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/04/2022] [Indexed: 11/05/2022] Open
Abstract
Background Axial length (AL) and corneal curvature (CC) are one of the furthest critical parameters for optometry and oculoplastic surgery. These two variables are crucial in biometry for accurately measuring the power of the intraocular lens in cataract surgery. This research aimed to determine the association linking axial length and corneal curvature with demographic characteristics in emmetropic eyes of Bangladeshi people. Methods This descriptive cross-sectional research was carried out among 200 emmetropic eyes of Bangladeshi people attending the Department of Ophthalmology at Rajshahi Medical College, Bangladesh, with different eye conditions, between July 2017 and June 2018. Data was gathered by conducting person-to-person interviews, checking visual activity using the Snellen chart, and measuring corneal curvature using an auto-keratometer and axial eyeball length using A-scan ultrasonography. Results A total of 200 attendances were studied, 90 males and 110 females. All were emmetropic. The age range was 21-52 years, and the highest contributors were in the 21-30-year age group. The association between right axial length and right corneal curvature shows a negative relation among both sexes. It was -0.61 (β-coefficient (β-coff)), and highly significant in females at -0.89 (β-coff). Additionally, the association between left axial length and left corneal curvature shows a negative relation of -0.65 (β-coff), which was again highly significant in females at -0.87 (β-coff). Both were not significant in males. There was no significant association linking axial length and eye axis in both sexes. The multivariate regression model was used to assess the p-value, and the regression model was adjusted by age. Conclusion Optical parametric measurement is a noninvasive diagnostic and assessment tool that might help in the actual measurement of intraocular lens implantation in cataract surgery and may also provide supplementary information to the researcher domain.
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Alhussain SHA, Mallen EAH, Strang NC, Jonuscheit S. The role of peripheral ocular length and peripheral corneal radius of curvature in determining refractive error. JOURNAL OF OPTOMETRY 2022; 15:129-137. [PMID: 33879375 PMCID: PMC9068529 DOI: 10.1016/j.optom.2021.02.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 01/28/2021] [Accepted: 02/10/2021] [Indexed: 05/06/2023]
Abstract
PURPOSE The purpose of this study was to extend the knowledge of peripheral biometric component and its relationship to refractive status in healthy individuals by determining the correlation between peripheral ocular length to peripheral corneal radius ratio and the refractive error. METHODS This prospective study was conducted on thirty-three healthy adult participants. Refractive error was assessed objectively and subjectively and recorded as the mean spherical equivalent. Central and peripheral ocular lengths at 30° were assessed using partial coherence interferometry under dilation with 1% tropicamide. Central and peripheral corneal radius of curvature was assessed using Scheimpflug topography. Peripheral ocular lengths at 30° were paired with peripheral corneal curvatures at the incident points of the IOLMaster beam (3.8mm away from corneal apex) superiorly, inferiorly, temporally and nasally to calculate the peripheral ocular length-peripheral corneal radius ratio. Descriptive statistics were used to describe the distribution and spread of the data. Pearson's correlation analysis was used to present the association between biometric and refractive variables. RESULTS Refractive error was negatively correlated with the axial length-central corneal radius ratio (r=-0.91; p<0.001) and with 30° peripheral ocular length-peripheral corneal radius ratio in all four meridians (r≤-0.76; p<0.001). The strength of the correlation was considerably lower when only axial length or peripheral ocular lengths were used. CONCLUSION Using the ratios of peripheral ocular length-peripheral corneal radius to predict refractive error is more effective than using peripheral corneal radius or peripheral ocular length alone.
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Affiliation(s)
- Saleh H A Alhussain
- Department of Vision Sciences, School of Health & Life Sciences, Glasgow Caledonian University, Glasgow, United Kingdom.
| | - Edward A H Mallen
- School of Optometry &Vision Science, University of Bradford, Bradford, United Kingdom
| | - Niall C Strang
- Department of Vision Sciences, School of Health & Life Sciences, Glasgow Caledonian University, Glasgow, United Kingdom
| | - Sven Jonuscheit
- Department of Vision Sciences, School of Health & Life Sciences, Glasgow Caledonian University, Glasgow, United Kingdom
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Cheng Q, Zhang F, Tian T, Wu L, Li L, Chen M, Zhou Y. Visual Corneal Photomechanical Analysis Is Combined with the Pentacam Correlation Index for the Diagnosis of Cone Corneas at Different Stages of Progression. JOURNAL OF HEALTHCARE ENGINEERING 2022; 2022:4682901. [PMID: 35237391 PMCID: PMC8885271 DOI: 10.1155/2022/4682901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 01/20/2022] [Indexed: 11/29/2022]
Abstract
Cone-shaped corneas are blinding eye diseases characterised by dilated and thinning corneal tissue and forward conical protrusions, most often in adolescents. Early detection and intervention can prevent further dilatation of the cornea. The prevailing examination methods and techniques are not difficult to diagnose clinical cone corneas, but there are limitations in the diagnosis of early cone corneas (static cone corneas and subclinical cone corneas). In this study, we investigated the diagnostic value of the combination of these two instruments in the diagnosis of clinical cone corneas and subclinical cone corneas by performing the Pentacam and Corvis ST examinations in healthy eyes and dystrophic cone corneas. This study provides a theoretical basis for early cone cornea screening and diagnosis. The analysis revealed that only TP, SPA1, ARTh, and bIOP were normally distributed among all included parameters, and only bIOP was normally distributed with equal variance. TBI and CBI indices have a certain sensitivity and specificity for the diagnosis of subclinical cone corneas, with a strong diagnostic ability, and can be used for screening and early diagnosis of cone corneas.
