Explainer: What you need to know about cataracts

If you’ve been told you have a cataract, you’re in very good company.

Cataracts are one of the most common age-related changes in the human body, and most of us, if we live long enough, will develop them.

When surgery becomes necessary, it is one of the safest and most successful procedures in modern medicine. But what is a cataract?

Think of your eye like a camera. There is a lens near the front that focuses light onto the retina - the ‘film’ - at the back of your eye.

When you are young, this lens is clear and flexible, allowing you to shift your focus from distant to near objects. As the lens ages, a number of changes occur: First, the lens stiffens - affecting its ability to adjust your focus to see near objects - which is why most people eventually need reading glasses; next its shape (and hence your glasses prescription) begins to change; Finally, the lens starts to lose its clarity and becomes foggy. This foggy lens is what we call a cataract.

Developing a cataract is a normal part of ageing, and typically does not damage your eye. In the early stages, the fogging may be so subtle you are not even aware of it, and it is often possible to compensate through small adjustments to your glasses or by improving the lighting when you read.

Over time, however, as the lens becomes cloudier, you may notice you are experiencing more difficulty - colours may seem duller, driving at night may become harder because of glare, or you may find that even with updated glasses, things are no longer as sharp as you like.

When the cataracts are starting to hold you back in these or other ways that are important to you, it might be the time to start thinking about surgery.

As the cataract does not usually damage your eye, there is no fixed point at which you must have surgery. There are minimum standards of vision for driving, and if your cataracts are causing difficulty in this area, you may need to think about surgery to help you drive with more confidence, but outside of this scenario, the timing of surgery is very much up to the individual.

When you do decide to have surgery, you do not need to be fearful. It is remarkably safe.

The procedure itself typically takes 20-30 minutes (although your hospital visit may be several hours in total) and is performed under local anaesthesia.

Most patients notice a significant improvement within a day or two.

Serious complications such as infection or bleeding are very rare, occurring in fewer than one in 1,000 cases, and while there is a long list of issues which can make the surgery more complicated, most can be thought of as technical challenges - that is to say, they may mean your surgery takes a little longer or, very occasionally, that you might require a follow-up procedure, but they typically can be addressed and usually do not have a major impact on the final outcome.

During surgery, your surgeon will remove the foggy lens from inside your eye and replace it with an artificial one. Thanks to recent advances in surgical and lens technology, it is now possible to estimate reasonably accurately what lens will give you the best vision in the distance, so many patients find that, after surgery, they are much less dependent on their glasses than they were before.

It is worth being realistic, though, about what surgery can and cannot do.

1. For most patients, the artificial lens chosen will give distance vision that is ‘good enough’ to meet the driving standard without glasses - but ‘good enough’ is not the same as perfect. You will always see better with an up-to-date pair of glasses, and many people choose to continue to wear their glasses after surgery because they prefer this additional sharpness.

2. The artificial lens also does not adjust its focus the way your natural lens once did, so most patients will still need glasses for reading.

Some newer lens technologies attempt to provide sharp vision both for near and distance objects without glasses, but achieve this at the cost of introducing other imperfections and so the ability to guarantee high-quality glasses-free vision remains elusive.

3. Finally of course, cataract surgery is not a panacea, so if you have other eye conditions the improvement after cataract surgery may be limited.

Understanding these limitations beforehand helps ensure you are genuinely pleased with the result of your surgery, rather than disappointed by an expectation that was never quite realistic.

If your cataract is very mild and you find your vision overall is still quite good, surgery may not offer enough improvement to make it feel worthwhile. The more noticeably the cataract is affecting your vision before you have surgery the more you have to gain.

As cataracts develop slowly, people can underestimate how much they are affecting them, and many patients are pleasantly surprised that colours appear brighter and everyday activities like reading or driving feel easier and more comfortable again.

If you are currently living with a cataract, the most reassuring thing I can tell you is that it will not damage your eyes, so the timing of surgery is largely up to you, Modern treatment is safe and the experience of it is not nearly as daunting as most people imagine.

When the time is right, you can approach surgery with real confidence. In the meantime updated glasses and good lighting can go a long way.