# Corneal and Ocular Aberrations: A Comparative Study of Hyperopic, Emmetropic, and Myopic Eyes

## TL;DR

This study compares corneal and ocular aberrations in hyperopic, emmetropic, and myopic eyes, finding higher aberrations in hyperopic eyes.

## Contribution

The study identifies significant differences in corneal coma and fifth-order ocular aberrations among different refractive error groups.

## Key findings

- Hyperopic eyes had significantly higher RMS values for corneal coma and fifth-order ocular aberrations compared to emmetropic and myopic eyes.
- Zernike coefficient Z4–2 was significantly higher in hyperopic eyes compared to emmetropic and myopic eyes.
- No significant differences were found in compensation factors for RMS and Zernike coefficients among the groups.

## Abstract

To investigate differences in corneal and ocular aberrations between hyperopic, emmetropic, and myopic eyes.

This cross-sectional study included 84 eyes from 84 healthy participants (age range 18-35 years), who were equally divided into three refractive error groups of hyperopia, emmetropia, and myopia. Following comprehensive optometric examinations, corneal and ocular aberrations were measured using Pentacam and Zywave imaging systems, respectively. Aberrations were measured for a pupil diameter of 5 mm. Root-mean-square (RMS), Zernike coefficients, and compensation factor (CF) between total ocular and corneal aberrations were calculated for statistical analysis.

The mean spherical equivalent was +1.96
±
1.64, –0.17
±
0.19, and –2.46
±
1.56 diopters in hyperopic (H), emmetropic (E), and myopic (M) eyes, respectively. The amount of corneal Zernike coefficients Z4
–2 in the hyperopic eyes (H: 0.015
±
0.040) was significantly higher than that of emmetropic eyes (E: –0.018
±
0.054) and myopic eyes (M: –0.003
±
0.038) with a P-value of 0.029. The RMS of corneal total coma (H: 0.228
±
0.097, E: 0.183
±
0.086, M: 0.164
±
0.083, P-value: 0.009, respectively) and RMS of ocular fifth-order (H: 0.045
±
0.018, E: 0.036
±
0.020, M: 0.032
±
0.016, P-value: 0.002) showed a significant difference between refractive error groups, with higher value in hyperopic eyes compared to the two other groups. There was no significant difference in CF for RMS and Zernike coefficients among the refractive error groups.

Hyperopic eyes showed a higher RMS value for ocular fifth-order and corneal coma aberrations compared to the emmetropic and myopic eyes.