| IDA | idamycin; image display and analysis; iminodiacetic acid; insulin-degrading activity; iron deficienc... |
|---|---|
| IDB | image data baser |
| IGS | image-guided surgery; inappropriate gonadotropin secretion; internal guide sequence |
| II | icterus index; image intensification or intensifier; Roman numeral two |
| IIG | interactive image-guided [surgery] |
| 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) |
| rhegmatogenous retinal detachment | Retinal separation associated with a break, a hole, or a tear in the sensory retina. (05 Mar 2000) |
| pigmented retinal epithelium | Layer of unusual phagocytic epithelial cells lying below the photoreceptors of the vertebrate eye. The dorsal surface of the PRE cell is closely apposed to the ends of the rods and as discs are shed from the rod outer segment they are internalised and digested by the PRE. Do not have desmosomes or cytokeratins in some species. (18 Nov 1997) |
| trans-retinal | The orange retinaldehyde resulting from the action of light on the rhodopsin of the retina, which converts the 11-cis-retinal component of the rhodopsin to all-trans-retinal plus opsin. Synonym: trans-retinal, visual yellow. (05 Mar 2000) |
| exudative retinal detachment | Detachment of the retina without retinal breaks, arising from inflammatory disease of choroid, retinal tumours, and retinal angiomatosis. (05 Mar 2000) |
| falciform retinal fold | A congenital fold from the disk to the ciliary region in the inferior temporal quadrant of the retina. (05 Mar 2000) |
| 11-cis-retinal | The isomer of retinaldehyde that can combine with opsin to form rhodopsin; it is formed from 11-trans-retinal by retinal isomerase. Synonym: neoretinal b. (05 Mar 2000) |
| Abbe theory of image formation | <optics, physics> Abbe's theory is based on the fact that a non-self-luminous particle, which is illuminated by an extraneous source, gives rise to diffracted light rays, in addition to the dioptric pencil. He stated that to form a good microscopical image as many of the diffracted rays as possible should be intercepted by the objective. With closely ruled lines, his theory is easily demonstrated by observing the back lens of the objective, for here the diffracted rays can be observed directly if the aperture diaphragm is closed. It can be shown that, when the illumination is arranged to exclude the diffracted images, resolution is lost. (11 Mar 1998) |
| accidental image | Continuation of visual impression after cessation of stimuli causing the original image. (12 Dec 1998) |