Purpose Primate eyes feature a physiologic accommodative system identical to that of humans. Nonetheless, their biometric changes before and after cycloplegia have not been investigated. In this study, we aimed to evaluate the characteristics of pseudomyopia and explore factors associated with cycloplegic changes in young cynomolgus macaques. Methods Refractive and biometric measurements were performed on both eyes before and after cycloplegia in 88 cynomolgus macaques aged 3−6 years without ocular diseases. Pseudomyopia was defined as autorefraction-estimated noncycloplegic spherical equivalent (NSE) −0.50 D and cycloplegic spherical equivalent (CSE) ≥ −0.50 D. Linear mixed models were established to identify factors associated with cycloplegic differences. Results After excluding low-quality ophthalmic data, 149 eyes were included in the final analysis. The median NSE was −0.38 (interquartile range: −1.50, 0.25) D and the median CSE was 0.13 (−0.50, 0.90) D, exhibiting a robust Pearson’s correlation coefficient of 0.89 (95% confidence interval: 0.78−0.92). Pseudomyopia was observed in 35 of the 149 eyes, with a greater hyperopic shift (median, 1.42 D) compared to that in non-myopic and true-myopic eyes (median, 0.50 D for both, p0.001). Pseudomyopic eyes demonstrated active accommodation before cycloplegia and exhibited biometric changes after cycloplegia akin to those in true-myopic eyes. Under cycloplegia, non-myopic and pseudomyopic eyes exhibited similar biometric measurements. A greater hyperopic shift correlated with a higher hyperopic NSE and greater reductions in lens thickness. Conclusions The use of 1% cyclopentolate yielded discernible alterations in refractive and biometric parameters in 3- to 6-year-old cynomolgus macaques. Notably, compared with non-myopia and true myopia, pseudomyopia exhibited associations and discrepancies in accommodative status. These findings underscore the importance of investigating the role of the lens in animal models employed in myopia research.
Ye et al. (Thu,) studied this question.