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Details About Anatomy Of Retina Along With Anatomical terminology

Anatomy Of Retina
Anatomy Of Retina

DEFINITION

  • Retina is the innermost tunic of the eyeball.
  • It is a thin, delicate and transparent membrane.
  • It is the most highly-developed tissue of the eye.
  • It appears purplish-red due to the visual purple of the rods and underlying vascular choroid.

GROSS ANATOMY

  • Retina extends from the optic disc to the ora serrata with a surface area of about 266 mm2.
  • Retina is thickest in the peripapillary region (0.56 mm) and thinnest at ora serrate (0.1 mm).
  • Grossly, it can be divided into two distinct regions: Posterior Pole & Peripheral Retina separated by the so called retinal equator.
  • POSTERIOR POLE
  • Posterior pole refers to the area of retina posterior to the retinal equator.
  • The posterior pole of the retina includes two distinct areas:
  • Optic Disc
  • Macula Lutea
  • Optic Disc
  • It is a pink coloured, well-defined vertically oval area with average dimension of 1.76 mm horizontally and 1.88 mm vertically.
  • It is placed 3.4 mm nasal to the fovea.
  • At the optic disc all the retinal layers terminate except the nerve fibres (1–1.2 million), which pass through the lamina cribrosa to run into the optic nerve.
  • The optic disc thus represents the beginning of the optic nerve and so is also referred to as Optic Nerve Head.
  • A depression seen in the disc is called the Physiological Cup.
  • The central retinal artery and vein emerge through the centre of this cup.
  • Macula Lutea
  • It is also called the yellow spot.
  • It is comparatively deeper red than the surrounding fundus and is situated at the posterior pole temporal to the optic disc.
  • It is about 5.5 mm in diameter.
  • Fovea centralis is the central depressed part of the macula.
  • It is about 1.5 mm in diameter and is the most sensitive part of the retina.
  • PERIPHERAL RETINA
  • Peripheral retina refers to the area bounded posteriorly by the retinal equator and anteriorly by the ora serrata.
  • Peripheral retina is best examined with indirect ophthalmoscopy and by the use of Goldman three mirror contact lens.

Ora Serrate

  • It is the serrated peripheral margin where the retina ends.
  • Here the retina is firmly attached both to the vitreous and the choroid.
  • The pars plana extends anteriorly from the ora serrata.

MICROSCOPIC STRUCTURE

Retina consists of ten layers, arranged in two distinct functional components :

  1. The pigment epithelium
  2. The neurosensory retina with a potential space between the two.
LAYERS OF RETINADESCRIPTION
Pigment EpitheliumOutermost layer of retina.Consists of a single layer of cells containing pigment. It is firmly adherent to the underlying basal lamina (bruch’s membrane) of the choroid.
Layer Of Rods And ConesRods and cones are the end organs of vision and are also known as photoreceptors. Layer of rods and cones contains only the outer segments of photoreceptor cells arranged in a palisade manner. There are about 120 millions rods and 6.5 millions cones
External Limiting MembraneIt is a fenestrated  membrane, through which pass processes of the rods and cones.
Outer Nuclear LayerIt consists of nuclei of rods and cones.
Outer Plexiform LayerIt consists of connections of rod spherules and cone pedicles with the dendrites of bipolar cells and horizontal cells.
Inner Nuclear LayerIt mainly consists of cell bodies of bipolar cells
Inner Plexiform LayerIt essentially consists of connections between the axons of bipolar cells and dendrites of the ganglion cells, and processes of amacrine cells.
Ganglion Cell LayerIt mainly contains the cellbodies of ganglion cells
Nerve Fibre Layer (Stratum Opticum)Consists of axons of the ganglion cells, which pass through the lamina cribrosa to form the optic nerve.
Internal Limiting MembraneIt is the innermost layer and separates the retina from vitreous

STRUCTURE OF FOVEA CENTRALIS

  • In this area , there are no rods, cones are tightly packed and other layers of retina are very thin.
  • Its central part (foveola) largely consists of cones and their nuclei covered by a thin internal limiting membrane.
  • All other retinal layers are absent in this region.

FUNCTIONAL DIVISIONS OF RETINA

  • Functionally, retina can be divided into temporal retina and nasal retina by a line drawn vertically through the centre of fovea.

ARTERIAL  SUPPLY

LAYERSARTERIES
Outer four layers of the retinaChoroidal and vascular system formed by contribution from anterior ciliary arteries and posterior ciliary arteries.
Inner six layers of retinaCentral retinal artery, which is a branch of the ophthalmic artery

VENOUS DRAINAGE

  • The central retinal vein drains into the cavernous sinus directly or through the superior ophthalmic vein.

