Abstract
Purpose: :
Monocular occlusion is currently the reference method to symptomatically treat binocular diplopia (BD). In some pathological conditions however, monocular central scotomata with preserved peripheral visual field have been shown to abolish BD. Here we evaluate a novel contact lens that abolishes BD by changing the spatial visual acuity in one eye to approximate the inverse of the spatial acuity function across the retina. The performance of the device is compared with conventional eye patching in normal subjects and in patients with BD.
Methods: :
The normal cohort included 12 subjects with normal vision in whom full field 10° of vertical BD was induced using Fresnel lenses. The patient cohort included 12 patients with BD of diverse causes. Comparisons were made during reading, room navigation, self-examination and distance viewing, using a structured questionnaire with scores ranging from 1 (worst) to 10 (perfect). Estermann perimetry was also performed in the normal cohort. The distributions of responses were compared using paired Kolmogorov-Smirnov two sample tests with mean scores and asymptotic p values.
Results: :
In the normal cohort, the two methods were equally effective in abolishing BD (patch (P) 8.42, lens (L) 8.75, p=0.991) and in comfort (P 6.50, L 6.17, p=0.990), but the lens was rated superior in aesthetics (P 2.33, L 8.75, p<0.001) and overall (P 6.42, L 8.67, p=0.005). Performance on Estermann perimetry was superior with the lens (P 14.92 missed locations, L 0.92 missed locations, p<0.001). In the patient cohort, both methods were identically effective in abolishing BD (P 9.73, L 9.27, p=0.985), but the lens was superior on other measures: aesthetics (P 2, L 9.45, p<0.001), comfort (P 4.36, L 7.45, p=0.047) and overall (P 4.18, L 8.54, p<0.001).
Conclusions: :
This novel device offers an effective method to abolish BD, while being superior to conventional patching in terms of visual field preservation, aesthetics comfort and overall effectiveness.
Keywords: visual impairment: neuro-ophthalmological disease • neuro-ophthalmology: cortical function/rehabilitation