Engin Bilge Ozgurhan

Comparison of corneal hysteresis and corneal resistance factor after small incision lenticule extraction and femtosecond laser-assisted LASIK: A prospective fellow eye study

PURPOSE To compare corneal hysteresis (CH) and corneal resistance factor (CRF) between eyes treated with small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (femto-LASIK). SETTING Beyoğlu Eye Training and Research Hospital. DESIGN Prospective comparative case series. METHODS Sixty eyes from 30 patients with bilateral myopia or myopic astigmatism were studied. Inclusion criteria were spherical equivalent of subjective manifest refraction (SE) <10diopters (D) and a difference ≤0.50D between the SEs of both eyes. One eye of each patient was treated with SMILE, and the fellow eye underwent femto-LASIK. Randomization was performed using a sealed envelope system. The main outcome measures were CH and CRF measured preoperatively and postoperatively (1 and 6 months). RESULTS Preoperative SE was similar in both groups (p=0.852). CH and CRF values were reduced postoperatively in both groups compared to their corresponding preoperative values (p<0.001). At the 6-month follow-up visit, the mean CH values in the SMILE and femto-LASIK groups were 8.95±1.47 and 9.02±1.27, respectively (p=0.852), and the mean CRF values were 7.77±1.37 and 8.07±1.26, respectively (p=0.380). CONCLUSION CH and CRF decreased after SMILE. There were no differences between SMILE and femto-LASIK treatments in postoperative CH or CRF values.

Corneal sensation after corneal refractive surgery with small incision lenticule extraction.

Purpose To compare effects of small-incision lenticule extraction (SMILE) and femtosecond laser-assisted in situ keratomileusis (F-LASIK) on corneal sensation and dry eye parameters. Methods In this prospective, randomized, contralateral-eye study, 28 patients with myopia or myopic astigmatism in both eyes were enrolled. One eye of each patient was treated by SMILE, and the fellow eye was treated by F-LASIK. Mean outcome measures Cochet-Bonnet esthesiometry, Schirmer test with anesthesia, tear breakup time, and tear film osmolarity were evaluated preoperatively as well as 1 week, 1 month, 3 months, and 6 months after surgery. Results Corneal sensation was reduced after both SMILE and F-LASIK surgeries 1 week, 1 month, and 3 months after surgery (p < 0.05 in both groups). Corneal sensation was significantly lower after F-LASIK than after SMILE at postoperative 1 week, 1 month, and 3 months (p < 0.01 for all points). Dry eye parameters such as tear breakup time, Schirmer test, and tear film osmolarity did not change significantly in any of the procedures and were not significantly different between the procedures at any follow-up visits. Conclusions The findings of the study revealed that, although both F-LASIK and SMILE procedures changed the corneal sensation 1 week, 1 month, and 3 months after surgery, they did not affect the dry eye parameters at any point.

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 Cross-linking in Pediatric Patients With Keratoconus: 24-Month Outcomes

PURPOSE To compare the efficiency and safety of accelerated corneal cross-linking in pediatric patients with progressive keratoconus. METHODS In this retrospective interventional case series, 44 eyes of 38 pediatric patients with progressive keratoconus were enrolled. All consecutive patients underwent accelerated corneal cross-linking with settings of 30 mW/cm(2) for 4 minutes, corresponding to a total dose of 7.2 J. The efficacy and safety of the procedure were assessed over a 24-month follow-up period. RESULTS Mean ± standard deviation age of 10 girls and 28 boys was 15.3 ± 2.1 years (range: 9 to 18 years). Uncorrected distance visual acuity improved significantly from 0.52 ± 0.36 to 0.39 ± 0.26 logMAR (P = .002), and corrected distance visual acuity improved significantly from 0.38 ± 0.24 to 0.30 ± 0.20 logMAR (P < .001). Mean spherical and cylindrical refraction were not significantly altered (P > .001 for both). At the last follow-up visit, the flat keratometry value decreased from baseline from 46.4 ± 3.0 to 46.0 ± 2.9 diopters and the steep keratometry value decreased from 50.6 ± 4.2 to 50.1 ± 4.0 diopters (P < .001 for both). The total higher-order aberrations, coma, and astigmatism II values were also significantly decreased at 24 months after treatment (P < .05 for all). No serious complications were recorded during the follow-up. CONCLUSIONS The findings revealed that accelerated corneal cross-linking halted the keratoconus progression without relevant side effects in pediatric patients over a 24-month follow-up period. Visual acuity, keratometric values, and corneal aberrations also improved.

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.

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 microstructure in keratoconus: a confocal microscopy study.

