Standardizing the Yamane flanged intrascleral haptic fixation: A framework for efficacy, complication mitigation, and reproducible training

Abstract

The Yamane technique for flanged intrascleral haptic fixation has emerged as a pivotal sutureless method for scleral fixation of a posterior chamber intraocular lens (IOL) in the absence of capsular support. This methodological review provides a technically oriented, stepwise description of the Yamane technique, emphasizing critical procedural nuances and evidence-based refinements that influence surgical control to achieve proper, long-term lens fixation. Key steps are consolidated from the original descriptions and subsequent mechanical studies evaluating haptic behavior, needle-haptic compatibility, tunnel geometry, and IOL centration. Surgical parameters—including needle gauge selection, bevel orientation, entry angle relative to the limbus, symmetric scleral tunnel creation, tunnel length, controlled haptic externalization, and flange formation—are reviewed in relation to postoperative lens position and stability. Comparative studies of the Yamane technique and those utilizing suture-based fixation techniques suggest broadly comparable refractive stability and a potentially favorable mechanical complication profile. However, variability across studies and the absence of long-term randomized controlled trial data warrant cautious interpretation. The methodological framework presented consolidates current evidence and technical refinements of the Yamane technique. Standardizing the key procedural steps of this technique is essential to enhance reproducibility, minimize avoidable complications, and improve the ability to compare outcomes across clinical studies.

Key Words: Yamane technique; Scleral fixation; Intrascleral fixation; Secondary intraocular lens implantation; Cataract surgery methods; Surgical efficiency; Surgical training; Cost-effectiveness

Core Tip: The Yamane technique is a sutureless approach for scleral fixation of secondary intraocular lenses based on symmetric intrascleral haptic fixation anchored by terminal flange formation. This review addresses technical factors that directly influence fixation stability, including needle gauge selection, bevel orientation, scleral tunnel length and angulation, haptic externalization, and flange sizing. By linking mechanical principles with clinical experience, a practical methodological framework is proposed to reduce tilt, promote centration, and avoid postoperative slippage, while improving reproducibility in both surgical training and clinical research.

INTRODUCTION

The development of the Yamane flanged intrascleral haptic fixation technique represents a major advance as a sutureless method for scleral fixation of a posterior chamber intraocular lens (IOL) in the absence of capsular support. The initial needle-guided concept and its subsequent flanged modification have drawn attention to its advantages including smaller incisions and reduced manipulation of ocular tissues in secondary IOL implantation cases[1,2]. This sutureless approach relies on a 27-gauge, double-needle guided method with flanged haptic formation to achieve scleral fixation[3-5].

Fixation of IOLs is often challenging in eyes that lack adequate capsular support. Angle-supported, anterior chamber IOLs risk endothelial cell loss, corneal edema, or bullous keratopathy, and may cause secondary glaucoma (pupillary-block, pigment dispersion, uveitis-glaucoma-hyphema syndrome, peripheral anterior synechiae) and cystoid macular edema (CME)[6,7]. Traditional suture-based techniques for secondary IOL implantation risk complications from knot exposure, chronic inflammation, CME, and late suture degradation or breakage leading to lens dislocation[8]. Comparative meta-analyses suggest broadly similar long-term visual outcomes and complication rates relative to sutured scleral fixation. Surgical time and early visual recovery may be more favorable with the Yamane approach, though study heterogeneity warrants cautious interpretation[5].

Although widely adopted since its introduction in 2014[1], procedural differences exist that may influence long-term IOL stability and alignment. This variability across studies highlights the need for a unified methodological framework. Experimental and cadaveric studies illustrate that variations in scleral tunnel length, needle angulation, and needle-haptic compatibility significantly impact postoperative lens centration, tilt, and axial stability. Despite its popularity, there is considerable variability in how key procedural steps—such as scleral tunnel creation, haptic externalization, and flange formation—are performed and reported, which limits reproducibility and complicates comparisons across studies[9]. Systematic reviews and meta-analyses confirm this heterogeneity and emphasize the need for standardized surgical protocols and reporting to improve consistency and outcomes[5,10]. Importantly, the decision to perform concurrent pars plana vitrectomy (PPV) or anterior vitrectomy prior to IOL fixation represents a critical surgical consideration that influences both intraoperative safety and postoperative outcomes[11,12]. This review provides a structured methodological framework for the Yamane technique, incorporating evidence-based refinements to enhance surgical control and standardization. The aim of this review is not to propose a new surgical method, but to identify technical steps that should be performed and variables reported to improve consistency and reproducibility of the technique, standardize training, and allow for comparison across studies.

Indications and clinical context

The Yamane technique is primarily indicated for secondary IOL implantation in eyes lacking sufficient capsular support, such as after complicated cataract surgery resulting in aphakia (Table 1). This technique offers a sutureless and minimally invasive method for stable posterior chamber IOL fixation[4,6-8]. In cases of late dislocation of an in-the-bag IOL-capsular bag complex, often because of progressive zonular weakness, the Yamane technique provides secure secondary IOL fixation independent of any residual capsular structures[5]. For traumatic lens loss where capsular remnants are absent or unstable, the technique allows controlled posterior chamber IOL placement with minimal additional tissue manipulation and has demonstrated safety and efficacy in trauma cases[11]. Finally, IOL explantation due to opacification or malposition may leave the eye aphakic with compromised capsular integrity, rendering standard fixation options unsuitable. In these cases, the Yamane technique enables stable secondary fixation[4,5].

Table 1 Clinical indications for the Yamane scleral-fixated intraocular lens technique.

