He conducted important research into aspects of binocular vision, including cyclophoria and aniseikonia. This is a common adaptation to strabismus, amblyopia and aniseikonia. Little is known yet about the possibilities of using surgical intervention to correct aniseikonia. Epiretinal membrane has been found to cause metamorphopsia and aniseikonia. Retinoschisis is another eye disease that has been shown to cause aniseikonia. One cause of significant anisometropia and subsequent aniseikonia has been aphakia. Note however that before the optics can be designed, first the aniseikonia should be measured. Aniseikonia is known to be associated with certain retinal conditions. Meridional aniseikonia occurs when these refractive differences only occur in one meridian (see astigmatism). A way to demonstrate aniseikonia is to hold a near target (ex.