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S. Tomac, T. Akin, F.M. Mutlu, H.I. Altinsoy; Binocularity Following Surgical Correction of Longstanding Strabismus in Adults . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2953.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine whether or not surgical correction of longstanding strabismus provides restoration of fusion and stereopsis. Methods: Thirty–four adults with a history of early–onset, constant strabismus, and who were 20 years of age or older at the time of surgery were prospectively studied. No patient had undergone strabismus surgery previously. They were tested with the Bagolini glasses (BG) test, Worth 4–dot (W4D) test, TNO, and stereo–fly plate of the Titmus test before and 6 weeks after the surgery. Results: Preoperatively, no patient had binocularity. Postoperatively, all had a manifest deviation of less than 15 prism diopters (1 patient required second operation), and all demonstrated fusion with the BG test at near. Thirty patients (88.2%) showed fusion with the BG test at distance, 26 (76.5%) had fusion with the W4D test at near, and 7 (20.6%) had fusion with the W4D test at distance. There were significant differences between the results of the BG and W4D test at distance (p= .000), as well as between the results of the W4D at near and distance (p= .000). Seven (20.6%) patients had a mild or moderate level of decrease in the best–corrected visual acuity of the deviating eye (range, 20/25 to 20/50). There was a significant association between the decrease in visual acuity and the absence of fusion by the BG test at distance, as well as by the W4D test at near (respectively, p= .000, p= .003). No patient had measurable stereopsis. Conclusions: The findings suggest that surgical alignment provides fusion in natural seeing circumstances for almost all adult patients with longstanding constant strabismus. The difference in results, using the BG and W4D test at near or distance, seems to be related to the binocular rivalry effect of the W4D and to the increase in binocular rivalry at distance. Probably, the decrease in visual acuity weakens fusion and causes a deterioration in fusion with the effect of binocular rivalry. In addition, it appears that achievement of stereopsis is not possible with surgery in this group of patients.
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