Category	Clinical indication	Surgical context	Typical etiology
Aphakia	Aphakia after complicated cataract surgery	Insufficient capsular support prevents standard in-the-bag implantation; Yamane fixation allows stable posterior chamber IOL placement without sutures	Posterior capsule rupture, zonular dialysis
IOL-capsular bag complex instability	Late dislocation of in-the-bag IOL-capsular bag complex	Progressive zonular weakness leads to displacement of the entire complex; fixation independent of residual capsule is required	Pseudoexfoliation syndrome, zonulopathy, high myopia, aging
Trauma	Traumatic lens loss or unstable capsular remnants	Loss of crystalline lens or unstable capsule makes conventional fixation unreliable; Yamane technique permits controlled posterior chamber positioning	Ocular trauma
Secondary aphakia	Aphakia after IOL explantation	Removal of opacified or malpositioned IOL may leave insufficient capsular support; Yamane fixation enables secure secondary implantation	IOL opacification, malposition, prior surgical complications
Post surgical	Vitreoretinal surgery/PPV complications	Capsular instability after pars plana vitrectomy	Compromised capsular integrity

IOL: Intraocular lens; PPV: Pars plana vitrectomy.

The procedure requires minimal conjunctival manipulation, preserving conjunctival integrity and making it especially suitable for eyes with prior ocular surgery, scarring, or limited conjunctival mobility[8]. Its emphasis on preserving conjunctival integrity is especially important, as eyes that require scleral fixation of IOLs may later need glaucoma surgery—particularly implantation of glaucoma drainage devices—which depends on maintaining healthy, intact conjunctiva[3].

The Yamane technique allows posterior chamber IOL placement, which more closely approximates the physiological position of the native crystalline lens. This posterior positioning reduces risks associated with iris-fixated IOLs, such as chronic iris irritation, pigment dispersion, uveitis, and secondary glaucoma caused by prolonged contact between the IOL and iris tissue[3,13]. Additionally, posterior chamber placement minimizes anterior chamber crowding, lowering the likelihood of pupillary capture and endothelial cell loss—complications more common with anteriorly positioned lenses[1,3].

Patient selection is critical; adequate scleral thickness and integrity are necessary for stable intrascleral tunnel creation and haptic fixation, while eyes with severe scleral thinning, active inflammation, or extensive conjunctival scarring may not be ideal candidates[4]. In eyes with vitreous prolapse, dropped nucleus, dislocated IOL into the vitreous cavity, or incomplete prior vitrectomy, anterior vitrectomy or PPV should be strongly considered prior to Yamane fixation to reduce the risk of vitreous traction, CME, and retinal detachment[11,12].

Limited reports have described the use of the Yamane flanged intrascleral fixation technique in pediatric or adolescent patients with conditions such as ectopia lentis, traumatic aphakia, or hereditary connective tissue disorders including Marfan syndrome. In these cases, the sutureless nature of the technique may offer a potential advantage by avoiding long-term suture degradation, which is a known limitation of sutured scleral fixation in younger patients with long life expectancy. However, pediatric eyes present unique anatomical considerations, including thinner sclera, stronger vitreoretinal adhesion, and ongoing ocular growth, all of which may influence long-term IOL stability and refractive outcomes. For this reason, careful patient selection and thorough vitreous management are recommended when considering the Yamane technique in younger individuals. Current evidence remains limited to small case series and retrospective reports, and further studies are needed to better define long-term safety and refractive stability in pediatric populations. Given this limited evidence base, the Yamane technique should not be considered standard of care in pediatric patients, and its use in this population requires careful case-by-case judgment by experienced surgeons[14-16].

METHODOLOGICAL CONSIDERATIONS

Literature search and review methodology

This manuscript was prepared as an expert-informed focused review of the Yamane flanged intrascleral fixation technique. A targeted literature search was performed using PubMed/MEDLINE, Scopus, and Web of Science for studies published from 2014 onward, corresponding to the original description of the technique. The literature search and review process was conducted between January and March 2026. Search terms included “Yamane technique”, “flanged intrascleral fixation”, “scleral-fixated intraocular lens”, “secondary intraocular lens implantation”, “30-gauge needle”, and related terms. Original studies, case series, technical reports, cadaveric or experimental studies, and relevant reviews addressing surgical technique, outcomes, complications, or methodological refinements were considered (Table 2). Duplicate entries, articles written in languages other than English, and publications that were unrelated or not pertinent to the topic were excluded. Relevant studies from the bibliographies were also included in the review. Because the aim of this article was to provide a practical methodological synthesis rather than a formal quantitative systematic review, PRISMA methodology was not applied.

Table 2 Summary of key studies informing the methodological recommendations.

Ref.	Study design	n	Key outcomes/findings	Notable limitations/risk of bias	Role in this review
Yamane et al[1], 2014	Prospective case series	14 eyes	Original description of flanged ISHF; demonstrated secure scleral fixation without sutures	Very small sample; single surgeon; no comparative control group; short follow-up	Foundational technique description
Yamane et al[2], 2017	Prospective case series	100 eyes	Flanged modification introduced; strong centration results; low dislocation rate	Single center; single surgeon; no randomization; retrospective outcome assessment	Primary clinical validation
Stem et al[9], 2019	Retrospective case series	55 eyes	Learning curve analysis; improved outcomes with increasing surgical experience	Retrospective; small sample; variable follow-up; potential selection bias	Learning curve and training
Rocke et al[4], 2020	Retrospective case series	112 eyes	Tunnel geometry analysis; IOL stability data; CT Lucia PVDF haptic outcomes	Retrospective; heterogeneous surgical technique across cases; variable follow-up	Tunnel geometry & IOL stability
Schranz et al[11], 2023	Comparative retrospective study	78 eyes	AR40e vs CT Lucia outcomes; haptic behavior and flange formation comparison	Retrospective; limited long-term follow-up; single center; small groups	IOL model comparison
Zhang et al[5], 2024	Systematic review & meta-analysis	1847 eyes (pooled)	Pooled CME rate approximately 13%-14%; favorable visual outcomes; shorter OR time vs sutured fixation	High heterogeneity across included studies; retrospective designs dominate; variable definitions of complications	Broadest comparative evidence
LoBue et al[17], 2024	Bench/cadaveric experimental study	Ex vivo (4 IOL models)	Haptic tensile strength: CT Lucia 153 N > MA60AC 1.00 N > AR40e 087 N > LAL 0.83 N	Non-clinical; ex vivo findings may not fully predict in vivo behavior; limited generalizability	Haptic material & tensile strength

Studies are listed chronologically. CME: Cystoid macular edema; IOL: Intraocular lens; ISHF: Intrascleral haptic fixation; PVDF: Polyvinylidene fluoride; PMMA: Polymethylmethacrylate; LAL: Light-adjustable lens; OR: Operating room.

