Monochromatic Optical Aberrations in Myopic and Astigmatic Anisometropia
Narrative Responses:
Purpose
Comparing high and low order monochromatic aberrations of the more myopic and less myopic eyes of 25 myopic and astigmatic anisometropic patients.
Methods
Twenty five anisometropic subjects with at least 2.00 D spherical equivalent difference between eyes were enrolled. All had spherical equivalent refractive error between +3.25D and -21.75 D and refractive astigmatism of less than -3.00 D. High (up to 5 th order) and low order monochromatic aberrations were measured for 5mm pupils using the OPD Scan II (Nidek). Many biometric and aberrometry parameters were compared between the more myopic and less myopic eye of the patients using Student paired t test.
Results
The spherical equivalents and axial lengths of the more myopic eyes were significantly larger than the less myopic eyes (p< 0.0001 and p < 0.0001) but the cylindrical difference was not significant (p>0.005) as for the corneal curvatures (p = 0.108) and the magnitude of corneal astigmatism between the 2 groups. The more myopic eyes showed significantly higher root mean square (RMS) values of corneal fourth-order (p< 0.0001) and corneal spherical aberration (p=0.015) than the less myopic eyes. Corneal asphericity was less negative for the more myopic eyes (less prolate) but this difference was not significant (p=0.541).
Conclusion
The less negative asphericity in myopes and therefore the tendency for less rapid flattening in the corneal periphery may explain the more positive spherical aberrations in the more myopic eyes than in the less myopic eyes.The relationship between positive spherical aberrations and myopia might contribute to image degradation in myopes.