Hatice Nur Colak

Corneal collagen crosslinking for ectasia after laser in situ keratomileusis: Long-term results

Purpose To report the long‐term results of corneal collagen crosslinking (CXL) treatment for post‐laser in situ keratomileusis (LASIK) ectasia. Settings Turkiye Hospital Eye Clinic and Fatih University Medical Faculty, Department of Ophthalmology, Istanbul, Turkey. Design Retrospective case series study. Methods Consecutive patients with ectasia after LASIK were treated with CXL. The main outcome measures were uncorrected (UDVA) and corrected (CDVA) distance visual acuities, spherical and cylindrical refractions, and simulated keratometry (K) values. Results The study enrolled 20 eyes (14 patients; 7 women) with a mean age of 34.8 years ± 6.0 (SD) (range 25 to 45 years) and mean follow‐up of 42 months (range 36 to 60 months). The UDVA and CDVA improved significantly, from 0.78 ± 0.61 logMAR to 0.53 ± 0.36 logMAR (P=.007) and from 0.27 ± 0.23 logMAR to 0.19 ± 0.13 logMAR, respectively (P≤.028). No eye lost 1 or more Snellen lines of UDVA or CDVA. Although the mean spherical refraction was not significantly different at the last visit (P=.074), the mean cylindrical refraction decreased significantly (P=.036). The maximum K value decreased from 46.0 ± 4.4 diopters (D) at baseline to 45.6 ± 3.8 D at the last visit (P=.013). By the last visit, the maximum K value decreased (≥1.0 D) in 5 eyes and remained stable in 15 eyes. No serious complications occurred. Conclusions Corneal collagen crosslinking yielded long‐term stability in cases with post‐LASIK corneal ectasia without significant side effects. Improvements in visual acuity, cylindrical refraction, and maximum K values occurred. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

Risk Factors in Post-LASIK Corneal Ectasia.

Purpose. To evaluate the risk factors for post-laser in situ keratomileusis (LASIK) ectasia. Materials and Methods. Medical records of 42 eyes of 28 (10 women, 18 men) patients who developed corneal ectasia after LASIK were retrospectively reviewed. Topographical features and surgical parameters of those patients were evaluated. Results. The mean age of patients was 34.73 ± 6.50 (23–48) years and the mean interval from LASIK to the diagnosis of post-LASIK ectasia was 36.0 ± 16.92 (12–60) months. The following factors were determined as a risk factors: deep ablation (>75 μm) in 10 eyes, FFK (forme fruste keratoconus) in 6 eyes, steep cornea (>47 D) in 3 eyes, pellucid marginal degeneration (PMD) in 2 eyes, thin cornea (<500 μm) in 2 eyes, thin and steep cornea in 2 eyes, thin cornea and deep ablation in 5 eyes, FFK and steep cornea in 2 eyes, and FFK, steep cornea, and deep ablation in 1 eye. However no risk factor has been determined in 9 eyes (21.4%). Conclusion. The findings of our study showed that most of the patients who developed post-LASIK ectasia have a risk factor for post-LASIK ectasia. However, the most common risk factor was deep ablation.

Choroidal and peripapillary retinal nerve fiber layer thickness in adults with anisometropic amblyopia.

Purpose To evaluate choroidal thickness, macular thickness, and peripapillary retinal nerve fiber layer (RNFL) thickness in amblyopic eyes compared to fellow and normal control eyes using high-definition spectral-domain optical coherence tomography (SD-OCT). Methods Fifty-four without any systemic problem and ocular disease participated in this prospective study. Inclusion criteria included individuals older than 18 years with anisometropic amblyopia. Choroidal thickness, central macular thickness (CMT), and RNFL thickness were measured by using enhanced depth imaging SD-OCT. The choroidal thickness was measured at the fovea and at 500 μm intervals from the foveal center in both temporal and nasal directions. Axial length measurements of the cases were also recorded. Results Mean peripapillary RNFL thickness of the amblyopic, fellow, and control eyes was 107.5 ± 15.5 μm, 109.3 ± 12.7 μm, and 108.8 ± 8.6 μm, respectively (p = 0.343). The average CMT was 231.7 ± 14.7 μm in amblyopic eyes, 232.5 ± 15.7 μm in fellow eyes, and 230.8 ± 14.8 μm in control eyes (p = 0.599). Mean subfoveal choroidal thickness was significantly greater in the amblyopic eyes than in the fellow and control eyes (396.3 ± 104.3 μm, 361.0 ± 103.9 μm, 390.6 ± 91.7 μm). Mean axial measurement in amblyopic eyes was 22.7 ± 1.3 mm (20.5–26.1), in fellow eyes 23.1 ± 0.9 mm (20.9–25.0), and in control eyes 23.3 ± 0.9 mm. Conclusions In adults with anisometropic amblyopia, subfoveal, temporal, and nasal choroidal thickness of amblyopic eyes are significantly thicker than in fellow eyes. However, no significant differences in peripapillary RNFL thickness or CMT were found between amblyopic and fellow or control eyes.