IOL power calculation

Compared with conventional in-the-bag implantation, selecting the appropriate IOL power for secondary scleral-fixated lenses presents unique challenges. The absence of capsular support alters the effective lens position, and variability in surgical technique—particularly haptic externalization length and optic centration—can influence postoperative refraction[10]. Despite these challenges, modern biometry and formula selection can yield predictable refractive outcomes when methodological factors are carefully controlled.

The commonly used formulas for scleral-fixated IOLs include the SRK/T, Haigis, Hoffer Q, and Holladay formulas, with recent attention to newer-generation formulas such as Barrett Universal II and Kane. Studies evaluating refractive predictability in cases using versions of this procedure have reported comparable accuracy to sutured scleral fixation, with mean absolute errors generally within 0.5-1.0 diopters when appropriate A-constants or lens constants are used[4,5,10]. Selection of formula may depend on axial length, with Haigis and Barrett formulas often favored in eyes with extreme axial lengths due to their incorporation of anterior chamber depth as a variable[4,10].

A critical consideration is the use of an appropriate A-constant, or lens-specific constant optimized for scleral fixation. Standard A-constants derived from in-the-bag positioning may overestimate or underestimate the effective lens position in scleral-fixated cases. Some investigators have proposed adjusted constants specific to the Yamane technique, though consensus values have not been universally established. Surgeons are encouraged to track their own postoperative refractive outcomes and optimize constants based on institutional experience[4,5,10]. Axial length measurement remains foundational for selecting the optimal lens power, with optical biometry preferred when media clarity permits [e.g., using the IOLMaster 700 (Carl Zeiss Meditec AG, Jena, Germany) or Lenstar LS 900 (Haag-Streit AG, Köniz, Switzerland)]. In eyes with dense cataracts, vitreous hemorrhage, or other media opacities, immersion B-scan ultrasound provides a reliable alternative, though operator-dependent variation in these measurements is higher compared with automated optical biometers. Keratometry should be obtained preoperatively, recognizing that irregular astigmatism or prior corneal surgery may complicate interpretation[4,10].

Anterior chamber depth measurement has additional relevance in scleral fixation cases. A shallow anterior chamber or narrow angle anatomy may influence IOL selection or technique modification, particularly regarding optic positioning relative to the iris plane. Excessive postoperative tilt or decentration may induce refractive cylinder, highlighting the importance of symmetric haptic externalization[4,5].

Several three-piece IOLs have been reported for use with the Yamane flanged intrascleral fixation technique, each with distinct mechanical characteristics that may influence surgical handling. A detailed comparison of IOL models, including haptic material, configuration, tensile strength, and technical handling notes, is provided in Supplementary Table 1. The MA60AC (Alcon Laboratories, Inc., Fort Worth, TX, United States) features polymethyl methacrylate (PMMA) haptics but has a relatively weaker optic-haptic junction and a curved C-shaped haptic tip that may make docking into the needle lumen more challenging. The ZA9003 (Johnson & Johnson Vision, Santa Ana, CA, United States) also incorporates PMMA haptics with a modified C-loop configuration and has been reported in several early Yamane series. More recently, lenses with polyvinylidene fluoride (PVDF) haptics, such as the CT Lucia series (Carl Zeiss Meditec AG, Jena, Germany), have gained popularity due to their higher flexibility and resistance to deformation; however, PVDF haptics have also been associated with the so-called “rotisserie syndrome”, a pattern of postoperative axial IOL rotation attributed to a loose haptic-optic junction, as described in case reports and bench-based analyses[4,17]. Precise incidence data are not yet available, as the phenomenon has not been systematically quantified in prospective series. The AR40e (Johnson & Johnson Vision, Santa Ana, CA, United States) remains one of the most commonly used three-piece lenses for this technique in current surgical practice[4,5,10,17].

Premium IOL options such as toric or multifocal designs have not been systematically studied in the context of Yamane flanged intrascleral fixation. Because the technique requires a three-piece IOL for safe haptic externalization and flange formation, most premium lenses—typically single-piece designs—are not suitable for Yamane technique. In addition, use of three-piece lenses for Yamane fixation generally represents an off-label application. Therefore, caution is advised due to potential concerns regarding rotational stability and refractive predictability in the absence of capsular support. For residual astigmatism, corneal-based approaches such as limbal relaxing incisions or postoperative excimer laser correction may represent more predictable options in selected cases[5,18].

The light-adjustable lens (LAL) has been proposed as a potential option to address refractive unpredictability in scleral-fixated IOLs through postoperative ultraviolet-based adjustment. However, bench testing indicates lower haptic tensile strength compared with PMMA, suggesting a greater risk of deformation and the need for careful intraoperative handling. Clinical experience with LAL in Yamane-style fixation remains limited to small reports, and further evaluation is needed[17].

In summary, IOL power calculation for the Yamane technique requires consideration of the expected effective lens position in a scleral-fixated configuration, appropriate formula selection, and use of optimized lens constants when available. Biometric assessment should include verification of axial length measurements, keratometry consistency, and comparison with the fellow eye when uncertainty exists, as small errors may have greater impact without capsular bag support. In patients with prior refractive surgery, advanced calculation methods and realistic counseling regarding refractive variability remain essential. Systematic documentation of postoperative refractive outcomes may help surgeons refine constants and improve predictability over time.

Surgical principles of the Yamane technique

The Yamane technique is based on achieving stable posterior chamber IOL fixation through symmetric intrascleral haptic anchoring without sutures. Mechanical stability arises from friction within the scleral tunnels combined with terminal haptic flanges created by cauterizing the haptic tips, which act as physical stops to prevent inward migration of the haptics, reducing the risk of gradual loosening over time compared with suture-based fixation[2,4]. Symmetric tunnel placement distributes forces evenly across both haptics, with clinical studies demonstrating visual outcomes comparable or potentially favorable to sutured scleral fixation techniques[8,19].

