A cataract—a clouding of the lens of the eye—blocks the normal passage of light through the eye.
Surgery for cataracts involves removing the natural lens of the eye that contains the cataract and either replacing it with an artificial lens called an intraocular lens implant (IOL) or compensating for its absence with eyeglasses or contact lenses.
The most common replacement is an IOL. Before having surgery, review with your doctor the advantages and disadvantages of each type of replacement lens. A variety of IOL types are available. Your doctor can help you choose the type that may work best for you. Not all types are covered by your provincial insurance.
An IOL is placed inside the eye during surgery. Corrective glasses may be needed after surgery for reading and close work. But they are not as thick and heavy as traditional cataract glasses.
Studies are being done to find the age at which children can benefit from an IOL. If your child needs cataract surgery, talk with your eye specialist (preferably a pediatric ophthalmologist) about what current studies are showing about the use of IOLs in children.
For nearsightedness, with or without cataracts
If you have cataracts and you are nearsighted, you may be able to have cataract surgery and get an IOL to help treat both issues. The chance of having retinal detachment after the surgery is higher than if you were not nearsighted, though. Talk to your doctor about all the pros and cons of cataract surgery.
If you don't have cataracts but you are nearsighted, there are two ways that IOLs may be able to help treat the nearsightedness:
- When the surgeon replaces the eye's natural lens with an IOL, it's called "clear lens extraction."
- When the surgeon does not remove the eye's natural lens, the IOL implants are called "phakic intraocular lenses" or "implantable contact lenses." These IOLs are placed in front of the natural lens, either in front of or behind the iris.
Cataracts that begin in the centre of the lens (nuclear cataracts) are the most common cause of nearsightedness getting worse in adults.
Types of IOLs
Most people choose distance-vision IOLs over near-vision IOLs, and they use glasses for sharp near vision. But some people choose IOLs that provide better near vision for reading, and they use glasses for distance vision.
If you are having the lenses in both eyes replaced, your doctor may recommend monovision. With monovision, the IOL in one eye provides for better near vision, and an IOL that gives better distance vision is implanted in the other eye. Many people who try monovision can adjust to it. But it's not an option for everyone. One drawback of monovision is that each eye must work more independently. This can cause problems with depth perception. You may have to adjust your gaze more often to allow one eye or the other to see properly.
When thinking about how an IOL will affect your vision following cataract surgery, some types of IOL to consider are:
- Multifocal (or accommodative) IOLs. This type of intraocular lens design provides correction for both near and distance vision, and both near and far objects can be in focus at the same time. Your brain must learn to select the visual information it needs to form an image of either near or distant objects, so multifocal IOLs may require some adjustment. A person may adjust better to multifocal IOLs if they are placed in both eyes. This type of lens is not an option for some people. It may be considered a premium lens and not be covered by your provincial health insurance.
- Monofocal IOLs. This type of intraocular lens is designed for either near or distance vision. If you have this type of IOL implanted in your eye(s), you will probably need to also wear glasses. For example, it is common for the IOLs to be chosen to provide better distance vision than near vision. Then glasses are used for sharp near vision.
- Toric IOLs. This is a type of monofocal IOL that helps correct astigmatism. It may be considered a premium lens and not be covered by your provincial health insurance.
Talk to your eye doctor about the pros and cons of each type of IOL.
Other Works Consulted
- Barsam A, Allan B (2012). Excimer laser refractive surgery versus phakic intraocular lenses for the correction of moderate to high myopia. Cochrane Database of Systematic Reviews (1).
Current as of: August 31, 2020
Author: Healthwise Staff
Kathleen Romito MD - Family Medicine
Donald Sproule MDCM, CCFP - Family Medicine
Adam Husney MD - Family Medicine
Carol L. Karp MD - Ophthalmology