PURPOSE To compare the corneal microstructure in patients with manifest keratoconus (KCN), subclinical KCN, and topographically normal relatives of patients with KCN and in healthy controls. DESIGN Prospective and cross-sectional study. METHODS We enrolled 145 subjects in the study. The participants were divided into 4 groups, based on clinical and topographical evaluation: the manifest KCN group (n = 30), the subclinical KCN group (n = 32), the KCN relatives group (n = 53), and the control group (n = 30). Corneal microstructure was assessed by corneal in vivo confocal microscopy in all of the individuals. Mean outcome measures were basal epithelial cell density, endothelial cell density, anterior keratocyte density, posterior keratocyte density, sub-basal nerve density, sub-basal nerve diameter, and stromal nerve diameter. RESULTS The mean basal epithelial cell density, endothelial cell density, and sub-basal nerve diameter were not significantly different among the 4 groups (P = 0.057, P = 0.592, and P = 0.393, respectively). The mean anterior and posterior stromal keratocyte densities were significantly lower in the manifest group, in the subclinical group, and in the relatives group when compared with the control group (for both parameters; P < 0.001, P < 0.001, and P< 0.001, respectively). The mean stromal nerve diameter in the manifest group, subclinical group, and relatives group was significantly higher than in the control group (P = 0.001, P = 0.049, and P = 0.004, respectively). CONCLUSION The anterior and posterior stromal keratocyte densities were statistically lower and stromal nerve diameter was statistically higher in patients with manifest KCN, subclinical KCN, and topographically normal KCN relatives compared with controls. Confocal microscopy may be useful for the determination of early corneal microstructural changes before manifestation of typical or subtle topographic signs.

Topical Application of Bevacizumab as an Adjunct to Recurrent Pterygium Surgery

Purpose: To evaluate the clinical outcomes of topical bevacizumab as adjunctive to the surgical excision for treatment of recurrent pterygium. Methods: The 44 patients who underwent recurrent pterygium excision with conjunctival autograft transplantation were enrolled in this prospective and interventional study. The patients were randomized in 2 groups: study group, 1 month after surgery, 22 patients received only topical bevacizumab (5 mg/mL) 4 times daily for 2 months; control group, 1 month after surgery, 22 patients were administered only an artificial tear 4 times daily for 2 months. Patients were prospectively followed for 6 months after pterygium surgery. The main outcome measures were pterygium recurrence, corneal neovascularization, and other postoperative complications. Results: No statistically significant differences were observed between the 2 groups in terms of age, gender distributions, laterality, length of pterygium, and number of recurrence. A pterygium recurrence was not noted in any patients in the study group but was noted in 2 of 22 eyes (9%) in the control group during the follow-up after surgery (P = 0.244). Although none of the patients developed corneal neovascularization in the study group, 5 of 22 eyes (22.7%) developed this condition in the control group during the follow-up after surgery (P = 0.024). No serious complications were observed during the follow-up period in both the groups. Conclusions: Topical bevacizumab therapy 1 month after surgical excision of recurrent pterygium is well tolerated and effective to prevent neovascularization. Although the recurrence rate is lower in the study group without significant difference, further studies are required to support this result.

Accuracy and precision of cap thickness in small incision lenticule extraction.

Aims To report and compare the cap thickness predictability of small incision lenticule extraction (SMILE) and flap thickness of femtosecond laser-assisted in situ keratomileusis (femto-LASIK). Settings and design Beyoglu Eye Training and Research Hospital, Refractive Surgery Department, Istanbul, Turkey. Retrospective pilot study. Materials and methods Medical records of patients who had SMILE in one eye and femto-LASIK in the other eye were reviewed. Visante corneal Optical Coherence Tomography (OCT) images at 1 week and 1 month post-surgery were analyzed. Both cap and flap thickness at the temporal edge and the nasal edge were measured and compared to each other. Statistical analyses used PAWS Statistics 18 and unpaired student t-test were used to compare the groups. Results The study included 66 eyes of 33 patients (24.7 ± 3.8 years, 20 females and 13 males). Mean flap thickness was 114.88 μm ± 4.96 μm, and mean cap thickness was 114.63 μm ± 5.18 μm. In group 1 (SMILE), cap thickness values were 115.84 μm ± 6.84 μm, 114.75 μm ± 7.36 μm, 113.66 μm ± 6.88 μm, and 114.27 μm ± 6.90 μm in measurement zones 1, 2, 3, and 4, respectively. In group 2 (FemtoLASIK), flap corneal thickness values were 115.96 mmHg ± 7.01 mmHg, 114.72 mmHg ± 7.17 mmHg, 113.54 mmHg ± 6.45 mmHg, and 115.30 mmHg ± 6.64 mmHg in measurement zones 1, 2, 3, and 4, respectively. In both groups, no statistically significant change within the measurement zones was observed. Conclusion The predictability of cap thickness in SMILE surgery does not differ from the femto-LASIK flaps created using the same femtosecond laser platform.

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.