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Field Expansion for Acquired Monocular Vision (AMV) Using a Multiplexing Prism
Acquired monocular vision (AMV), the loss of an eye or complete loss of sight in one eye, is frequently due to injury, although it is also caused by many asymmetric eye diseases, such as advanced glaucoma, optic neuropathies, proliferative diabetic retinopathy, intraocular tumors, etc. AMV results in loss of stereoscopic binocular vision, but numerous monocular depth cues may provide adequate depth perception and compensate for the loss after a period of adaptation. However, the field loss of approximately 30° (temporal crescent) on the side of the non-seeing eye is persistent. It results in missing about 30% of possible collisions with other pedestrians. Bumping into other people and cutting them off have been frequently reported.
We recently developed a novel optical device, the multiplexing prism (MxP), which enables the user to see scenes from the blind side and seeing side simultaneously (multiplexing). Whereas other previous aids allowed users to see a portion of the blind side, this was done by reducing the user’s existing seeing field. Our prototype glasses with a partial MxP segment attached (base-in) near the nose bridge can provide about 30° of field expansion into the blind side without any loss of seeing field. This recovery is almost the same size as the visual field of normally sighted people (total 180°). We also consider the effect of spectacle prescriptions on these settings. The results are verified perimetrically, and all participated patients with AMV had field-of-view expansions up to 90° nasally without any loss of seeing field.