Cataract surgery: Seeing the world through a different lens

The Bottom Line

  • Cataracts occur when a part of the lens in your eye or eyes becomes cloudy, and are a common cause of blindness worldwide.  
  • Cataract surgery is the only way to treat cataracts that cause more severe symptoms, but there are different types of lenses that can be used, each with their own pros and cons. 
  • Monofocal and multifocal lenses are likely equally beneficial for distance vision. 
  • Multifocal lenses may be better for near vision and reducing dependence on glasses, but may also cause more cataract-like symptoms after surgery. Speak with your doctor about which option is best for you. 

Our eyes are our windows to the world. So, when that window clouds over, our lives are impacted.

Cataracts are one common source of cloudy vision—caused by clouding of the lens inside the eye (1;2)—and can lead to partial or total blindness (2;3). In fact, cataracts are the cause of approximately half of all cases of blindness worldwide (4).

Cataracts usually develop slowly (5), and often go unchecked until they start to affect daily activities like reading or driving (3). Common symptoms include blurry vision, seeing haloes around lights (1), glare, and changes to colour vision (2). You may also find that you need to crank up the lights while reading (1), or that your eyeglass prescription is constantly changing (1;2).

Aging is a common cause of cataracts, but they can also occur with injury (5). Diabetes, previous eye surgery, and steroid medications put you at even greater risk (5). You are also at higher risk if you smoke, drink large amounts of alcohol (5), are obese or have high blood pressure, so keeping these factors in check can help ward off this condition (1).

Cataract surgery—which replaces the cloudy lens in the eye with an artificial lens (3)—is becoming more and more common (6). In fact, as many as 175,000 surgeries are performed in Ontario each year (7). Although cataract surgery is the only way to treat cataracts that cause more than mild symptoms, different types of artificial lenses can be used. The two most common choices are monofocal and multifocal lenses (2).

But just how do these two lens options compare?

What the research tells us

One systematic review shows that there are pros and cons to both monofocal and multifocal lenses for cataract surgery. Monofocal lenses correct either distance or near vision, whereas multifocal lenses correct near and distance vision at once.

For distance vision, monofocal and multifocal lenses appear to produce similar results. However, multifocal lenses may have some advantages over monofocal lenses—such as potentially producing better near vision, and helping people reduce their likelihood of needing glasses. The downside is that people with multifocal lenses did report more cataract-like symptoms—such as seeing glare and halos—following surgery than those with monofocal lenses. Unfortunately, most studies in the review did not assess the effects of the different lenses on outcomes such as satisfaction with the surgery or quality of life, and where data did exist, the findings were inconsistent (2).

Cataract surgery provides an opportunity to see the world through a different lens. Although the quality of the evidence varies, both multifocal and monofocal lenses are effective options for cataract surgery (2). Speak with your healthcare provider about which lens might work best for you.

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  1. Mayo Clinic. Cataracts. [Internet] 2018. [cited September 2018]. Available from 
  2. de Silca SR, Evans JR, Kirthi V, et al. Multifocal versus monofocal intraocular lenses after cataract extraction. Cochrane Database Syst Rev. 2016; 12:CD003169. doi: 10.1002/14651858.CD003169.pub4.
  3. Jacobs DS, Trobe J, Kunins L. Cataracts in adults. [Internet] 2018. [cited September 2018]. Available from 
  4. Thylefors B. The World Health Organization’s programme for the prevention of blindness. Int Opthalmol. 1990; 14(3):211-219.  
  5. Mathew MC, Ervin AM, Tao J, et al. Antioxidant vitamin supplementation for preventing and slowing the progression of age-related cataract. Cochrane Database Syst Rev. 2012; 6:CD004567.
  6. Mayo Clinic. Cataract surgery. [Internet] 2018. [cited September 2018]. Available from
  7. Canadian Association of Optometrists. Cataract surgery in Canada: What you need to know according to the Canadian Journal of Optometry. [Internet] 2015. [cited September 2018]. Available from 

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