Plus lens, prism, and bifocal effects on myopia progression in military students, Part II

Military academies routinely lose a percentage of their pilot-qualified students to myopia during the 4-year academic program. This study investigated the progression of myopia during such a program and evaluated the usefulness of reading glasses to prevent myopia progression and subsequent acuity loss. A group of students at the United States Naval Academy comprised three randomly divided groups: a placebo group (no. 1 pink tint), a plus with prism group (+1.25 D with 2 delta base-in each eye), and a bifocal group (+1.50 D near addition). All the lens powers were relative to the experimental subject's distance refraction and were for use full-time when reading. The pre- and post-test refractive errors at distance were determined using 1% tropicamide HCl. At the end of 4 years, the tropicamide refraction showed approximately -0.25 D of myopic shift in all groups. There were no significant differences between the myopic shifts in the controls and experimental groups.