Do Anisometropic Eyes Have Steeper Retinas Than Their Isometropic Counterparts?

SIGNIFICANCE: Our findings suggest that retinal shapes of the eyes of anisometropes are not different from that of the eyes of isometropes with the same refractions.

PURPOSE: We investigated ( a ) intereye differences in relative peripheral eye lengths between isometropes and anisometropes and ( b ) if the retinal shape is different between isometropic and anisometropic eyes with the same central refraction.

METHODS

Central and peripheral eye lengths were determined along the horizontal meridian in 10° intervals out to ±30° using a noncontact biometer in 28 isometropes and 16 anisometropes. Retinal coordinates were estimated using these eye lengths and ray tracing. Retinal shape was determined in terms of vertex radius of curvature ( Rv ), asphericity ( Q ), and equivalent radius of curvature ( REq ). Linear regression was determined for the REq as functions of central refraction in a subset of isometropic and anisometropic eyes having the same refraction.

RESULTS

The differences in relative peripheral eye lengths between the two eyes of anisometropes were significantly greater than for isometropes at ±30° eccentricities. Higher myopic eyes of anisometropes had smaller Rv , more negative Q , and smaller REq than the lower myopic eyes for both isometropes and anisometropes (mean ± standard error of the mean: Rv , 9.8 ± 0.5 vs. 11.7 ± 0.4 mm [ P = .002]; Q , -1.1 ± 0.2 vs. -0.5 ± 0.2 [ P = .03]; REq , 11.5 ± 0.3 vs. 12.4 ± 0.2 mm [ P = .01]). Intercepts and slopes of the linear regressions of REq in anisometropes and their isometropic counterparts with the same refraction were not significantly different from each other ( P > .05).

CONCLUSIONS

Higher myopic eyes of anisometropes had similar retina shapes along the horizontal meridian to those of isometropic eyes with the same refraction.