The disk is sharply demarcated temporally and to a lesser degree nasally from the background retina, which is all the retina that is not disk, vessels, or macula. ![]() The disk is a yellow-pink color that stands out from the redder, browner, or more orange retina proper (see Figure 117.4D). The term temporal is used in describing ophthalmoscopic landmarks and findings, rather than "lateral" and nasal replaces "medial." The optic nerve head or disk is seen when one looks through the pupil from an angle about 15 degrees temporal to the optical axis (the patient's line of sight, "straight ahead"). In wall-mounted instruments, this is located instead on the fixed panel, b. Rheostat runs along circumference of tube and controls intensity of beam output. (A) A portable ophthalmoscope in front (patient's-eye) view. Only ophthalmologists perform retinoscopy and indirect ophthalmoscopy, which require other equipment and provide different information. Synonyms for funduscopic examination include funduscopy, ophthalmoscopy, and direct ophthalmoscopy. In comparison to the ophthalmologist, the internist, neurologist, or pediatrician concentrates particularly on funduscopic manifestations of systemic disease and less on local ocular disease. One paralyzes the pupilloconstrictor muscle of the iris with nonabsorbable, short-acting topical parasympatholytic drugs, resulting in a larger pupillary aperture. ![]() The pupil is frequently dilated pharmacologically to render retinal inspection easier, and for examination of the macula. In the procedure, one looks at structures lying in the innermost aspect of the globe, collectively known as the eyegrounds: retina, retinal blood vessels, optic nerve head (disk), and to a limited degree, subjacent choroid. The viewing aperture (window) of the ophthalmoscope contains a lens that modifies light rays to assist the user. Light rays forming the image of the retina re-emerge through the pupil. The ophthalmoscope illuminates the retina through the normal iris defect that is the pupil. One looks through the ophthalmoscope ( Figure 117.1), which is simply a light with various optical modifications, including lenses. ![]() Funduscopic examination is a routine part of every doctor's examination of the eye, not just the ophthalmologist's.
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