Effect of preoperative factors on visual acuity, corneal flattening, and corneal haze after accelerated corneal crosslinking

PURPOSE: To evaluate the preoperative characteristics that might influence corneal flattening, visual acuity, and corneal haze after accelerated (9 mW/cm(2)) corneal collagen crosslinking (CXL). SETTING: Ulucanlar Eye Hospital, Ankara, Turkey. DESIGN: Retrospective case series. METHODS: Accelerated corneal CXL was performed in eyes with progressive keratoconus. Preoperative characteristics included age, sex, uncorrected distance visual acuity and corrected distance visual acuity (CDVA), maximum keratometry (K), corneal thickness, corneal hysteresis, the corneal resistance factor, cone location, and densitometry values. Regression analysis was performed to determine the predictive factors for accelerated corneal CXL outcomes. RESULTS: The study included 162 eyes of 146 patients with a mean age of 19.3 years +/- 4.4 (SD). There was 0.20 logMAR improvement in CDVA (P = .011), 1.85 diopter flattening in maximum K (P < .001), and 5.84 grayscale unit increase in densitometry (P < .001) at 1 year. Multivariate analysis found that preoperative CDVA was a predictive factor for CDVA improvement (ss coefficient, 0.233; 95% confidence interval [CI], -0.054 to 0.477; P = .003). Preoperative maximum K was a predictive factor for corneal flattening (8 coefficient, 0.506; 95% CI, 0.185 to 0.681; P < .001). Univariate analysis found that preoperative densitometry was a predictive factor for increasing corneal densitometry (ss coefficient, 0.466; 95% CI, -0.122 to 0.683; P = .001) and corneal scar formation (ss coefficient, 0.256; 95% CI, 0.012 to 0.421; P = .041). CONCLUSIONS: Patients with a worse preoperative CDVA and higher maximum K were most likely to have improvement after accelerated CXL. Patients with high preoperative densitometry were most likely to have scar formation after the procedure.