How the Retina Helps Us To See
It’s estimated that the retina makes up somewhere between 65-70% of your eye. Most often when we talk about the retina, we are referring to a thin tissue of nerve cells at the back of your eye; the rest of the area is a fluid-filled area called the vitreous chamber. The retinal tissue at the back of the eye is held in place by the pressure of the vitreous fluid (also called the ‘vitreous humor’).
This very small orb of tissue and fluid connects us in many vital ways to the world. It helps us navigate and survive our surroundings, enjoy the aesthetic beauty of art and nature, and is one of the most important ways we communicate and bond with each other as humans. That’s a tall order for an organ, less than one inch in size.
Here’s how the retina works. Our visual system is dependent on how we process light. (That’s why we can’t see very well in the dark.) Light reflects off of the objects we’re looking at. The lens at the front of our eyelets in the light, which is refracted (reflected back at an angle) towards the retina. The light-sensitive cells, called photoreceptors (the root meaning of ‘photo’ is ‘light’), convert the light into an image. Then, the image is compressed and sent along the optic nerve, a bundle of nerve fibres that connects the eye to the brain. The brain then interprets the image to tell us what we are seeing. And all of this transpires so quickly we’re not even aware that it’s happening.
The two primary types of photoreceptor cells are called rods and cones. Rods are the cells that specialize in black and white and help us to see in dim lighting. They are also quite sensitive to high-speed movement. Cones, on the other hand, provide us with the ability to see color; there are three different types of cones that are sensitive to red, green, and blue light frequencies. The retina has about 125 million rod cells, and about 5-7 million cone cells.
However, each of us is different in the number of rods and cones we have. This accounts for why some people are colour-blind (more rods than usual) or see colors differently (differing numbers of the three types of cones).
With the retina playing such a vital function in our ability to see, it’s of course very important we look after it. Regular eye examinations are the best way to monitor your retina for any signs of a problem, so you could begin treatment, if you need it, before the problem becomes worse. One of the conditions your eye doctor will look for during your exam is a detached retina. This is when the retinal tissue separates from the wall at the back of the eye, and vitreous fluid leaks in behind it, cutting the retina off from the essential blood vessels that provide it with oxygen and nutrients.
Symptoms of retinal detachment include suddenly seeing multiple ‘floaters’ (bits of dust or debris in your field of vision), a curtain or shadow, blurred vision, or flashes of light. If any of these occur, see a doctor right away – it’s considered an emergency situation as your sight could be at risk.
This content is proudly brought to you by Moorfields eye Hospital in Dubai.