Correlation between refractive errors and ocular biometric parameters at Al-Mustaqbal University, Iraq.

Purpose: To establish the relationship between ocular biometry and refractive errors in young adult Iraqis by analyzing three critical biometric ocular parameters, including axial length (AL), corneal radius (CR), and central corneal thickness (CCT).

Methods: A cross-sectional study was conducted on individuals aged 18-33 years at Al-Mustaqbal University, Iraq, including 1841 participants (3682 eyes). Quantitative measurements of AL, CR, and CCT were obtained using an Auto Kerato-Refractometer, IOL Master, and pachymetry techniques. Statistical analyses included Pearson correlation, multiple linear regression, one-way ANOVA, and independent samples t-tests to compare biometric parameters between refractive error groups. Generalized Estimating Equations (GEE) were applied to account for the correlation between fellow eyes.

Results: The overall mean AL was 24.45 ± 1.10 mm, mean CR was 7.37 ± 0.77 mm, and mean CCT was 555.83 ± 50.83 μm. Myopic participants had a significantly longer AL (25.11 ± 0.42 mm) compared to hyperopic participants (22.71 ± 0.65 mm; p < 0.001). Likewise, myopic eyes had significantly thicker corneas (CCT: 565.62 ± 12.68 μm) than hyperopic eyes (495.42 ± 18.74 μm; p < 0.001), as determined by independent samples t-tests. Females exhibited slightly longer ALs than males across both myopic and hyperopic groups (p < 0.0001). Regression analysis showed that AL was the strongest predictor of spherical equivalent (SE), followed by CR and CCT. The regression model including AL and CR explained 94.5% of the variance in SE (R² = 0.945).

Conclusions: The findings confirm that AL and CCT are strongly associated with refractive errors, with AL being a primary determinant. This study highlights the role of gender differences in biometric ocular parameters and provides valuable insights into the prevalence of refractive errors in young adults in Iraq. These results can inform future public health initiatives aimed at addressing refractive errors in this population.