General Medical Information

Diplopia

Jean Edwards Holt

Diplopia is another symptom of visual abnormality. Physiologic diplopia is a normal phenomenon in which objects not within the area of fixation are seen as double. This is easily seen when one looks at a near object with attention directed at a distant object, which then appears double. Usually this does not impinge on consciousness. Pathologic diplopia is a cardinal sign of weakness of one or more of the extraocular muscles and usually is caused by neurologic disease, trauma, or diabetes mellitus. Diplopia also can occur with normal muscles if the globe is displaced, as in orbital disease or tumors that prevent proper alignment of visual stimuli. Monocular diplopia (that which does not go away when one eye is covered) is rare and usually due to splitting of light rays by an irregularity in the cornea, certain types of cataracts, or misaligned photoreceptors in the macula. More commonly, monocular diplopia is a neurotic or functional disorder.