DEFINITION

  • Retina is the innermost tunic of the eyeball.
  • It is a thin, delicate and transparent membrane.
  • It is the most highly-developed tissue of the eye.
  • It appears purplish-red due to the visual purple of the rods and underlying vascular choroid.

GROSS ANATOMY

  • Retina extends from the optic disc to the ora serrata with a surface area of about 266 mm2.
  • Retina is thickest in the peripapillary region (0.56 mm) and thinnest at ora serrate (0.1 mm).
  • Grossly, it can be divided into two distinct regions: Posterior Pole & Peripheral Retina separated by the so called retinal equator.
  • POSTERIOR POLE
  • Posterior pole refers to the area of retina posterior to the retinal equator.
  • The posterior pole of the retina includes two distinct areas:
  • Optic Disc
  • Macula Lutea
  • Optic Disc
  • It is a pink coloured, well-defined vertically oval area with average dimension of 1.76 mm horizontally and 1.88 mm vertically.
  • It is placed 3.4 mm nasal to the fovea.
  • At the optic disc all the retinal layers terminate except the nerve fibres (1–1.2 million), which pass through the lamina cribrosa to run into the optic nerve.
  • The optic disc thus represents the beginning of the optic nerve and so is also referred to as Optic Nerve Head.
  • A depression seen in the disc is called the Physiological Cup.
  • The central retinal artery and vein emerge through the centre of this cup.
  • Macula Lutea
  • It is also called the yellow spot.
  • It is comparatively deeper red than the surrounding fundus and is situated at the posterior pole temporal to the optic disc.
  • It is about 5.5 mm in diameter.
  • Fovea centralis is the central depressed part of the macula.
  • It is about 1.5 mm in diameter and is the most sensitive part of the retina.
  • PERIPHERAL RETINA
  • Peripheral retina refers to the area bounded posteriorly by the retinal equator and anteriorly by the ora serrata.
  • Peripheral retina is best examined with indirect ophthalmoscopy and by the use of Goldman three mirror contact lens.

Ora Serrate

  • It is the serrated peripheral margin where the retina ends.
  • Here the retina is firmly attached both to the vitreous and the choroid.
  • The pars plana extends anteriorly from the ora serrata.

MICROSCOPIC STRUCTURE

Retina consists of ten layers, arranged in two distinct functional components :

  1. The pigment epithelium
  2. The neurosensory retina with a potential space between the two.
LAYERS OF RETINADESCRIPTION
Pigment EpitheliumOutermost layer of retina.Consists of a single layer of cells containing pigment. It is firmly adherent to the underlying basal lamina (bruch’s membrane) of the choroid.
Layer Of Rods And ConesRods and cones are the end organs of vision and are also known as photoreceptors. Layer of rods and cones contains only the outer segments of photoreceptor cells arranged in a palisade manner. There are about 120 millions rods and 6.5 millions cones
External Limiting MembraneIt is a fenestrated  membrane, through which pass processes of the rods and cones.
Outer Nuclear LayerIt consists of nuclei of rods and cones.
Outer Plexiform LayerIt consists of connections of rod spherules and cone pedicles with the dendrites of bipolar cells and horizontal cells.
Inner Nuclear LayerIt mainly consists of cell bodies of bipolar cells
Inner Plexiform LayerIt essentially consists of connections between the axons of bipolar cells and dendrites of the ganglion cells, and processes of amacrine cells.
Ganglion Cell LayerIt mainly contains the cellbodies of ganglion cells
Nerve Fibre Layer (Stratum Opticum)Consists of axons of the ganglion cells, which pass through the lamina cribrosa to form the optic nerve.
Internal Limiting MembraneIt is the innermost layer and separates the retina from vitreous

STRUCTURE OF FOVEA CENTRALIS

  • In this area , there are no rods, cones are tightly packed and other layers of retina are very thin.
  • Its central part (foveola) largely consists of cones and their nuclei covered by a thin internal limiting membrane.
  • All other retinal layers are absent in this region.

FUNCTIONAL DIVISIONS OF RETINA

  • Functionally, retina can be divided into temporal retina and nasal retina by a line drawn vertically through the centre of fovea.

ARTERIAL  SUPPLY

LAYERSARTERIES
Outer four layers of the retinaChoroidal and vascular system formed by contribution from anterior ciliary arteries and posterior ciliary arteries.
Inner six layers of retinaCentral retinal artery, which is a branch of the ophthalmic artery

VENOUS DRAINAGE

  • The central retinal vein drains into the cavernous sinus directly or through the superior ophthalmic vein.

