Intrastromal CXL for Early Subclinical Post-LASIK Ectasia
Purpose
CXL for post-LASIK ectasia (PLE) is performed either epi on or off on the corneal surface. This study describes a novel technique by treating subclinical/early PLE with CXL under the flap directly on the stroma, and reports on outcomes.
Methods
Small case series of topography diagnosed subclinical/early PLE eyes were treated with CXL on the stromal bed. Inclusion criteria: New inferior steepening with UCVA of 20/40 or better, and BCVA of 20/20 or better, and/or new cylinder ≥ 0.75 and ≤ 1.50D. Existing LASIK flaps were lifted, riboflavin applied directly to the stromal bed, flap repositioned, and 18mW/cm2 UV light applied for 3 minutes to flap surface. Post-CXL manifest refraction, UDVA and CDVA were compared to preop and pre-CXL measurements, and a Quality of Vision (QoV) questionnaire was administered at final postop.
Results
Ten eyes (9 pts). Time to CXL, 38±34 mths post-LASIK. Pre-CXL sphere -0.03±0.68D (-1.50 to +0.50D), cyl -0.78±0.63D (-0.25 to -1.50D). F/U 2.5±2.3 mths. Post-CXL sphere -0.36±0.81D (-2.00 to +0.25D), cyl -0.89±0.57D (-2.00 to 0.00D). 20, 60, 70% within ±0.25, ±0.50, ±1.00D post-CXL vs 50, 80, 80% pre-CXL. Cumulative post-CXL UDVA 20/20, 20/25, 20/40 in 22, 44, 56% vs pre-CXL 10, 50, 80%; efficacy index unchanged. Cumulative post-CXL CDVA 20/20, 20/25, 20/40 in 67, 89, 100% vs 60, 100, 100% pre-CXL. CDVA loss: 2 lines 1 eye, 1 line 2 eyes, no change 4 eyes, gain 3 eyes; safety index unchanged. No change in max K. One eye had mild haze. Longer-term f/u and QoV results to follow.
Conclusion
Preliminary results with under flap stromal CXL for early PLE are promising, demonstrating maintenance of accuracy, efficacy, safety, and keratometry, with quicker recovery times than surface CXL.