Randomized Controlled Trial of Corneal CXL in Progressive Keratoconus: 4-Year Results
Purpose
We report the 4 year results in a randomized, controlled clinical trial of CXL for progressive keratoconus.
Methods
This is an unmasked, prospective, randomized, controlled, clinical trial of 100 eyes with progressive keratoconus randomized to CXL (riboflavin 0.1% for 30 minutes followed by ultraviolet A irradiation for 30 minutes) or a control group and followed at 1, 2, 3 and 4 years. The primary outcome measure was the maximum simulated keratometry value (Kmax) on computerised videokeratography. Secondary outcome measures include uncorrected (UCVA) and best spectacle corrected visual acuity and endothelial cell density (ECD). Eyes in the control group which continued to progress over the follow-up period were offered compassionate CXL treatment.
Results
In the control group, Kmax increased by +1.91D (p<0.01), UCVA deteriorated by 0.1 logMAR (p=0.039) and BSCVA was unchanged (-0.08 logMAR, p=0.108) at 4 years compared to baseline. In the CXL group, Kmax flattened by -1.16D (p<0.01), UCVA was unchanged (-0.1 logMAR, p=0.066) and BSCVA improved by -0.12 logMAR (p=0.002). The ECD was stable in both groups. In the control group, 17 eyes have been treated with CXL for progressive keratoconus and 3 eyes have undergone transplantation. Conversely, only one eye in the CXL group has progressed more than 1.00D (+1.40D) and no eyes have undergone transplantation.
Conclusion
After 4 years, there was sustained improvement in Kmax after CXL whereas control eyes progressed.