Cataracts are a common condition which affect many people as they get older. Thankfully cataracts are almost always easy to permanently fix with a simple, safe and painless operation.

At the same time as removing a cataract, it will almost always be replaced by a new intraocular lens (IOL) made of a special biocompatible acrylic plastic.

With modern cataract surgery there are several choices of IOL design. Traditional lenses have a single plane of focus, which can be set at whatever distance is desired. In most cases this will be both eyes set for distance for best possible distance and night vision. Most people with bilateral distance lenses will require reading glasses after surgery. Some people may choose to have both eyes set for near vision so they can read without glasses but need spectacles for distance or even one eye set for near and one for distance (this is called monovision). Generally, monovision is used in people who have worn this in contact lenses for a period of time to be sure they are happy with this option as not everyone adapts well to it.

For people who are keen to be glasses free and have otherwise healthy eyes the most popular options now are one of the modern diffractive multifocal IOLs. These come in a range of configurations, but all have a pattern of concentric rings on them which split the light allowing distance vision and reading without the need for glasses. The main noticeable downside is that lights at night time will appear to have circles or halos around them. In the big majority of cases the rings do not interfere with night vision and they tend to fade away over time like background noise.

Trifocal diffractive lenses allow excellent unaided reading vision but are slightly weaker at typical computer distance and the halos are more obvious. Extended Depth of Focus (EDOF) IOLs have a different pattern which means computer distance is stronger and night time halos are less obvious, but small print reading or very close work is more difficult.

The choice of IOL depends on many factors including lifestyle, expectations, desire to be glasses free and the health of each eye, so it needs to decided in consultation with a cataract surgeon experienced with all these options.