Our eyes are one of the most precious sensory organs of our body, with the retina being its most important tissue lining the back of the eyeballs, which is responsible for converting the light coming in into nerve signals that are sent to the brain to be able to see objects. The retina is thus in charge of helping us see objects in various lighting conditions, may it be day or night, clear or foggy, by making the required adjustments in the eye. So, you can imagine how terrible it can be if the retina in your eye gets damaged!
Let us understand the design and functioning of the retina first, after which we’ll learn about the diseases associated with the retina.
The basic design of the retina
The retina is shaped like a plate, and is a quarter millimeters in thickness, consisting of three layers of nerve-cell bodies, which are separated by layers that contain synapses made by the axons and dendrites of these cells. The retina consists of sensory neurons that respond to light, thus making adjustments when entering from bright light into a dark room, and vice-versa. It also consists of intricate neural circuits that are responsible for initial image processing. All these tiny elements work together to perceive the light and object in front of the eyes, sending the images to the brain through the optic nerve to further process the visual perception, helping the eyes to understand what it is seeing.
The functioning of the retina
The sensory cells, better known as photoreceptors, lying at the back of the retina, contain pigments that need to be in touch with the epithelial layer of the eye, while having the light pass completely through the retina to reach these pigment molecules. When light touches these molecules, they undergo a conformational change, and are recycled back into the pigment epithelium, containing melanin granules that absorb stray photons, thus preventing them from creating a reflection on the photoreceptors, which can cause images to appear blurred.
The two types of photoreceptors
There are two types of photoreceptors in the retina – the rods and the cones. The rods are used for low-light vision, and the cones are used for daylight and bright-coloured vision. These rods and cones help us see images starting from the grey shades of sawn to the dazzling bright noon lights when the sun is the brightest. It is these cones and rods that can adjust to the surrounding light, making it possible for us to see during both day and night. The cones adapt to the daylight brightness, while the rods adapt to the low intensity of light after dusk.
The macula
The macula within the retina is a region that has a very high presence of cones, smaller and tightly packed as compared to any other region in the retina. The data that is received by the eyes ranges from a field of up to 200°, with the visual acuity over most of that range being very poor. In order to form high resolution images, the light must fall on the macula, limiting your acute vision angle to about 15°. In low light, the macula constitutes a second blind spot as the cones have low light sensitivity. Thus, during evening and night, for the maximum visual acuity, the vision needs to be slightly shifted to one side by atleast 4-12°, making the light fall on some rods.
You can see how intricate and complex the retina and its functioning is! And, you would be surprised to know that the so-tiny retina within the small eyes we have around 3.5 million retinal pigment epithelium cells, 4-5 million cones, and about 77-107 million rods! Can you imagine the intricacy of all these rods and cones!? With such intricate rods, cones, and other elements in the retina, even the tiniest problem may result in dangerous defects. This is why you need to take complete care of your retina right from this moment onwards. And for this, you need to have a healthy and balanced diet containing fresh vegetables and lean meat, drink plenty of water, avoid unhealthy food and drinks, quit smoking, regularly exercise your eyes, and avoid over-exposure to the sunlight. Moreover, it is advisable that you have regular eye examinations to keep a check on every part of your eye, just to be sure. If you don’t take good care now, you’ll be likely to face any of these retinal problems in the future –
- Macular degeneration – This is the damage of the macula, which results in loss of central vision, and hindering you to see fine details.
- Diabetic retinopathy – This is the swelling and leaking of the retinal blood vessels caused by high sugar in diabetic patients, thus stopping blood flow, causing vision loss.
- Retinal vein occlusion – This is the blocking of the veins and hardening of the arteries in the retina, which causes blood clots in the eye.
- Retinal detachment – This includes the tearing or the detachment of the retina from the rest of the eye, caused due to the vitreous moving away, pulling hard on the retina. This causes blurred vision, or even blindness at the worst!
- Macular hole – This is a hole observed in the macula, caused due to the shrinking or separation of the vitreous in the retina, resulting in sudden decrease in vision.
All the above problems and more in the retina can cause serious problems such as blurred vision, partial vision, or even complete blindness! So, if you notice any kind of changes in your vision, it is advisable to immediately get in touch with the best retina specialist in Mumbai to have your eyes thoroughly checked to detect the exact problem, and have it treated at the earliest. Arohi Eye Hospital is one place where you can have your appointment made quickly and easily. So, just give us a call as soon as you notice something suspicious in your eyes, and we’ll have your appointment arranged for as early as possible with the best eye doctors in the country.
Dr. Shradha Goel
Dr. Shradha Goel, Chief Surgeon at Arohi Eye Hospital, is a renowned Phaco-LASIK surgeon with over 10,000 surgeries to her credit. She earned her MBBS from Grant Medical College, Mumbai, and a Master’s in Ophthalmology from Kasturba Medical College, Manipal. As a member of the American Academy of Ophthalmology, Dr. Goel specialises in LASIK, refractive errors, and cataract treatments.