Yusuf Yildirim

Accelerated corneal crosslinking concurrent with laser in situ keratomileusis.

PURPOSE: To assess accelerated corneal collagen crosslinking (CXL) applied concurrently with laser in situ keratomileusis (LASIK) in a small group of patients. SETTING: Beyoglu Eye Research and Training Hospital, Istanbul, Turkey. DESIGN: Prospective pilot interventional case series. METHODS: In May 2010, patients had LASIK with concurrent accelerated CXL in 1 eye and LASIK only in the fellow eye to treat myopia or myopic astigmatism. The follow‐up was 12 months. The attempted correction (spherical equivalent) ranged from −5.00 to −8.50 diopters (D) in the LASIK–CXL group and from −3.00 to −7.25 D in the LASIK‐only group. Main outcome measures were manifest refraction, uncorrected (UDVA) and corrected (CDVA) distance visual acuities, and the endothelial cell count. RESULTS: Eight eyes of 3 women and 1 man (age 22 to 39 years old) were enrolled. At the 12‐month follow‐up, the LASIK–CXL group had a UDVA and manifest refraction equal to or better than those in the LASIK‐only group. No eye lost 1 or more lines of CDVA at the final visit. The endothelial cell loss in the LASIK–CXL eye was not greater than in the fellow eye. No side effects were associated with either procedure. CONCLUSIONS: Laser in situ keratomileusis with accelerated CXL appears to be a promising modality for future applications to prevent corneal ectasia after LASIK treatment. The results in this pilot series suggest that evaluation of a larger study cohort is warranted. Financial Disclosure: Drs. Yilmaz and Marshall are paid consultants to Avedro, Inc. No other author has a financial or proprietary interest in any material or method mentioned.

Comparison of visual acuity and higher-order aberrations after femtosecond lenticule extraction and small-incision lenticule extraction.

PURPOSE To compare postoperative visual acuity and higher-order aberrations (HOAs) after femtosecond lenticule extraction (FLEX) and after small-incision lenticule extraction (SMILE). METHODS Medical records of refractive lenticule extraction patients were retrospectively reviewed. Twenty patients were treated with FLEX. A comparable group of 20 SMILE patients were retrospectively identified. Only one eye of each patient was randomly chosen for the study. Visual acuity, subjective manifest refraction and corneal topography before and 6 months after the surgery were analyzed for both groups. Total HOAs, spherical aberrations, coma and trefoil were calculated from topography data over the 4- and 6-mm-diameter central corneal zone. RESULTS The mean preoperative SE was -4.03 ± 1.61 in the SMILE group and -4.46 ± 1.61 in the FLEX group. One year after surgery, the mean SE was -0.33 ± 0.25 in the SMILE group and -0.31 ± 0.41 in the FLEX group (p=0.86). In the SMILE group a greater number of eyes were within ±0.50D of the target refraction (95% versus 75%); however, the difference was not statistically significant (p=0.18). Furthermore, 80% of FLEX eyes and 95% of SMILE eyes had an uncorrected distance visual acuity of 20/25 or better (p=0.34). Total HOAs, spherical aberration, coma and trefoil increased postoperatively in both groups. However, there was no statistically significant difference between the groups preoperatively and postoperatively. CONCLUSION FLEX and SMILE result in comparable refractive results. In addition, corneal aberrations induced by different techniques of lenticule extraction seemed similar to each other.