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Affiliation(s)
- Qiong Cheng
- Department of Ophthalmology, Taikang Tongji (Wuhan) Hospital, Sixin Road North, Wuhan 430050, China
| | - Feng Zhang
- Key Laboratory of Metallurgical Equipment and Control Technology, Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081, China
- Hubei Key Laboratory of Mechanical Transmission and Manufacturing Engineering, Wuhan University of Science and Technology, Wuhan 430081, China
| | - Tixian Tian
- Key Laboratory of Metallurgical Equipment and Control Technology, Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081, China
- Precision Manufacturing Institute, Wuhan University of Science and Technology, Wuhan 430081, China
| | - Lan Wu
- Department of Ophthalmology, Taikang Tongji (Wuhan) Hospital, Sixin Road North, Wuhan 430050, China
| | - Linna Li
- Department of Ophthalmology, Taikang Tongji (Wuhan) Hospital, Sixin Road North, Wuhan 430050, China
| | - Meixia Chen
- Department of Ophthalmology, Taikang Tongji (Wuhan) Hospital, Sixin Road North, Wuhan 430050, China
| | - Ye Zhou
- Department of Ophthalmology, Taikang Tongji (Wuhan) Hospital, Sixin Road North, Wuhan 430050, China
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Yu AY, Ye J, Savini G, Wang Y, Zhang T, Chen M, Wang Q, Huang J. Reliability and agreement of the central and mid-peripheral corneal thickness measured by a new Scheimpflug based imaging. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:1136. [PMID: 34430577 PMCID: PMC8350684 DOI: 10.21037/atm-20-7895] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Accepted: 04/24/2021] [Indexed: 11/06/2022]
Abstract
Background To assess the intra-observer repeatability and inter-observer reproducibility of central corneal thickness (CCT) and mid-peripheral corneal thickness (MPCT) measurements using a new Scheimpflug imaging instrument (Scansys) and compare the agreement with the rotating Scheimpflug corneal tomographer (Pentacam HR). Methods The same well-trained operator performed the measuring using the two devices, after which Scansys measurements were repeated by another operator. Both instruments required three consecutive measurements per subject. Corneal thickness measurements were obtained by each instrument, including CCT, thinnest corneal thickness (TCT), pupil corneal thickness (PCT), and MPCT. Test-retest repeatability (TRT), within-subject coefficient of variation (CoV), and intra-class correlation coefficient (ICC) were used to evaluate repeatability and reproducibility. A paired t-test was used to compare the differences between Scansys and Pentacam, and the agreement was compared with Bland-Altman plots. Results This study enrolled 112 healthy subjects. The CoV were <0.91% and 0.55% for repeatability and reproducibility, respectively. The ICC was close to 1 in all measurements. For intra-observer repeatability in the CT2mm region, TRT was <10.30 µm. Moreover, TRT was <15.26 µm within the CT5mm region. The paired t-test showed significant differences in all corneal thickness measurements (P<0.001). The central region and CT2mm agreement were high, but the largest range of 95% limits of agreement (LoA) appeared in the CTnasal-5mm. Conclusions The new Scheimpflug imaging instrument showed excellent intra-observer repeatability and inter-observer reproducibility for corneal thickness measurements. The agreement analysis suggested that Scansys and Pentacam could be interchangeably used between the central region and CT2mm, except CT5mm.
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Affiliation(s)
- A-Yong Yu
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China.,State Key Laboratory of Optometry, Ophthalmology and Vision Science, Wenzhou, China
| | - Junming Ye
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
| | | | - Yiran Wang
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
| | - Tianjiao Zhang
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
| | - Min Chen
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
| | - Qinmei Wang
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China.,State Key Laboratory of Optometry, Ophthalmology and Vision Science, Wenzhou, China
| | - Jinhai Huang
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China.,State Key Laboratory of Optometry, Ophthalmology and Vision Science, Wenzhou, China
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Doll T, Moore J, Shihab AH, Lopes BT, Eliasy A, Maklad O, Wu R, White L, Jones S, Elsheikh A, Abass A. Which feature influences on-eye power change of soft toric contact lenses: Design or corneal shape? PLoS One 2020; 15:e0242243. [PMID: 33237951 PMCID: PMC7688134 DOI: 10.1371/journal.pone.0242243] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 10/30/2020] [Indexed: 12/25/2022] Open
Abstract
PURPOSE This study investigates how both the peripheral zone design and corneal shape affect the behaviour of soft contact lenses on-eye. METHODS In this study, soft contact lenses of varying nominal cylindrical powers and peripheral zone designs-a single-prism gravity-based stabilised lens (G1P), two-prism blink-based stabilised lens (B2P) and four-prism blink-based stabilised lens (B4P)-were generated as finite element models. The on-eye simulation results were analysed to identify the impact of each peripheral zone design (Each with different volume ratios) on the effective power change (EPC) when worn by a subject. Topographies of three eyes of varying average simulated anterior corneal curvature (flat, average & steep) were used in this study. RESULTS The volume of the lens's peripheral zone as a ratio of the total lens volume (Vp) recorded very weak correlations with the effective power change (EPC) among the three investigated designs when they were fitted to the flat eye (R = -0.19, -0.15 & -0.22 respectively), moderate correlations with the average eye (R = 0.42, 0.43 & 0.43 respectively) and strong correlations with the steep eye (R = 0.91, 0.9 & 0.9 respectively). No significant differences were noticed among the three investigated designs and none of the cylindrical lenses designed with axis 90° recorded EPC values outside the acceptance criteria range (ACR) of ±0.25 D. No significant differences in EPC were recorded among the three designs G1P, B2P and B4P (p>0.6) when they were designed with three axes at 90°, 45° and 0°. Moving the toric lens axis away from 90° dragged the EPC to the negative side and most of the investigated lenses with axes at 45° and 0° recorded EPCs outside the ±0.25D range. CONCLUSIONS In all cases, the shape of the cornea had a more dominant effect on EPC when compared to the peripheral zone design. Corneal shape influences the soft toric contact lens's on-eye power change more than the lens design.
