DD
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 :
- The pigment epithelium
- The neurosensory retina with a potential space between the two.
| LAYERS OF RETINA | DESCRIPTION |
| Pigment Epithelium | Outermost 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 Cones | Rods 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 Membrane | It is a fenestrated membrane, through which pass processes of the rods and cones. |
| Outer Nuclear Layer | It consists of nuclei of rods and cones. |
| Outer Plexiform Layer | It consists of connections of rod spherules and cone pedicles with the dendrites of bipolar cells and horizontal cells. |
| Inner Nuclear Layer | It mainly consists of cell bodies of bipolar cells |
| Inner Plexiform Layer | It essentially consists of connections between the axons of bipolar cells and dendrites of the ganglion cells, and processes of amacrine cells. |
| Ganglion Cell Layer | It 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 Membrane | It 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
| LAYERS | ARTERIES |
| Outer four layers of the retina | Choroidal and vascular system formed by contribution from anterior ciliary arteries and posterior ciliary arteries. |
| Inner six layers of retina | Central 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 :
- The pigment epithelium
- The neurosensory retina with a potential space between the two.
| LAYERS OF RETINA | DESCRIPTION |
| Pigment Epithelium | Outermost 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 Cones | Rods 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 Membrane | It is a fenestrated membrane, through which pass processes of the rods and cones. |
| Outer Nuclear Layer | It consists of nuclei of rods and cones. |
| Outer Plexiform Layer | It consists of connections of rod spherules and cone pedicles with the dendrites of bipolar cells and horizontal cells. |
| Inner Nuclear Layer | It mainly consists of cell bodies of bipolar cells |
| Inner Plexiform Layer | It essentially consists of connections between the axons of bipolar cells and dendrites of the ganglion cells, and processes of amacrine cells. |
| Ganglion Cell Layer | It 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 Membrane | It 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
| LAYERS | ARTERIES |
| Outer four layers of the retina | Choroidal and vascular system formed by contribution from anterior ciliary arteries and posterior ciliary arteries. |
| Inner six layers of retina | Central 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 :
- The pigment epithelium
- The neurosensory retina with a potential space between the two.
| LAYERS OF RETINA | DESCRIPTION |
| Pigment Epithelium | Outermost 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 Cones | Rods 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 Membrane | It is a fenestrated membrane, through which pass processes of the rods and cones. |
| Outer Nuclear Layer | It consists of nuclei of rods and cones. |
| Outer Plexiform Layer | It consists of connections of rod spherules and cone pedicles with the dendrites of bipolar cells and horizontal cells. |
| Inner Nuclear Layer | It mainly consists of cell bodies of bipolar cells |
| Inner Plexiform Layer | It essentially consists of connections between the axons of bipolar cells and dendrites of the ganglion cells, and processes of amacrine cells. |
| Ganglion Cell Layer | It 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 Membrane | It 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
| LAYERS | ARTERIES |
| Outer four layers of the retina | Choroidal and vascular system formed by contribution from anterior ciliary arteries and posterior ciliary arteries. |
| Inner six layers of retina | Central 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.
GIPHY App Key not set. Please check settings