When examining the internal eye, the eye doctor uses a slit lamp, a diagnostic tool with a powerful microscope and a narrow slit of light, to explore different levels of the eye's transparent tissue and assess the inner workings of the eye. As you keep your head steady on a chin rest, a beam of light is projected onto your eye. The instrument's use of narrow light beams and high magnification provides a cross-sectional picture of eye tissue. This gives the doctor a close-up view of the cornea, anterior chamber, lens, vitreous humor, and retina.
The doctor will check for many things, including degeneration or the presence of foreign particles in the cornea (curved, transparent dome of tissue at the front of the eye), inflammation within the anterior chamber (space behind the cornea and in front of the iris that is filled with aqueous humor), cataract (clouding of the lens), floaters (seeing spots), tumors or abnormal blood vessels in the iris (colored part of the eye that controls how much light enters the eye), and circulatory or degenerative conditions of the retina (the film in the back of the eye).
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