Corneal Backscatter Analysis by In Vivo Confocal Microscopy: Fellow Eye Comparison of Small Incision Lenticule Extraction and Femtosecond Laser-Assisted LASIK

Purpose. To evaluate and compare corneal backscatter from anterior stroma between small incision lenticule extraction (SMILE) and femtosecond laser-assisted LASIK (femto-LASIK). Methods. A cohort of 60 eyes of 30 patients was randomized to receive SMILE in one eye and femto-LASIK in the fellow eye. In vivo confocal microscopy was performed at 1 week and 1, 3, and 6 months after surgery. The main outcome measurements were maximum backscattered intensity and the depth from which it was measured, the backscattered light intensity 30 μm below Bowmans membrane at the flap interface and 150 μm below the superficial epithelium, and the number of refractive particles at the flap interface. Results. The mean backscattered light intensity (LI) at all measured depths and the maximum backscattered LI were higher in the SMILE group than the femto-LASIK group at all postoperative visits. LI differences at 1 week and 1- and 3-month visits were statistically significant (P < 0,05). LI differences at 6 months were not statistically significant. There was no difference in the number of refractive particles at the flap interface between the groups at any visit. Conclusions. SMILE results in increased backscattered LI in the anterior stroma when compared with femto-LASIK were evaluated.

Accelerated Corneal Collagen Cross-Linking in Thin Keratoconic Corneas.

PURPOSE To report the outcomes of accelerated corneal collagen cross-linking in patients with thin corneas (minimum corneal thickness < 400 µm). METHODS Thirty-four eyes of 34 patients with a minimum corneal thickness less than 400 µm were included. All patients underwent accelerated corneal collagen cross-linking (irradiance power of 30 mW/cm² at 3 minutes with a total surface dose of 5.4 J/cm²). Uncorrected (UDVA) and corrected distance visual acuity (CDVA), manifest refraction (diopters [D]), and topography were evaluated at baseline and at the 1-, 6-, and 12-month follow-up visit. Endothelial cell density (cells/mm²) was calculated preoperatively and postoperatively at 12 months. The corneal stromal demarcation line was measured using anterior segment optical coherence tomography at 1 month postoperatively. RESULTS The mean age of all patients (14 women and 20 men) was 23.08 ± 3.90 years (range: 16 to 29 years). UDVA and CDVA increased but not significantly. UDVA improved from 0.67 ± 0.32 (20/93 ± 20/41 Snellen) to 0.56 ± 0.28 logMAR (20/72 ± 20/38 Snellen) (P = .033) and CDVA improved from 0.49 ± 0.19 (20/61 ± 20/30 Snellen) to 0.42 ± 0.19 logMAR (20/52 ± 20/30 Snellen) (P = .009) at the last follow-up visit. The mean spherical and cylindrical refractions did not significantly change (P = .100 and 0.139, respectively). At the last follow-up visit, the flat keratometry decreased from 47.40 ± 2.52 to 46.95 ± 2.48 D, steep keratometry decreased from 51.04 ± 3.71 to 50.62 ± 3.57 D, and apex keratometry decreased from 57.58 ± 4.49 to 56.26 ± 4.47 D (P = .001, = .0019, = .001, respectively) from baseline. The mean endothelial cell density changed from 2,726.02 ± 230.21 to 2,714.58 ± 218.26 cells/mm² at 12 months postoperatively (P =.086). CONCLUSION The results of this study revealed that accelerated corneal collagen cross-linking stabilized the progression of keratoconus without a significant endothelial cell density loss during the 12 months of follow-up.

Evaluation of Corneal Stromal Demarcation Line after Two Different Protocols of Accelerated Corneal Collagen Cross-Linking Procedures Using Anterior Segment Optical Coherence Tomography and Confocal Microscopy

