Optically induced hyperopic defocus: axial length changes in emmetropes from mobile screen exposure

Background: The rapid increase in smartphone screens led to eye problems. The study measured transient axial length variations during mobile screen exposure before and after hyperopic defocus. Methods: A quasi-experimental study on students utilizing non-probability sampling was conducted at Al-Shifa Trust Eye Hospital. LogMAR measured visual acuity, and retinoscopy measured refractive status of right eye only. Samsung Galaxy A7 provided full-blue screen exposure. -3.00 DS lens in trial frame caused hyperopic defocus. IOL Master Zeiss 700 measured axial length and ocular biometrics. The online web program Data tab was entered, and data was analyzed. Results: A total of 30 subjects, which includes 6 (20%) males and 24 (80%) females, with a mean age of 20.67 (±0.96) years. Mean visual acuity and Spherical Equivalent Refraction were 0.00 (±0.00) and 0.10 (±0.01). Comparing the median interquartile range (Median-IQR) pre-defocus axial length (PDAXL) and after defocus axial length (ADAXL), pre-defocus lens thickness (PDLT) and after defocus lens thickness (ADLT) following 1 h exposure to mobile screen a statistically significant difference were observed respectively – 23.2 (±0.93), 23.14 (±0.92), p value = 0.003 and 3.61 (±0.28), 3.61 (±0.22), p value = 0.001. Other ocular parameter like pre-defocus anterior chamber depth (PDACD) and after-defocus anterior chamber depth (ADACD), pre-defocus central corneal thickness (PDCCT) and after-defocus central corneal thickness (ADCCT) no statistically significant were observed respectively – 3.45 (±0.29), 3.44 (±0.26), p value = 0.861 and 528 (±31.50), 525.17 (±24.75), p value = 0.139. Conclusion: Exposure to mobile screens in blue mode, along with hyperopic defocus, was found to cause axial length shortening, offering potential implications for managing myopia progression.