Symmetry is fundamental; bilateral scleral tunnels must be created at equal distances from the limbus and with similar angulation to ensure proper IOL centration and minimize tilt. Asymmetric tunnel geometry or unequal haptic externalization has been shown to increase the risk of decentration and refractive unpredictability[5,11]. Posterior chamber positioning of the IOL optic is preserved by maintaining parallel alignment between the two haptics and the iris plane.

Needle-haptic compatibility represents another core surgical principle. Thin-wall 30-gauge needles provide an optimal balance between scleral penetration and smooth haptic capture, reducing deformation or notching of commonly used PMMA haptics during externalization[5,10]. Proper bevel orientation facilitates atraumatic engagement of the haptic and contributes to controlled passage through the scleral tunnel.

Scleral tunnel geometry directly influences long-term fixation. An entry angle of approximately 5° relative to the iris surface and 20° relative to the limbus has been described in original technique reports and is supported by cadaveric observations; however, direct comparative studies evaluating alternative angulation parameters are limited, and this recommendation reflects both published technique descriptions and expert-informed surgical reasoning[2,5,10]. This trajectory is designed to produce a tunnel of approximately 2.0-2.5 mm, enhancing frictional resistance while maintaining adequate tissue coverage over the haptic[5,10].

Based on convergent evidence from experimental, cadaveric, and clinical studies, scleral tunnel lengths of 2.0-2.5 mm are consistently recommended as optimal; this range is the most robustly supported quantitative parameter in the current literature[2,5,10]. The Yamane entry site lies within the pars plana — the same anatomically safe zone used for intravitreal injections, which are conventionally placed 3.5-4.0 mm posterior to the limbus in phakic eyes and 3.0-3.5 mm in pseudophakic eyes, specifically to avoid retinal breaks and hemorrhage[20]. Tunnels shorter than 2.0 mm position the IOL optic too far posterior to the iris plane, resulting in a clinically significant hyperopic refractive shift, increased lens tilt, and reduced frictional resistance of the haptic within the tunnel — increasing the risk of late IOL slippage and decentration[4,10]. Conversely, tunnels that are too long or created at an excessively steep angle risk premature entry into the vitreous cavity, ciliary body trauma and hemorrhage, and difficulty externalizing the haptic through the scleral channel[2,4].

Finally, controlled flange formation is essential for durable fixation. Thermal enlargement of the haptic tip creates a flange that anchors the haptic at the tunnel entry while allowing it to be buried beneath the scleral surface. Available evidence, though largely derived from case series and technique reports rather than controlled comparative studies, suggests that a flange diameter of approximately 0.3-0.4 mm represents a practical target; flanges within this range appear to balance resistance to haptic slippage with minimization of conjunctival irritation, although optimal sizing has not been established through direct experimental comparison[5,10]. These factors are critical for maintaining long-term IOL stability and centration[2].

These technical considerations are supported by comparative experimental and clinical studies. Evidence suggests that thin-wall 30-gauge needles, appropriate tunnel trajectory, and symmetric haptic externalization contribute to improved IOL stability and refractive predictability[5,10]. These findings further support the importance of standardized surgical execution in achieving consistent outcomes.

The role of vitreous management is an integral surgical principle. Whether anterior vitrectomy or comprehensive PPV is performed depends on the clinical scenario; however, ensuring adequate vitreous clearance around the haptics prior to fixation reduces the risk of vitreous incarceration, postoperative traction, and CME[11,12,21].

STEP-BY-STEP METHODOLOGY

The Yamane technique begins with careful preoperative planning to ensure symmetric scleral access and appropriate IOL selection. Marking of the sclera is typically performed 2.0-2.5 mm posterior to the limbus on opposite meridians to guide tunnel creation and promote centration[1,2]. The scleral entry sites and tunnel trajectory are illustrated in Figure 1 and Video.

Figure 1 Diagram of Yamane flanged intrascleral intraocular lens fixation technique in a right eye. A sterile surgical marking pen is used intraoperatively to identify the scleral fixation sites at the 3 and 9 o’clock meridians. The scleral entry points (purple dots) are marked at 2.0 mm (2 mm to 2.5 mm) posterior to the limbus to guide symmetric tunnel creation. Pre-bent 30-gauge thin-wall needles with different flexion angles (needle #1: Approximately 40°; needle #2: Approximately 55°) are prepared to facilitate ergonomic handling and controlled transscleral entry. The needles are then advanced toward the planned intraocular penetration points (blue dots) along an intrascleral trajectory (approximately 20-30°), creating tunnels of about 2.0-2.5 mm before entering the posterior chamber. This configuration facilitates controlled haptic externalization and stable posterior chamber intraocular lens fixation. Asterisks (*) indicate the three pars plana vitrectomy port entry sites: One superotemporal infusion cannula and two instrument ports placed approximately 3.5 mm posterior to the limbus in the inferotemporal and superior quadrants, respectively. T: Temporal; N: Nasal; OD: Oculus dexter (right eye).

Several instruments facilitate accurate and symmetric port marking. A surgical caliper is the most widely available tool for measuring the entry site distance 2.0 mm posterior to the limbus; however, a caliper alone does not confirm that the two tunnel sites are positioned precisely 180° apart because it measures only radial distance and not angular relationship. Expert consensus and technical reasoning suggest that a toric marker or Mendez ring should be used in conjunction with the caliper to verify that ports are placed exactly 180° apart relative to the center of the visual axis; direct clinical studies comparing marked vs unmarked port placement are lacking, but this practice is broadly recommended to minimize the risk of asymmetric haptic fixation, IOL tilt, and induced refractive cylinder[2,5,10]. Commercially available dedicated devices such as the Fram Marker (Epsilon), Yamane Marker (Geuder), and Kim Calipers (Epsilon) have been developed to ensure symmetric placement at 180°, though these specific devices are not yet detailed in the peer-reviewed literature. Additionally, the Yamane double-needle stabilizer, as described by Besozzi et al[22], provides a mechanical guide that simultaneously positions both needles at exactly 180° and standardizes intrascleral tunnel depth, contributing to improved bilateral symmetry and more predictable refractive outcomes.