Purpose. To evaluate the depth of corneal stromal demarcation line using AS-OCT and confocal microscopy after two different protocols of accelerated corneal collagen cross-linking procedures (CXL). Methods. Patients with keratoconus were divided into two groups. Peschke CXL device (Peschke CCL-VARIO Meditrade GmbH) applied UVA light with an intended irradiance of 18.0 mW/cm2 for 5 minutes after applying riboflavin for 20 minutes (group 1) and 30 minutes (group 2). One month postoperatively, corneal stromal demarcation line was measured using AS-OCT and confocal microscopy. Results. This study enrolled 34 eyes of 34 patients (17 eyes in group 1 and 17 eyes in group 2). The mean depth of the corneal stromal demarcation line was 208.64 ± 18.41 μm in group 1 and 240.37 ± 18.89 μm in group 2 measured with AS OCT, while it was 210.29 ± 18.66 μm in group 1 and 239.37 ± 20.07 μm in group 2 measured with confocal microscopy. Corneal stromal demarcation line depth measured with AS OCT or confocal microscopy was significantly deeper in group 2 than group 1 (P < 0.01). Conclusion. The group in which riboflavin was applied for 30 minutes showed significantly deeper corneal stromal demarcation line than the group in which riboflavin was applied for 20 minutes.

Long-term results of phacoemulsification combined with primary posterior curvilinear capsulorhexis in adults

Objective: To evaluate the 2-year outcomes of phacoemulsification combined with primary posterior curvilinear capsulorhexis (PPCC) in adults. Materials and Methods: In this retrospective case series, 93 eyes of 91 patients with bilateral age-related cataract who underwent phacoemulsification combined with PPCC were evaluated. The study included cases due to postoperative residual posterior capsule opacification despite careful polishing. Data were evaluated on preoperative and postoperative best corrected visual acuity (CDVA) (Snellen acuity), slit-lamp biomicroscopy and intraocular pressure (IOP) measurement. Perioperative and postoperative complications were also recorded. Results: The mean follow-up was 24.9 ±13.5 months (range, 12-53 months). At the last visit, 87.1% of the eyes had CDVA ≥ 20/40 and 58% had ≥ 20/25. Posterior capsular opacification (PCO) occurred in 2 (2.2%) of patients. No serious complications such as retinal detachment and endophthalmitis were observed during follow-up. Conclusions: Cataract surgery combined with PPCC is a safe procedure with a low rate of complications over the long term. This procedure reduced the necessity of Nd:YAG laser capsulotomy in adults with postoperative residual posterior capsule opacification despite careful polishing.

Evaluation of Corneal Morphologic and Functional Parameters After Use of Topical Cyclosporine-A 0.05% in Dry Eye

PURPOSE To report the effect of topical Cyclosporine-A (CsA) 0.05% on corneal morphologic and functional parameters in patients with dry eye. METHOD In this prospective and observational study 30 eyes of 30 patients who received topical CsA 0.05% for treatment of dry eye were evaluated. Each clinical examination included a routine Schirmer I test and tear film break-up time (TBUT) was performed at baseline and after 1, 2, 3, and 6 months of treatment. All participants also underwent central corneal thickness (CCT) measurements with ultrasound pachymetry, endothelial cell density (ECD) with specular microscopy, corneal topographical evaluation with Orbscan II, and corneal biomechanical parameters with Ocular Response Analyzer measurements at baseline and after treatment. RESULTS The Schirmer I test and TBUT were significantly improved after treatment (for both; P<0.01). The CCT, topographical findings, ECD, and corneal biomechanical parameters were not significantly different at baseline and follow-up visits (P>0.05). No serious adverse effects were seen at follow up visits. CONCLUSION The study showed that Topical CsA 0.05% caused no changes on corneal morphology and function.

Fellow Eye Comparison of Nerve Fiber Regeneration After SMILE and Femtosecond Laser-assisted LASIK: A Confocal Microscopy Study.

