Purpose:
To verify pre-operative tomographic indices as predictive parameters for the improvement in best corrected visual acuity (BCVA) in one year after corneal collagen crosslinking (CXL) procedure for keratoconus.
Methods:
Retrospective study that included 63 eyes of 53 patients with progressive keratoconus submitted to CXL following the Dresden’s protocol: topical anesthesia, 9.0 mm of epithelial abrasion, riboflavin 0.1% drops for 30 minutes and ultraviolet-light A (UVA) with an irradiance of 3mW/cm2 for 30 minutes. Corneal tomography taken by Scheimplug rotational system (Pentacam, Oculus) before CXL was evaluated along with pre and 1 year post-operative BCVA. Statistical analysis was accomplished with the Kolmogorov-Smirnov test, student’s t-test and Receiver Operating Characteristic (ROC) curve.
Results:
There were statistically significant differences (p<0.05) between patients who improved BCVA in one year after CXL and those who did not experienced improvement in BCVA in the same period of time in the pre-operative tomographic indices related to corneal volume and thickness. Among those who had its BCVA improved all of them had a corneal volume in 6.0mm grater then 14.55mm3 and 97.2% of them had corneal volume in 6.5mm grater then 17.76mm3. So with 94.29% of them hadthickness in 4.0mm grater then 487μm and 82.86% had thickness on the thinnest point grater then 421μm.
Conclusion:
Patients with less advanced keratoconus (grater corneal volume and thickness) in the pre-operative had more chances to improve its BCVA in one year after CXL. Prospective studies involving others variables related to total aberrometry and corneal biomechanics are relevant to increase the prognostic capability of CXL result.
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