| retinal necrosis syndrome, acute | <ophthalmology> Mild to fulminant necrotizing vaso-occlusive retinitis associated with a high incidence of retinal detachment and poor vision outcome. (12 Dec 1998) |
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| retinal neovascularization | <ophthalmology> New blood vessels originating from the retinal veins and extending along the inner (vitreal) surface of the retina. This process is characterised by a diseased retina with a disturbed vascular bed. Neovascularization is associated with a variety of conditions including vascular occlusion, sickle cell diseases, sarcoidosis. (12 Dec 1998) |
| retinal perforation | <ophthalmology> Perforations through the whole thickness of the retina including the macula as the result of inflammation, trauma, degeneration, etc. The concept includes retinal breaks, tears, dialyses, and holes. (12 Dec 1998) |
| retinal pigmented epithelial cell | See: pigmented retinal epithelium, retina. (18 Nov 1997) |
| retinal pigments | <ophthalmology, physiology> Chemicals functioning in the visual cycle in retinal rod cells. Through excitation by visible light, a series of complex molecular changes occur that serve to trigger in the optical nerve endings an impulse transmitted to the brain, resulting in the perception of vision. (12 Dec 1998) |
| retinal reductase | Alcohol dehydrogenase (NAD(P)+). (05 Mar 2000) |
| retinal rod | <ophthalmology, physiology> Major photoreceptor cell of vertebrate retina (about 125 million in a human eye). Columnar cells (about 40m long, 1m diameter) having three distinct regions: a region adjacent to and synapsed with, the neural layer of the retina contains the nucleus and other cytoplasmic organelles, below this is the inner segment, rich in mitochondria, that is connected through a thin neck (in which is located a ciliary body) to the outer segment. The outer segment largely consists of a stack of discs membrane infoldings that are incompletely separated in cones) that are continually replenished near the inner segment and that are shed from the distal end and phagocytosed by the pigmented epithelium. The membranes of the discs are rich in rhodopsin, the pigment that absorbs light. (03 Jul 1999) |
| retinal vein | <ophthalmology> Central retinal vein and its tributaries. It runs a short course within the optic nerve and then leaves and empties into the superior ophthalmic vein or cavernous sinus. (12 Dec 1998) |
| retinal vein occlusion | <ophthalmology> Occlusion of the retinal vein. Those at high risk for this condition include patients with hypertension, diabetes mellitus, arteriosclerosis, and other cardiovascular diseases. (12 Dec 1998) |
| retinal vessels | <ophthalmology> The vessels which supply and drain the retina. (12 Dec 1998) |
| retinaldehyde | <chemical> A carotenoid constituent of visual pigments. It is the oxidised form of retinol which functions as the active component of the visual cycle. It is bound to the protein opsin forming the complex rhodopsin. When stimulated by visible light, the retinal component of the rhodopsin complex undergoes isomerization at the 11-position of the double bond to the cis-form; this is reversed in "dark" reactions to return to the native trans-configuration. Chemical name: Retinal (03 Jul 1999) |
| retinaldehyde dehydrogenase | An oxidoreductase catalyzing the interconversion of retinaldehyde and NAD+ to retinoic acid and NADH; thus affecting growth and differentiation. Synonym: retinaldehyde dehydrogenase. (05 Mar 2000) |
| retinaldehyde isomerase | <enzyme> Converts all-trans-retinal to 11-cis-retinal Registry number: EC 5.2.1.3 Synonym: retinal photoisomerase (26 Jun 1999) |
| retinaldehyde reductase | Alcohol dehydrogenase (NAD(P)+). (05 Mar 2000) |
| retinalite | <chemical> A translucent variety of serpentine, of a honey yellow or greenish yellow colour, having a waxy resinlike luster. Origin: Gr. Resin. Source: Websters Dictionary (01 Mar 1998) |
| iridial part of retina | iridial part of retina |
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| optic part of retina | The internal layer of the retina containing the neural elements, as distinguished from the outer leaf of the retina, or pigmented layer. Synonym: pars optica retinae, neural layer of retina, optic part of retina, stratum cerebrale retinae. (05 Mar 2000) |
| temporal venules of retina | See: inferior temporal venule of retina, superior temporal venule of retina. (05 Mar 2000) |
| tigroid retina | A normal fundus to which a deeply pigmented choroid gives the appearance of dark polygonal areas between the choroidal vessels, especially in the periphery. Synonym: fundus tigre, leopard fundus, leopard retina, mosaic fundus, tigroid fundus, tigroid retina. (05 Mar 2000) |
| external nuclear layer of retina | The outermost layer of the cerebral layer of retina, composed of the primary receptor cells of the retina; the stratum consists of two sublayers: 1) an external layer made up of the rods and cones, the photosensitive processes of the receptor cells, and 2) the external nuclear layer containing the cell bodies of these cells; the external limiting membrane forms a perforated supporting plate between the two sublayers; the name refers to the fact that the retinal receptor cells are a specialised form of (epithelial) ependyma cell and thus, in a sense, are comparable to the neuroepithelial cells (e.g., hair cells) of other sense organs. Synonym: external nuclear layer of retina, stratum neuroepitheliale retinae, stratum nucleare externum retinae. (05 Mar 2000) |
| flecked retina | An retina exhibiting fundus flavimaculatus, hereditary drusen, or fundus albipunctatus. (05 Mar 2000) |
| flecked retina syndrome | <syndrome> Hereditary retinal disorder with abnormal transmission of fluorescence through the retinal pigment epithelium on angiography. (05 Mar 2000) |
| fleck retina of Kandori | An autosomal-recessive disorder of the retinal pigment epithelium occurring among Japanese. (05 Mar 2000) |
| layers of retina | Light sensitive layer of the eye. In vertebrates, looking from outside, there are four major cell layers: (i) the outer neural retina, which contains neurons (ganglion cells, amacrine cells, bipolar cells) as well as blood vessels, (ii) the photoreceptor layer, a single layer of rods and cones, (iii) the pigmented retinal epithelium (PRE or RPE), (iv) the choroid, composed of connective tissue, fibroblasts and including a well vascularised layer, the chorio capillaris, underlying the basal lamina of the PRE. Behind the choroid is the sclera, a thick organ capsule. In molluscs (especially cephalopods such as the squid) the retina has the light sensitive cells as the outer layer with the neural and supporting tissues below. See: retinal rods, retinal cones, rhodopsin. (18 Nov 1997) |
| leopard retina | A normal fundus to which a deeply pigmented choroid gives the appearance of dark polygonal areas between the choroidal vessels, especially in the periphery. Synonym: fundus tigre, leopard fundus, leopard retina, mosaic fundus, tigroid fundus, tigroid retina. (05 Mar 2000) |
| limiting membrane of retina | One of two layers of the retina: (05 Mar 2000) |