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Michael Lai, Steven Greenstein, John Gelles, Peter Hersh; Manifest Refraction Versus Wavefront Refraction in Patients with Keratoconus. Invest. Ophthalmol. Vis. Sci. 2021;62(8):768.
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© ARVO (1962-2015); The Authors (2016-present)
This study was a restrospective, observational clinical study to compare refractive results of manifest refraction and wavefront (WF) refraction for patients with keratoconus.
The manifest and WF refractions of 613 eyes diagnosed with keratoconus were analyzed. Refractive parameters (sphere, cylinder, axis, and spherical equivalent) were compared based on stratified cohorts of increasing maximum keratometry (Kmax) (Kmax<50 diopters (D), 50-55D, 55-60D, >60D). The percentage of WF refraction axes (against-the-rule (ATR) (60-120o), with-the-rule (WTR) (0-30o and 150-180o), oblique (OBL) (30-60o and 120-150o)) that correctly corroborated with manifest refraction axes were compared, and more specifically, the percentage of patients with WF axes ± 10o of manifest axes were analyzed.
In the entire cohort, there was no difference between wavefront and manifest spherical refraction (P=0.07). However, cylindrical refraction and spherical equivalent were significantly different (both P<0.001). In the stratified subgroups, there was more cylindrical refraction measured on wavefront than manifest refraction for all Kmax subgroups (all P<0.001). Similarly, wavefront spherical equivalent was more myopic than the manifest spherical equivalent in the Kmax <50D, 50-55D, and 55-60D subgroups (P=0.01, <0.001, <0.001, respectively). Overall, 56.61% of WF refraction axes (ATR, WTR, or OBL) correctly corroborated with manifest refraction axes, and only 34.4% of WF refraction axes were within ± 10o of manifest refraction axes. In the Kmax subgroups, 62.1%, 54.7%, 56.7%, and 48.5% of WF refraction axes correctly corroborated with manifest refraction axes in the Kmax <50D, 50-55D, 55-60D, and >60D subgroups, respectively. Additionally, 38.5%, 37.4%, 32.9%, and 18.2% of WF refraction axes were ± 10o of the manifest refraction axes in the Kmax <50D, 50-55D, 55-60D, and >60D subgroups, respectively.
WF refraction is a convenient tool for obtaining refractive parameters of patients, but physicians should be cognizant that there can be significant differences between WF and manifest refraction for patients with keratoconus. In particular, as the severity of keratoconus increases, the reliability of the wavefront astigmatism measurements appears to decrease.
This is a 2021 ARVO Annual Meeting abstract.
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