LaserVision

Purpose of Review To investigate the latest findings in the field of intraocular lenses and their future development.

This is a case series of patients suffering from neurotrophic keratopathy. The main categorisation of the disease is discussed as well as the management that should be followed on each stage. Several cases of patients with neurotrophic keratopathy are analysed and the treatment (different on every patient) of them is presented. Newer substances that are beginning to be used in the treatment of neurotrophic keratopathy are discussed as well.

Corneal cross linking (CXL) has significant supporting evidence suggesting that it stabilizes keratoconus (KC) and increases corneal rigidity. Randomized clinical trials demonstrating this in a statistically significant manner would still be welcomed however.

INTRODUCTION. The purpose of the study was to evaluate the safety and efficacy of photorefractive keratectomy (PRK) combined with corneal collagen crosslinking (CXL) in patients with potential risk of developing postoperative ectasia, who were not good candidates for LASIK. MATERIALS AND METHODS. Twenty eyes were treated with transepithelial PRK combined with CXL. Patients were evaluated preoperatively for best corrected visual acuity (BCVA), refraction, keratometry, topography, and endothelial cell count. All eyes were treated with Amaris 750s Excimer Laser and KXL system for 90 seconds at 30 mW/cm 2 . RESULTS. Mean BCVA was improved from 0.0075 ± 0.08 logMAR to 0.025 ± 0.05 logMAR postoperatively. Average keratometry reduced from 44.9 ± 1.9 D to 39.8 ± 3.9 D. Mean minimal corneal thickness reduced from 504 ± 16.7 μm to 405 ± 41 μm. None of the cases developed regression, corneal ectasia, or corneal haze. CONCLUSIONS. Photorefractive keratectomy combined with high-fluence corneal collagen crosslinking (PRK XTRA) appears to be a safe and effective treatment for patients who are not good candidates for LASIK.

To evaluate ex vivo the possible difference in corneal cross-linking (CXL) biomechanical effect of different ultraviolet-A (UV-A) irradiances. The study involved 25 human donor corneas, randomly allocated to 5 groups (n = 5 each). CXL was applied with UV-A irradiances of 3, 9, 18, 30, and 45 mW/cm2, maintaining equal cumulative energy dose of 5.4 J/cm2. UV-A was delivered on half of the cornea. The nonirradiated halves served as controls. Specimens were subjected to collagenase-A enzymatic digestion. The time to complete dissolution in each specimen was recorded. Time to dissolution in group-A (3 mW/cm2 for 30 minutes) was 321 ± 13.4 minutes (range: 300-330) compared with 171 ± 8.2 (range: 165-180) for their control. In group-B (9 mW/cm2 for 10 minutes), it was 282 ± 19.6 minutes (range: 270-315) compared with 177 ± 6.7 (165-180) for their control. In group-C (18 mW/cm2 for 5 minutes), it was 267 ± 19.6 minutes (range: 240-285) compared with 177 ± 7.7 (range: 165-180) for their control. In group-D (30 mW/cm2 for 3 minutes), it was 252 ± 12.5 minutes (range: 240-270) compared with 180 ± 10.6 minutes (range: 165-195) for their control. In group-E (45 mW/cm2 for 2 minutes), it was 204 ± 17.1 minutes (range: 180-225) compared with 186 ± 8.2 minutes (range: 180-195) for their control. The data in this ex vivo human corneal study indicate that the biomechanical effect of CXL studied by resistance to enzymatic digestion in human corneas is comparable between irradiances of 9, 18 and 30 mW/cm and seems to be reduced at a fluence of 45 mW/cm2.

BackgroundThe purpose of this study is to evaluate the extent and incidence of opaque bubble layer (OBL) using laser-assisted in situ keratomileusis (LASIK) flaps created with the Alcon/WaveLight® FS200 femtosecond laser as a result of a recent change in flap programming parameters aiming to reduce further the incidence and extent of OBL.MethodsIntraoperative digital images of flaps from 36 consecutive patients (72 eyes) subjected to bilateral femtosecond-assisted LASIK were analyzed using a proprietary computerized technique. The incidence and extent of OBL was measured and reported as a percentage of the entire flap area. Flap creation was performed with a 1.7 mm wide canal, implemented as an updated design intended to reduce the extent of OBL (group A). The same OBL parameters were investigated and compared in an age-matched and procedure-matched patients in whom the previous standard setting of a 1.3 mm wide canal was implemented (group B).ResultsIn group A, the average extent of OBL was 3.69% of the flap area (range 0%–11.34%). In group B, the respective values were 6.06% (range 0%–20.24%). We found the difference to be statistically significant (one-tailed P = 0.00452).ConclusionThis study suggests that there is a significant reduction in the incidence and extent of OBL when novel LASIK flap ventilation canal parameters of width and spot line separation are used.

PurposeTo survey the standard keratoconus grading scale (Pentacam®-derived Amsler–Krumeich stages) compared to corneal irregularity indices and best spectacle-corrected distance visual acuity (CDVA).Patients and methodsTwo-hundred and twelve keratoconus cases were evaluated for keratoconus grading, anterior surface irregularity indices (measured by Pentacam imaging), and subjective refraction (measured by CDVA). The correlations between CDVA, keratometry, and the Scheimpflug keratoconus grading and the seven anterior surface Pentacam-derived topometric indices – index of surface variance, index of vertical asymmetry, keratoconus index, central keratoconus index, index of height asymmetry, index of height decentration, and index of minimum radius of curvature – were analyzed using paired two-tailed t-tests, coefficient of determination (r2), and trendline linearity.ResultsThe average ± standard deviation CDVA (expressed decimally) was 0.626 ± 0.244 for all eyes (range 0.10–1.00). The average flat meridian keratometry was (K1) 46.7 ± 5.89 D; the average steep keratometry (K2) was 51.05 ± 6.59 D. The index of surface variance and the index of height decentration had the strongest correlation with topographic keratoconus grading (P < 0.001). CDVA and keratometry correlated poorly with keratoconus severity.ConclusionIt is reported here for the first time that the index of surface variance and the index of height decentration may be the most sensitive and specific criteria in the diagnosis, progression, and surgical follow-up of keratoconus. The classification proposed herein may present a novel benchmark in clinical work and future studies.