photosensitive

photosensitive /pho·to·sen·si·tive/ (-sen´sĭ-tiv)

1. reacting to light; said of a cell or organism.

2. having abnormally heightened sensitivity of the skin or eyes to sunlight.

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pho·to·sen·si·tive (ft-sns-tv)

adj.

1. Sensitive or responsive to light or other radiant energy.

2. Abnormally sensitive or reactive to light.

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photosensitive

[-sen′sitiv]

Etymology: Gk, phos + L, sentire, to feel

pertaining to increased reactivity of the skin to sunlight caused by a disorder such as albinism or porphyria, or, more frequently, by the use of certain drugs. Relatively brief exposure to sunlight or to an ultraviolet lamp may cause edema, papules, urticaria, or acute burns in individuals with endogenous or acquired photosensitivity. Treatment involves avoidance of exposure to sunlight or the photosensitizing agent.

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photosensitive

exhibiting abnormally heightened sensitivity to sunlight.

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photosensitive conjunctivitis

conjunctivitis that begins on the lateral quadrant of the cornea and reduces in severity to the center of the cornea—the area exposed to the sun's rays. If left unattended progresses to keratitis.

photosensitive dermatitis

is confined to the dorsal parts of the body exposed to the sunlight, and to parts with little or no pigment and the least hair or wool covering. The dermatitis is diffuse and often sufficiently severe to kill the animal. Initially there is itching and rubbing, then edema, followed by weeping, then necrosis or gangrene. Additional lesions may be on the undersurface of the tongue, at the mucocutaneous junction at the lips and on the lateral aspects of the teats.

Photosensitive dermatitis on the teat of a cow. By permission from Blowey RW, Weaver AD, Diseases and Disorders of Cattle, Mosby, 1997