What you should know about: Cataracts

A cataract is the clouding of the lens in the eye and is one of the most common eye diseases. In fact, everyone will develop cataracts if they live long enough. 

The lens is a structure that sits behind the iris, the coloured part of the eye. The lens is critical for your vision, because when light shines through your pupil, it must pass through your lens to reach the retina at the back of your eye. The retina is sensitive to light patterns and transmits signals to your brain, which interprets what you see. This is why the lens must remain clear for optimal vision. 

Babies can be born with cataracts. Children can develop cataracts too. These are called congenital cataracts and are rare. 

Damage to the lens, due to a blow to the eye or another eye injury, can also lead to cataracts, whether soon after the injury or years later. These are called traumatic cataracts, and they can occur at any age. 

Age-related cataracts are by far the most common. Most people will develop cataracts at some point in their lives. It is a natural part of the aging process, so while you may not be able to prevent them entirely, a healthy lifestyle can delay their development and progression.  

The health of your lens can be influenced by your overall health and medications. Significant disturbances to the lens can be caused by high blood sugar in conditions like diabetes or by some medications like steroids. This is one example of why it is important to appropriately manage chronic diseases for better eye health and why it is also important to let your optometrist know of all the medications you are using. 

External influences can also affect the health of the lens. An example of this is UV light, which can cause cataracts to develop sooner. This is why individuals who spend a lot of time outside or live near the equator tend to develop cataracts earlier and may experience faster progression. In addition to a healthy lifestyle, you should protect your eyes from UV rays with anti-UV lenses, which may or may not be sunglasses – you can get anti-UV coatings on clear lenses too. Cataracts generally develop in both eyes, though not necessarily at the same rate or with the same level of severity. A traumatic cataract might occur only in one eye. 

The predominant symptom of a cataract is reduced visual acuity, which means your vision becomes blurry or less clear. You may also experience sensitivity to glare, halos around lights, difficulty driving at night, or difficulty reading. In the initial stages of cataract development, these symptoms can be mild.  

You may start to experience glare sensitivity and difficulty reading in your 40s or 50s, but these issues might not be significantly bothersome at first. Most people are not diagnosed with cataracts until their 60s or 70s.  

If you are experiencing symptoms such as these, book an appointment with your optometrist.  

Your optometrist is usually the person who identifies cataracts. During a comprehensive eye exam, your optometrist will use an instrument called a slit lamp (above), which is a type of microscope that allows observation of the inner parts of your eye by shining a bright light into it. Lens discoloration and cloudiness are visible to your optometrist through the slit lamp. Your optometrist may also use an ophthalmoscope (hand-held device to see into your eye) or imaging devices to rule out other causes for changes in your vision. 

Your optometrist may recommend you have your eyes dilated, so it is easier to see into your eye to assess you for cataracts and other conditions. Dilation involves putting drops in your eyes that widen your pupils. This can result in slightly blurry vision for a few hours afterwards.

Ultimately, cataract treatment involves a surgical procedure to remove the cloudy lens and replace it with an artificial one.  

If your cataract symptoms are not yet advanced enough to justify cataract surgery, your optometrist may help to reduce your symptoms by adjusting your prescription for glasses or contact lenses. Special coatings on your lenses may help counteract glare. You can also use other interventions such as using a brighter light when you read. 

When the opacity (cloudiness or discoloration) of your lens can no longer be offset with glasses, the cataract has reached a point where it requires surgical intervention. Your optometrist will then refer you to an ophthalmologist (eye surgeon). 

In Canada, there are over 500,000 cataract surgeries performed annually, making it one of the most common surgical procedures as well as among the most effective and low risk.  

During cataract surgery, the surgeon makes a small incision at the very front of the eye and removes the cloudy lens. An artificial lens (intraocular lens or IOL) is then implanted in its place to allow for unobstructed light transmission from the front to the back of the eye.  

Surgical techniques have improved in recent decades, so healing is easier and quicker than it used to be. Many patients can see well the same day.  

In most cases, the artificial lens will correct your sight for good distance vision, so you may need to use glasses for reading. However, some patients (if eligible) opt for a multifocal lens implant to allow for both distance and close-up vision, potentially eliminating the need for glasses. 

Your optometrist will take charge of your care after the completion of immediate post-operative care. This typically means observing your recovery, helping you if you have side effects such as dry eye and advising you if you experience other complications.  

Post-Operative Complications 

The most common complications following a cataract surgery are: 

• Dry eye 
• Posterior capsular pacification 
• Cystoid macular edema 

Dry eye is common because of irritation to the surface of the eye during surgery, which can affect the stimulus to blink and/or reduce tear production. For most people, dry eye following cataract surgery is temporary. It is likely to be worse in the weeks following surgery and to improve significantly within a few months. If dry eye symptoms persist, see your optometrist. Read more about dry eye. 

Posterior capsular opacification, often called a secondary cataract, is a common complication following cataract surgery. Your lens sits inside a capsule, and when it is removed, the new lens is implanted in this capsule. What can end up happening three months to five years after surgery is that the cells in this capsule can become cloudy or discoloured, acting like a second cataract. This is more common in younger cataract patients. This secondary cataract does not affect the intraocular lens. It does require surgical intervention, but this is a quick and low-risk laser procedure generally done in an ophthalmologist’s office.  

Cystoid macular edema is inflammation of the macula, the structure at the back of the eye responsible for clear central vision. It is more common in patients who have experienced macular edema in the past or have had other macular conditions. Often, patients are pre-treated for this condition through topical steroids or non-steroid anti-inflammatory eye drops. If macular edema is not present before surgery, it can develop around three months later and will also be treated with eye drops. Following treatment, your vision is likely to improve. If you experience consistent blurred or distorted vision following cataract surgery, see your optometrist or ophthalmologist without delay. 

A rare but serious complication following cataract surgery is retinal detachment. This is more common in patients who have had retinal detachment in the past or are very nearsighted. Your optometrist and ophthalmologist will take your ocular health history into account when assessing you for risk and treatment. If you experience the sudden onset of blurriness, flashing lights or floaters in your vision or you feel as though a curtain has been pulled over part of your vision, contact your ophthalmologist immediately. After hours, head to the nearest hospital emergency room. 

A comprehensive eye exam is all it takes to find out if your blurry vision comes from cataracts. You can book an appointment with our primary care service at our Waterloo or Kitchener clinics by phone or online. 

Costs & Coverage 

Eye exams for patients over the age of 65 are covered by the Ontario Health Insurance Plan (OHIP). You are eligible for one comprehensive eye exam plus two follow-ups every 18 months.  

If you have an eligible medical condition, you will be covered for one comprehensive exam plus two follow-ups every 12 months regardless of your age. These conditions include: 

• Diabetes 
• Cataracts (meeting specific criteria)  
• Certain chronic eye diseases (example:  glaucoma, macular degeneration) 

For patients under 65 who do not have an eligible condition, a comprehensive eye exam is $120 at the WEI (as of 2025; subject to change). We recommend everyone get an exam once every year to monitor your ocular health.  

A 2021 study in the Clinical and Experimental Optometry journal listed the University of Waterloo School of Optometry and Vision Science as fifth in research excellence out of 245 optometry schools around the world, third in North America. Researchers at the School are currently investigating different treatments, therapies, and technologies to be used in practice. You can contribute to advancements in eye care through participation in our various research studies. You can sign up for our ongoing studies or consent to research when booking an eye examination.

Article and video by Ameera Khan and Karen Kawawada

Reviewed by Dr. Andre Stanberry, OD, Ocular Disease and Family Practice residency, Dipl. ABO