FALSE SCOTOMAS ASSOCIATED WITH HIGH UNCORRECTED REFRACTIVE ERRORS

A CAUSE of false scotoma is deserving of presentation because the potential frequency of the type of scotoma is greater than the combined incidence of all other types and because false scotoma simulates a genuine scotoma so closely that it may be misleading. At the University of Michigan eye clinic we use a 10-mm. white circle for a fixation target at 1 meter on the black campimeter screen; and when searching for central scotomas we not infrequently move the appropriately sized object out from this central target until the patient says that he sees it. With this method, however, a central scotoma almost invariably appears under cycloplegia in patients with uncorrected ametropia. The intensity of this scotoma depends on the degree of ametropia and is essentially unchanged by changes in illumination, ranging from ordinary indoor lighting to very subdued light. If there is no associated macular or other pathologic change