Q: My elderly father is having cataract surgery. What are his options in terms of lenses?

A:These days, there are many choices when it comes to IOLs (intraocular lenses) to treat cataracts. Your father should discuss this with his eye doctor to determine what is right for him. Factors that may need to be considered are the type of correction he needs, any previous eye conditions he may have as well as the overall cost of each type of lens. However, before your father speaks to his eye doctor, it doesn't hurt to educate yourselves about the different types of lenses available for cataract surgery.

Before we talk about lenses, let's review some basic facts about cataracts and cataract surgery.

Our Changing Vision

As we get older, the lenses in our eyes begin to lose their flexibility (making it harder to focus) and their optical clarity (making it harder to see clearly). Cataracts develop slowly and many people do not realize they have one at first. Initially, the changes in our vision from a cataract can be corrected by getting a new eyeglass prescription. However, over time, a cataract will only make our vision worse. Many people know they are ready for surgery when cataracts begin to interfere with the quality of their lives. They may have difficulty with driving, watching TV or reading a book.

Cataract Surgery

Cataract surgery is among the safest and most successful procedures in medicine, with 95 per cent of people treated having improved vision afterwards. The procedure is performed on an outpatient basis, with the patient usually awake and given a local anaesthetic to prevent any pain.

Surgery happens relatively quickly. The doctor makes a small incision on the side of the cornea about the width of a pencil. Then an instrument is put through the incision to emit high pulse ultrasound waves that break up the cataract. After the cataract is removed from the eye in a vacuum process, an IOL is folded up, inserted through the incision and then allowed to reopen in the eye.

Many people notice an instant improvement in vision following surgery; however, it takes about a month for the eye to completely heal to get the best vision. In most cases, patients will be able to resume normal activities almost immediately, although strenuous activity, such as lifting heavy objects, should be avoided for about a month.

Types of Lenses

There are four main types of IOLs:

Monofocal - This type of lens corrects for distance vision, allowing the person who receives it to do things such as driving and going to the movies without needing glasses. The monofocal lens is the most basic lens available and is covered by most government health insurance plans (other types of lenses may not be - ask your doctor). With a monofocal lens, you will still need glasses for intermediate and near distances, such as when you are working on a computer or reading a book.

Aspheric - This lens provides correction for distance vision as well as contrast vision. Your night vision and ability to distinguish colours will improve, because this lens reduces the occurrence of glare and halos. However as with monofocal lenses, you will still need glasses for near and intermediate distances.

Toric - Toric lenses correct for astigmatism, which is caused when the cornea is shaped irregularly. These lenses are for cataract patients who have astigmatism and do not want to wear eyeglasses for distance vision. However, as with monofocal and aspheric lenses, patients will need glasses for near and intermediate distances.

Multifocal - Multifocal lenses (also known as accommodating lenses) correct for all distances and give you good near and far vision. One possible drawback to these lenses is you may experience halos around lights when driving at night. However, this usually will fade over time. Also, some patients report difficulty with intermediate vision with some types of multifocal lenses.

UV-B-Filtering - Almost all IOLs these days - whether they are monofocal, aspheric, toric or multifocal - are also designed to filter ultraviolet-B light. Excessive exposure to UV-B light rays is thought to be one risk factor for AMD, the leading cause of vision loss in Canada. Normally, the natural lenses in our eyes filter out some of these light rays, but after the natural lens is removed during cataract surgery, this is no longer the case. UV-B lenses help to protect your eyes against UV-B light damage even after cataract surgery.

Blue Light-Filtering - High energy blue light is thought to be a risk factor for cataracts and AMD. As with UV-B light, the natural lenses in our eyes filter out blue light rays and help to reduce the risk of these conditions. After the lens is removed in cataract surgery, this natural protection is also removed. However, blue-light filtering IOLs can add this protection back. These lenses are coloured a transparent yellow (similar to the colour of your natural lens), but they don't alter the colour of your vision.

As you can see, these days there are many lens options to choose from. While there is no guarantee that your father won't have to wear glasses after surgery, he will most likely see a lot better than he has for a long time. Good luck with the decision.

The Expert:

Colour picture of Dr. Allan Slomovic

Dr. Allan Slomovic specializes in cornea, cataract and refractive surgery at Toronto Western Hospital. He is the research director of the Cornea/External Disease Service for the University Health Network, Toronto Western Hospital and an associate professor of Ophthalmology at the University of Toronto. He is also the chairman of Continuing Professional Development for the Canadian Ophthalmological Society.

Dr. Slomovic has published numerous articles on cataract surgery, cornea/external diseases of the eye and refractive surgery and has also lectured on these topics locally, nationally and internationally.

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