Is the retina part of the optic nerve?
In the center of the retina is the optic nerve, a circular to oval white area measuring about 2 x 1.5 mm across. From the center of the optic nerve radiate the major blood vessels of the retina.
What is a retina?
(REH-tih-nuh) The light-sensitive layers of nerve tissue at the back of the eye that receive images and sends them as electric signals through the optic nerve to the brain.
What is the retina made of?
The retina consists of millions of cells packed together in a tightly knit network spread over the surface of the back of the eye. These cells can be divided into a three basic cell types, photoreceptor cells, neuronal cells, and glial cells. Photoreceptor cells consist principally of cones and rods.
Does the retina have nerve endings?
It's pretty straightforward; the retina has NO nerve endings, thus, retinal disease, including diabetic retinopathy and macular degeneration don't hurt because…it can't.
How do you repair damaged retina?
Options include:Using a laser. Laser surgery can repair a retinal tear or hole. ... Shrinking abnormal blood vessels. ... Freezing. ... Injecting air or gas into your eye. ... Indenting the surface of your eye. ... Evacuating and replacing the fluid in the eye. ... Injecting medicine into the eye. ... Implanting a retinal prosthesis.
What happens if retina is damaged?
Damage to the retina often leads to vision loss. Medical experts explain that when the retina is injured through disease or an accident, blood vessels are affected. The veins carry neurons between the optic nerve and the brain. When they are damaged, neurons die, and the brain doesn't receive visual information.
Can you see without retina?
The retina is a thin layer of light-sensitive nerve cells. People need a healthy retina to be able to see clearly. At first, detachment might only affect a small part of the retina. Without treatment, however, the whole retina can peel off, and a person risks losing the vision from that eye.
How serious is retinal tear?
Retinal tears deprive your retina of oxygen, which can lead to permanent damage and vision loss. However, the small tear can also allow liquid to seep under the retina, which causes detachment.
Is the retina an organ?
The retina is actually an extension of the brain, formed embryonically from neural tissue and connected to the brain proper by the optic nerve. The retina is a complex transparent tissue consisting of several layers, only one of which contains light-sensitive photoreceptor cells.
Can retina feel pain?
Van Gelder clarified that "the retina has no pain fibers. The cornea, in the front of the eye, has more pain receptors per square inch than anywhere else in the body. But those don't provide sensation to the back of the eye."
Can a damaged optic nerve be restored?
There are no effective treatments to regenerate nerve cells or to restore connections between the eye and brain once the optic nerve is lost. This is a major barrier in the field and one that must be overcome, given the substantial number of patients suffering from optic neuropathy-associated blindness.
Does the eye feel pain?
Eye pain is also known as ophthalmalgia. Depending on where you experience the discomfort, eye pain can fall into one of two categories: Ocular pain occurs on the eye's surface, and orbital pain occurs within the eye. Eye pain that occurs on the surface may be a scratching, burning, or itching sensation.
What are the signs of retina problems?
SymptomsSeeing floating specks or cobwebs.Blurred or distorted (straight lines look wavy) vision.Defects in the side vision.Lost vision.
What is the retina responsible for?
visual processingThe retina is the innermost layer in the eye that is responsible for the visual processing that turns light energy from photons into three-dimensional images.
What is retinal used for?
Retinol increases skin cell production (proliferation). It helps unclog pores. Retinol also exfoliates your skin and increases collagen production, which can reduce the appearance of fine lines and wrinkles, giving your skin a fresher, plump appearance.
How does a retina work?
When light hits the retina (a light-sensitive layer of tissue at the back of the eye), special cells called photoreceptors turn the light into electrical signals. These electrical signals travel from the retina through the optic nerve to the brain. Then the brain turns the signals into the images you see.
What is the function of the retina?
Function. Associated Conditions. Tests. The retina is a thin layer of tissue that lines the very back of the inside of the eyeball. The retina contains millions of cells that perceive light, color, and fine details in the things you see. A number of diseases can affect the retina, including cancer.
What are the parts of the retina?
The retina is a single layer of tissue that contains nerve cells that transmit images to the optic nerve. The parts of the retina include: 1 Macula: A small area at the very center of the retina. The macula provides the best focus for seeing small details on items directly in front of you, such as the text of a book. 2 Fovea: A tiny depression at the center of the macula. The fovea (also called the fovea centralis) is the point of sharpest focus. 3 Photoreceptor cells: These are the nerve cells that enable the eye to perceive light and color. 4 Cones: One type of photoreceptor cell, the cones sense and process the colors red, blue, and green to provide full-color vision. The retina holds approximately 6 million cones. 5 Rods: Another type of photoreceptor cell, responsible for sensing light levels and providing peripheral vision. The retina holds approximately 120 million rods. 6 Peripheral retina: The retinal tissue that extends beyond the macula. The nerves in the peripheral retina process peripheral vision.
