Characterization of Corneal Biomechanics Using CORVIS ST Device in Different Grades of Myopia in a Sample of Middle Eastern Ethnicity.

Purpose: To characterize corneal biomechanical properties using the CORVIS-ST device in myopic individuals. Methods: This prospective cross-sectional study included patients with myopia. Our study included 154 eyes of 154 myopic patients aged between 18 and 40 years, with stable refraction for at least 2 years. A full ophthalmological examination and corneal tomography were performed using a Pentacam HR device. Corneal biomechanical parameters were assessed using the CORVIS-ST device in mild, moderate, severe, and extreme myopia groups. Results: Statistically significant differences were observed in the DA ratio (p = 0.033), SP-A (p=0.009), CBI (p=0.041), SSI (p=0.000), and Peak distance (p = 0.032). In correlation with different Corvis ST biomechanical variables, SE was found to be correlated with DA ratio(r=-0.191, p=0.018), SP-A(r=0.199, p=0.013) and SSI(r=-0.336, p=0.000), while in multiple regression analysis, SE was found to be independently correlated with SSI and peak distance(p=0.036,0.038 respectively) while the grade of myopia was found to be independently correlated with SP-A(p=0.034). Conclusion: SSI, Peak distance, and SP-A were independently related to SE and myopia grade, confirming the hypothesis that eyes with higher myopia are more deformable and less stress resistant.

CHANDELIER-ASSISTED VERSUS STANDARD SCLERAL BUCKLING FOR PRIMARY RHEGMATOGENOUS RETINAL DETACHMENT: A Randomized Clinical Study.

PURPOSE: To compare anatomical outcomes, functional outcomes, and rate of complications of standard scleral buckling (SSB) versus chandelier-assisted scleral buckling (CSB) in phakic eyes with rhegmatogenous retinal detachment. METHODS: Patients were randomly assigned to either SSB or CSB. Surgical success/failure rate, corrected distance visual acuity, surgical operating time, and rate of intraoperative and postoperative complications including epiretinal membranes by spectral domain optical coherence tomography were compared between groups. RESULTS: A total of 50 eyes of 49 patients were included. At 6 months, there was no statistically significant difference between groups in primary success, or final anatomical success ( P > 0.9); mean corrected distance visual acuity at any visit ( P values >0.05); or mean surgical time: 120.3 ± 39.05 and 102.48 ± 43.76 minutes for the SSB and CSB, respectively ( P = 0.1). The CSB had a higher rate of postoperative complications (34.8%) compared with the SSB (3.8%) ( P < 0.05). On spectral domain optical coherence tomography, CSB had a statistically significant higher rate of epiretinal membranes compared with SSB (44% vs. 19% [ P < 0.05]) and showed vitreous entrapment in the chandelier sclerotomy site on the ultrasonic biomicroscopy. CONCLUSION: Chandelier-assisted scleral buckling surgery does not offer encouraging advantages over SSB. On the contrary, we detected a higher rate of complications with CSB especially epiretinal membranes development.

Long-term changes in ocular rigidity following scleral buckling for rhegmatogenous retinal detachment.

PURPOSE: To investigate the long-term effect of scleral buckling on corneal biomechanics and the effect of change of scleral properties on intraocular pressure (IOP) measurements. METHODS: This is a prospective case series, patients with rhegmatogenous retinal detachment prepared for scleral buckling were included. Goldmann applanation tonometry was used to measure IOP (GAT IOP). Ocular Response Analyzer (ORA) was used to measure corneal hysteresis (CH), corneal resistance factor (CRF), goldmann-corrected IOP (IOPg), and corneal-compensated IOP (IOPcc) preoperatively, and 1, 3, and 6 months postoperatively. RESULTS: Thirty-three eyes included in the final analysis, with an average age 38.4 ± 16.2 years. CH and CRF decreased significantly at first, third, sixth months post-scleral buckling; however, this effect decreased with time as follows; preoperative: 8.9 ± 1.5 and 8.5 ± 2.1, first month: 6.8 ± 1.6 and 7.1 ± 1.8 (P value = 0.00, 0.002), third month: 7.8 ± 1.5 and 7.6 ± 1.6 (P value = 0.001, 0.008), and sixth month: 7.7 ± 1.3 and 7.6 ± 1.7 (P value = 0.002, 0.055). IOP cc was 19.3 ± 3.6, 17.1 ± 4, and 17.6 ± 2.9 at 1, 3, and 6 months, and these readings were significantly higher than GAT (13.6 ± 7.6, 12.4 ± 5.1, and 12.1 ± 2.9, P values = 0.00) and IOPg (14.9 ± 3.6, 13.5 ± 4.1, and 13.9 ± 3.5, P values = 0.00). The change in CH at each visit is correlated with the difference between the IOPcc and GAT measurements. CONCLUSION: The conventional Goldmann applanation tonometry underestimates post buckle IOP measurements due corneal biomechanics changes. ORA might be an alternative and accurate method of measurement; however, further investigation is warranted.