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Affiliation(s)
- Tamsin Doll
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
| | - Joshua Moore
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
- Department of Mathematical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Ahmad H. Shihab
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
- School of Engineering, University of Hertfordshire, Hatfield, United Kingdom
| | - Bernardo T. Lopes
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
- Department of Ophthalmology, Federal University of Sao Paulo, Sao Paulo, Brazil
| | - Ashkan Eliasy
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
| | - Osama Maklad
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
| | - Richard Wu
- Department of Optometry, Central Taiwan University of Science and Technology, Taichung, Taiwan
- College of Optometry, Pacific University, Forest Grove, Oregon, United States of America
| | - Lynn White
- Ultravision CLPL, Leighton Buzzard, United Kingdom
| | - Steve Jones
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
| | - Ahmed Elsheikh
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
- School of Biological Science and Biomedical Engineering, Beihang University, Beijing, China
- National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, United Kingdom
| | - Ahmed Abass
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
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Moore J, Shu X, Lopes BT, Wu R, Abass A. Limbus misrepresentation in parametric eye models. PLoS One 2020; 15:e0236096. [PMID: 32970690 PMCID: PMC7514007 DOI: 10.1371/journal.pone.0236096] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 06/29/2020] [Indexed: 11/20/2022] Open
Abstract
Purpose To assess the axial, radial and tangential limbus position misrepresentation when parametric models are used to represent the cornea and the sclera. Methods This retrospective study included 135 subjects aged 22 to 65 years (36.5 mean ±9.8 STD), 71 females and 64 males. Topography measurements were taken using an Eye Surface Profiler topographer and processed by a custom-built MATLAB code. Eye surfaces were freed from edge-effect artefacts and fitted to spherical, conic and biconic models. Results When comparing the radial position of the limbus, average errors of -0.83±0.19mm, -0.76±0.20mm and -0.69±0.20mm were observed within the right eye population for the spherical, conic and biconic models fitted up to 5mm. For the same fitting radius, the average fitting errors were -0.86±0.23mm, -0.78±0.23mm and -0.73±0.23mm for the spherical, conic and biconic models respectively within the left eye population. For the whole cornea fit, the average errors were -0.27±0.12mm and -0.28±0.13mm for the spherical models, -0.02±0.29mm and -0.05±0.27mm for the conic models, and -0.22±0.16mm and 0.24±0.17mm for the biconic models in the right and left eye populations respectively. Conclusions Through the use of spherical, conic and biconic parametric modelling methods, the eye’s limbus is being mislocated. Additionally, it is evident that the magnitude of fitting error associated with the sclera may be propagating through the other components of the eye. This suggests that a corneal nonparametric model may be necessary to improve the representation of the limbus.
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Affiliation(s)
- Joshua Moore
- Department of Mathematical Sciences, University of Liverpool, Liverpool, United Kingdom
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
| | - Xuhan Shu
- College of Physical Sciences, University of Guelph, Guelph, Canada
| | - Bernardo T. Lopes
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
- Department of Ophthalmology, Federal University of Sao Paulo, Sao Paulo, Brazil
| | - Richard Wu
- Department of Optometry, Central Taiwan University of Science and Technology, Taichung, Taiwan
- College of Optometry, Pacific University, Forest Grove, Oregon, United States of America
| | - Ahmed Abass
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
- * E-mail:
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Dogra A, Kaur K, Ali J, Baboota S, Narang RS, Narang JK. Nanoformulations for Ocular Delivery of Drugs - A Patent Perspective. ACTA ACUST UNITED AC 2020; 13:255-272. [PMID: 31985387 DOI: 10.2174/1872211314666200127101149] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 11/05/2019] [Accepted: 12/09/2019] [Indexed: 01/29/2023]
Abstract
Efficient delivery of ocular therapeutics with improved efficacy, enhanced bioavailability, and acceptable patient compliance presents unique challenges. This can be attributed to the presence of protective mechanisms, physicobiological barriers, and structural obstacles in the eye. Nanotherapeutic interventions have been explored extensively over the past few years to overcome these limitations. The present review focusses on the nanoformulations developed for the diagnosis and treatment of various ocular diseases besides providing an in-depth insight into the patents reported for the same.
