A cataract is a clouding of the natural lens of the eye which causes visual blurring and glare. The most common cause is aging. However, cataracts can occur in all age groups, even infants and children. Other causes include ultraviolet light exposure, eye trauma, diabetes, inflammatory eye disease, smoking, genetic disorders, and certain medications (notably corticosteroids).
Diagram of the eye. Note that the lens is clear (i.e. there is no cataract). Light rays will be clearly focused onto the retina.
Diagram showing a cataract. Note how cloudy the lens is; light rays will not clearly pass through the lens and blurrry vision will result.
What are the symptoms of a cataract?
An early cataract will cause mild blurring of vision, difficulties with vision at night and some fading of colours. As a cataract grows, it will lead to frequent changes in the prescription of a patient’s glasses. As the cataract gets bigger, vision continues to blur to a point where reading or viewing the television becomes difficult. At this point, the cataract may prevent a person from driving.
How does an ophthalmologist diagnose a cataract?
Visual blurring can be caused by a variety of eye conditions. A complete eye examination is needed to decide whether or not a cataract is present and how the health of the eye is. This includes looking for other common diseases such as glaucoma and age-related macular degeneration.
How does an ophthalmologist treat cataracts?
The symptoms of early cataracts can be reduced with an adjustment in glasses. In time, if the vision decreases to a point where one cannot do the things in life they want to (such as drive or read), then the ophthalmologist will often suggest cataract surgery.
Cataract surgery is the most commonly performed and safest surgery in all of medicine. During surgery, a microscopic cut is made and the clouded lens is removed using an ultrasonic machine called a phacoemulsifier. An artificial lens (called an intraocular lens or IOL) is placed inside the eye to replace the focusing power of the original lens.
Pre-operative measurements of the eye are used to calculate the power of IOL that best suits the patient. A small amount of sedation is used and usually no needles or stitches are required.
Sometimes, months or years after surgery, the original capsule behind the lens can become cloudy. This is called a secondary cataract. This is easily removed with a quick and painless laser treatment called a YAG laser capsulotomy performed in the clinic.
