Purpose: To identify topographic and wavefront aberration parameters that distinguish early post-LASIK (PL) ectasia (PLE) from stable PL corneas, keratoconus (KC), and normal eyes when matched for mean central keratometry. Methods: This retrospective comparative study included 200 patients (n = 50 per group): early PLE, stable PL, early KC, and normal eyes, matched for mean central keratometry (∼41. 0 D). Corneal topographic indices index of surface variance (ISV), index of vertical asymmetry (IVA), index of height asymmetry (IHA), index of height decentration, central keratoconus index, keratometric parameters (flat K, steep K, Kₘax), pachymetry, higher-order aberrations (HOAs), coma, astigmatism, and a novel asymmetry-to-symmetry (A/S) aberration ratio. Results: PLE exhibited higher Kₘax (46. 9 ± 3. 1 D) compared with PL (45. 2 ± 1. 7 D; P 0. 54 yielded 96% specificity for ectasia detection. Conclusions: Early PLE shows distinctive disproportionate increases in asymmetric aberrations, quantified by the A/S ratio. In combination with ISV, IVA, and coma, this metric may facilitate early diagnosis of PLE, enabling timely intervention to prevent progression.
Prakash et al. (Wed,) studied this question.