DEFINITION

  • Retina is the innermost tunic of the eyeball.
  • It is a thin, delicate and transparent membrane.
  • It is the most highly-developed tissue of the eye.
  • It appears purplish-red due to the visual purple of the rods and underlying vascular choroid.

GROSS ANATOMY

  • Retina extends from the optic disc to the ora serrata with a surface area of about 266 mm2.
  • Retina is thickest in the peripapillary region (0.56 mm) and thinnest at ora serrate (0.1 mm).
  • Grossly, it can be divided into two distinct regions: Posterior Pole & Peripheral Retina separated by the so called retinal equator.
  • POSTERIOR POLE
  • Posterior pole refers to the area of retina posterior to the retinal equator.
  • The posterior pole of the retina includes two distinct areas:
  • Optic Disc
  • Macula Lutea
  • Optic Disc
  • It is a pink coloured, well-defined vertically oval area with average dimension of 1.76 mm horizontally and 1.88 mm vertically.
  • It is placed 3.4 mm nasal to the fovea.
  • At the optic disc all the retinal layers terminate except the nerve fibres (1–1.2 million), which pass through the lamina cribrosa to run into the optic nerve.
  • The optic disc thus represents the beginning of the optic nerve and so is also referred to as Optic Nerve Head.
  • A depression seen in the disc is called the Physiological Cup.
  • The central retinal artery and vein emerge through the centre of this cup.
  • Macula Lutea
  • It is also called the yellow spot.
  • It is comparatively deeper red than the surrounding fundus and is situated at the posterior pole temporal to the optic disc.
  • It is about 5.5 mm in diameter.
  • Fovea centralis is the central depressed part of the macula.
  • It is about 1.5 mm in diameter and is the most sensitive part of the retina.
  • PERIPHERAL RETINA
  • Peripheral retina refers to the area bounded posteriorly by the retinal equator and anteriorly by the ora serrata.
  • Peripheral retina is best examined with indirect ophthalmoscopy and by the use of Goldman three mirror contact lens.

Ora Serrate

  • It is the serrated peripheral margin where the retina ends.
  • Here the retina is firmly attached both to the vitreous and the choroid.
  • The pars plana extends anteriorly from the ora serrata.

MICROSCOPIC STRUCTURE

Retina consists of ten layers, arranged in two distinct functional components :

  1. The pigment epithelium
  2. The neurosensory retina with a potential space between the two.
LAYERS OF RETINADESCRIPTION
Pigment EpitheliumOutermost layer of retina.Consists of a single layer of cells containing pigment. It is firmly adherent to the underlying basal lamina (bruch’s membrane) of the choroid.
Layer Of Rods And ConesRods and cones are the end organs of vision and are also known as photoreceptors. Layer of rods and cones contains only the outer segments of photoreceptor cells arranged in a palisade manner. There are about 120 millions rods and 6.5 millions cones
External Limiting MembraneIt is a fenestrated  membrane, through which pass processes of the rods and cones.
Outer Nuclear LayerIt consists of nuclei of rods and cones.
Outer Plexiform LayerIt consists of connections of rod spherules and cone pedicles with the dendrites of bipolar cells and horizontal cells.
Inner Nuclear LayerIt mainly consists of cell bodies of bipolar cells
Inner Plexiform LayerIt essentially consists of connections between the axons of bipolar cells and dendrites of the ganglion cells, and processes of amacrine cells.
Ganglion Cell LayerIt mainly contains the cellbodies of ganglion cells
Nerve Fibre Layer (Stratum Opticum)Consists of axons of the ganglion cells, which pass through the lamina cribrosa to form the optic nerve.
Internal Limiting MembraneIt is the innermost layer and separates the retina from vitreous

STRUCTURE OF FOVEA CENTRALIS

  • In this area , there are no rods, cones are tightly packed and other layers of retina are very thin.
  • Its central part (foveola) largely consists of cones and their nuclei covered by a thin internal limiting membrane.
  • All other retinal layers are absent in this region.

FUNCTIONAL DIVISIONS OF RETINA

  • Functionally, retina can be divided into temporal retina and nasal retina by a line drawn vertically through the centre of fovea.

ARTERIAL  SUPPLY

LAYERSARTERIES
Outer four layers of the retinaChoroidal and vascular system formed by contribution from anterior ciliary arteries and posterior ciliary arteries.
Inner six layers of retinaCentral retinal artery, which is a branch of the ophthalmic artery

VENOUS DRAINAGE

  • The central retinal vein drains into the cavernous sinus directly or through the superior ophthalmic vein.

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