A reference mark corresponding to the intended intrascleral tunnel length (approximately 2.0 mm) is then placed on the needle shaft using a sterile marking pen. This mark serves as a depth guide during scleral passage. The needle is advanced tangentially within the sclera, and once the shaft marking reaches the scleral entry point, the trajectory is redirected (“turn-in”) to enter the eye. This maneuver standardizes tunnel length and improves bilateral symmetry.

Prior to insertion, 30-gauge thin-wall needles are pre-bent to facilitate controlled transscleral entry. Different flexion angles (approximately 40° for the first needle and 55° for the second needle) may be used to optimize ergonomics and maintain a shallow scleral trajectory; the needle preparation and marking process are depicted in Figure 2A. Appropriate flexion supports formation of a consistent intrascleral tunnel.

Figure 2 Stepwise illustration of the Yamane technique for flanged intrascleral haptic fixation of a posterior chamber intraocular lens in a right eye, performed in conjunction with pars plana vitrectomy. Trocar cannulas (teal) for 25-gauge pars plana vitrectomy ports placed prior to intraocular lens (IOL) fixation to allow complete vitreous clearance and to reduce the risk of postoperative traction and cystoid macular edema are visible throughout panels A-H; A: Needle marking and needle flexion planning. Blue marking ink dots are visible on the conjunctiva, identifying the planned 30-gauge thin-wall needle entry sites (2.0 mm posterior to the limbus); a reference mark is placed on the needle shaft to guide the intended intrascleral tunnel length (approximately 2.0-2.5 mm); pre-bent 30-gauge thin-wall needles are prepared with different flexion angles (inset: Needle #1: Approximately 40°; needle #2: Approximately 55°); B: Transscleral needle entry; C: Haptic docking into the needle lumen; D: Externalization of the haptic through the scleral tunnel, the externalized haptic is highlighted by an arrow at the scleral exit site; E: Flange formation of the first haptic by low-temperature cautery; F: Externalization of the second haptic and symmetric positioning; G: Flange formation of the second haptic by low-temperature cautery; H: Burial of the flanged haptics and final IOL centration. T: Temporal; N: Nasal.

Maintaining adequate intraocular pressure during needle passage is important to stabilize the globe and scleral surface; this may be achieved using an anterior chamber maintainer or pars plana infusion when vitrectomy is performed. The Yamane technique is typically performed using 30-gauge thin-wall needles. Prior to lens loading, surgeons may verify the fit of the IOL haptic within the lumen of the needle, as minor variations in internal lumen diameter can occur even among thin-wall needles from different manufacturing batches. These variations may influence haptic docking, particularly with commonly used lenses such as the AR40e, whose haptic may fit tightly within the lumen of a 30-gauge thin-wall needle. For example, commonly used needles from TSK Laboratory (Tochigi-Shi, Tochigi, Japan), such as the PRC-300131-100 thin-wall model, provide a slightly wider internal lumen that facilitates smoother haptic passage than HPC-30013E-100 standard-wall model. Based on expert experience and awareness of known manufacturing differences between needle configurations, confirming haptic-needle compatibility before lens insertion is advisable; formal comparative data on this practice are not yet available[2,23].

Scleral tunnels are created using 30-gauge thin-wall needles introduced at an angle of 20° relative to the corneal limbus and 5° relative to the iris surface. This angulation allows formation of an intrascleral tunnel of sufficient length while minimizing the risk of premature entry into the vitreous cavity[2,23]. Maintaining consistent tunnel length and trajectory on both sides is essential for symmetric haptic fixation (Figure 2B).

After the needles are positioned within the eye, the IOL is inserted into the anterior chamber. Each haptic is then sequentially engaged into the lumen of the corresponding needle (Figure 2C). Proper bevel orientation, with the bevel facing the approaching haptic, facilitates smooth capture and reduces the likelihood of haptic deformation or resistance during externalization[2,23]. Coordinated manipulation of the needle and forceps is critical at this stage to maintain control and avoid excessive stress on the optic-haptic junction.

The needle is then withdrawn through the scleral tunnel while maintaining capture of the haptic, allowing controlled externalization (Figure 2D). The first externalized haptic is cauterized using low-temperature cautery to create a terminal flange that prevents inward migration (Figure 2E). Both haptics are then adjusted to achieve symmetric positioning and appropriate IOL centration (Figure 2F). The second haptic is subsequently cauterized in the same manner, completing formation of bilateral flanges (Figure 2G). This step creates a small terminal flange that serves as a mechanical stop, preventing retraction of the haptics into the scleral tunnels[1,2]. The flanges are then gently buried within the scleral tunnels, ensuring adequate tissue coverage and minimizing the risk of conjunctival erosion (Figure 2H)[24].

Final assessment includes confirmation of IOL centration, optic stability, and absence of excessive tilt. Minor adjustments can be made before concluding the procedure to optimize alignment. When performed in a controlled and symmetric manner, this stepwise approach provides reliable fixation with favorable mechanical stability and refractive outcomes[5,23].

BENEFITS, CHALLENGES, AND LIMITATIONS

Key technical variables and pitfalls

Several technical variables play a decisive role in the success of the Yamane technique and may also represent common sources of error when not adequately controlled. Among these, scleral tunnel placement and symmetry are particularly critical. Inconsistent tunnel distances from the limbus or asymmetric angulation can result in IOL decentration, tilt, and refractive unpredictability, even when the procedure is otherwise uneventful[2,4].

Tunnel geometry is closely linked to long-term stability, and flange formation is another frequent source of variability. Inadequate or asymmetric flanges may allow haptic migration or contribute to subtle tilt and decentration over time[2,4].

Finally, inadequate intraoperative assessment of centration before completion of the procedure represents a common pitfall. Minor asymmetries that are not addressed intraoperatively may become clinically significant postoperatively, underscoring the importance of careful inspection and adjustment prior to closure[2,5,11]. Vitreous management considerations are discussed in detail in the section on PPV below[11,12].

Complications and prevention strategies

Although the Yamane technique is generally associated with favorable outcomes, several intraoperative and postoperative complications have been reported. Many of these complications are technique-related and can be mitigated through adherence to standardized procedural steps.