Comparison of corneal topographic measurements and high order aberrations in keratoconus and normal eyes

PURPOSE The aim of this report was to compare corneal topographic measurements and anterior high order corneal aberrations in eyes with keratoconus and normal eyes by using Scheimpflug-Placido topography. METHODS Eighty cases diagnosed with mild (group 1), moderate (group 2), and advanced (group 3) stage keratoconus (KC) according to Amsler-Krumeich Classification and 81 healthy (control group) cases were retrospectively examined. The mean keratometric measurements (as both diopters (Kavg) and mm values (mmavg)), central corneal thickness values (CCT), high order aberration (HOA), total wavefront aberration (TWA), coma, trefoil, and spherical aberration measurements were performed using Sirius topography equipment. The topographic values were compared between the groups. RESULTS There were 25 cases in group 1 KC (15.5%), 34 cases in group 2 KC (21.1%), 21 cases in group 3 KC (13.1%), and 81 cases (50.3%) in the control group. In terms of mean age and gender distributions, there was no statistically significant difference between the groups (p>0.05). However, there was significant difference between the groups in terms of Kavg, CCT, HOA, TWA, coma, trefoil, and spherical aberration values (p<0.01). Mean HOA, TWA, coma, trefoil, and spherical aberration values were observed to increase with the severity of KC disease. CONCLUSIONS Anterior high order corneal aberrations were significantly increased in eyes with moderate and advanced keratoconus. Anterior high order corneal aberration measurements are a useful tool to guide the physician in diagnosis and classification of keratoconus.

Retinal nerve fiber layer, ganglion cell complex, and choroidal thicknesses in migraine

PURPOSE To evaluate the thicknesses of the peripapillary retinal nerve fiber layer (RNFL), ganglion cell complex (GCL), and choroid layer using spectral domain optical coherence tomography (SD-OCT) for investigating the effects of vascular changes on the eye and optic nerve in patients who have migraine with aura. METHODS Forty-five patients who had migraine with aura (migraine group) and 45 healthy individuals (control group) were enrolled in the study. Age, gender, duration after migraine diagnosis, intraocular pressure, and axial length measurements were recorded in each case. RNFL, GCL, and choroid layer thicknesses were measured using SD-OCT in all participants. RESULTS The mean age was 36.1 ± 6.7 (20-45) years in the migraine group and 35.7 ± 8.6 (19-45) years in the control group. There was no significant difference in the RNFL thicknesses of the temporal and nasal quadrants (p >0.05). The RNFL thicknesses of the superior and inferior quadrants were significantly lower in the migraine group compared with those in the control group (p =0.001, p <0.01, respectively). Measurements for the superior and inferior GCL were not significantly different between the groups (p >0.05). Subfoveal, temporal, and nasal choroidal thickness measurements at 500 µm, 1000 µm, and 1500 µm were significantly lower in the migraine group than in the control group (p =0.001; p <0.01, respectively). CONCLUSIONS Compared with the controls, the RNFL and choroid layer were determined to be thinner in patients who had chronic migraine with aura.

A PILOT STUDY OF CHOROIDAL THICKNESS IN LONG-TERM SMOKERS.

Purpose: To compare the choroidal thicknesses in long-term smokers with those of nonsmoking healthy individuals using spectral domain optical coherence tomography. Participants: Forty-six individuals who had been smoking at least for 20 years, but otherwise without systemic problems, participated in this prospective pilot study. The control group comprised 42 nonsmoking individuals. Methods: The ages, refractions, and axial length measurements of the cases were recorded. Central macular thickness and choroidal thickness at the fovea and at 500 &mgr;m intervals from the foveal center in both temporal and nasal directions were measured using spectral domain optical coherence tomography. Results: Although the smoking period of the smokers was mean 32.4 ± 9 years (range: 20–60), the mean pack-years of cigarettes was 35.1 ± 23.8 (range: 10–120). No significant difference was observed regarding refraction value and axial length between smokers and nonsmokers group. In addition, no significant difference was observed for central macular thickness and choroidal thickness values at 500, 1,000, 1,500, and 2,000 &mgr;m nasal and temporal part of the fovea, between 2 groups. Conclusion: Macular and choroidal thicknesses in long-term smokers were observed to be similar to those of healthy individuals.

Effect of Hydroxychloroquine on the Retinal Layers: A Quantitative Evaluation with Spectral-Domain Optical Coherence Tomography

Purpose. To evaluate the effect of hydroxychloroquine on retinal pigment epithelium- (RPE-) Bruchs membrane complex, photoreceptor outer segment, and macular ganglion cell-inner plexiform layer (GCIPL) thicknesses using spectral-domain optical coherence tomography (SD-OCT). Methods. In this prospective case-control study, 51 eyes of 51 hydroxychloroquine patients and 30 eyes of 30 healthy subjects were included. High-quality images were obtained using a Cirrus HD-OCT with 5-line raster mode; the photoreceptor inner segment (IS) and outer segment (OS), sum of the segments (IS + OS), and RPE-Bruchs membrane complex were analyzed. Results. The thicknesses of the IS + OS and OS layers were significantly lower in the hydroxychloroquine subjects compared to the control subjects (P < 0.05). RPE-Bruchs membrane complex thicknesses were significantly higher in the hydroxychloroquine subjects than for those of the control subjects (P < 0.05). The minimum and temporal-inferior macular GCIPL thicknesses were significantly different between the patients with hydroxychloroquine use and the control subjects (P = 0.04 and P = 0.03, resp.). Conclusions. The foveal photoreceptor OS thinning, loss of GCIPL, and RPE-Bruchs membrane thickening were detected in patients with hydroxychloroquine therapy. This quantitative approach using SD-OCT images may have important implications to use as an early indicator of retinal toxicity without any visible signs of hydroxychloroquine retinopathy.