The+10 diopter lens occluder

Background: It would be useful to be able to visualize the eye under cover during the cover test. Used as an occluder, a +10 diopter (D) lens will per mit such visualization. It is important to know if a +10D lens creates diss ociation that is qualitatively similar to an opaque occluder. Methods: The angle of strabismus was measured in 33 patients with esotropia . Seventeen had intermittent exotropia, and 15 had dissociated vertical div ergence with both an opaque occluder and a +10D lens used as an occluder. T he findings were then compared. Results: In 64 of the 65 patients participating in this study, the measurem ents obtained with the 2 occluders agreed within 3 prism diopters on repeat ed testing. In the remaining patient, the measurements differed by 5 prism diopters. In all patients, the dissociated eye could be clearly visualized through the +10D lens. Conclusion: A +10D lens permits excellent visualization of the dissociated eye and provides measurements that are qualitatively similar to those obtai ned with a standard occluder.