Effect of short-term peripheral myopic defocus on ocular biometrics using Fresnel “press-on” lenses in humans 

This study assessed axial length and choroidal thickness changes following short-term peripheral myopic defocus in normal adult subjects. Twenty subjects underwent defocus sessions by viewing a full-field projected movie 4 meters away for 4 hours in the morning, while wearing spectacle lenses, corrected for distance vision in both eyes. The right eye, serving as the test eye, was peripherally defocused using a Fresnel lens overlay of + 3.50D with a central aperture of 11.5 mm, while the left eye served as the control. A subset of 10 subjects from the same cohort also underwent additional defocus sessions with + 5.00D of peripheral defocus. Axial length was measured and radial sub-foveal choroidal scans were obtained before and after the defocus sessions. The mean increase in axial length of the test eyes was 8 µm (p < 0.05) less than that of the control eyes with + 3.50D peripheral defocus condition and 14 µm (p < 0.05) less than the control eyes with + 5.00 D peripheral defocus condition. The difference in mean changes for choroidal thickness between test and control eyes were not significant for both dioptric conditions. Our results demonstrated that short-term peripheral myopic defocus significantly inhibited axial elongation in adult humans, without significant changes in choroidal thickness.