PURPOSE To compare postoperative corneal nerve fiber regeneration after small incision lenticule extraction (SMILE) and femtosecond laser-assisted LASIK (FS-LASIK). METHODS The medical records of patients who underwent SMILE were retrospectively reviewed. Patients with SMILE in one eye (the SMILE group) and FS-LASIK in the fellow eye (the FS-LASIK group) and who had undergone a confocal microscopy study were retrospectively identified. Subbasal nerve fiber density was measured and compared between the groups preoperatively and at 1 week and 1, 3, and 6 months postoperatively. RESULTS Thirty eyes of 15 patients were included in the study. Preoperative characteristics of the eyes were similar between the groups. However, there was a statistically significant difference in subbasal nerve fiber density between the groups at 1 month (SMILE group: 1,505 ± 627 µm/mm(2) [range: 625 to 2,540 µm/mm(2)], FS-LASIK group: 1,107 ± 509 µm/mm(2) [range: 595 to 2,313 µm/mm(2)], P = .003) and 3 months (SMILE group: 1,534 ± 503 µm/mm(2) [range: 650 to 2,255 µm/mm(2)], FS-LASIK group: 1,194 ± 485 µm/mm(2) [range: 530 to 1,695 µm/mm(2)], P = .004) postoperatively. No statistically significant difference was detected at 1 week and 6 months postoperatively. CONCLUSION Eyes treated with SMILE have a higher density of subbasal nerve fibers than eyes treated with FS-LASIK in the early postoperative period (1 week to 3 months) but the two procedures are equivalent by 6 months postoperatively.

Corneal biomechanical properties in children with diabetes mellitus.

Purpose. To compare the biomechanical properties of corneas in eyes of children with diabetes mellitus and in eyes of children without diabetes mellitus. Methods. In this prospective, comparative, and cross-sectional study, 46 patients with diabetes mellitus (study group) and 50 healthy individuals (control group) were enrolled. The corneal hysteresis (CH) and corneal resistance factor (CRF) were measured in children with and without diabetes using the Ocular Response Analyzer. Differences in the corneal biomechanical properties were determined using an independent-samples t test. Correlations between ocular and diabetic parameters were also evaluated. Results. Mean CH was 12.3±1.3 (SD) mmHg and 12.5±1.5 mmHg and the mean CRF was 12.4±1.7 mmHg and 11.9±1.5 mmHg in the diabetic and control groups, respectively (p>0.05). Corneal hysteresis and CRF were not correlated with fasting glucose level, HbA1c, age, or duration of diabetes. Conclusions. The findings indicate that diabetes mellitus does not affect corneal biomechanical parameters such as CH and CRF in children. In addition, CH and CRF are not affected by fasting glucose level, HbA1c, age, or duration of diabetes.

Refractive, Topographic, and Aberrometric Results at 2-Year Follow-Up for Accelerated Corneal Cross-Link for Progressive Keratoconus

Purpose. To report the visual, refractive, and corneal topography and wavefront aberration results of accelerated corneal cross-linking (CXL) during a 24-month follow-up. Methods. Forty-seven eyes underwent riboflavin-ultraviolet A-induced accelerated CXL treatment (30 mW/cm2 with a total dose of 7.2 joules/cm2). Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), spherical and cylindrical values, keratometry (K) measurements (K steep, K flat, K avg, and K apex), central corneal thickness, and anterior corneal aberrometric analyses including total wavefront error (WFE), total high order aberration (HOA), astigmatism, trefoil, coma, quadrafoil, secondary astigmatism, and spherical aberration were evaluated. Results. The mean UDVA and CDVA were significantly improved at 1 (p = 0.003 and p = 0.004, resp.) and 2 years after treatment (p = 0.001 and p = 0.001, resp.). The mean K steep, K flat, K average, and K apex values were significantly lower than baseline at 12 months (p = 0.008, p = 0.024, p = 0.001, and p = 0.014, resp.) and 24 months (p = 0.014, p = 0.017, p = 0.001, and p = 0.012, resp.). Corneal thickness showed a significant decrease at 1 month. Total HOA and coma decreased significantly at the 12-month (p = 0.001 and p = 0.009, resp.) and 24-month visits (p = 0.001 and p = 0.007, resp.). Conclusion. Accelerated CXL (30 mW/cm2) was found to be effective in improving UDVA, CDVA, corneal topography readings, total HOA, and coma aberrations during the 24-month follow-up.