| retinal cone | <ophthalmology, physiology> One of the two photoreceptor cell types in the vertebrate retina. In cones the photopigment is in invaginations of the cell membrane of the outer segment. Cones are less sensitive to light than rods, and are differentially sensitive to particular wavelengths of light and therefore important for colour vision. They provide vision with higher spatial and temporal acuity, and it is the combination of signals from cones with different pigments that facilitates colour vision. There are three types of cones, each type sensitive to red, green or blue. Present in large numbers in the fovea. (03 Jul 1999) |
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| retinal degeneration | <ophthalmology> A retrogressive pathological change in the retina, focal or generalised, caused by genetic defects, inflammation, trauma, vascular disease, or aging. Degeneration affecting predominantly the macula lutea of the retina is macular degeneration. (03 Jul 1999) |
| retinal 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) |
| retinal detachment | <ophthalmology> A painless disorder (when spontaneous) where the patient complains of a gradual raising or lowering of a curtain over the visual field of the affected eye. May also occur as the result of trauma. (27 Sep 1997) |
| retinal disease | <ophthalmology> A general term which describes any retinal changes (haemorrhages or exudates) that can affect vision (for example diabetic retinopathy, hypertensive retinopathy). (27 Sep 1997) |
| retinal disparity | The slight difference in retinal images that arises because of the lateral separation of the two eyes that stimulates stereoscopic vision. (05 Mar 2000) |
| retinal drusen | <ophthalmology> Colloid or hyaline bodies lying beneath the retinal pigment epithelium. They may occur either secondary to changes in the choroid that affect the pigment epithelium or as an autosomal dominant disorder of the retinal pigment epithelium. (12 Dec 1998) |
| retinal dysplasia | <ophthalmology> Congenital, often bilateral, retinal abnormality characterised by the arrangement of outer nuclear retinal cells in a palisading or radiating pattern surrounding a central ocular space. This disorder is sometimes hereditary. (12 Dec 1998) |
| retinal embolism | Embolism of an artery of the retina. (05 Mar 2000) |
| retinal fold | A congenital or secondary fold, consequent to membrane contraction, producing star-shaped, meridional, or circular fold's on the retina. (05 Mar 2000) |
| retinal ganglion cell | <pathology> A type of interneuron that conveys information from the retinal bipolar, horizontal and amacrine cells to the brain. (18 Nov 1997) |
| retinal ganglion cells | Cells of the innermost nuclear layer of the retina, the ganglion cell layer, which project axons through the optic nerve to the brain. They are quite variable in size and in the shapes of their dendritic arbors, which are generally confined to the inner plexiform layer. (12 Dec 1998) |
| retinal image | A real image formed on the retina. (05 Mar 2000) |
| retinal isomerase | <enzyme> Converts all-trans-retinal to 11-cis-retinal Registry number: EC 5.2.1.3 Synonym: retinal photoisomerase (26 Jun 1999) |
| retinal monooxygenase | <enzyme> Cytochrome p-450 and NADPH-dependent enzyme from rabbit liver microsomes Registry number: EC 1.14.13.- Synonym: retinoic acid synthase (26 Jun 1999) |
| neural retina | <embryology> Layer of nerve cells in the retina, embryologically part of the brain. The incoming light passes through nerve fibres and intermediary nerve cells of the neural retina, before encountering the light sensitive rods and cones at the interface between neural retina and the pigmented retinal epithelium. (04 Jul 1999) |
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| neuroepithelial 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) |
| nuclear layers of retina | The outer nuclear layer, layer 4, of the retina, neuroepithelial layer of retina, and the inner layer, layer 6, of the retina, ganglionic layer of retina. Synonym: granular layers of retina, stratum nucleare externum et internum retinae. (05 Mar 2000) |
| superior nasal arteriole of retina | The branch of the central artery of the retina that passes to the upper medial, or nasal, part of the retina. Synonym: arteriola nasalis retinae superior. (05 Mar 2000) |
| superior nasal venule of retina | The small vein that drains blood from the upper medial (nasal) part of the retina; it joins the central vein. Synonym: venula nasalis retinae superior. (05 Mar 2000) |
| superior temporal arteriole of retina | The branch of the central artery of the retina that passes laterally above the macula to supply the upper lateral or temporal part of the retina. Synonym: arteriola temporalis retinae superior. (05 Mar 2000) |
| superior temporal venule of retina | The venule that passes from the upper lateral (temporal) part of the retina to join the central vein. Synonym: venula temporalis retinae superior. (05 Mar 2000) |
| sustentacular fibres of retina | Sustentacular neuroglial cells of the retina running through the thickness of the retina from the internal limiting membrane to the bases of the rods and cones where they form a row of junctional complexes. Synonym: Muller's radial cells, sustentacular fibres of retina. (05 Mar 2000) |
| demarcation line of retina | Junction of avascular and vascular retina in retinopathy of prematurity; line marking the limits of an old retinal detachment. (05 Mar 2000) |
| detached retina | <ophthalmology> A painless disorder (when spontaneous) where the patient complains of a gradual raising or lowering of a curtain over the visual field of the affected eye. May also occur as the result of trauma. (27 Sep 1997) |
| inferior nasal arteriole of retina | The branch of the central artery of the retina that supplies the lower medial, or nasal, part of the retina. Synonym: arteriola nasalis retinae inferior. (05 Mar 2000) |
| inferior nasal venule of retina | The small vein that passes from the inferior medial (nasal) part of the retina to join the central vein. Synonym: venula nasalis retinae inferior. (05 Mar 2000) |
| inferior temporal arteriole of retina | The branch of the central artery of the retina that passes laterally below the macula to supply the lower lateral or temporal part of the retina. Synonym: arteriola temporalis retinae inferior. (05 Mar 2000) |
| inferior temporal venule of retina | The small vein that passes from the lower lateral (temporal) part of the retina to enter the central vein. Synonym: venula temporalis retinae inferior. (05 Mar 2000) |
| internal nuclear layer of retina | The intermediate layer of neurons in the retina composed largely of bipolar cells. Synonym: internal nuclear layer of retina, stratum ganglionare retinae, stratum nucleare internum retinae. (05 Mar 2000) |