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Affiliation(s)
- Anmol Dogra
- Department of Pharmaceutics, Khalsa College of Pharmacy, Amritsar, Punjab-143001, India
| | - Kuljeet Kaur
- Department of Pharmaceutics, Khalsa College of Pharmacy, Amritsar, Punjab-143001, India
| | - Javed Ali
- Department of Pharmaceutics, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi-110062, India
| | - Sanjula Baboota
- Department of Pharmaceutics, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi-110062, India
| | - Ramandeep Singh Narang
- Department of Oral & Maxillofacial Pathology and Microbiology, Sri Guru Ram Das Institute of Dental Sciences and Research, Amritsar, Punjab-143001, India
| | - Jasjeet Kaur Narang
- Department of Pharmaceutics, Khalsa College of Pharmacy, Amritsar, Punjab-143001, India
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Hashmani N, Hashmani S, Murad A, Asghar N, Islam M. Effect of Demographic Variables on the Regional Corneal Pachymetry. Asia Pac J Ophthalmol (Phila) 2019; 8:324-329. [PMID: 31356367 PMCID: PMC6727915 DOI: 10.1097/apo.0000000000000252] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Accepted: 04/20/2019] [Indexed: 11/25/2022] Open
Abstract
PURPOSE The measurement of corneal thickness by corneal pachymetry provides valuable information in the setting of corneal disease; however, spectral-domain optical coherence tomography (SD-OCT)-based assessment of different corneal sectors has been scarce in Pakistan. DESIGN We aimed to obtain a whole-corneal thickness map using SD-OCT and to evaluate its correlation with age, sex, and axial length. METHODS Our study included 214 subjects with healthy corneas; each eye was scanned with an SD-OCT covering a 9-mm diameter, and reproducibility was evaluated in a subset of 50 participants by means of an identical scan protocol repeated by 2 different OCT operators. RESULTS Our analysis revealed corneal thickness to be thinnest inferotemporally whereas thickest in the superior and superonasal quadrants. No statistically significant differences could be detected between male and female participants with respect to corneal thickness, age, intraocular pressure, axial length, and refractive errors. However, we identified a significant negative correlation between age and corneal thickness in all corneal sections, excluding the inner and middle superior, inner superonasal, and inner and middle superotemporal quadrants. Conversely, the correlation between axial length and corneal thickness was found to be positive in the central region (P = 0.03, R = 0.149), the outer inferotemporal quadrant (P = 0.012, R = 0.171), throughout the temporal quadrant (P = 0.024, R = 0.154 for inner; P = 0.025, R = 0.153 for middle; P = 0.006, R = 0.186 for outer), and in the inner superotemporal quadrant (P = 0.018, R = 0.162). CONCLUSIONS Different corneal sectors may interact heterogeneously with patient-related characteristics. This may provide incentive to evaluate whole-corneal thickness as a distinct parameter for clinical identification of disease processes.
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Affiliation(s)
- Nauman Hashmani
- Department of Ophthalmology and Visual Sciences, Hashmanis Hospital, Karachi, Pakistan
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Rampersad N, Hansraj R. Distribution of corneal thickness measured using optical coherence tomography in South African young adults. AFRICAN VISION AND EYE HEALTH 2019. [DOI: 10.4102/aveh.v78i1.467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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Wang BH, Xu YS, Xie WJ, Yao YF. Effects of corneal thickness distribution and apex position on postoperative refractive status after full-bed deep anterior lamellar keratoplasty. J Zhejiang Univ Sci B 2019; 19:863-870. [PMID: 30387336 DOI: 10.1631/jzus.b1800230] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE To investigate the effects of corneal thickness distribution and apex position on postoperative refractive status after full-bed deep anterior lamellar keratoplasty (FBDALK). METHODS This is a retrospective analysis of patients who were diagnosed with advanced keratoconus between 2011 and 2014 in our hospital. The base of the cone in all patients did not exceed the central cornea at a 6-mm range. The FBDALK was performed by a same surgeon. All patients had a complete corneal suture removal and the follow-up records were intact. Patients who had graft-bed misalignment or who were complicated with a cataract or glaucoma were excluded. Uncorrected visual acuity (UCVA), best spectacle corrected visual acuity (BSCVA), and Pentacam examination data were recorded at two years postoperatively. The recorded data included the superior-inferior (S-I) and nasal-temporal (N-T) corneal thickness differences in 2, 4, 6, and 8 mm diameter concentric circles with the corneal apex as the center (S-I2 mm, S-I4 mm, S-I6 mm, S-I8 mm, N-T2 mm, N-T4 mm, N-T6 mm, and N-T8 mm), the linear, X-axis, and Y-axis distance between the corneal pupillary center and the cornea apex, total corneal astigmatism at a zone of 3 mm diameter from the corneal apex (TA3 mm), the astigmatic vector values J0 and J45, and the corneal total higher-order aberration for 3 and 6 mm pupil diameters (HOA3 mm and HOA6 mm). Statistical analysis was performed by SPSS 15.0. RESULTS A total of 47 eyes of 46 patients met the criteria and were included in this study. The mean follow-up time was (28±7) months. The mean UCVA was 0.45±0.23 (logMAR) (MAR: minimum angle of resolution) and the mean BSCVA was 0.19±0.15 (logMAR), which were all significantly positively correlated with postoperative TA3 mm and HOA3 mm. The mean S-I corneal thickness differences were (44.62±37.74) μm, and the mean N-T was (38.57±32.29) μm. S-I2 mm was significantly positively correlated with J0 (r=0.31), J45 (r=0.42), HOA3 mm (r=0.37), and HOA6 mm (r=0.48). S-I4 mm and S-I8 mm were significantly positively correlated with HOA3 mm (r=0.30, r=0.40) and HOA6 mm (r=0.46, r=0.35). The X-axis distance between corneal pupillary center and corneal apex was significantly positively correlated with J45 (r=0.29). CONCLUSIONS In patients with advanced keratoconus after FBDALK, the unevenly distributed thickness at corneal pupillary area and the misalignment of corneal apex and pupillary center might cause significant regular and irregular astigmatism, which affected the postoperative visual quality.
