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EXCIMER Ophtalmologic Clinics
ophtalmologic clinic
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EXCIMER Ophtalmologic Clinics Ophtalmologic clinic
Moscow St. Petersburg Novosibirsk Nizhny Novgorod Rostov-on-Don
Рус Eng Version for visually impaired
офтальмологическая клиника
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EXCIMER Ophtalmologic Clinics Ophtalmologic clinic
Moscow St. Petersburg Novosibirsk Nizhny Novgorod Rostov-on-Don

Structure of the retina

structure of the retina The retina is a light-sensitive layer of nerve tissue lining the inner surface of the eye. The retina creates an image projected on its surface with help of the cornea and crystalline lens, and transforms it into nerve impulses sent to the brain.

The retina is most closely linked with the underlying layers of the eyeball along the edge of the optic nerve head. The retina has varying thickness in different sections: 0.4 – 0.5 mm at the edge of the optic nerve head; 0.2 – 0.25 mm at the central fovea; only 0.07 – 0.08 mm at the foveal pit; about 0.1 mm at the ora serrata.

The retina is most closely linked with the underlying layers of the eyeball along the edge of the optic nerve head. The retina has varying thickness in different sections: 0.4 – 0.5 mm at the edge of the optic nerve head; 0.2 – 0.25 mm at the central fovea; only 0.07 – 0.08 mm at the foveal pit; about 0.1 mm at the ora serrata.

The macula (macular zone, yellow spot) is the most important part of the retina. The macula ensures central vision since it contains numerous photo receptors – namely the cones. They allow good vision in daylight. Macula disorder may considerably reduce the vision.

Anatomy of the retina

The retina has a complex structure. The microscope discerns 10 layers in the retina – counted from inside -out. The main layers are pigment epithelium and light-sensitive cells (photoreceptor layer). These are followed by external limiting membrane, outer nuclear layer, outer plexiform (synaptic) layer, inner nuclear layer, inner plaxiform layer, ganglion cell layer, nerve fiber layer, inner limiting membrane.

anatomy of the retinaи

The first layer – pigment epithelium

The pigment epithelium extends over the whole optic section of the retina and borders directly on the underlying choroid, being connected to the vitreous plate.

The pigment epithelium is composed of a single layer of densely packed cells containing a big amount of pigment. The pigment epithelium cells have the shape of a hexahedral prism and are simply arranged in a line. These cells are a part of a so-called hematoretinal barrier which ensures selective input of substances from the blood capillaries of the choroid into the retina.

The second layer – light-sensitive cells (photoreceptors)

The cone-shaped and rod-shaped cells, or simply the rods and cones, were called so because of the shape of the outer segment. These types of cells are considered to be the first neuron of the retina.

The rods represent regular cylindrical formations from 40 to 50 microns long. The total number of rods in the retina is about 130 million. They ensure eyesight in poor illumination, e.g. at night, and have high sensitivity to light.

The cones are active only in bright illumination conditions. The number of the cones amounts to 7 million in the human retina. They ensure central form vision and colour perception.

Structure of the retina
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