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(fō″tō-sĕn′ sĭ-tī″zĕr) A substance that, in combination with light, will cause a sensitivity reaction in the substance or organism.


(fō′ tō-sĕn″sĕr) A device that detects light.


(fō′ tō-stā″b’l) [″+ L. stabilis, stable] Uninfluenced by exposure to light.


(fōt″ō-sin′thĕ-sĭs) [photo- + synthesis] The process by which plants manufacture carbohydrates and oxygen by combining carbon dioxide and water, using light energy in the presence of chlorophyll. photosynthesize (fōt″ō-sin′thĕ-sīz″), v.


(fōt″ō-tak′sĭs) [photo- + taxis] The reaction and movement of cells and microorganisms under the stimulus of light. phototactic (fōt″ō-tak′tik), adj.


(fō′tō-tĕst″) The use of controlled exposures to ultraviolet light (and ambient or polychromatic light) to determine the cause, or presence of, a rash, thought to be triggered by sunlight exposure.


(fō″tō-thĕr′ ă-pē) [″ + therapeia, treatment] Exposure to sunlight or to ultraviolet (UV) light for therapeutic purposes. One example of phototherapy is the treatment of neonatal jaundice, in which the jaundiced infant is exposed to UV light to decrease bilirubin levels in the bloodstream, thereby reducing the risk of bilirubin deposition in the brain. Phototherapy also is used to treat some skin diseases, including cutaneous T-cell lymphoma and psoriasis, and to relieve the symptoms of seasonal affective disorder. SYN: light therapy. SEE: photodynamic therapy; seasonal affective disorder.

image The eyes and often the gonads of treated patients are shielded from the light source to prevent them from being damaged.


(fō″tō-thĕr′ măl) [″ + therme, heat] Pert. to heat produced by light.


(fō″tō″thĕr-mol′ ĭ-sĭs) [photo- + thermolysis] The use of light produced by lasers to produce heat damage. photothermolytic (-moï’lit-ik), adj.

fractional p. A method of laser skin resurfacing in which laser energy is directed at pinpoint, broadly separated islands of skin instead of larger swaths to remove cosmetically unappealing blemishes in skin color and texture. The technique is used to minimize the time it takes to restore normal epithelium to the treated surface. SYN: fractional ablation.

selective p. The use of short pulses of light to treat skin conditions. This method causes less damage to normal tissue than do continuous beam lasers.


(fōt″ō-tok′ sik) [photo- + toxic] Pert. to the harmful reaction produced by light energy, esp. that produced in the skin. Simple sunburn of the skin is a kind of phototoxicity. phototoxicity (-tok-sis′ĭt-ē), n.


(fōt″ō-trof′ik, fōt″ō-trō′fik) [photo- + -trophic,] Pert. to the ability ...

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