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Affiliation(s)
- Bing-Hong Wang
- Department of Ophthalmology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310016, China
| | - Ye-Sheng Xu
- Department of Ophthalmology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310016, China
| | - Wen-Jia Xie
- Department of Ophthalmology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310016, China
| | - Yu-Feng Yao
- Department of Ophthalmology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310016, China
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Cagini C, Di Lascio G, Messina M, Riccitelli F, Dua HS. Correlation of central and peripheral keratometric parameters after corneal collagen cross-linking in keratoconus patients. Int Ophthalmol 2018; 39:2041-2048. [PMID: 30421316 DOI: 10.1007/s10792-018-1041-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 11/07/2018] [Indexed: 02/06/2023]
Abstract
PURPOSE To evaluate the difference in the central and peripheral keratometric parameters in patients with keratoconus after corneal collagen cross-linking (CXL). METHODS Forty-eight eyes of 32 patients (18 males, 16-28 years) affected by progressive keratoconus in different stages of evolution underwent CXL using the standard epithelium-off protocol. Corneal thickness and corneal curvature before CXL and after 6 and 12 months using the Sirius tomographer were analyzed. The values of the mean corneal thickness at the corneal apex (CAT), center of the pupil (PCT), thinnest point (CTTL) and along concentric circles of 2, 4, 6, 8, 8.5, 9, 9.5 and 10 mm diameter were evaluated; the values of the mean curvature at the corneal apex and at the points in which the inferior, superior, nasal and temporal meridians crossed the above-mentioned concentric circles were also evaluated. RESULTS The mean preoperative values for CAT, PCT and CTTL were 461.4 ± 30.3, 475.3 ± 30.5 and 441 ± 32.0, respectively. The values after 12 months of CXL were 444.6 ± 36.2, 451.6 ± 36.7 and 418.2 ± 41.4. The peripheral corneal thickness at the eight points ranged from 479 to 733 preoperatively. At 12-month post-CXL, the values ranged from 444.6 to 734.1. The mean posterior curvature from apex to periphery ranged from - 4.5 to - 9.1 days preoperatively and from - 4.5 to - 9.2 days at 12 months. These were not statistically significant (ANOVA and unpaired T test). CONCLUSIONS Our data suggest that CXL over an 8-mm zone can stabilize the peripheral cornea. Longer-term follow-up studies on the peripheral cornea after CXL will provide useful information.
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Affiliation(s)
- C Cagini
- Ophthalmology Section, Department of Biomedical and Surgical Sciences, S. Maria della Misericordia Hospital, University of Perugia, Piazza Menghini 1, S. Andrea delle Fratte, 06156, Perugia, Italy.
| | - G Di Lascio
- Ophthalmology Section, Department of Biomedical and Surgical Sciences, S. Maria della Misericordia Hospital, University of Perugia, Piazza Menghini 1, S. Andrea delle Fratte, 06156, Perugia, Italy
| | - M Messina
- Ophthalmology Section, Department of Biomedical and Surgical Sciences, S. Maria della Misericordia Hospital, University of Perugia, Piazza Menghini 1, S. Andrea delle Fratte, 06156, Perugia, Italy
- Section of Academic Ophthalmology, Division of Clinical Neuroscience, Nottingham University Hospitals NHS Trust, University of Nottingham, Nottingham, UK
| | - F Riccitelli
- Ophthalmology Section, Department of Biomedical and Surgical Sciences, S. Maria della Misericordia Hospital, University of Perugia, Piazza Menghini 1, S. Andrea delle Fratte, 06156, Perugia, Italy
| | - H S Dua
- Section of Academic Ophthalmology, Division of Clinical Neuroscience, Nottingham University Hospitals NHS Trust, University of Nottingham, Nottingham, UK
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Abstract
Important functions of cornea in the eye include protecting the structures inside the eye, contributing to the refractive power of the eye, and focusing light rays on the retina with minimum scatter and optical degradation. Considerable advances have taken place in understanding the organization of collagen in the corneal stroma and its clinical significance. In this review, the structure and function of various components of cornea and ocular surface are presented.
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Affiliation(s)
- Mittanamalli S Sridhar
- Department of Ophthalmology, Krishna Institute of Medical Sciences, Hyderabad, Telangana, India
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Aberrant ocular architecture and function in patients with Klinefelter syndrome. Sci Rep 2017; 7:13130. [PMID: 29030589 PMCID: PMC5640645 DOI: 10.1038/s41598-017-13528-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 09/25/2017] [Indexed: 11/25/2022] Open
Abstract
Klinefelter Syndrome (KS), the most common chromosomal disorder in men (47,XXY), is associated with numerous comorbidities. Based on a number of isolated case reports, we performed the first systematic and comprehensive evaluation of eye health in KS patients with a focus on ocular structure and vascularization. Twenty-one KS patients and 26 male and 38 female controls underwent a variety of non-invasive examinations investigating ocular morphology (examination of retinal thickness, optic nerve head, and cornea) and function (visual field testing and quantification of ocular vessel density by optical coherence tomography angiography). In comparison to healthy controls, KS patients exhibited a smaller foveal avascular zone and a decreased retinal thickness due to a drastically thinner outer nuclear layer. The cornea of KS patients showed a decreased peripheral thickness and volume. In perimetry evaluation, KS patients required brighter stimuli and gave more irregular values. KS patients show an ocular phenotype including morphological and functional features, which is very likely caused by the supernumerary X chromosome. Thus, KS should not be limited to infertility, endocrine dysfunction, neurocognitive and psychosocial comorbidities. Defining an aberrant ocular morphology and function, awareness for possible eye problems should be raised.
