Keratoconus therapeutics advances

Table 1 Clinical classification of keratoconus[3]

Stage	Characteristics
Stage I	Eccentric bulging
	Induced myopia and/or astigmatism of 5 D
	Average central keratometry of 48 D
Stage II	Induced myopia and/or astigmatism of 5 to 8 D
	Average central keratometry > 48 D but < 53 D
	Absent scarring
	Minimum corneal thickness of 400 microns
Stage III	Induced myopia and/or astigmatism of 8 to 10 D
	Average central keratometry > 53 D
	Absent scarring
	Central corneal thickness of 300 to 400 microns
Stage IV	Invaluable refraction
	Average central keratometry > 55 D
	Central corneal scar
	Corneal thickness < 200 microns

Table 2 Paraclinic criteria for diagnosis of keratoconus[4]

Criteria	Values in keratoconus
Curvature	> 46 to 47 D
Asymetry I-S	> 1.4 D
Irregularity	> 20 or 30 degrees with respect to the vertical meridian
Keratometric difference between the 2 eyes	> 1 D
Anterior elevation	< 15 m in Placido rings images and < 12 m in Scheimpflug images
Posterior elevation	< 35 m in Placido rings images and < 18 m in Scheimpflug images
Pachymetry	Thinnest, decentered point, difference of 100 m between center and periphery
Aphericity (Q)	Between -0.5 and < -1
Eccentricity	Approaching 1
Form factor	Approaching 0
Corneal irregularity	> 1.1-5
Medium toric keratometry	47.3-60 D
Surface irregularity index	> 1.55
Predicted corneal acuity (Holladay Report)	> 0
Keratoconus index (Maeda)	> 0
Keratoconus % index	> 100
Keratoconus prediction index	> 0.38
Surface variation index	> 41
Vertical asymmetry index	0.32
Keratoconus index	> 1.07
Central keratoconus index	> 1.03
Smallest curvature radius	> 6.71
Largest asymmetry index	> 21
Height decentration index	> 0.016
Aberration coefficient	> 1
Aberration	Vertical Coma and Coma-like RMS (> 1.5 m)
Corneal volume analysis	> 57.98 ± 2.65 mm3
Corneal hysterisis	> 9.64 mmHg
Corneal resistance factor	> 9.6 mmHg

Table 3 Phakic intraocular lenses for keratoconus studies

Ref.	Criteria	Lens	Preoperative	Postoperative	P-value
Leccisotti et al[12]	12 eyes. KC I y II	Angular supported, spherical	Sphere -10.23 ± 2.85 D	Sph 0.46 ± 0.45 D	0.002
			Cyl -2.79 ± 1.11 D	Cyl -2.35 ± 1 D
			CDVA 0.13 ± 0.17	UCVA 0.44 ± 0.8
				CDVA 0.03 ± 0.05
Alfonso et al[14]	25 eyes	Posterior chamber, spherical	Sph -8.54 ± 4.15 D	Sph 0.0 ± 0.25 D	< 0.05
			Cyl -1.24 ± 1.19 D	Cyl -0.45 ± 0.73 D
			CDVA 0.13 ± 0.15	SE -0.32 ± 0.55 D
				UCVA 0.17 ± 0.19
				CDVA 0.12±0.12
Venter et al[15]	18 eyes	Iris supported, toric/spherical	Sph -4.64 ± 2.74 D	SE -0.46 ± 0.6 D	< 0.05
			Cyl -3.07 ± 2.04 D	UDVA ≥ 0.2 en 94%
			CDVA ≥0.5
Alfonso et al[16]	30 eyes	Posterior chamber, toric	SE -5.38 ± 3.26 D	SE -0.08 ± 0.37 D
			Cyl -3.48 ± 1.24 D	Cyl 0.41 ± 0.61 D
			UDVA 0.8 logMar	UDVA 0.10 logMar
			CDVA 0.10	CDVA 0.10
Kamiya et al[17]	27 eyes, mild KC	Posterior chamber, tori	SE -10.11 ± 2.46 D	SE 0.00 ± 0.35 D
			Cyl -3.03 ± 1.58 D	UCVA -0.09 ± 0.16
			UCVA 1.51 ± 0.2	CDVA -0.15 ± 0.09
			CDVA -0.11 ± 0.08
Sedaghat et al[18]	16 eyes,	Anterior chamber, iris supported	Sph -12.5 ± 4.61 D	Sph -0.03±1.81 D	< 0.0001
			Cyl 2.95 ± 4.06 D	Cyl 2.08 ± 1.04 D
			SE -13.9 ± 4.61 D	UDVA 0.15 ± 0.13
			UDVA CF	CDVA 0.11 ± 0.1
			CDVA 0.21 ± 0.14
Kato et al[19]	36 eyes	Iris supported, toric, spherical	SE -8.38 ± 3.42 D	SE -0.42 ± 0.89 D
			Cyl 2.44 ± 2.25 D	Cyl 0.62 ± 0.69 D
			UDVA 1.39 ± 0.42	UDVA 0.02 ± 0.21
	Hashemian et al[20]		22 eyes	ICL toric		SE -4.98 ± 2.63 D	SE -0.33 ± 0.51 D
			Cyl -2.77 ± 0.99 D	Cyl -1.23 ± 0.65 D
			UDVA 0.63 ± 0.2 dec.	UDVA 0. 85 ± 0.21 dec.
Combined procedures
Moshirfar et al[21]	19 eyes	Intacs/verisyse, sequential vs simultaneous	SE -12.38 ± 4.2 D	SE -1.2 ± 1.15 D	No difference regarding sequential vs simultaneous
			Cyl 3.3 ± 1.8 D	Cyl 2.06 ± 1.1 D
			UCVA 2.025 ± 0.32	UCVA 0.465 ± 0.18
			CDVA 0.34 ± 0.22	CDVA 0.15 ± 0.09
Izquierdo et al[22]	11 eyes Progressive KC I and II	Crosslinking/verisyse	Sph -5.7 D	Sph -0.27 D	< 0.05
			Cyl -1.45 D	Cyl -0.9 D
			SE -6.42 D	SE -0.72 D
			UDVA 1.4 ± 0.4	UDVA 0.16 ± 0.06
			CDVA 0.14 ± 0.06	CDVA 0.04 ± 0.05
Alfonso et al[23]	40 eyes	Keraring/ICL	SE -9.65 ± 6.9 D	SE -1.2 ± 1.3 D
			UDVA 1.0	UDVA 0.3
			CDVA 0.3	CDVA 0.18
Güell et al[24]	17 eyes Progressive KC I and II	Crosslinking and toric artiflex/artisan	SE -6.99 ± 3.2 D	SE -0.22 ± 0.33 D
			Cyl -3.54 ± 1.38 D	Cyl -0.62 ± 0.39 D
			UDVA < 1	0.17 ± 013
			CDVA 0.1 ± 0.09	CDVA 0.10 ± 0.09
Navas et al[25]	11 eyes KC I-IV	ICRS and toric and spherical ICL	Sph -9.04 ± 6.03 D	Sph -0.06 ± 0.46 D	< 0.01
			Cyl -2.95 ± 1.35 D	Cyl -1.22 ± 0.65 D
			SE -10.52 ± 5.88 D	SE -0.68 ± 0.45 D
			UDVA 1.31 ± 0.37	UDVA 0.14 ± 0.04
			CDVA 0.289 ± 0.14	CDVA 0.16 ± 0.08

CDVA: Corrected distance visual acuity; UDVA: Uncorrected distance visual acuity; ICRS: Intrastromal corneal ring segments.