What is the retina and how does it assist with vision?

Basic breakdown of the eye

In order to understand the retina and the functions it serves, we need to first take a look at the human eye. The eye consists of many different and complex parts, but we will only describe the main parts of the eye and how they relate to the retina.

How the eye sees

Light rays enter the eye through the cornea which is at the front of the eye. The light passes through the aqueous humor, which is a watery fluid at the front. 

Our lens then changes thickness to bend light, in order to focus it onto the retina at the back of the eye. 

As the light hits the retina at the back of the eye, our optic nerve then translates the light into electric impulses that our brain interprets as sight. 

Retina part of the eye 

The retina is a membrane located on the inside part at the back of the eyeball. The retina is made up of many layers. One of these layers is called a photoreceptor. Our eyes have two types of photoreceptors, one is called a rod, the other is called a cone. 

Rod receptors are responsible for identifying motion. Rods also provide black and white vision and so function well in low light conditions. Cones on the other hand are responsible for our central vision and also our color vision and so it performs better in medium and bright vision. 

There are millions and millions of rods and cones in our retina, 125 million roughly. Rods are by far the most common photoreceptor, outnumbering cones by about 18 to 1. When you are trying to find your keys in the dark you can thank your rods, but at the moment the cones in your eyes are allowing you to read this article. 

The information that our rods and cells collect are gathered up and then transmitted to another layer in the retina. This layer is called the ganglion cell layer. The ganglion cells deliver the information to the brain via the optic nerve. 

How can I tell if I have problems with my retina?

There are various quick fire ways that you can use to determine if you might have retinal problems. Some of these include;

• If you have a shadow like vision of your field of view
• Your peripheral vision gradually becomes smaller
• Vision that is blurred
• Small bug-like particles that look like they are in your eye, called floaters. 

This is not an exhaustive list and these may only be preliminary indicators. If you suspect that you might be suffering from any type of retinal damage, the best thing to do is to seek medical assistance from an ophthalmologist. 

Retina problems and diseases include:

Hypertensive retinopathy, solar retinopathy, detached retina, central serous retinopathy, diabetic retinopathy, macular edema and macular degeneration. In our next article we will take a closer look at retina diseases.