2012) aberrations and lower best spectacle-corrected visual acuities (SCVA) (Gobbe & Guillon 2005) compared to normal subjects, with the corneal anomalies as the chief contributing factor to the reduction in visual performance (Tan et al. Patients with KC show significantly higher corneal (Alio & Shabayek 2006 Prakash et al. Keratoconus (KC) has a negative impact on the quality of vision and often on the overall quality of life (Kymes et al. Eccentric LRT may become a valuable tool in the demanding task of subjective refraction in KC.
In KC, eccentric LRT measurements gave better SCVA than standard autorefraction more often than in healthy eyes. Pentacam HR ® showed higher keratometry readings infero-temporally, but also lower readings supero-nasally, compared to controls. Multiple refractions rendered similar SCVA:s in KC. The UCVA:s and SCVA:s were worse in KC, and the KC eyes showed inferior myopia and superior hyperopia. There were no significant variation in M between the different LRT measurement points in the control group, but central data provided the best SCVA. In KC, the refraction from the upper nasal zone rendered a higher SCVA than the standard autorefraction more often than in the controls (p < 0.001). Pentacam HR ® was used to generate keratometry readings of the corresponding zones. The spherical equivalent ( M) and two astigmatic power vectors (C0 and C45) were calculated for all refractions. The uncorrected (UCVA) and spectacle-corrected (SCVA) Early Treatment Diabetic Retinopathy Study (ETDRS) visual acuities based on refractions derived from LRT in central and four eccentric zones were compared to those achieved with standard autorefraction.
Twenty-nine eyes of 29 patients with KC and 29 eyes of 29 healthy controls were included in this prospective unmasked case–control study. To compare objective refraction using small-zone eccentric laser ray tracing (LRT) wavefront aberrometry to standard autorefraction in keratoconus (KC), and whether the visual acuities achieved with these refractions differ from corresponding values in healthy eyes.
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