Changes in Axial Length and Refractive Profile in Different Illumination: A Comparative Study to Understand the Impact of Myopia Control

Purpose: The purpose of the study was to evaluate and compare the changes in axial length and refractive profile in myopic patients exposed with different illumination. Methodology: A cross-sectional study among 15 myopic subjects was conducted in the tertiary eye care institute. Before participating in the study, individuals underwent comprehensive ocular examinations to ensure their suitability. For each participant, the experiment was conducted in two phases: Phase I procedures occurring at the initial visit and Phase II procedures taking place 1 week later. In Phase I, baseline measurements of axial length and refractive profiles were taken for all participants, followed by exposure to illumination below 500 Lux for 30 min. Phase II replicated the baseline measurements, followed by exposure to lighting above 1000 Lux for the same duration. Axial length measurements were performed using Lenstar LS-500, and refractive profiles were determined using an autorefractometer, both administered by experienced optometrists. Three consecutive measurements were taken for each eye, and the average value was recorded for both axial length and refractive parameters. Paired t -test was used to compare axial length measurements at baseline and after exposure to different illumination levels. Linear regression was used to determine the association between axial length and illumination levels. Statistical significance was considered if P < 0.05. Results: Mean axial length measurements varied across the two illumination groups: 23.62 ± 0.18 mm in the high illumination group (>1000 lux) and 23.96 ± 0.23 mm in the low illumination group (<500 lux). Paired t -test revealed a significant difference in axial length among the groups ( P = 0.01). Similarly, the mean spherical equivalent refractive error also varied significantly across the illumination groups: −1.52 ± 0.60 Diopter (D) in the high illumination group, and − 2.01 ± 0.16 D in the low illumination group. There was a significant negative correlation between axial length and refractive error for high illumination group. Conclusion: Higher levels of illumination were associated with shorter axial length and less myopic refractive error in individuals.