Cataracts occur as your lenses naturally harden as you age. This hardening may also turn cloudy, which blocks light from reaching the retina and interferes with vision; the effect is like looking through a dirty car windshield. Cataracts may form in one or both eyes, at the same time or at different times.
They are painless, develop within the existing lenses in your eyes, and are usually detected during routine eye exams.
There are several types of cataracts:
- Age-related cataracts - Most cataracts occur because of aging, but it is possible to develop age-related cataracts as early as 40. Age-related cataracts usually progress slowly and don’t affect your vision at first. As a cataract develops and the lens clouds over, your vision blurs and this can make driving, cooking, and other activities difficult.
- Traumatic cataracts - This type of cataracts, caused by eye injuries, can happen at any age. A traumatic cataract may occur as a result of a blunt force injury (from a finger, fist, or tennis ball, for example) that directly damages the lens. It can result from a penetrating injury, in which your eye is pierced by a sharp object, such as a knife, a splinter, or a pencil. A traumatic cataract may form soon after an injury or months to years later.
- Radiation cataracts - Prolonged exposure to ultraviolet radiation (UV) from sunlight is another cause of cataracts. Wearing sunglasses with 100% UVA and UVB protection in bright sunlight (both in winter and summer) can reduce your risk of developing this type of cataracts.
- Congenital cataracts - Some babies are born with cataracts. These may be inherited or caused by an infection or illness that a mother has during pregnancy, such as German measles (rubella). A cataract at birth can stop the eye from learning to see, so surgical treatment is often needed to allow the child’s visual system to develop normally.
- Secondary cataracts - Secondary cataracts are cataracts that form as a result of another medical conditions like diabetes. They can develop after surgery for glaucoma or after eye infections such as uveitis and retinitis. Long-term use of oral steroids, like prednisone, also increases your risk.
How do cataracts affect vision?
Cataracts are caused by chemical changes that occur within the lens of the eye. Your eyes’ lenses are made up of water and proteins that are arranged in a way that keeps the lens clear and allows light to pass through. However, the proteins can begin to clump together causing the lens to become cloudy. Since the lens helps to focus light on the retina to form images, this cloudiness affects our vision.
At first the clouding may have little effect on your vision depending on its location on the lens. Over time the cataract may grow larger, clouding more of the lens and making it harder to see.
If you have any of the following cataract symptoms, see your eye doctor immediately:
Sensitivity to bright light or experiencing glares and haloes around lights
- Difficulty seeing details and poor central vision
- An inability to distinguish colours
- Difficulty seeing at night
- Double vision
Risk factors include:
- Family history
- Other health problems (e.g., complications from diabetes)
- Drinking alcohol
- Excessive sun exposure
- Eye injury (puncture, cut, intense heat, or chemical burn to the eye)
If you have any risk factors or are experiencing any of the common symptoms for cataracts, see an eye doctor right away. Cataracts can be removed and vision can often be restored. Surgery is usually recommended if you feel your vision interferes with daily activities like driving, reading, or watching TV.