It consists of a main unit (commonly referred to as the head) with a built-in light source directed through the pupil to illuminate the interior of the eyeball, a mirror with a single hole for viewing, and a dial containing lenses of different powers; a dedicated power supply handpiece may be included with the head. An electrically-powered, hand-held, ophthalmic instrument designed to be held close to the patient’s eye to examine the interior of the eye and related structures [e.g., fundus (retina), cornea, aqueous, lens, and vitreous] by producing an upright (unreversed) image of approximately 5 times magnification.
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