Carlo Aleci^1,, Tiziana Usai¹, Marzia Paiola²

A consistent body of literature maintains that the use of monocular sector prisms may enlarge the field of view of hemianopic patients, leading to a substantial improvement of their everyday life. Despite the potential interest, as far as we know clinical trials focusing on this last topic are few. Indeed, the effect of the monocular sector prisms on the whole extent of the binocular visual field and on the differential light sensitivity of the monocular ipsilateral visual field has not been fully investigated. This study aims at estimating the effect of a particular monocular prismatic sector, halfmoon shaped, placed on the carrier lens on the side of the loss, on the differential light sensitivity as well as on the binocular visual field extent in hemianopic patients. The only significant ameliorative finding is the reduction of the gradient of sensitivity between the blind and the responsive side of the monocular visual field in the eye under the prism. However, it fails to increase the differential light sensitivity of the eye fitted with the prism. Likewise, the extent of the binocular visual field did not change significantly, irrespective whether an adaptation period had occurred or not. In conclusion, our results suggest that the ameliorative effect in hemianopes provided by the of prismatic treatment depends on the enlargement of the field of view rather than on substantial enlargement of the visual field and/or on increased light sensitivity.

hemianopia, visual field, differential light sensitivity, prismatic treatment, monocular sectors