Cataract: common, treatable, and still a leading cause of blindness

Cataract is a clouding of the lens inside the eye. It is overwhelmingly a consequence of age, it is extremely common, and it is treated by an operation with a high success rate that takes well under an hour.

It is also the leading cause of blindness in Nigeria. The gap between those two statements is not a medical problem. It is a problem of access, cost, information and delay.

How it develops

The lens is made of transparent protein arranged in a precise structure. Over decades the proteins accumulate damage, clump together, and scatter light instead of transmitting it. The lens yellows and clouds.

This is why the change is gradual and why people often do not report it as blurring. They report that lights glare at night, that colours have faded or yellowed, that they need brighter light to read, that headlights dazzle unbearably when driving after dark. Some find their reading vision temporarily improves as the lens changes shape — occasionally mistaken for the eyes getting better.

Risk factors beyond age

• Ultraviolet exposure — relevant year round at this latitude.
• Diabetes, which brings cataract on earlier and faster.
• Smoking.
• Long-term steroid use, including unsupervised steroid eye drops.
• Previous eye injury or inflammation.
• Some are congenital, which is why newborn eyes are checked for a red reflex — a cataract present at birth must be treated urgently or the visual system does not develop.

The operation

The clouded lens is removed and an artificial intraocular lens is put in its place. It is usually done under local anaesthetic as a day case. Most people see a clear improvement within days.

The lens implant can be chosen to reduce dependence on spectacles — a single-focus lens set for distance is standard, with reading spectacles afterwards; multifocal and toric options exist with their own trade-offs. This is a conversation with the surgeon beforehand, not a decision made on the day.

A common and easily misunderstood sequel: months or years later, the capsule holding the implant can cloud, and vision dims again. This is not "the cataract coming back". It is treated in minutes with a laser, in clinic.

Why people wait too long

Cost and access are the obvious reasons and the largest ones. But three others recur in practice and are worth addressing directly.

"It must be ripe." This is outdated. Modern surgery does not require a dense, mature cataract, and a very hard lens is actually more difficult to remove and carries more risk. The right time is when the cataract interferes with what you need to do — driving, working, reading, recognising faces.

Fear of the operation. Understandable, and usually based on stories from decades ago or on someone's poor outcome from a different procedure. It is worth discussing specifically with the surgeon rather than deciding in the abstract.

Assuming poor vision is just old age. A great deal of avoidable blindness in Nigeria sits behind this assumption. Reduced sight in an older person is worth examining, not accepting.

What an optometrist does about cataract

Detects and grades it, updates the prescription while it is still correctable, judges when it has reached the point of referral, advises on which eye and when, and provides post-operative refraction once the eye has settled. Much of cataract care is not surgical, and the surgical part is usually short.

If night driving has become difficult or lights have started to glare, have it looked at. That is often the first sign.