Systematic underablation in laser in situ keratomileusis: ablation pattern identified by advanced topographical...

Topographical analysis based on the differential geometry of surfaces-curvature topography-was developed and applied to a patient after laser in situ keratomileusis. The patient had a minimal residual refractive error and normal best corrected visual acuity but had multiple visual aberrations, including ghosting and glare, unless the pupils were maximally constricted. The corneal loci responsible for the aberrations were difficult or impossible to identify on axial topographies but were readily identified with curvature topography. The patient's ablations appeared to be miniature versions of the intended ablation profiles, with small areas of emmetropic central cornea surrounded by annuli of rapidly increasing keratometric power; that is, systematic underablation. This may explain why some patients have visual aberrations with pupil diameters smaller than the programmed optical zones.