An Attempt of Subjective Refraction Test Maintaining Everyday Pupil Diameter Using Ground Glass Lens

Purpose: To investigated the effects of pupil dilation on subjective refraction by using ground glass lens. Methods: Forty-two subjects (22.1 ± 1.2 years) participated in the study. We measured the change in pupil diameter during binocular and monocular vision (using an occluder and a ground glass lens). And we conducted subjective refraction test using an occluder and a ground glass lens. Paired t-test was used for statistical analysis of pupil diameter and subjective refraction. Pearson’s rank correlation test was performed to assess the relationship between subjective refraction change and pupil diameter change. The p-value of < 0.01 was considered statistically significant. Results: The average pupil diameter measured before and after covering with an occluder was 4.35 ± 0.55 mm and 5.77 ± 0.75 mm (P < 0.0001). The average pupil diameter measured before and after covering with ground glass lens was 4.38 ± 0.65 mm and 4.39 ± 0.68 mm (P = 0.78). The average spherical equivalent subjective refraction using an occluder and a ground glass lens was -3.89 ± 2.15D, -3.67 ± 2.02D. Using an occluder resulted in significantly more myopia than using a ground glass lens (P < 0.0001). The bigger the change in pupil diameter, the bigger was the change in subjective refraction (P = 0.0005; R2 = 0.25). Conclusions: Our results indicate using a ground glass lens is effective method for measuring the exact refraction value.