Vertical fusional amplitudes in patients wearing vertical anisometropic correction.

OBJECTIVE: To examine the relationship between vertical anisometropic spectacle correction and vertical fusional amplitudes in patients. DESIGN: Comparative observational case series. PARTICIPANTS: Twenty-one patients exposed to greater than 0.5 diopters of vertical anisometropic spectacle correction were compared with 46 patients not exposed to anisometropic correction. METHODS: Vertical fusional amplitudes were recorded in all patients using a prism bar. MAIN OUTCOME MEASURES: Vertical fusional amplitudes and vertical anisometropia. RESULTS: In patients exposed to greater than 0.5 diopters of vertical anisometropic spectacle correction, vertical fusional amplitudes measured 5.2+/-1.4 prism diopters. Patients not exposed to anisometropic correction had vertical fusional amplitudes of 2.7+/-1.2 prism diopters (P < 0.0001). CONCLUSION: Patients with vertical anisometropic correction have increased vertical fusional amplitudes. This finding is relevant when evaluating patients with ocular motility disorders, especially with regard to distinguishing acquired versus longstanding deviations.