Early intraoperative complications include hypotony, vitreous prolapse, and localized hemorrhage at the scleral entry sites. These events are often related to excessively steep needle entry or inadequate tunnel length. Creating shallow, well-controlled intrascleral tunnels of sufficient length reduces sudden intraocular pressure fluctuations and limits scleral trauma[2,23].

Haptic-related complications represent another important category. Incomplete capture of the haptic within the needle lumen or excessive force during externalization may result in haptic deformation or breakage. Proper needle-haptic alignment, appropriate bevel orientation, and gentle coordinated manipulation are essential to minimize these risks[5,9,23]. Repeated attempts at haptic engagement should be avoided, as they increase intraocular manipulation and mechanical stress.

Postoperative complications include IOL decentration, tilt, and late haptic exposure. These issues are frequently associated with asymmetric tunnel placement or inconsistent flange size. Ensuring bilateral symmetry in tunnel geometry and controlled, uniform flange formation reduces the likelihood of late instability[1,2,5]. Adequate burial of the flange beneath the scleral surface further decreases the risk of conjunctival erosion.

Pupillary capture and iris chafing have also been described, particularly in eyes with shallow anterior chambers or inadequate posterior positioning of the optic. Careful assessment of IOL centration and optic position at the conclusion of surgery allows for early correction before wound closure[5,11].

Postoperative hypotony may occur due to sclerotomy wound leak, particularly in eyes with thin sclera or in combined vitreoretinal procedures, though most cases resolve spontaneously as wounds self-seal. In rare instances, cyclodialysis cleft formation may contribute to persistent hypotony and require surgical intervention[11]. Endophthalmitis has been notably absent in most published series, suggesting that small gauge sclerotomies reduce infection risk compared to larger incision techniques[5,11]. However, late haptic exposure could theoretically provide a route for infection if not promptly addressed[2,5].

CME represents one of the most frequent postoperative complications, with reported rates ranging from 13%-14% in published series, although these percentages represent approximate ranges reported across different studies and may vary depending on patient population and surgical technique[5,11]. CME may occur more frequently following fixation of a lens by means of the Yamane technique compared to suture-based scleral fixation, though most cases respond to topical or periocular corticosteroid therapy[5]. In cases where CME or uveitis becomes refractory to conventional treatment, the use of suprachoroidal triamcinolone acetonide has been described as a successful targeted intervention to stabilize the macula and manage ocular inflammation[25]. Retinal detachment has been reported in 2%-5% of cases, particularly in eyes with pre-existing vitreoretinal pathology or incomplete vitreous removal. Other reported complications include transient corneal edema, elevated intraocular pressure or glaucoma progression, and epiretinal membrane formation during long-term follow-up[5,11].

Overall, most complications associated with the Yamane technique are preventable. A systematic approach that emphasizes symmetry, controlled tissue handling, and intraoperative verification of stability plays a central role in optimizing outcomes and minimizing adverse events.

Although many published studies report favorable visual and refractive outcomes with the Yamane technique, interpretation of these results should be made cautiously. The available evidence derives predominantly from retrospective case series with relatively small sample sizes and heterogeneous surgical techniques, limiting the strength of conclusions that can be drawn. Complication rates reported across studies vary substantially depending on surgeon experience, case complexity, and differences in vitreous management strategies — for example, rates of CME range from under 5% to over 25% across published series, and rates of IOL decentration or tilt similarly show wide variation[5,11,26]. The learning curve associated with symmetric scleral tunnel creation and controlled haptic externalization may also influence outcomes early after the adoption of the technique[5,10,23]. These limitations underscore the importance of standardized surgical reporting and prospective comparative studies to more precisely define the technique’s true complication profile and reproducibility across surgeons and institutions. Surgical expertise represents an additional and frequently underreported source of variability. Outcome heterogeneity across published series partly reflects differences in surgeon experience level. Complication rates — particularly IOL decentration, tilt, and haptic-related complications — are demonstrably higher during early adoption of the technique. This learning curve effect should be considered when interpreting pooled outcome data from the literature.

Considering comprehensive pars plana vitrectomy

In the preoperative setting, the decision to perform a complete PPV should be carefully considered to minimize both intraoperative and postoperative complications. There are multiple clinical scenarios in which PPV may be particularly advantageous. In cases of dislocated or subluxated IOLs—such as those associated with Marfan syndrome, high myopia, trauma, pseudoexfoliation, or dropped lenses—a comprehensive vitrectomy with removal of the posterior vitreous can reduce the risk of postoperative complications. These include CME, IOL tilt, or decentration due to residual vitreous traction, and retinal tears or detachment resulting from vitreous manipulation[11].

Beyond lens-related pathology, a history of vitreoretinal disease, including prior retinal detachment, extensive peripheral retinal degeneration, or high myopia, may further support the decision to perform a PPV in order to mitigate the risk of postoperative retinal tears or detachment. Patient age is also an important consideration, as younger patients tend to have more adherent vitreous, increasing the likelihood of postoperative traction and CME if vitreous is left behind[11,21].

In select high-risk situations, intraoperative involvement of a vitreoretinal specialist may be warranted, particularly when unexpected events arise, such as the need for extracapsular cataract extraction or the occurrence of intraoperative vitreous hemorrhage. While performing a PPV in every Yamane case may represent an added burden for both patients and surgeons—given longer operative times, increased procedural risk, and the potential need for vitreoretinal expertise—it may ultimately reduce the incidence of significant complications. These include IOL tilt or decentration, CME, uveitis-glaucoma-hyphema syndrome, retinal tears, and retinal detachment[11,12]. When PPV is performed in conjunction with the Yamane technique, strong consideration should be given to suturing all sclerotomy ports at the conclusion of the case. The combined presence of multiple scleral entries—from both the vitrectomy ports and the Yamane tunnel sites—significantly increases the risk of postoperative hypotony, particularly in eyes with compromised scleral integrity such as those with high myopia, diabetes, or prior ocular surgery[11,12]. Suturing the vitrectomy ports reduces this risk and should be considered routine in these settings.

