The effect of the eye’s anatomy on your vision
Having good vision is a hugely important part of your overall health and wellbeing. More often than not, your local optician can identify diseases or other health problems through examining the condition of your eyes. Your vision can be at risk of many different conditions, such as refractive errors. These can occur at birth, or can develop gradually as you get older or can even occur due to trauma.
The way in which your eyes develop, as well as many health issues, can have a huge impact on your vision. For this reason, it’s important to understand the anatomy of the eye and how it can make a difference to your vision abilities. Essilor give a brief overview of the anatomy of the eye and how it works.
Understanding the anatomy of the eye
Your eye is made up of many different parts and each has its own important job to do in providing optimal vision. Here is a brief overview of some of those parts and what role they play in your vision.
The iris regulates the amount of light that enters your eye through your pupil. It forms the coloured part of your eye in front of the lens. The pupil is the black centre of the iris. Light passes through the pupil into the lens.
The cornea is the transparent circular part of the front of your eyeball. The cornea refracts, or bends, the light that enters the eye. Your cornea is extremely sensitive to pain.
The lens is the transparent structure behind your pupil. The lens also helps to refract incoming light, focusing it on to the retina. The retina lines the inside of your eye, forming a light-sensitive layer. The retina is made up of light-sensitive cells; rods, which are necessary for seeing in dim light, and cones that function in bright light. The cone cells are also necessary for seeing accurate images and for recognising colour.
The macula is a yellow spot on the retina at the back of the eye. This surrounds the fovea. The fovea forms a small indentation at the centre of the macula and it has the greatest concentration of cone cells. When you’re looking at something, the part of the image that is focused on the fovea is the image most accurately recognised by your brain.
Lastly, the optic disc is the visible portion of the optic nerve, which is found on the retina. The optic disc forms the start of the optic nerve, and is also known as the blind spot. The optic nerve leaves the eye at the disc, transferring visual information to the brain.
Common eye conditions and how they occur
There are many different conditions that can affect your vision, but did you know that some of the them occur because of the shape or development of your eye itself?
Refractive errors are incredibly common and are usually fixed by wearing prescription lenses. Refractive errors include short and long-sightedness, also known as myopia and hypermetropia respectively. Myopia occurs when the eye has grown slightly too long, and the light entering the eye is focused just in front of the retina. This makes distant objects appear blurry.
Hypermetropia is the opposite; the eyeball is too short, or in some cases the cornea is too flat. The light is focused just behind the retina, making close objects appear blurry.
Another common refractive error is astigmatism. This occurs when there is an imperfection in the curvature of the cornea. The cornea is usually symmetrically round, but astigmatism means the cornea is more egg-shaped. This makes it difficult to focus the light equally on the retina, which can lead to blurry vision.
Presbyopia is an age-related long-sightedness, which affects your ability to see objects close up. It occurs when the lens loses flexibility. As a result, presbyopia makes it difficult to see objects up close due to the reduction in the lens’s focusing ability.