EFFECT OF CORNEAL CROSS-LINKING vs STANDARD CARE ON KERATOCONUS PROGRESSION IN YOUNG PATIENTS: THE KERALINK RANDOMIZED CONTROLLED TRIAL.

Abstract

OBJECTIVE\nTo examine the efficacy and safety of corneal cross linking (CXL) for stabilisation of progressive keratoconus.\n\n\nDESIGN\nObserver-masked, randomized, controlled, parallel group superiority trial PARTICIPANTS: 60 participants aged 10-16 years with progressive keratoconus. One eye of each patient was deemed the study eye.\n\n\nINTERVENTION\nAccording to randomization the study eye received either CXL plus standard care or standard care alone, with spectacle or contact lens correction as necessary for vision.\n\n\nMAIN OUTCOME MEASURES\nThe primary outcome was K2 in the study eye as a measure of the steepness of the cornea at 18 months. Secondary outcomes included keratoconus progression defined as 1.5 dioptres (D) increase in K2, visual acuity, keratoconus apex corneal thickness and quality of life.\n\n\nRESULTS\nOf 60 participants, 30 were randomized to CXL and standard care groups. Of these, 30 patients in the CXL group and 28 patients in the standard care group were analyzed. The mean (SD) K2 in the study eye 18 months post-randomization was 49.7D (3.8) in CXL and 53.4D (5.8) in standard care groups. The adjusted mean difference in K2 in the study eye was -3.0D (95% CI -4.9 to -1.1; p=0.002), favouring CXL. Uncorrected and corrected differences in logMAR vision at 18 months was better in eyes receiving CXL, -0.31 (95% CI -0.50 to -0.11, p=0.002) and -0.30 (95% CI -0.48 to -0.11, p=0.002). Keratoconus progression in the study eye occurred in 2 patients (7%) randomized to CXL compared to 12 (43%) randomized to standard care. The unadjusted odds ratio (OR) suggests that on average patients in the CXL arm had 90% (OR 0.1, 95% CI 0.02 to 0.48, p= 0.004) lower odds of experiencing progression compared to those on standard care. Quality of life outcomes were similar in both groups.\n\n\nCONCLUSIONS\nCXL arrests progression of keratoconus in the great majority of young patients. These data suggest that CXL should be considered as first line treatment in progressive disease. If the arrest of keratoconus progression induced by CXL is sustained in longer follow up, there may be particular benefit in avoiding a later requirement for contact lens wear or corneal transplantation.