Preoperative imaging can play a critical role in guiding the decision to pursue a complete PPV. Optical coherence tomography findings demonstrating abnormal vitreomacular adhesion, absence of a posterior vitreous detachment, or pre-existing CME may influence the surgeon to plan for PPV in conjunction with Yamane fixation. These findings suggest an increased risk of postoperative traction-related complications if vitreous is left unaddressed[11].

In cases where visualization of the posterior segment is limited—which is common in patients requiring Yamane fixation—B-scan ultrasonography can be particularly valuable in surgical planning. Ultrasonographic evidence of retinal tears or detachment, vitreous hemorrhage, or retained lens material within the vitreous cavity should strongly prompt consideration of a PPV[11].

The extent of vitrectomy—whether limited anterior vitrectomy or comprehensive PPV—should be guided by the clinical scenario. A limited anterior vitrectomy is generally sufficient when vitreous has prolapsed into the anterior segment following complicated cataract surgery, or when only anterior vitreous clearance is needed to facilitate safe IOL placement without evidence of posterior segment pathology. In contrast, comprehensive PPV is preferred when there is a dislocated IOL or lens fragment in the vitreous cavity, a history of retinal detachment or significant peripheral retinal degeneration, evidence of vitreomacular traction or adhesion on preoperative optical coherence tomography, vitreous hemorrhage obscuring the posterior segment, or in younger patients with adherent vitreous who are at higher risk of postoperative traction-related complications. In these higher-risk cases, a vitreoretinal surgeon should be involved either preoperatively for planning or intraoperatively to ensure complete and safe vitreous removal[11,12,21].

The principal benefit of PPV in this context lies in its ability to ensure complete absence of vitreous around the IOL haptics and to eliminate undesirable vitreoretinal interfaces, thereby promoting long-term IOL stability and improved postoperative outcomes[11,12].

TRAINING AND REPRODUCIBILITY CONSIDERATIONS

The Yamane technique is increasingly incorporated into surgical practice and training programs; however, its reproducibility depends heavily on consistent execution of several technically demanding steps. While conceptually straightforward, the procedure requires precise spatial judgment, coordinated bimanual manipulation, and careful intraoperative assessment, all of which contribute to a measurable learning curve[1,2].

For surgeons in training, the most challenging aspects include symmetric scleral tunnel creation, controlled haptic capture, and balanced flange formation. Minor deviations during these steps may not be immediately apparent intraoperatively but can manifest as postoperative tilt or decentration. Studies have shown that variability in these parameters contributes to inconsistent outcomes, particularly during early surgical experience[5,9]. Structured guidance is therefore essential for effective skill acquisition.

Standardization of key procedural elements plays a central role in improving reproducibility. Consistent use of defined landmarks for scleral entry, uniform needle gauge selection, and clear criteria for tunnel length and flange size allow trainees to follow reproducible patterns rather than relying on subjective judgment alone[2,4,5]. This approach also facilitates meaningful comparison of outcomes across surgeons and institutions.

Simulation-based training, including wet-lab models and cadaveric studies, has been proposed as a valuable adjunct for mastering needle trajectory and haptic manipulation before performing the technique in live surgery[5,23]. Stepwise teaching protocols and explicit reporting of technical parameters further support reproducibility in both clinical practice and research settings.

From a methodological perspective, emphasizing standardized technique descriptions may reduce heterogeneity across studies and enhance the quality of comparative research evaluating scleral fixation methods[5].

Surgical time and cost-effectiveness

The Yamane technique has been associated with shorter operative times compared with traditional suture-based scleral fixation methods, primarily due to the elimination of suture placement and extensive conjunctival dissection. Reduced surgical steps may translate into more efficient operating room workflow, particularly in cases where secondary IOL implantation is performed as a standalone procedure[5].

From a cost perspective, the sutureless approach avoids expenses related to permanent sutures and their potential complications, such as suture erosion or late breakage, which may require additional surgeries. Although the technique requires specific needles or intraoperative cautery, these costs are generally comparable to standard microsurgical instruments and do not substantially increase overall procedural expenses. When factoring in shorter operative times and fewer suture-related reoperations, the Yamane technique may offer practical economic advantages without compromising outcomes[5].

It should be noted that true cost-effectiveness depends on multiple factors, including surgeon experience, institutional resources, and case complexity. Nevertheless, the available evidence suggests that the Yamane technique may offer an efficient and resource-conscious alternative to sutured scleral fixation, with generally comparable outcomes reported in the literature[5,27] (Table 3).

Table 3 The Yamane technique: Advantages, limitations, and key technical challenges of the Yamane scleral-fixated intraocular lens technique.

Category	Details
Advantages	Sutureless - eliminates suture degradation, erosion, and late dislocation
	Minimal conjunctival manipulation preserves tissue
	Shorter operative time vs sutured fixation
	Small incision (30-gauge needles), self-sealing sclerotomies
	Good IOL centration and axial stability
	Posterior chamber positioning maintains normal anatomy
	Comparable or superior outcomes vs sutured fixation
	Cost-effective (no sutures, fewer reoperations)
	Mechanical stability via intrascleral friction + flanges
	Reproducible with standardized steps
Limitations	Significant learning curve requiring precise coordination
	Refractive predictability less precise than in-the-bag IOL
	Requires specific three-piece IOLs with appropriate haptic material (e.g., PMMA or PVDF)
	Limited options for premium IOLs
	Risk of tilt/decentration with asymmetric placement
	Haptic deformation risk during externalization
	Not ideal for very thin sclera (high myopia, Marfan)
	Higher CME rates than sutured techniques
	Potential late haptic exposure if inadequately buried
	Limited long-term data beyond 5 years
	Often benefits from a complete vitrectomy
Key technical challenges	Symmetric and precise scleral tunnel creation
	Controlled haptic capture within the needle lumen
	Symmetric beveled entry to prevent lens tilt
	Uniform flange and haptic formation to promote lens centration
	Adequate burial of flanged ends to prevent erosion or migration
	Assessment of lens centration intraoperatively with irregular pupils

IOL: Intraocular lens; PMMA: Polymethyl methacrylate; PVDF: Polyvinylidene fluoride; CME: Cystoid macular edema.