What is the most common type of macular degeneration?
Age-related macular degeneration (AMD): One of the most common types of retinal disease, AMD causes progressive central vision loss. It does not affect peripheral vision. AMD occurs in two types—dry and wet. Dry AMD is the more common type and occurs when the tissue layer of the macula becomes thinner with age. Wet AMD is rarer and occurs when new blood vessels grow abnormally in the retina, leak fluids, and cause scarring of the macula.
What is the area of the retina that provides the best focus for seeing small details on items directly in front of you?
Macula : A small area at the very center of the retina. The macula provides the best focus for seeing small details on items directly in front of you, such as the text of a book.
What are the conditions that affect the retina?
These conditions include: Achromatopsia: Complete color blindness. Choroideremia: Progressive loss of photoreceptor cells in the retina. Leber congenital amaurosis: A group of genetic mutations that affect nearly every nerve cell in the retina and cause severe impairment of vision.
How many cones are there in the retina?
The retina holds approximately 6 million cones.
Which part of the retina is the most important for seeing small details?
The retina is a single layer of tissue that contains nerve cells that transmit images to the optic nerve. The parts of the retina include: Macula : A small area at the very center of the retina. The macula provides the best focus for seeing small details on items directly in front of you, such as the text of a book.
What is the function of the retina?
The retina contains millions of light-sensitive cells (rods and cones) and other nerve cells that receive and organize visual information. Your retina sends this information to your brain through your optic nerve, enabling you to see. Treatment is available for some retinal diseases.
What is the condition where the retina breaks?
Common retinal diseases and conditions include: Retinal tear. A retinal tear occurs when the clear, gel-like substance in the center of your eye (vitreous) shrinks and tugs on the thin layer of tissue lining the back of your eye (retina) with enough traction to cause a break in the tissue. It's often accompanied by the sudden onset ...
What is a macular hole?
Objects may appear blurred or crooked. Macular hole. A macular hole is a small defect in the center of the retina at the back of your eye (macula). The hole may develop from abnormal traction between the retina and the vitreous, or it may follow an injury to the eye. Macular degeneration.
What part of the eye is responsible for color vision?
Parts of the eye. Located at the back of your eye in the center of your retina, a healthy macula allows for normal central vision acuity. The macula is made up of densely packed light-sensitive cells called cones and rods. Cones are responsible for color vision, and rods enable you to see shades of gray. Retinal diseases vary widely, but most of ...
What is the term for the presence of fluid under the retina?
Retinal detachment. A retinal detachment is defined by the presence of fluid under the retina. This usually occurs when fluid passes through a retinal tear, causing the retina to lift away from the underlying tissue layers. Diabetic retinopathy.
What causes the retina to swell?
Diabetic retinopathy. If you have diabetes, the tiny blood vessels (capillaries) in the back of your eye can deteriorate and leak fluid into and under the retina. This causes the retina to swell, which may blur or distort your vision. Or you may develop new, abnormal capillaries that break and bleed.
What is the scar on the top of the retina?
This also worsens your vision. Epiretinal membrane. Epiretinal membrane is a delicate tissue-like scar or membrane that looks like crinkled cellophane lying on top of the retina. This membrane pulls up on the retina, which distorts your vision.
What is the retina?
58301. Anatomical terminology. The retina (from Latin: rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which translates that image into electrical neural impulses to ...
What is the retina in the human eye?
The retina (from Latin: rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs.
What are the cells that are responsible for the visual perception of color?
The neural retina consists of several layers of neurons interconnected by synapses and is supported by an outer layer of pigmented epithelial cells. The primary light-sensing cells in the retina are the photoreceptor cells, which are of two types: rods and cones. Rods function mainly in dim light and provide black-and-white vision. Cones function in well-lit conditions and are responsible for the perception of colour, as well as high-acuity vision used for tasks such as reading. A third type of light-sensing cell, the photosensitive ganglion cell, is important for entrainment of circadian rhythms and reflexive responses such as the pupillary light reflex .
Why is it important to compress the optic nerve?
Compression is necessary because there are 100 times more photoreceptor cells than ganglion cells . This is done by " decorrelation ", which is carried out by the "centre–surround structures", which are implemented by the bipolar and ganglion cells.
How many layers does the retina have?
The vertebrate retina has ten distinct layers. From closest to farthest from the vitreous body:
Why do birds have a retina?
