Layers of retina
Retina is the innermost layer of eye. Beneath retina there is vitreous humor of the eye. Beneath choroid there is retina. There are 10 layers of retina. Retina has 2 parts. One is the pigmented part and the other one is neural part of retina:
- Pigmented epithelium
- Neurosensory retina
To grab the knowledge thoroughly it should always be in your mind that anything towards the scleral layer of eye is outer layer or outer part. Likewise, any cellular layer or part of retina locating towards the inner chamber is inner layer or inner part.
10. Retinal pigmented epithelium RPE
It is the outermost layer of retina. It consists of pigmented cells . The apex of these cells face neural retina. The base of them faces choroid. They are more densely pigmented in macular region. These cells form outer blood retinal barrier. They provide nutrients to the neural layer of retina and perform phagocytosis of the waste materials. Hence this layer performs macrophagic and metabolic functions.
Its cells have melanin pigment. The pigment absorbs extra amount of light that reaches to photoreceptors. Hence this layer protects the retina from damage due to excessive light.
Neurosensory retina
The neural retina has further 9 layers. Photo receptor cells i.e. rods and cones, ganglion cells and bipolar cells make these layers of neurosensory retina. In the outer most region of neurosensory retina, cone and rods are present. They relay with bipolar cells. The bipolar cells relay with ganglionic cells. They also relay with ganglion cells. The ganglionic cells have nerve fibers at the endings which form nerve fibers layer.
Photoreceptor cells
The cones are the photoreceptors that help to perceive colors. The rods are those cells which help our eyes to perceive the intensity of light i.e. whether the light is dim or bright. They doesn’t play role in perceiving colors.
These cells have nucleus, one outer and one inner segment. The outer segment as shown in diagram also known as transductive region. The outer segment looks like a stack of discs. These discs disintegrate with the passage of time as a part of aging. They are taken by RPE for phagocytosis purpose.
9.Inner and outer segment layer
This layer has only inner and outer segments of rods and cones.
8.Outer limiting membrane
At the level of nucleus of rods and cones, there is an outer limiting membrane. It is called so because of its lesser distance from RPE.
7.Outer nuclear layer
It contains nuclei of both rods and cones.
6.Outer plexiform layer
The rods and cones form relay or synapsis with bipolar neurons. This layer does not contain nucleus of cells. It only has dendrites and axons forming plexus or synapsis.
5.Inner nuclear layer
This layer is present inside outer plexiform layer. It has predominantly nucleus of bipolar neurons. It also has other types of cells that are Amacrine cells and horizontal cells. The Muller cells, Horizontal cells and Amacrine cells provide a supportive framework to the neural tissue. The muller cells have horizontal arrangement of cells.
4.Inner plexiform layer
This layer contains synapsis of ganglion cells and bipolar neurons. The axons of ganglion cells form synapse with dendrites of bipolar neurons. It is known as inner plexiform as it is located near the vitreous chamber of the eye.
3.Ganglion cell layer
The ganglion cell layer contains the nuclei of ganglion cells predominantly.
2.Nerve fiber layer
The processes of ganglion cells make this layer of retina. These processes make the optic nerve.
1.Inner limiting membrane
The inner most part of the Muller cells separating the vitreous are known as inner limiting membrane.
Retinal detachment
In Retinal detachment, there is the separation of neurosensory retina from pigmented epithelial layer. There is a misconception regarding RD. We perceive that whole retina gets detached. Actually its the separation between two retinal parts. Hence we can say that it is not the detachment of retina rather its a separation with in the layers of retina.
Founder of EyesMatterMost- an optometry student who loves talking about eyes. I tend to cover topics related to optometry, ophthalmology, eye health, eyecare, eye cosmetics and everything in between. This website is a medium to educate my readers everything related to eyes.
