Eye
Retina
General

Author: Nat Pernick, M.D. (see Authors page)

Revised: 17 May 2018, last major update February 2014

Copyright: (c) 2004-2018, PathologyOutlines.com, Inc.

PubMed Search: retina [title] review[ptyp] pathology

Cite this page: Pernick, N. Retina: General. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/eyeretinageneral.html. Accessed September 25th, 2018.
Definition / general
  • Embryologic derivative of diencephalon, responds to injury via gliosis
  • Composed of photoreceptors, neurons and glial cells
  • Lines inside surface of eye posterior to ora serrata
  • Neurons give rise to retinoblastoma, glial cells to astrocytomas
  • No lymphatics
  • Bruch membrane: separates choroid from overlying retinal pigment epithelium, is 2 - 4 microns thick, has 5 distinct layers (basal lamina of overlying retinal pigment epithelium, collagenous layer, elastic fiber rich layer, collagenous layer and basal lamina of endothelial cells of choriocapillaris), thickens with age, has focal excrescences known as drusen

    Layers from outside in:
    • (1) retinal pigment epithelium; (2) rods and cones (photoreceptors); (3) external limiting membrane; (4) outer nuclear layer; (5) outer plexiform layer; (6) inner nuclear layer; (7) inner plexiform layer; (8) ganglion cell layer; (9) nerve fiber layer; (10) inner limiting membrane; (11) vitreous
    • (1) Retinal pigment epithelium: derived from primary optic vesicle, an outpouching of brain; helps maintain outer segments of photoreceptors (rods and cones); is a monolayer of cells containing intracytoplasmic melanosomes; has phagocytic function that assists in turnover of photoreceptor elements; undigested phagoliposomes become lipofuscin granules
    • (2) Rods and cones: rods are cylindrical, cones are longer and thicker; light is converted by photoreceptor cells into electric impulses

  • Hemorrhage in nerve fiber layer appears in ophthalmoscope as horizontal streaks or flames
  • Hemorrhage in external retinal layers appears as dots
  • Fovea centralis: center of macula, slightly depressed, 1.5 mm in diameter, responsible for most visual acuity; lacks blood vessels (relies on choroidal circulation) and rods
  • Macula: has highest density of photoreceptors and high ganglion cell / photoreceptor ratio; ganglion cells are several layers thick
  • Macula lutea: yellow specialized portion of retina in posterior pole of eye
  • Ora serrata: irregular, anterior margin of retina, internal to junction of choroid and ciliary body
  • Retinal detachment: separation of neurosensory retina (rods and cones) from retinal pigment epithelium
  • Cysts develop in peripheral retina in everyone age 20+ years
Drawings

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Layers of retina

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Retinal neurons

Microscopic (histologic) images

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Layers of retina

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Fovea centralis (no ganglion cell layer or nerve fiber layer)



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Layers of retina

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Fovea centralis, choroid and sclera


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Fovea and retina

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Ora serrata