The bird retina is devoid of blood vessels, perhaps to give unobscured passage of light for forming images, thus giving better resolution. It is, therefore, a considered view that the bird retina depends for nutrition and oxygen supply on a specialized organ, called the "pecten" or pecten oculi, located on the blind spot or optic disk. This organ is extremely rich in blood vessels and is thought to supply nutrition and oxygen to the bird retina by diffusion through the vitreous body. The pecten is highly rich in alkaline phosphatase activity and polarized cells in its bridge portion – both befitting its secretory role. Pecten cells are packed with dark melanin granules, which have been theorized to keep this organ warm with the absorption of stray light falling on the pecten. This is considered to enhance metabolic rate of the pecten, thereby exporting more nutritive molecules to meet the stringent energy requirements of the retina during long periods of exposure to light.
Which area of the retina is avascular?
Some vertebrates, including humans, have an area of the central retina adapted for high-acuity vision. This area, termed the fovea centralis, is avascular (does not have blood vessels), and has minimal neural tissue in front of the photoreceptors, thereby minimizing light scattering.
What is the area of the retina that extends from the posterior pole?
Equator and Mid Peripheral Retina: This is the area of the retina as it extends from the posterior pole. Ora Serrata: The ora serrata is the serrated area between the retina and the ciliary body. This junction marks the transition from the non-photosensitive area of the retina to the photosensitive area of the retina.
Which part of the retina is responsible for visual processing?
It is made of millions of nerve fibers and transmits visual information to the brain for processing. Macula: The macula is a specialized pigmented part of the retina in the very center of the retina that gives us central vision. In the center of the macula is the fovea. The fovea has the region of best visual acuity.
What is the condition where the central retina develops a cyst and central vision becomes distorted?
Central Serous Retinopathy: Central serous retinopathy is a relatively common condition in which the central retina develops a cyst and central vision becomes distorted. Macular Degeneration: Macular degeneration is a disease of the macula in which there is a loss in the center of the field of vision.
What is the layer of the eye that absorbs light?
The retina is a light-sensitive layer that lines the back of the eye. It is only 0.2 mm thick and is about the size of a silver dollar. The retina is made up of 200 million neurons, many of which are photoreceptors. Photoreceptors absorb light and then convert and transmit those signals through the optic nerve to the brain. 1 .
Which type of photoreceptors are better detectors?
There are two main types of photoreceptors, rods and cones, in the retina. The fovea in the macula, which is a central space of the retina, has the highest concentration of cones but not one single rod. 2 Cones deliver a better resolution of images. The periphery of the retina on the other hand, has many rods, and these types of photoreceptors are better detectors. This organization of cones and rods means that a night star looked at directly will appear very dim, but if seen using peripheral vision, will be perceived as brighter and more visible.
What is retinal tear?
Retinal Tear or Detachment: A retinal tear or detachment is considered an ocular emergency where the light-sensitive retina is torn or detached away from the back of the eye that feeds in oxygen and nourishment.
What is the fundus of the eye?
The fundus includes the retina as well as the following parts: Posterior Pole: The posterior pole in the back portion of the retina and includes the optic nerve and macula. Optic Nerve Head: The optic nerve head is the face of the optic nerve as it enters the back of the eye.
Which layer of the retina is the only one that is continuous across the optic nerve head?
The ganglion cells send a single axon which eventually forms the optic nerve. Thus, ganglion cell is the only layer that is continuous across the optic nerve head.
Where does the sensory retina develop?
Sensory retina develops from the inner layer of the neuroectoderm, whereas RPE is derived from the outer layer of the neuroectoderm. The RPE is continuous anteriorly with the pigment epithelium of the ciliary body. Sensory retina extends from the optic disc to ora serrata, where it is continuous with non-pigmented ciliary epithelium.1.
How many layers are there in the retina?
The retina consists of 10 layers which include nine layers within the sensory retina and retinal pigment epithelium. Embryologically RPE is developed from the outer layer of the optic cup and photoreceptors are developed from the inner layer of the cup and there is a potential space between RPE and sensory retina, known subretinal space. Absence of specialized molecules like laminin and fibronectin, lack of junctional complexes between RPE cells and photoreceptors are responsible for this loose attachment of RPE cells to the photoreceptors. In retinal detachment, the sensory retina detaches from retinal pigment epithelium (RPE). RPE remains firmly attached to the choroid during retinal detachment.
How thick is the retina?
Human retina measures 32 mm from ora to ora along the horizontal meridian and t he total surface area of the retina in each eye is approximately 1,100 square mm.2 The average thickness of retina is 200 micrometers, it is slightly thicker near optic nerve head and near the macula and gradually thins out at the ora serrata and fovea.3 Broadly the retinal surface can be divided into the following areas:
What is the space between the neural retina and the RPE?
