Cataracts occur when the lens of the eye becomes cloudy. The lens sits behind the iris and pupil and helps to focus light onto the back of the eye (the retina). Signals are then sent to the brain, allowing us to see. Cataracts most commonly develop in later life, and this is known as age-related cataracts.
What are the types of cataracts and how do they affect my vision?
There are several types of cataracts, some more common than others. It’s also possible for more than one type to affect your eyes at the same time. Here are four distinct variants:
Nuclear sclerotic cataracts
The type of cataract most frequently diagnosed by optometrists is the nuclear sclerotic cataract. This type forms in the centre of the lens (the nucleus), causing it to harden and turn yellow or brown over time.
Nuclear sclerotic cataracts can lead to increased short-sightedness, meaning they cause difficulty seeing at a distance. They can also cause halos and glare around bright lights.
Posterior subcapsular cataracts
This type of cataract develops quickly and can affect vision from the outset, as its position in the eye is fairly central. It affects the back of the lens — the part that allows light to pass through the eye — which can be blocked by the cataract.
Posterior subcapsular cataracts most significantly affect near vision.
Cortical cataracts
Cortical cataracts are those where the protein build-up takes a triangular shape, forming a ring around the outer edge of the lens with the points of the triangles pointing towards the centre. They scatter light entering the eyes, causing glare and potentially affecting night vision.
This type of cataract can cause astigmatic changes to your prescription.
Congenital cataracts
While most types of cataract develop later in life, congenital cataracts are present from birth. They can develop if the mother had certain illnesses during pregnancy, such as rubella.
Congenital cataracts don’t usually affect a child’s vision, but in exceptional cases they cover the lens and cause more pronounced vision problems.
What causes cataracts?
In most cases, cataracts are caused by age, as the lens becomes less flexible and transparent over time. However, there are other factors that can accelerate their progression, or trigger them earlier in life, such as medical conditions, traumatic eye injuries, or certain medications taken to treat other conditions.
UV exposure
Unprotected exposure to UV rays from the sun can damage the eyes in many ways and is thought to be one of the risk factors for developing cataracts. People exposed to UV rays over long periods of time may develop cataracts at an earlier age.
Although this usually only occurs after years of UV exposure, it’s always important to properly protect your eyes with sunglasses that offer adequate protection.
Medical conditions
Certain health conditions can increase the risk of developing cataracts. Diabetes is one example — people with diabetes are more likely to develop a cataract at an earlier age, as high blood sugar levels affect protein build-up and cause the lens of the eye to cloud more quickly.
Other conditions associated with cataract progression include rubella, Down’s syndrome, and uveitis.
Medication
Long-term use of steroids, commonly used to treat arthritis, asthma, or multiple sclerosis, can lead to cataracts developing at an earlier age. You should always inform your optometrist when you’re using this type of medication to treat other conditions, so they can watch for signs and offer appropriate advice and treatment.
Trauma
Cataracts can be caused by physical trauma — following a head or eye injury, a previous eye operation, or radiation exposure. Trauma can alter the structure of the lens immediately, causing rapid cataract progression, or it can trigger the development of a cataract that takes several years to progress.
Symptoms of cataracts
Most forms of cataract progress over several years before any changes in vision become apparent. Once the cataract does affect your vision, symptoms include blurry and cloudy vision, glare when looking at lights in dark environments, and colours that appear faded.
Cloudy vision
As the protein in the lens begins to clump together, vision may become blurry or unclear, gradually worsening until it starts to impair sight. Cloudy vision most commonly affects one or both eyes in people with posterior subcapsular or nuclear cataracts.
Difficulty seeing at night
As nuclear sclerotic cataracts begin to develop, the lens of your eye can turn yellow or brown. This affects your ability to see clearly in the dark and can impact activities like night driving. You may also start to notice halos around lights or find yourself sensitive to bright lights at night, which can also cause complications when driving in the dark.
Reduced colour perception
Due to the possible discolouration of the lens, as protein build-up causes it to turn yellow or brown, light entering your eyes may take on a yellow tint. Depending on the severity of the cataracts, this can change how you perceive colours — particularly blues and purples.
However, if colour perception is affected, it’s likely to be restored following surgical removal of the cataract.
How is a cataract diagnosed?
Cataracts can be detected during a routine eye examination. When opticians look through the lens, they will be able to detect any abnormalities. They can determine the stage of progression and advise on how to manage and treat it. In some cases, your optician may refer you to an ophthalmologist for further tests.
Can cataracts be treated?
Most people opt for surgery to treat cataracts, but if your optometrist has detected a cataract in its early stages, the symptoms and effects can be managed with stronger prescription glasses or sunglasses. However, if the cataract is significantly affecting your vision and quality of life, surgery will be the only treatment option.
Surgery
Cataract surgery is a routine procedure that typically takes around an hour.
You will be awake during the operation, but while you may notice lights and movement, the surgery is usually completely painless, as your surgeon applies anaesthetic eye drops beforehand.
There are several types of surgery to remove cataracts, but in all of them the ophthalmologist makes an incision to break up the lens and remove the cataract. The lens is then replaced with an artificial one.
When can cataracts be removed?
Cataracts can be removed as soon as they are noticeably affecting your vision to the point where they impact daily life — for example, driving.
After cataract surgery
Generally, your vision improves within a few days of the operation. Although most people recover without complications, it’s possible for the intraocular lens to become cloudy. This can happen a few years after the operation, or even a decade later.
In this case, you’ll likely undergo YAG laser treatment. This procedure is less invasive than the original cataract operation and takes around twenty minutes. The ophthalmologist uses a laser to make a small hole in the lens membrane. This allows light to pass through again, resulting in clear vision.
Although cataracts can feel quite daunting, lifestyle changes such as quitting smoking and improving your diet can help prevent them from developing. Why not read our article on ‘6 Simple Ways to Protect Your Eyes as You Age’?