Binocular function in patients with pseudophakic monovision

PURPOSE: To evaluate the relationship between ocular deviation and stereopsis and fusion in patients who had pseudophakic monovision surgery. SETTING: Department of Ophthalmology, Kitasato University Hospital, Kanagawa, Japan. DESIGN: Retrospective comparative case series. METHODS: Patients had surgical monovision correction with monofocal intraocular lens placement followed by routine postoperative examinations. The alternate prism cover test was used to measure motor alignment. Sensory tests for binocularity included sensory fusion determinations using the Worth 4-dot test, near stereopsis test, and fusion amplitude measured with a prism bar. Patients with monovision were categorized as having small-angle exophoria (<= 10.0 prism diopters [Delta]) or moderate-angle exophoria (> 10.0 Delta). RESULTS: This study comprised 60 patients with a mean age of 70.2 years +/- 7.7 (SD). The difference in the mean stereopsis values between patients with small-angle exophoria and patients with moderate-angle exophoria was statistically significant (P<.001). In the moderate-angle exophoria group, 10 patients (62.5%) developed intermittent exotropia after surgery; however, no serious ocular deviation problems were observed. The fusion amplitudes in patients with pseudophakic monovision were approximately similar to normal values. Patients with moderate-angle exophoria were more likely to fail the Worth 4-dot test than those with small-angle exophoria. CONCLUSIONS: In patients with pseudophakic monovision having a near exophoria angle of more than 10.0 Delta, the possibility of changes in ocular deviation and stereopsis after surgery is a concern. Moreover, the application of monovision in patients with a previous moderate-angle exophoria should be carefully considered.