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What causes cataract?

Arief Salim

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March 28, 2022

• Cataract
• Eye Health
• Healthy living

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What is a cataract?

A cataract is an eye condition whereby the typically clear lens of your eye is clouded. If you have clouded lenses, you would have clouded vision and find it challenging to read, see your friend’s expression or drive. While most cataracts develop slowly in the initial stages, cataracts would impair your vision as time goes on. This article explores what causes cataracts in people.

What are the causes of cataracts?

There are various causes of cataract. Aging or eye injuries alter the tissue in the lens of your eye, causing formation of a cataract. When the tissue in the lens changes, proteins and fibers in the lens disintegrate, resulting in cloudy vision. Various hereditary disorders that are linked to other health problems can raise your risk of cataracts. Other eye conditions, previous eye surgery or medical conditions like diabetes as well as a long-term reliance on steroid medications can cause cataracts.

How does a cataract develop?

Let us explore what a healthy lens does in your eye. Normally, the lens is located behind your iris (coloured part of your eye). The function of the lens is to focus light that enters your eye to form distinct and sharp images on the retina (a light-sensitive membrane in the eye).

As you grow older, proteins and fibers within the lenses disintegrate and clump together causing the lenses in your eyes to become more rigid, thicker and more opaque. Consequently, you suffer from blurry vision.

The clouding in the lenses becomes denser as your cataract progresses. The cataract blocks and disperses the light as it enters the lens. A sharply defined image cannot be produced on the retina, leading to blurry vision. While cataracts usually develop in both eyes, they do not do so at the same pace. A difference in vision quality between eyes can happen when the cataract in one eye is more developed than the other.

What are the types of cataracts?

There are various kinds of cataracts, as seen below.

• Nuclear cataracts impacting the centre of the lens: Initially, a nuclear cataract may lead to more myopia (nearsightedness) or even a temporary improvement in your vision when reading. Over time, the lens eventually becomes more densely yellow or even brown and further impairs your vision. You may not be able to tell the differences between shades of colour as a result.
• Cortical cataracts impacting the edges of the lens: A cortical cataract starts as whitish streaks on the outer edge of the lens cortex. After some time, the streaks expand to the centre and intercept with light passing through the center of the lens, leading to blurry vision.
• Posterior subcapsular cataracts affecting the back of the lens: A posterior subcapsular cataract begins as a tiny opaque area near the back of the lens that intercepts the path of light. Thus you may suffer from an impaired vision in bright light as well as glare or halos around lights at night.
• Congenital cataracts that happen at birth: Such cataracts may be genetic, or linked to trauma or infection. Usually, congenital cataracts do not impair vision significantly but can be removed if they do.

What are the risk factors of cataract?

• Ageing
• Conditions like diabetes
• Excessive sunlight exposure
• Smoking
• Obesity
• High blood pressure
• Prior eye surgery, infection or inflammation
• Excessive drinking of alcohol
• Long-term use of certain medications

Consult your eye care professional if you suspect you have a cataract

Consult your eye care professional as soon as you notice any changes in your vision. Even more so, should you experience abrupt vision changes, such as double vision or eye pain, go to the doctor immediately.

References

“Cataracts,” Mayo Clinic, 02-Sep-2021. [Online]. Available: https://www.mayoclinic.org/diseases-conditions/cataracts/symptoms-causes/syc-20353790#:~:text=Most%20cataracts%20develop%20when%20aging,increase%20your%20risk%20of%20cataracts. [Accessed: 11-Mar-2022].