Optical Fogging is an Effective Method of Reducing Overestimation of Myopia

This study aimed to investigate the effectiveness of optical fogging in controlling accommodation and to evaluate its efficiency in reducing myopic overestimation among young adults, with the goal of providing scientific evidence for clinical refraction measurement. A total of 142 young adults aged 17 to 23 years (284 eyes) were enrolled. Refractive status and ocular biometric parameters were measured using open-field autorefractor and partial coherence interferometry under three conditions: baseline, optical fogging, and cycloplegia. Optical fogging was induced by wearing +2.00 D spherical lenses for 20 minutes, while cycloplegia was induced using 0.5% compound tropicamide-phenylephrine eye drops. Eyes were categorized into overestimated and non-overestimated myopia groups based on whether the difference in spherical equivalent (SE) between cycloplegic and baseline measurements was ≥0.50 D. Changes in SE and lens thickness under the three conditions were analyzed, and the efficiency of fogging-induced accommodative control was calculated. In the overestimated myopia group (82 eyes), optical fogging reduced accommodation by an average of 0.28 ± 0.37 D compared to baseline (p < 0.001), accounting for 36.84% of the effect of cycloplegia (0.76 ± 0.29 D). In the total sample eyes, fogging reduced accommodation by 0.07 ± 0.34 D (p < 0.001), which corresponded to 21.88% of the cycloplegic effect (0.32 ± 0.37 D). Lens thickness showed no significant change after optical fogging, whereas cycloplegia significantly reduced lens thickness (overestimated myopia group: -0.07 ± 0.10 mm, p = 0.003; total: -0.05 ± 0.19 mm, p < 0.001). Optical fogging effectively suppresses unnecessary accommodative responses in young adults, significantly reducing myopic overestimation, with particularly pronounced effects in those with notable myopic overestimation. Although optical fogging is less effective than cycloplegia in relaxing accommodation, it offers advantages in terms of ease of use, non-invasiveness, and good tolerance, making it highly applicable in clinical refraction measurement.