Corneal Collagen Cross-Linking in the Treatment of Progressive Keratoconus: A Randomized Controlled Contralateral Eye Study.

BACKGROUND: To assess the short-term efficacy and safety of corneal collagen cross-linking (CXL) in preventing the progression of keratoconus (KCN). MATERIALS AND METHODS: This randomized controlled clinical trial enrolled 26 patients diagnosed with bilateral progressive KCN and were eligible for CXL. In each patient, one eye was randomly selected for treatment, and the contralateral eye served as the control. The patients underwent CXL with riboflavin drops and ultraviolet radiation in the treated eye. One year follow-up data are presented. Postoperatively, patients were assessed for progression of KCN, visual changes, and other findings. The main outcome measures were maximum simulated keratometry (K-max), best spectacle-corrected visual acuity (BSCVA), and average simulated keratometry. P <0.05 was considered as statistically significant. RESULTS: In the treated eyes, the mean K-max values decreased by 0.22 D at 1-year postoperatively and increased by 0.41 D in the control group. This difference was statistically significant (P < 0.001). BSCVA improved slightly (a decrease of 0.13 LogMAR) and decreased slightly in the control group (a 0.01 LogMAR increase). The difference between groups was statistically significant (P = 0.014). There was no decrease in visual acuity attributable to complications of CXL in the treated eyes. At 1-year, the keratometry in 3 (12%) treated eyes increased by more than 0.50 D and were considered cases of failed treatment. CONCLUSION: Preliminary and 1-year results indicate CXL can halt the progression of KCN in most cases without causing serious complications.

Improvement in visual acuity and contrast sensitivity in patients with central serous chorioretinopathy after macular subthreshold laser therapy.

PURPOSE: The purpose of the study was to measure the improvement in vision and contrast sensitivity in patients with central serous chorioretinopathy after macular subthreshold laser therapy. METHODS: Cases included in this clinical trial were patients diagnosed with acute central serous chorioretinopathy less than 1 month in duration. Each patient was randomized to either observation group or treatment group with subthreshold argon laser. First and sixth month of follow-up results were then recorded, and visual improvement and contrast sensitivity were compared between the two groups. RESULTS: Of 37 patients with central serous chorioretinopathy, 25 were men and 12 were women with a mean age of 38.6 ± 5.9 years. At 6 months, mean best-corrected visual acuity improved from 0.26 to 0.03 logarithm of the minimum angle of resolution in the laser group and from 0.12 to 0.04 logarithm of the minimum angle of resolution in the observation group (P < 0.001). Except spatial frequencies of 18 cycles per degree (P = 0.207), the contrast sensitivity in spatial frequencies of 3, 6, and 12 cycles per degree was significantly more favorable in the laser group during the first and sixth month. CONCLUSION: Treatment of patients with acute central serous chorioretinopathy with subthreshold laser improved the best-corrected visual acuity and contrast sensitivity compared with those in the observation group. The laser group also showed a more rapid improvement. In both groups, best-corrected visual acuity improved in most patients after 6 months; however, the contrast sensitivity was significantly better in the treatment group.

Confocal microscopy of corneal stroma and endothelium after LASIK and PRK.

PURPOSE: To compare with confocal microscopy the changes in stromal keratocyte density and endothelial cell count due to photorefractive keratectomy (PRK) and LASIK. METHODS: In this prospective study, 32 eyes (16 myopic patients) were examined with the NIDEK Confoscan 3 confocal microscope before and 6 months after PRK and LASIK. The preoperative mean myopia was -2.85+/-0.99 diopters (D) (range: -1.00 to -4.00 D) in 24 eyes that underwent PRK and -2.94+/-0.96 D (range: -2.00 to -4.25 D) in 8 eyes that underwent LASIK. Keratocyte density in the anterior and posterior stroma and the endothelial cell count were measured. Statistically significant changes were assessed using the t test. P<.05 was considered statistically significant. RESULTS: Preoperative hexagonal cell percentage in the LASIK group was 52.17+/-11.43 and 51.33+/-10.98 in the PRK group. Postoperatively, the percentages were 52.96+/-7.55 and 53.34+/-10.2, respectively. Six months postoperatively, keratocyte density changed by 367.12+/-103.35 cells/mm(2) (34.7% reduction) in the anterior stroma (P<.05) and 9.25+/-28.28 cells/mm(2) (1.31% reduction) in the posterior stroma (P>.05) for the LASIK group. In the PRK group, these values were 319.71+/-83.45 cells/mm(2) (31.13% reduction) in the anterior stroma (P<.05) and 0.17+/-38.97 cells/mm(2) (0.02% reduction) in the posterior stroma (P>.05). The changes in keratocyte densities were not statistically significant between groups (P>.05). The mean number of keratocytes decreased by 37.2% in the retroablation zone of the LASIK group (P<.05). No changes were noted in endothelial cell counts. CONCLUSIONS: A significant decrease occurred in the number of stromal keratocytes in the anterior stroma. Despite differences in surgery, the change in keratocyte density and endothelial cell counts were similar between LASIK and PRK groups (P>.05).