Lens replacement options after cataract surgery

What is a cataract?

A cataract is a clouding of the lens inside the eye. With cataracts, the vision gradually becomes misty or foggy, making it difficult to read or drive (especially at night). For people who have cataracts, seeing through cloudy lenses is a bit like looking through a frosty or fogged-up window.

Cataracts usually build slowly as we age, and early on they do not interfere with vision. But with time, cataracts will eventually interfere with the clarity of your vision, affecting your daily activities, and at that point, they will need treatment.

How are cataracts treated?

When the cataract interferes with your lifestyle or daily activities, it will need treatment. Surgery is the only way to treat cataracts by replacing the cloudy lens with a clear plastic lens, called an Intraocular lens or IOL.

Cataract surgery is one of the most successful procedures performed worldwide The surgery is mostly done under local anaesthetic with some numbing drops or occasionally with a small volume of anaesthetic injection around your eye. The surgery often takes between 10-15 minutes and then you can go home after the surgery.

What are the types of replacement lenses?

With recent advances in technology, there are different types of lens implants, called Intraocular lenses (IOL). The suitability of each design for you depends on multiple factors, which will be carefully considered and discussed in detail at your consultation. The decision is customised to the patient’s needs and their eye health.

There are 4 main types of replacement lenses:

1-Monofocal IOL

These lenses have a single focus and they are the standard treatment for cataract surgery. They are tailored to correct distance vision which means you are likely to need reading glasses, as most senior people

2-Toric IOL

Toric lenses are suitable for patients with astigmatism. Astigmatism is a common eye condition that causes blurred vision at all distances. It occurs when the cornea (the clear front part of the eye) is like a rugby ball rather than a football. This irregular shape of the cornea causes light to focus unevenly on the retina, leading to blurry vision.

Toric lenses correct the astigmatism as in the prescription glasses. They have a special mark on the lens which is aligned during the surgery to a certain angle to correct the axis of the astigmatism. The toric lenses can be combined with other advanced optics lenses as Extended depth of focus (EDOF) or multifocal IOL.

3-Multifocal IOL

Multifocal lenses have more than one focus, like varifocal glasses. They provide distance as well as near vision. The lens design has certain rings in the central part so that light entering the eye is divided and the brain selects which focused image to use.

They work well for many patients; however, some patients may experience some glare or halos from the lens. They need careful assessment to check the suitability for your condition.

4-Extended Depth of Focus (EDOF) IOL

Extended depth of focus (EDOF) is a new technology to correct vision after cataract surgery and offer an increased level of spectacle independence. EDOF lenses work by creating a single elongated focal point to enhance the “range of vision” or “depth of focus”. They offer distance as well as intermediate vision for more spectacle independence. The main advantage of the EDOF lenses that they extend the focus but with minimal chance of glare or haloes.

What are the considerations when choosing the replacement lenses?

The choice of replacement lens after cataract surgery depends on your vision needs, lifestyle, and eye health. Generally speaking, functional vision can be classified into 3 zones:

· Distance (e.g., driving, sports, cycling)

· Intermediate (e.g., computer, car dashboard, cooking, gardening).

· Near (e.g., reading, writing, or using a mobile phone).

Factors to consider when choosing the lens implant:

· Visual goals: What are your visual preferences? Do you want to be able to see clearly at certain distances, or do you want to be able to see without glasses for daily activities?

· Astigmatism: If you have astigmatism, it is recommended to have a lens that can correct the astigmatism, called “Toric lenses”. All the different types of replacement lenses have toric versions.

· Night driving: If you drive a lot at night or your profession involves night driving, you will better avoid multifocal lenses as they can potentially cause some glare or halo around light. Although most people adapt to these effects, those who drive at night a lot may be happier with monofocal or EDOF IOLs.

· Your eye health. If you have an ongoing eye condition (e.g macular degeneration, glaucoma, retinal problems, etc.), it is recommended to avoid lenses with advanced optics, such as multifocal lenses. A monofocal lens would be a better option for you.

Each patient has their own individual circumstances and preferences. The eye specialist will discuss the options with you to select the replacement lens that is customised for your needs and give you realistic expectations.