| photopsy | <medicine> An affection of the eye, in which the patient perceives luminous rays, flashes, coruscations, etc. See phosphene. Origin: Gr. Opsis = vision (09 Mar 1998) |
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| photoptarmosis | Reflex sneezing that occurs when bright light stimulates the retina. Origin: photo-+ G. Ptarmos, a sneezing, + -osis, condition (05 Mar 2000) |
| photoradiation | Treatment of cancer by intravenous injection of a photosensitizing agent, such as haematoporphyrin, followed by exposure to visible light of superficial tumours or of deep tumours by a fibreoptic probe. Synonym: photochemotherapy, photoradiation therapy. (05 Mar 2000) |
| photoradiation therapy | Treatment of cancer by intravenous injection of a photosensitizing agent, such as haematoporphyrin, followed by exposure to visible light of superficial tumours or of deep tumours by a fibreoptic probe. Synonym: photochemotherapy, photoradiation therapy. (05 Mar 2000) |
| photoreaction | A reaction caused or affected by light; e.g., a photochemical reaction, photolysis, photosynthesis, phototropism, thymine dimer formation. (05 Mar 2000) |
| photoreactivating enzyme | deoxyribodipyrimidine photolyase |
| photoreactivation | <molecular biology> The repair of DNA that has been damaged by ultraviolet radiation, by the DNA repair enzyme photolyase, which requires the presence of visible light. (31 Dec 1997) |
| photoreceptive | Functioning as a photoreceptor. (05 Mar 2000) |
| photoreceptor | <cell biology> A specialised cell type in a multicellular organism that is sensitive to light. This definition excludes single celled organisms, but includes noneye receptors, such as snake infra red (heat) detectors or photosensitive pineal gland cells. See: retinal rods, retinal cones. (31 Dec 1997) |
| photoreceptor cells | Rod and cone cell's of the retina. (05 Mar 2000) |
| photoreceptors | Cells specialised to detect and transduce light and darkness. Rods and cones are the photoreceptors in the vertebrate retina. (12 Dec 1998) |
| photoreceptors, invertebrate | Cells in invertebrates which are specialised to detect and transduce light and darkness and relay that information centrally in the nervous system. (12 Dec 1998) |
| photoreduction | <biochemistry, plant biology> The light-induced reduction of an electron acceptor during photosynthesis. (31 Dec 1997) |
| photorelief | A printing surface in relief, obtained by photographic means and subsequent manipulations. Source: Websters Dictionary (01 Mar 1998) |
| photorespiration | <plant biology> Increased respiration that occurs in photosynthetic cells in the light, due to the ability of RuDP carboxylase to react with oxygen as well as carbon dioxide. Reduces the photosynthetic efficiency of C3 plants. (31 Dec 1997) |