Humans are very dependent on their ability to see. The sense of sight not only alerts us to threats to our survival but also enriches our existence with descriptions of different colors and other vitals of the world. From the retinal receptors to the cerebrum’s primary visual cortex, the visual system consists of the eye and a long pathway of neural connections. An image of the external world is formed in our brain by processing the pattern of excitations within the retina. Several regions inside the occipital lobe interact to form this central representation that processes different aspects of the input simultaneously.
Retina vs Cornea
The main difference between the retina and cornea is that retina is the screen at the back of the eye where the light is projected to process it into an image. On the other hand, the cornea is the opening at the front of the eye which directs the light towards the retina.
Millions of cells that are sensitive to light make up the retina, along with other nerve cells responsible for receiving and processing visual information. Through your optic nerve, your retina sends these images to your brain and allows you to see. This is the membrane that lines the back of the eyeball and provides the sense of touch. Multiple layers make up the retina, including specialized cells known as photoreceptors.
The cornea is the transparent front surface of the eye. Light enters the eye through the cornea, which is directly in front of the pupil and iris. When looking at the cornea from the front, it looks wider than tall. It is because the front and back surfaces of the anterior cornea are slightly overlapped by the sclera.
Comparison Table Between Retina and Cornea
| Parameters of Comparison | Retina | Cornea |
| Colour | Orange Glow | Clear |
| Location | At the back of the eyes | In front of the iris and pupil |
| Importance | Processes the light into an image | Directs the light towards the retina |
| Size | 1,094 square mm | 11.5 mm |
| Disease | Retinitis pigmentosa | Keratitis |
What is Retina?
The retina is the screen at the back of the eye where the light is projected to process it into an image. Millions of cells that are sensitive to light make up the retina, along with other nerve cells responsible for receiving and processing visual information. Through your optic nerve, your retina sends these images to your brain and allows you to see. This is the membrane that lines the back of the eyeball and provides the sense of touch. Multiple layers make up the retina, including specialized cells known as photoreceptors. These tiny receptors are of two types:
- Cones: These cones are located at the macula, which is the center of the retina. It is these cells that allow for detailed vision and color perception. Reading and driving are made possible because of the macula, which provides high-definition vision.
- Rods: The outer retinal cells are denser than the inner ones. these cells are called rods. You can see in low lighting with these cells, which are used in peripheral vision.
There are various types of retinal diseases. Some of them are listed below –
- Retinal tear
- Retinal detachment
- Diabetic retinopathy
- Epiretinal membrane
- Macular hole
- Macular degeneration
- Retinitis pigmentosa
What is Cornea?
The cornea is the transparent front surface of the eye. Light enters the eye through the cornea, which is directly in front of the pupil and iris. When looking at the cornea from the front, it looks wider than tall. It is because the front and back surfaces of the anterior cornea are slightly overlapped by the sclera.
Patients who suffer from farsightedness, nearsightedness, astigmatism, or other eye disorders can benefit from corneal surgery. In addition to corneal transplants, Descemet’s Stripping Automated Endothelial Keratomileusis (DSAEK, for short) is a relatively new procedure. For those with damaged or cloudy lenses, donor corneas can be used to restore their vision. Using the newer technique, the cornea is replaced only partially, allowing for faster healing. Some of the most common corneal diseases are listed below:
- Keratitis: It refers to the reddening of the cornea. The inflammation due to bad quality contact lenses often leads to keratitis.
- Dry eye: it refers to when our eyes don’t secrete enough fluids to keep themselves wet, thus leading to visual problems and inflammation.
- Corneal dystrophies: This refers to the cloudy vision of the eyes due to accumulated waste near the cornea. This waste, if not treated, could lead to a permanent cloudy vision.
Main Differences Between Retina and Cornea
- The retina is located at the back of the eyes whereas the cornea is located in front of the iris and the pupil.
- The color of the retina has an orange glow and is translucent whereas the color of the cornea is clear.
- The retina processes the light into an image whereas the cornea directs that light towards the retina.
- The size of the retina is 1094 square mm whereas the size of the cornea is 11.5 mm.
- The retinal disease is termed retinitis whereas the corneal disease is termed keratitis.
Conclusion
The human eye is undoubtedly the most complex organ in terms of the visible features it provides to the human. The smallest mishappening to the human eye can lead to severe long-term damages and thus it is very necessary to keep your eye free of the diseases. In this article, we learned about two of the most important parts of the eyes – the retina and the cornea. The cornea is the transparent front surface of the eye. Light enters the eye through the cornea, which is directly in front of the pupil and iris. The retina is the screen at the back of the eye where the light is projected to process it into an image.
References
- https://www.pnas.org/doi/abs/10.1073/pnas.1516259112
- https://www.liebertpub.com/doi/full/10.1089/hum.2020.070