Limitations

This review is based on a focused, non-systematic literature search and represents an expert-informed synthesis rather than a formal systematic review or meta-analysis. As such, it is subject to the inherent limitations of narrative reviews, including potential selection bias in the studies emphasized. The procedural recommendations presented should be interpreted as evidence-informed guidance, acknowledging that the underlying evidence base consists predominantly of retrospective studies with small sample sizes and heterogeneous surgical techniques. Prospective randomized data and long-term follow-up beyond five years remain lacking[4,5].

FUTURE DIRECTIONS AND STANDARDIZATION

As the Yamane technique continues to evolve, future efforts should focus on further standardization of procedural steps and reporting parameters to enhance consistency across clinical practice and research. Although current literature demonstrates favorable outcomes, heterogeneity in technique description and outcome measures limits the ability to compare results across studies and institutions[4,5].

One important direction involves establishing consensus on key technical parameters, including scleral entry distance, tunnel length and angulation, needle gauge selection, and flange size. Uniform reporting of these variables would allow clearer interpretation of outcomes and facilitate multicenter comparisons. Standardized terminology for procedural steps may also reduce ambiguity and improve reproducibility, particularly in methodological and educational studies[1,2,4].

Advances in surgical instrumentation represent one concrete avenue for refinement. Purpose-designed needles with integrated depth markers, dedicated haptic-guiding tools, and standardized flanging devices may reduce intraoperative variability and improve reproducibility across surgeons and institutions[4,23]. Simulation-based training — including wet-lab and cadaveric models — is already recognized as a valuable adjunct for skill acquisition prior to live surgical exposure[5,23]; development of validated, structured training curricula incorporating these tools will be important as the technique becomes more widely adopted in residency and fellowship programs. Future research should also evaluate the technique’s performance in combined surgical settings, such as concurrent glaucoma drainage device implantation, where conjunctival integrity — preserved by the Yamane approach — may offer a practical advantage[8]. Finally, establishing consensus on standardized outcome reporting metrics, including definitions of acceptable centration, tilt thresholds, and long-term stability parameters, will be essential to enable meaningful cross-study comparison and to support future multicenter prospective trials[4,5,10].

To improve reproducibility and facilitate comparison across studies, key procedural elements that should be standardized or explicitly reported in studies of the Yamane technique are summarized in Tables 4 and 5.

Table 4 Stepwise procedural checklist for the Yamane flanged intrascleral haptic fixation technique.

Step	Stage	Action
1	IOL selection	Confirm three-piece IOL with PMMA haptics compatible with 30-gauge needle lumen
2	Scleral marking	Mark symmetric scleral entry points 180° apart, 2.0-2.5 mm posterior to the limbus
3	Needle insertion	Insert 30-gauge needles with bevel orientation optimized for haptic capture (bevel-up preferred); maintain entry angle of 20° relative to the limbus and 5° relative to the iris surface
4	Tunnel adequacy	Confirm intrascleral tunnel length ≥ 2.0 mm to ensure adequate haptic retention
5	Haptic externalization	Externalize haptics through needle lumen with controlled, minimal force to avoid deformation
6	Flange formation	Form flanges using low-temperature cautery; target flange diameter 0.3-0.5 mm; avoid excess heat to prevent haptic brittleness
7	Haptic retraction	Retract flanges into scleral tunnels and confirm fully seated position
8	IOL verification	Verify IOL centration and tilt under the operating microscope before wound closure

PMMA: Polymethylmethacrylate; IOL: Intraocular lens.

Table 5 Standardized surgical parameters for the Yamane flanged intrascleral haptic fixation technique.

Surgical parameter	Recommended value/range	Rationale
Needle gauge	30-gauge	Matches standard haptic diameter; minimizes scleral trauma
Scleral entry distance from limbus	2.0-2.5 mm	Avoids ciliary body; ensures adequate fixation depth
Entry angle	Approximately 20° to limbus/approximately 5° to iris plane	Achieves tunnel length ≥ 2.0 mm for stable haptic retention
Intrascleral tunnel length	≥ 2.0 mm	Reduces risk of haptic slippage and IOL dislocation
Needle separation (symmetry)	180° apart	Ensures IOL centration and minimizes postoperative tilt
Bevel orientation	Bevel-up (preferred); surgeon-dependent	Facilitates haptic capture and reduces deformation risk
Flange diameter	0.3-0.5 mm	Prevents haptic slippage without excessive thermal damage
Cautery application	Low-temperature, brief contact	Avoids haptic brittleness or fracture from excessive heat

IOL: Intraocular lens.

Finally, future research should prioritize prospective studies and standardized outcome reporting to better define long-term stability, complication profiles, and comparative effectiveness relative to alternative scleral fixation methods. Such efforts will be essential to fully establish the Yamane technique as a reproducible and standardized approach to secondary IOL fixation[4,5].

CONCLUSION

The Yamane technique has become a reliable option for sutureless scleral fixation of IOLs in eyes without capsular support. Although the concept is relatively simple, consistent outcomes depend on careful execution of several crucial steps, including symmetric scleral tunnel placement, appropriate needle selection, controlled haptic manipulation, and uniform flange formation. The consideration of preceding complete PPV may prevent undesirable intraoperative and postoperative complications.

This review emphasizes that small variations in these steps can meaningfully affect lens centration, stability, and complication profiles. By integrating foundational descriptions with experimental and clinical evidence, a practical methodological framework is presented to support reproducibility and surgical control. Greater consistency in both the mechanics of execution and reporting may help reduce procedural variability and improve comparability across studies.

Beyond individual surgical outcomes, standardization of the Yamane technique has important implications for training and research. A unified methodological approach may facilitate the acquisition of skills, shorten learning curves, and strengthen the quality of multicenter investigations. Continued efforts toward refinement and consensus will be essential as the technique continues to evolve and gain wider adoption. This expert-informed synthesis highlights key procedural and reporting elements that may improve consistency of surgical execution and enable more reliable comparison across future studies.

ACKNOWLEDGEMENTS

The authors thank Carol Spencer, Lahey Hospital librarian, for research support.