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Abstract
PURPOSE To evaluate the corneal horizontal diameter [white-to-white (WTW) distance] as a factor influencing surgically induced astigmatism (SIA) and postoperative astigmatism. METHODS A total of 330 eyes with corneal astigmatism ≤1.5 D underwent cataract surgery with phacoemulsification. A 3-step, superotemporal for the right eye and superonasal for the left eye, clear corneal incision of 3.0 mm was made. Four groups were created according to WTW distance: group A ≤11.6 mm, group B 11.7 to 11.9 mm, group C 12.0 to 12.2 mm, and group D ≥12.3 mm. SIA was calculated by vector analysis using the Alpins method. We noted all cases, in which a change greater than 0.5 diopters (D) in astigmatism took place and a change greater than 20 degrees in axis torque, despite axis direction, on the first and sixth postoperative months. RESULTS SIA was found in group A 0.98 D ± 0.6 (SD), B 0.79 D ± 0.43 (SD), C 0.68 D ± 0.45 (SD), and D 0.53 D ± 0.32 (SD) at the first postoperative month. At the sixth postoperative month, SIA was 0.77 D ± 0.43 (SD), 0.69 D ± 0.34 (SD), 0.62 ± 0.36 (SD), and 0.49 D ± 0.27 (SD), respectively. A change greater than 0.5 D in corneal astigmatic power at the first and sixth months postoperatively was significantly lower in eyes with WTW distance 12.0 to 12.2 mm and ≥12.3 mm in comparison with eyes with WTW distance ≤11.6 mm and 11.7 to 11.9 mm (P < 0.05). Changes greater than 20 degrees in astigmatic axis at the first and sixth postoperative months were not significantly different according to the horizontal corneal diameter. CONCLUSIONS WTW distance should always be measured preoperatively when planning cataract surgery and should be accounted for in cases of large and small corneas.
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Rampersad N, Hansraj R. A review of African studies on central corneal thickness. AFRICAN VISION AND EYE HEALTH 2016. [DOI: 10.4102/aveh.v75i1.341] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Recently, there has been increasing interest in understanding central corneal thickness (CCT) measurements in various populations. This may be related to the influence of CCT in the diagnosis, classification and management of glaucoma. In addition, CCT measurements are also important for monitoring corneal diseases and contact lens wear, indicating the overall health of the cornea and assessing eligibility for refractive surgery. This article reviews studies that have reported CCT measurements in non-glaucomatous African sub-populations. The CCT measurements, gender associations and limitations of these studies are highlighted. The findings of these studies and their implications are discussed in relation to global studies reporting on CCT measurements.
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Pattmöller J, Wang J, Zemova E, Seitz B, Eppig T, Langenbucher A, Szentmáry N. Correlation of corneal thickness, endothelial cell density and anterior chamber depth with ocular surface temperature in normal subjects. Z Med Phys 2015; 25:243-50. [DOI: 10.1016/j.zemedi.2014.09.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 09/10/2014] [Accepted: 09/16/2014] [Indexed: 10/24/2022]
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Theodoulidou S, Asproudis I, Kalogeropoulos C, Athanasiadis A, Aspiotis M. The role of sideport incision in astigmatism change after cataract surgery. Clin Ophthalmol 2015; 9:1421-8. [PMID: 26346741 PMCID: PMC4531009 DOI: 10.2147/opth.s86213] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
PURPOSE To study the changes in corneal astigmatism after cataract surgery when the sideport incision is performed at a predetermined location away from the tunnel incision. SETTING General Hospital of Piraeus "Tzaneio", Attiki, Greece. MATERIALS AND METHODS A total of 333 eyes with corneal astigmatism ≤1.5 diopters (D) underwent cataract surgery. A three-step superotemporal clear corneal incision for the right eye and a superonasal clear corneal incision for the left eye (3.0 mm) was made, while the sideport incision was located at <90°, 90°-110°, and >110°. Keratometric data were measured with corneal topography EyeSys Vista 2000 pre- and postoperatively at the 1st and 6th month. Surgically induced astigmatism was calculated by vector analysis. We noted all cases in which a change >0.5 D in corneal astigmatic power occurred, as well as a change >20° in axis torque, despite axis direction. RESULTS After multiple logistic regression analysis was conducted, cases with >110° distance between the tunnel and sideport incision had 2.22 times (P=0.021) greater likelihood for having changed >0.5 D in astigmatic power at the 1st month and 3.45 times (P=0.031) at the 6th month postoperatively, as compared with cases with a 90°-110° distance between the tunnel and sideport incision. As for the change in the astigmatic axis, cases with <90° distance had a 4.18 times greater likelihood for having a change >20° (P<0.001) (preoperative to 1st month) as compared with cases having 90°-110° of distance. CONCLUSION For surgeons that operate only from the superior position, we propose that in order to produce an incision that is as "astigmatically neutral" as possible, they should perform the sideport incision at a 90°-110° distance.
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Affiliation(s)
- Sofia Theodoulidou
- Department of Ophthalmology, Medical School, University of Ioannina, Ioannina, Greece
| | - Ioannis Asproudis
- Department of Ophthalmology, Medical School, University of Ioannina, Ioannina, Greece
| | | | | | - Miltiadis Aspiotis
- Department of Ophthalmology, Medical School, University of Ioannina, Ioannina, Greece
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[Corneal power after descemet stripping automated endothelial keratoplasty (DSAEK) - Modeling and concept for calculation of intraocular lenses]. Z Med Phys 2015; 26:120-6. [PMID: 25791739 DOI: 10.1016/j.zemedi.2015.02.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 02/02/2015] [Accepted: 02/22/2015] [Indexed: 11/21/2022]
Abstract
BACKGROUND AND PURPOSE Descemet stripping automated endothelial keratoplasty (DSAEK) is an established treatment option for pathologies of the corneal endothelium. It is typically accompanied with a hyperopic shift in refraction. The purpose of this work is to predict corneal geometry after DSAEK based on model data and to present a concept how to determine corneal power, e.g. for intraocular power calculation to prevent a refractive surprise with a subsequent cataract surgery. MATERIAL AND METHODS Based on data of the Kooijman schematic model eye we simulated a microkeratome cut parallel to the corneal front surface for donor trephination to determine the radial thickness profile of the posterior corneal donor lamella. This donor lamella was tension-neutrally adapted to the back surface of the host and the profile of the cornea after DSAEK was derived and characterized by a quadric surface. Comparison with the curvature of the host without and with donor could resample hyperopic shift which was published in literature. A method was shown how to determine corneal power after DSAEK. RESULTS From the data of the Kooijman schematic model eye and the donor characteristics central / peripheral corneal thickness was increased by 150 / 250μm due to adaptation of the donor lamella. Geometry of corneal back surface showed a reduced radius of curvature (by about 0.9mm) and a change in conic constant (by about -0.13). Persistent clinically observed hyperopic shift correlates to the change in geometry of the cornea due to adaptation of the donor lamella, which reduces corneal power by 0.88 D. CONCLUSION DSAEK leads to a hyperopic shift in refraction, which can be explained by a change in corneal back surface geometry. In case of subsequent cataract surgery, the intraocular lens power should be calculated with consideration of both corneal surfaces rather than keratometry or corneal topography in order to minimize a systematic hyperopic shift due to misinterpretation of corneal power after DSAEK. In case of a Triple-DSAEK, a target refraction of -1.5 D should be chosen in order to safely prevent postoperative hyperopia.
