Treatment of Progressive Keratoconus with CXL
The authors of this prospective clinical study sought to assess the long-term effects of treating 17 patients with progressive keratoconus with ultraviolet A-riboflavin collagen cross-linking (CXL). Three-year results following CXL show stable visual acuity, corneal thickness and corneal biomechanical parameters.
They examined patients preoperatively, at week one, months one, three, six, nine, 12, 24 and 36 after treatment. They also used Reichert's Ocular Response Analyzer to assess uncorrected visual acuity (UCVA) and best spectacle-corrected visual acuity (BSCVA), refraction, biomicroscopy and fundus appearance, intraocular pressure, endothelial cell density (ECD), corneal topography, minimal corneal thickness (MCT), macular optical coherence tomography, axial length and corneal biomechanics.
Comparing the 36-month time point results with pretreatment values, the authors found that UCVA and BSCVA were unchanged. They also noted that steepest meridian keratometry (D) and mean cylinder (D) did not show significant change compared with pretreatment values, but showed a slight increase as compared with the 24-month time point (53.9 vs. 51.7 vs. 52.5, and 10.5 vs. 8.1 vs. 9.2 before, at 24 months, and at 36 months, respectively). The study authors reported that axial length (mm) showed an elongation trend throughout the follow-up period (24.56 vs. 24.61 [p=0.04] vs. 24.71 [p=0.05], before, at 24 months, and at 36 months, respectively). They observed no significant change in ECD, corneal hysteresis and corneal resistance factor, MCT or foveal thickness.
The decreasing trend in keratometry values that the authors observed during the first two years following CXL was no longer evident. Longer follow-up is needed to decide whether it is a first sign of loss of achieved stability and resumption of keratoconus progression.