Between the neural retina and RPE, there is a potential space known as subretinal space . The adhesion between neural retina and RPE is relatively weak. The neural retina is firmly attached at its anterior termination, the ora serrata, and at the margins of the optic nerve head.
What is the innermost layer of the eye?
The retina is the innermost of the three coats of the eye. This layer is responsible for converting relevant information from the image of the external environment into neural impulses that are transmitted to the brain. Broadly retina consists of two primary layers: an inner neurosensory retina and retinal pigment epithelium (RPE). 1
Where is the central retinal artery located?
The central retinal artery, a branch of the ophthalmic artery, enters the retina through the optic disc. It divides into 4 main branches the upper and lower nasal and the upper and lower temporal. Retinal vessels are located in the nerve fiber layer just below the transparent internal limiting membrane. However, there are two types of capillary networks found in retina - superficial network is in the nerve fiber layer or ganglion cell layer and the deeper one is situated in the inner nuclear layer near the outer plexiform layer.
How many people have retina problems?
Retina Problems: Warning Signs You May Have a Retinal Disease. March 25, 2019. Over 1.3 billion people have some sort of vision impairment, whether that means they need glasses, readers, or have complete/partial blindness. As we age, our vision will naturally decline. However, not all vision issues are normal.
Why does my retina flash?
As we went over earlier, the retina is responsible for sending light signals to the brain. When the retina is damaged or diseased, it can send incorrect and/or abnormal signals to your brain, which could cause you to experience this “flashing light” phenomenon. “Dimmer” Vision.
What is the leading cause of vision loss in people age 50 and older?
Macular Degeneration (MD) Macular degeneration is the leading cause of vision loss in people age 50 and older. With this disease, the center of your retina starts to degenerate and deteriorate, which leads to worsened vision and vision loss. There are two subtypes: wet MD and dry MD.
What happens when light enters your eye?
When light enters your eye and hits the retina, the retina will process that light information and send signals to the brain through your optic nerve. Without the retina, your brain won’t receive any signals about what you’re seeing.
Why do we have blind spots in our eyes?
Blind Spots. We all have one blind spot in our peripheral vision because of how the optic nerve is situated in the back of the eye. Developing larger or an increased number of blind spots is cause for concern and a definite warning sign of retinal issues.
What is double vision?
Double Vision. Double vision is when you see a duplicate version at the same time as the real version. The doubled version is often blurry and less sharp compared to what you’re actually seeing.
What causes dark spots in the back of the eye?
Diabetic Eye Disease. Diabetic eye disease, also known as diabetic retinopathy, is caused by complications from diabetes. The blood vessels in the back of the eye can leak blood and fluid, which leads to blurred/distorted vision, dark spots, and the feeling of pressure in the eye.
Retinal tear
A retinal tear happens when there is a tear or hole in the retina. This typically occurs when the vitreous, which is a jelly-like substance in the eye, attaches to the retina and pulls hard enough to tear it. This can happen when the vitreous detaches as part of the aging process, or it can result from trauma.
Retinal detachment
Retinal detachment occurs when a buildup of fluid, which usually enters through a retinal tear, causes the retina to detach from the choroid, which is the eye layer that provides it with oxygen and nutrients.
Retinopathy
Retinopathy results from damage to the blood vessels at the back of the eye, which causes fluid to leak. This accumulation of fluid can affect the retina and result in changes to vision. Conditions that can cause retinopathy include diabetes, hypertension, and cancer.
Epiretinal membranes
Epiretinal membranes (ERMs), also called macular puckers or cellophane maculopathy, make up a thin layer that forms on the retina’s inner surface. It is usually scar tissue from a medical condition or injury.
Macular hole
Similar to retinal tears, macular holes are small breaks in the macula that occur due to an unusual pulling between the vitreous and the retina.
Macular degeneration
Because macular degeneration is more common among older adults, eye doctors usually call it age-related macular degeneration (AMD).
Retinitis
Retinitis refers to the inflammation of the retina. It usually results from viruses and bacteria. For example, Lyme disease, syphilis, and Dengue fever may cause retinitis.
Overview
The optic nerve is comprised of millions of nerve fibers that send visual messages to your brain to help you see. You have an optic nerve at the back of each eye that connects directly to your brain.
Function
The optic nerve is critical to your vision. It’s an extension of your central nervous system, which includes your brain and spine.
Anatomy
The optic nerve is the second of 12 cranial nerves. Each eye has its own optic nerve.
Overview
Structure
Function
Clinical significance
History
Additional images
See also
Further reading
The retina (from Latin: rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then processes that image within the retina and sends nerve impulses along the optic nerve to the visual cortex to create visual perception. The retina serves a function which is in many ways analogous to that of the film or image sensor in a camera.