Aneisokonia

Aneisokonia (etym. Gr. "an" = "not", + "is(o)" = "equal," + "eikōn" = "image") is an eye condition where there is a significant difference in magnification of images between the eyes. When this magnification difference becomes excessive the effect can cause diplopia, disorientation, eyestrain, headache, and dizziness and balance disorders. Treatment is with contact lenses, or special magnification size- matched lenses called isokonic lenses, or if possible and medically appropriate, by intraocular lenses (IOLs), or laser corneal ablation. When the image disparity is astigmatic (cylindrical) and not uniform, images can appear wider, taller, or diagonally different. When the disparity appears to be only in a part of the visual field, as in epiretinal membrane, the aneisokonia cannot be corrected optically, and may require surgical intervention if appropriate.