Cataract is an eye condition that can result in blindness. In cataracts, the lens of the eye becomes progressively opaque, resulting in blurred vision The good news is that, this type of blindness can be reversed. Nevertheless, we must learn to avoid it in the first place.
Before we delve into it, let us briefly look at how we see and the structures that help us to see.
The eye is divided into many structures. It is a delicate part of the body and it cannot be overemphasized.
- The sclera, or the white part of the eye, protects the eyeball.
- The pupil, or black dot at the centre of the eye, is an opening through which light can enter the eye.
- The iris, or coloured part of the eye, surrounds the pupil. It controls how much light enters the eye by changing the size of the pupil.
- The cornea, a clear window at the front of the eye, covers the iris and the pupil.
- A clear lens, located behind the pupil, acts like a camera lens by focusing light onto the retina at the back of the eye.
- The retina is a light-sensitive inner lining at the back of the eye. Ten different layers of cells work together in the retina to detect light and turn it into electrical impulses.
How we see
Light reflects(bounces) off the object we are looking at. The light rays enter the eye through the cornea at the front of the eye. The light passes through a watery fluid (aqueous humour) and enters the pupil to reach the lens.
The lens can change in thickness to bend the light, which will focus it onto the retina at the back of the eye. On the way to the retina, the light passes through a thick, clear fluid called the vitreous humour. The vitreous humour fills the eyeball and helps maintain its round shape.
The light reaches the back of the eye and hits the retina. The job of the retina is to turn light into signals about images that the brain can understand: The retina translates the light into electrical impulses which are then carried to the brain by the optic nerve.
Finally, the visual cortex (or centre) of the brain interprets these impulses as what we see.
Formation of cataract
In cataracts, the main issue has to do with the lens. The function of the lens just like the lens in any camera- is to focus light on a particular structure, in the case of the eye- the retina. The lens is made up of the lens capsule, the epithelial cells, the lens fibres and the zonules. These structures permit the lens to focus on objects at different distances.
The lens is at work when you see an object and you try to focus with your eye to get a clear image especially things that are afar.
A cataract develops when the lens in your eye, which is normally clear, becomes cloudy. What happens is that the proteins which form the structures of the lens becomes denatured and coagulate. This makes it form clumps and creates a cloudy lens, unlike the normally clear lens. This is like overcooking an egg, instead of it being clear and firm, it becomes rubbery and chalky(cloudy). This cloudy nature of the lens prevents it from focusing light which results in blurred vision.
Symptoms of cataracts
If you suspect that a person has a cataract, these are some of the symptoms you will observe.
The first thing symptom is blurry vision. At night, it becomes increasingly difficult to see. Sometimes, the person sees clear colours as faded. The person may begin to see halos (a circle around lights) surrounding light. Furthermore, a person may have double vision in the affected eye(when a person begins to see one image as two). Such person also complains of their glasses becoming dysfunctional and ineffective.
Just one symptom may not be an indication of a cataract but a combination of two or more. The best thing is to visit the eye clinic when you have suspicions.
We have observed how cataract is formed and what to look out for. The next thing is to see what causes it so that we can avoid them if possible.
Some types of cataracts may form at birth. After birth, any cataract you obtain is acquired. Some of these are:
· Eye injury
· Certain diseases such as diabetes, Wilson’s disease
· Steroids(medications) used to treat conditions such as arthritis
· Complications from eye problems such as high myopia, retinitis pigmentosa
· Trauma from UV radiation, eye surgery
A person may not experience the conditions above but certain actions and conditions will increase your chance of getting cataracts such as:
· Substances such as heavy alcohol use and smoking.
· Being old- elderly people around the 50s and 60s are at an increased risk.
· Spending too much time in the sun with no eye protection.
· A person with a family history of cataracts.
All these may cause or increase your chance of getting a cataract.
There are different types of cataracts. Below are a few:
1. Congenital cataracts- These are cataracts that you are born with or that form when you're a child. Some are linked to your genes, and others are due to an illness, like rubella, that your mother had during pregnancy.
2. Nuclear cataracts- Also called a nuclear sclerotic cataract, this is the kind doctors see most. Anyone who lives long enough usually ends up with one.
3. Cortical cataracts- They are wedge-shaped and form around the edges of the nucleus.
4. Posterior capsular cataracts- They form faster than nuclear and cortical cataracts and affect the back of the lens.
The doctor will perform a series of examinations before diagnosing you with a cataract.
There are no medications to treat cataracts at the moment. If your cataract symptoms are mild, the doctor might prescribe glasses or contacts to help with your vision. Cataracts usually worsen over time. Eventually, your doctor may suggest surgery.
Surgery is performed to remove the lens and replace it with an artificial one. The new lens is clear, shaped to fit your eye and personalized to your vision needs.
- Eye health- Cataracts. Available at https://www.webmd.com/eye-health/cataracts/what-are-cataracts.
- Cleveland Clinic. Cataracts. Available at https://my.clevelandclinic.org/health/diseases/8589-cataracts.
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