RESUMO
PURPOSE: To report visual outcomes and corneal biomechanical changes after femtosecond-assisted Intacs SK implantation in keratoconic eyes. METHODS: This prospective interventional case series is comprised of 32 keratoconic eyes of 25 patients with mean age of 23.8 ± 5.4 years. Uncorrected (UDVA) and corrected (CDVA) distance visual acuity, refraction, manifest refraction spherical equivalent (MRSE), keratometry, central corneal thickness (CCT), corneal hysteresis (CH) and corneal resistance factor (CRF) were measured preoperatively, and 1, 3 and 6 months postoperatively. RESULTS: Mean UDVA improved from 0.81 ± 0.3 LogMAR preoperatively to 0.53 ± 0.2 LogMAR six months postoperatively (P < 0.001). At 6 months, MRSE was significantly reduced only in eyes with moderate KCN (mean change, +2.61 ± 0.54 diopter [D]; P< 0.001). A significant improvement in sphere (mean change, +1.92 ± 0.37 D; P< 0.001) and mean keratometry (mean change, -3.34 ± 0.47D; P< 0.001) were observed. CCT increased from 446.1 ± 38 µm preoperatively to 462.2 ± 50 µm at six months (P < .001). CRF decreased from 6.5 ± 1.6 mmHg to 5.9 ± 1.1 mmHg six months after surgery (P = 0.02). CDVA, refractive cylinder and CH did not change significantly (P = 0.48, 0.203 and 0.55, respectively). Linear regression analysis disclosed that a decrease in CCT and moderate KCN are associated with higher CRF (standardized B,-0.513 and 0.314;P= 0.004 and 0.024, respectively; Adjusted R square = 0.353). CONCLUSION: Visual, refractive and keratometric indices remarkably improved in a parallel fashion. CRF was inversely associated with CCT. Changes in CRF represent the trend of changes in corneal biomechanics and thickness during the early postoperative months.
RESUMO
PURPOSE: To compare the 6-month results of accelerated and standard collagen crosslinking (CXL) treatment of progressive keratoconus. SETTING: Noor Eye Hospital, Tehran, Iran. DESIGN: Prospective randomized clinical trial. METHODS: Two groups of eyes (intervention and control) received corneal collagen crosslinking (CXL) treatment. The intervention group received accelerated CXL (18 mW/cm(2), 5 minutes), and the control group received standard CXL (3 mW/cm(2), 30 minutes). The eyes were evaluated for changes in the visual indices, refraction, and topography preoperatively and 1, 3, and 6 months postoperatively and regarding corneal rigidity indices and the endothelial cell count (ECC) preoperatively and at 6 months. RESULTS: The study evaluated 62 eyes (31 patient) in 2 groups. The mean changes in uncorrected (P = .733) and corrected (P = .646) distance visual acuities and manifest refraction spherical equivalent (P = .598) did not differ statistically significantly between the 2 groups. The central corneal thickness was higher in the standard group than the accelerated group (P = .025). The mean decrease in the maximum keratometry (K) (P = .865) and mean K (P = .974) and the mean changes in the asphericity (P = .272) were not statistically significantly different between the 2 groups. The mean changes in corneal hysteresis (CH) (P = .548) and the corneal resistance factor (CRF) (P = 1.000), CH-CRF (P = .282), and the area under the peak 2 (P = .260) were similar in both groups. The mean decrease in the ECC was not statistically significantly different between the 2 groups (P = .218). CONCLUSION: Based on 6-month results, accelerated and standard corneal CXL arrested the progression of keratoconus similarly. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.