Double vision.

1. Diplopia may require a simple change in the patient's glasses, various types of surgical correction, or even treatment for a life-threatening condition. Your job is to determine the urgent nature of the problem and have the patient scheduled in your office, clinic, or hospital appropriately. 2. When questions of diplopia arise, establish whether the diplopia is still present when either the right or left eye is covered (monocular or binocular diplopia). 3. Monocular diplopia is most always optical in nature. Binocular diplopia is caused by either aniseikonia (a difference in the relative sizes of the retinal images perceived by the patient) or, more commonly, misalignment of the visual axes.