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Jonuscheit S, Doughty MJ, Martin R, Río-Cristóbal A, Cruikshank V, Lang S. Peripheral nasal-temporal corneal asymmetry in relation to corneal thickness: a Scheimpflug imaging study. Ophthalmic Physiol Opt 2014; 35:45-51. [DOI: 10.1111/opo.12179] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 11/03/2014] [Indexed: 12/01/2022]
Affiliation(s)
- Sven Jonuscheit
- Department of Life Sciences; Glasgow Caledonian University; Glasgow UK
- Anterior Eye Research Group; Institute for Applied Health Research; Glasgow Caledonian University; Glasgow UK
- IOBA Eye Institute; Universidad de Valladolid; Valladolid Spain
| | - Michael J. Doughty
- Department of Life Sciences; Glasgow Caledonian University; Glasgow UK
- Anterior Eye Research Group; Institute for Applied Health Research; Glasgow Caledonian University; Glasgow UK
| | - Raul Martin
- Department of Life Sciences; Glasgow Caledonian University; Glasgow UK
- IOBA Eye Institute; Universidad de Valladolid; Valladolid Spain
| | | | | | - Sue Lang
- Department of Life Sciences; Glasgow Caledonian University; Glasgow UK
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Jonuscheit S. Data extraction and reporting strategies of studies assessing non-central corneal thickness by Pentacam: A review. Cont Lens Anterior Eye 2014; 37:323-30. [DOI: 10.1016/j.clae.2014.06.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Revised: 05/23/2014] [Accepted: 06/04/2014] [Indexed: 10/25/2022]
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Wu W, Wang Y, Xu L. Meta-analysis of Pentacam vs. ultrasound pachymetry in central corneal thickness measurement in normal, post-LASIK or PRK, and keratoconic or keratoconus-suspect eyes. Graefes Arch Clin Exp Ophthalmol 2013; 252:91-9. [PMID: 24218039 DOI: 10.1007/s00417-013-2502-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 10/08/2013] [Accepted: 10/10/2013] [Indexed: 10/26/2022] Open
Abstract
BACKGROUND The aim of this meta-analysis is to evaluate the central corneal thickness (CCT) measurement differences between Pentacam (Oculus Inc., Germany) and Ultrasound Pachymetry (USP) in normal (unoperated eyes , myopic and astigmatic eyes without corneal disease or topographic irregularity), after laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK), and keratoconic or keratoconus suspected eyes. We assess whether Pentacam and USP have similar CCT differences in normal, thinner corneas after LASIK or PRK procedures, and kerotoconic or keratoconus suspected eyes. METHODS Data sources, including PubMed, Medline, EMBASE, and Cochrane Central Registry of Controlled Trials on the Cochrane Library, were searched to find the relevant studies. Primary outcome measures were CCT measurement between Pentacam and USP. Three groups of eyes were analyzed: normal; LASIK or PRK eyes; and keratoconus suspected or keratoconic eyes. RESULTS Nineteen studies describing 1,908 eyes were enrolled in the normal group. Pentacam results were 1.47 μm ,95 % confidence interval (CI) -2.32 to 5.27, higher than USP without statistically significant difference (P = 0.45). Nine studies with total 539 eyes were included in the corneas after LASIK or PRK. The mean difference in the CCT measurement with Pentacam and ultrasound pachymetry was 1.03 μm, with the 95 % CI -3.36 to 5.42, there was no statistically difference (P = 0.64). Four studies with a total of 185 eyes were included in the keratoconic eyes or keratoconus-suspect group, however,the mean difference was -6.33 μm (95 % CI -9.17 to-3.49), which was statistically different between Pentacam and ultrasound pachymetry in the CCT measurement (P < 0.0001). CONCLUSIONS Pentacam offers similar CCT results to ultrasound pachymetry in normal eyes, thinner corneas after LASIK or PRK procedures. However, in keratoconic or keratoconus-suspect eyes, Pentacam slightly underestimates the central corneal thickness than does ultrasound pachymetry, which may result from the difficulty in fixation of keratoconic eyes, misalignment of Pentacam and the variation of ultrasonic velocity due to the histological deformation.
