Correlation analysis of myopia aberration and objective depth of focus in the human eye

Objective

To investigate the correlation between low-order and high-order aberrations and objective depth of focus in the human eye, and the factors that influence objective depth of focus.

Methods

A cross-sectional study was performed.Seventy-six patients (152 eyes) with myopia and astigmatism patients who were treated at the Refractive Surgery Center of Tianjin Eye Hospital from February to April 2022 were selected, including 41 males and 35 females.The patients’ whole-eye low-order and high-order aberrations and objective depth of focus were measured at 3, 4, 5, and 6 mm manually selected pupil diameters using the iTrace visual function analyzer.The correlation between objective depth of focus and low-order and high-order aberrations at different pupil diameters was analyzed by Spearman rank correlation analysis.Objective depth of focus was compared between individuals with different degrees of myopia and astigmatism, individuals with different pupil diameters, right and left eyes, and different sexes.This study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of Tianjin Eye Hospital (No.2022039).

Results

Objective depth of focus was positively correlated with total low-order aberrations at 3, 4, 5, and 6 mm pupil diameter (r_s=0.380, 0.317, 0.385, 0.519, all at P<0.01). Objective depth of focus was positively correlated with defocus at 3, 4, 5, and 6 mm pupil diameter (r_s=0.377, 0.323, 0.403, 0.512, all at P<0.01), and with astigmatism at 6 mm pupil diameter (r_s=0.255, P<0.05). There were statistically significant overall differences in objective depth of focus between groups with different degrees of myopia at 3, 4, 5, and 6 mm pupil diameter (H=6.440, 7.370, 9.990, 16.930; all at P<0.05). Among them, the objective depth of focus of high myopia was significantly higher than that of low myopia at different pupil diameters, and the objective depth of focus of high myopia was higher than that of moderate myopia at 6 mm pupil diameter, with statistically significant differences (all at P<0.05). Objective depth of focus was positively correlated with total high-order aberration at pupil diameters of 3, 4, 5, and 6 mm (r_s=0.911, 0.807, 0.733, 0.677; all at P<0.001). Among various high-order aberrations, objective depth of focus was positively correlated with total coma at 3, 4, 5, and 6 mm pupil diameter (r_s=0.727, 0.557, 0.620, 0.487; all at P<0.001), positively correlated with vertical coma at 3, 4, 5, and 6 mm pupil diameter (r_s=0.439, 0.405, 0.553, 0.400; all at P<0.001), positively correlated with horizontal coma at 5 and 6 mm pupil diameter (r_s=0.308, 0.308; both at P<0.01), positively correlated with trefoil aberration at 3, 4, 5, and 6 mm pupil diameter (r_s=0.344, 0.443, 0.316, 0.330; all at P<0.01), positively correlated with spherical aberration at 4, 5, and 6 mm pupil diameter (r_s=0.321, 0.310, 0.428; all at P<0.01). There was a significant difference in objective depth of focus between 3 and 4 mm, 5 and 6 mm pupil diameters (P=0.011, 0.004). There was no statistically significant difference in objective depth of focus between different degrees of astigmatism, between males and females, or between left and right eyes (all at P>0.05).

Conclusions

The objective depth of focus of the human eye is mainly strongly correlated with vertical coma, trefoil aberration in high-order aberrations, as well as defocus in low-order aberrations.Horizontal coma and spherical aberration are strongly correlated with objective depth of focus only when the pupil diameter is large.In addition, if the pupil diameter is too small (3 mm) or too large (6 mm), it has a significant effect on the objective depth of focus.

Myopia; Aberration; Visual quality; Objective depth of focus; Low-aberration; High-aberration