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an instrument for examining the interior of the eye.
direct ophthalmoscope one that produces an upright, or unreversed, image of approximately 15 times magnification. The direct ophthalmoscope is used to inspect the fundus of the eye, which is the back portion of the interior eyeball. Examination is best carried out in a darkened room. The examiner looks for changes in the color or pigment of the fundus, changes in the caliber and shape of retinal blood vessels, and any abnormalities in the macula lutea, the portion of the retina that receives and analyzes light only from the very center of the visual field. Macular degeneration and opacities of the lens can be seen through direct ophthalmoscopy.
indirect ophthalmoscope one that produces an inverted, or reversed, direct image of two to five times magnification. An indirect ophthalmoscope provides a stronger light source, a specially designed objective lens, and opportunity for stereoscopic inspection of the interior of the eyeball. It is invaluable for diagnosis and treatment of retinal tears, holes, and detachments. The pupils must be fully dilated for satisfactory indirect ophthalmoscopy.
scanning laser ophthalmoscope (SLO) an instrument for retinal imaging in which light from a low-power laser beam that scans the retina is reflected back to a sensor; the light detected by the sensor is used to create a full-color composite digital image.
an instrument designed to visualize the interior of the eye, with the instrument relatively close to the subject's eye and the observer viewing an upright magnified image.
di·rect oph·thal·mo·scope(dĭr-ekt' of-thal'mŏ-skōp)
An instrument designed to visualize the interior of the eye, with the instrument relatively close to the subject's eye and the observer viewing an upright magnified image.