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Affiliation(s)
- Wenjing Wu
- Tianjin Eye Hospital& Eye Institute, Tianjin Ophthalmology and Visual Science Key Laboratory, Clinical College of Ophthalmology, Tianjin Medical University, No 4. Gansu Rd, Heping District, Tianjin, 300020, China
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Ahmadi Hosseini SM, Abolbashari F, Mohidin N. Anterior segment parameters in Indian young adults using the Pentacam. Int Ophthalmol 2013; 33:621-6. [PMID: 23456513 DOI: 10.1007/s10792-013-9747-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Accepted: 02/20/2013] [Indexed: 11/29/2022]
Abstract
To evaluate Pentacam-Scheimpflug imaging of anterior segment parameters in young Indian adults. In this prospective study 120 eyes of 60 normal Indian subjects with a mean age of 25.93 ± 6.58 years (range 17-39 years) were assessed by Pentacam. Main outcome measures were central corneal thickness (CCT), thinnest corneal thickness (TCT), apex corneal thickness (apex CT), peripheral corneal thickness at 2, 4, 6 and 8 mm from the thinnest point, location of the thinnest pachymetry, corneal volume (CV), anterior chamber depth (ACD), anterior chamber volume (ACV) and anterior chamber angle (ACA). Independent samples t test, dependent samples t test, ANOVA and Pearson correlation test were used for statistical analysis. The mean CCT, TCT, Apex CT and CV were 544.95 ± 35.42, 542 ± 35.19, 545.43 ± 35.45 and 61.64 ± 4.17 μm, respectively. There was a gradual increase in CT from the thinnest point to the periphery. The mean ACD was 3.14 ± 0.33 mm, mean ACV was 177.77 ± 29.02 mm(3), and mean ACA was 39.36° ± 5.42°. There was no significant difference between CCT, TCT and Apex CT. A significant positive correlation was found between CCT and peripheral CT and also between anterior chamber parameters. TCT was mainly located in the inferotemporal and superotemporal zone. No significant difference was found in parameters between the right and left eyes and also between genders. This study provided information about a wide range of parameters in the anterior segment of healthy Indian eyes. These results could be helpful in assessment of patients with corneal diseases, glaucoma and screening for refractive surgeries.
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Affiliation(s)
- Seyed Mahdi Ahmadi Hosseini
- Refractive Errors Research Center, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran,
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Ursea R, Feng M, Urs R, RoyChoudhury A, Silverman RH. Comparison of artemis 2 ultrasound and Visante optical coherence tomography corneal thickness profiles. J Refract Surg 2012. [PMID: 23205905 DOI: 10.3928/1081597x-20121126-01] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To compare corneal thickness profiles of cross-sections of cornea determined by arc-scanned immersion ultrasound and optical coherence tomography (OCT). METHODS Corneas of 28 eyes from 14 participants were scanned in triplicate using the Artemis 2 high-frequency arc-scanned ultrasound system (ArcScan Inc) and the Visante OCT system (Carl Zeiss Meditec). Corneal thickness and reproducibility were compared within 3.5 mm of central cornea in the horizontal plane. RESULTS Although highly correlated, Visante central and peripheral corneal thickness values were systematically thinner than Artemis 2 values. Within the central 0.5 mm, the difference was approximately 8 μm, but the difference increased with distance from the center. Reproducibility for each instrument was comparable, measuring <4 μm centrally and increasing peripherally. CONCLUSIONS Visante OCT measurements of corneal thickness are thinner than Artemis 2 ultrasound values centrally with an increasing difference with peripheral position. Measurement reproducibility was comparable for the two techniques.
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Affiliation(s)
- Roxana Ursea
- Department of Opthalmology and Vision Science, University of Arizona, Tucson, AZ, USA
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Fares U, Otri AM, Al-Aqaba MA, Faraj L, Dua HS. Wavefront-optimized excimer laser in situ keratomileusis for myopia and myopic astigmatism: refractive outcomes and corneal densitometry. J Cataract Refract Surg 2012; 38:2131-8. [PMID: 23084157 DOI: 10.1016/j.jcrs.2012.07.041] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Revised: 07/17/2012] [Accepted: 07/31/2012] [Indexed: 10/27/2022]
Abstract
PURPOSE To determine the refractive outcomes of wavefront-optimized laser in situ keratomileusis (LASIK) treatments, in particular to measure corneal densitometry after LASIK using the densitometry function of the Pentacam Scheimpflug system. SETTING Division of Ophthalmology and Visual Sciences, University of Nottingham, United Kingdom. DESIGN Cohort study. METHODS Changes in postoperative visual acuity, refraction, and contrast sensitivity were evaluated after wavefront-optimized laser treatment. Corneal densitometry was evaluated with the Scheimpflug system before and after LASIK. RESULTS One year postoperatively, the uncorrected distance visual acuity was 6/6 or better in 92% of eyes and 6/9 or better in all eyes. Eighty-six percent of eyes had no change in the corrected distance visual acuity (CDVA); 4% gained 1 or more lines. Wavefront-optimized LASIK was stable over 1 year postoperatively. Eighty-nine percent of eyes were within ±0.50 diopter (D) and 100% were within ±1.00 D of the intended correction 1 year postoperatively. Contrast sensitivity showed a nonsignificant improvement (1.55 ± 0.10 [SD] preoperatively to 1.57 ± 0.09 12 months postoperatively) (P > .05). There was a nonsignificant increase in corneal densitometry 1 year postoperatively (from 12.72 ± 2.43 to 13.04 ± 2.58) (P > .05). No correlation was found between corneal densitometry and contrast sensitivity or CDVA. CONCLUSIONS Wavefront-optimized LASIK gave excellent refractive and visual outcomes and did not seem to affect corneal densitometry significantly 1 year postoperatively. However, larger studies may show a masked effect on corneal densitometry. FINANCIAL DISCLOSURE No author has a financial or proprietary interest in any material or method mentioned.
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Affiliation(s)
- Usama Fares
- Division of Ophthalmology and Visual Sciences, University of Nottingham, Nottingham, United Kingdom
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