The cataract is a disorder of vision that occurs when the crystalline lens, this little oval lens behind the pupil, loses its transparency .
When the lens becomes opaque, the light rays reach the retina less well, which explains why the vision becomes confused . The word cataract was chosen to describe this impression of looking through a waterfall (from the Latin cataracta , which means waterfall). The crystalline lens plays the same role as the objective lens of a camera: to focus the image according to the distance of the observed object. The lens achieves it by deforming to change its curvature.
Most often, cataracts form slowly, with aging . Over time, the structure of the lens changes. We do not know exactly why, but according to the main hypothesis, the proteins of the crystalline lens would be altered by free radicals , substances naturally produced by the body and contributing to aging. Free radicals are partly neutralized by antioxidants , mainly derived from the fruits and vegetables consumed.
Cataract is the 3 th cause of blindness in Canada. The main causes of blindness – macular degeneration , glaucoma and cataracts – usually occur with aging.
Who is affected?
From age 65 , most people have a cataract onset . Opacification of the lens does not cause significant visual discomfort if it is done in the peripheral layers of the lens.
After the age of 75, two-thirds of Americans have cataracts advanced enough to affect their vision. The loss of vision tends to worsen with age. Cataracts also affect men and women.
Types of cataract
There are several forms of cataracts, here are the main ones.
- Senile cataract. The majority of cataracts occur in the elderly. The normal aging process can result in hardening and opacification of the lens. Age-related cataract often affects one eye more than the other.
- Secondary cataract. Certain diseases (especially diabetes, if poorly controlled), taking certain medications (for example, oral cortisone) or exposure to high doses of radiation may be the cause of cataracts. In addition, having surgery to the eye or having certain eye problems (such as high myopia, glaucoma or retinal detachment) makes you at increased risk of cataracts.
- The traumatic cataract. It occurs as a result of an injury to the eye that damages the lens: a blow, a cut, exposure to intense heat, a chemical burn, etc.
- Cataract in children. Cataracts can occur from birth, but this is rare. It may accompany a congenital disease (for example, trisomy 21) or result from an infectious disease of the mother transmitted to the fetus during pregnancy, such as rubella, toxoplasmosis , genital herpes or syphilis.
When visual acuity drops to the point of significantly restricting daily activities, it is a possible sign of cataract. Generally, this decline in vision occurs slowly, over several years. However, sometimes it happens more quickly (in a few months).
When the cataract is more advanced, the pupil does not appear black, but rather gray or milky white . At an advanced stage, vision can be limited to the perception of light.
When to consult?
The cataract is usually detected during an eye examination by an optometrist. Any change in the quality of vision should prompt consultation with an optometrist or ophthalmologist.
Symptoms of cataract
- A view gradually more tangled or obscured.
- Double vision or glare easier in the presence of bright lights. Glare greatly impedes night driving.
- A bland and less lively perception of colors.
- A veiled vision . The objects appear as if they were behind a white veil.
- A more frequent need to change lenses prescription, because cataracts accentuate myopia . (However, people who are farsighted may initially feel that their vision is improving.)
People at risk
All people are at risk for cataracts because aging is the main risk factor. However, the risk is greater in people:
- have had diabetes for several years;
- having a family history of cataracts;
- who have previously suffered trauma or surgical treatment to the eye;
- who live in high altitude or near the equator, more exposed to the ultraviolet rays of the sun;
- who have received radiation treatment, a treatment commonly used against cancer.
- Taking certain medications can cause cataracts (eg, corticosteroids , long-term). It is necessary to consult a doctor in case of doubt.
- Exposure to ultraviolet rays from the sun . It increases the risk of developing senile cataracts. The sun’s rays, especially UVB rays, transform the lens proteins.
- Smoking. The tobacco damage lens proteins.
- The alcoholism .
- A diet low in fruits and vegetables . Research indicates a link between the occurrence of cataracts and a lack of antioxidant vitamins and minerals, such as vitamin C and vitamin E, selenium, beta-carotene, lutein and lycopene.
|Basic preventive measures|
|Do not smoke . Smokers can reduce their risk of senile cataracts by quitting smoking.
Protect your eyes from the sun . Excessive exposure to the sun is known to cause damage to the lens that may accelerate the onset of cataracts. It is therefore important to wear a broad- brimmed hat and sunglasses to protect against UVA and UVB rays. Limiting exposure to microwaves, X-rays and infrared radiation may also slow down cataract formation.
Eat enough fruits and vegetables . The antioxidants they contain help prevent cataracts. The Canada Food Guide recommends that women consume in 7 to 8 servings per day; and men, 7 to 10 servings. See also Complementary approaches .
Control your blood sugar in case of diabetes . People with diabetes need to monitor their blood glucose , blood pressure and cholesterol levels to prevent eye disorders. See the Complications of Diabetes fact sheet.
Protect your eyes at work and play . Cataracts due to certain injuries can be prevented by wearing adequate protection at work and during sports activities.
Treat an infection during pregnancy . In case of infectious disease (genital herpes, syphilis, etc.), pregnant women should consult their doctor. It is possible to reduce the risk that the infection will affect the newborn.
|Note. Cataracts are not treated with eye drops or laser rays. Surgery is the only treatment possible.|
When cataracts begin to form and the symptoms are not too bothersome, vision can be improved by simple measures:
– wear glasses with anti-reflective lenses to reduce glare;
– have an adequate prescription of lenses : the vision is often modified as the cataract progresses; if this is your case, consult an optometrist to adjust the lenses of your glasses or contact lenses;
– Make sure you have enough lighting to carry out your indoor activities.
It will also be beneficial to adopt preventive measures to slow the progression of the disease. See the Prevention section .
No treatment can restore the transparency of an opacified lens. Therefore, when the cataract is at a later stage, to the point of altering the quality of life, the only therapeutic option is surgical removal of the lens contents and replacement with a synthetic malleable lens . Commonly practiced, this intervention clearly improves vision in more than 90% of people. People who do not get improvement often have other eye problems (macular degeneration or glaucoma). It also happens that a surgical complication occurs (infection, detachment of the retina, hemorrhage, etc.).
The surgery is usually performed under local anesthesia (without puncture), and lasts 15 to 30 minutes. Only one eye is usually operated at a time. It is important to inform the surgeon of any health problems and medications used, especially those that work on the prostate as well as anticoagulants.
Procedure of the surgery
- An incision of about 2 mm is made through the cornea and an opening is created in the lens envelope.
- An ultrasound probe is then inserted into the lens. Ultrasound sprays the lens protein and softens it, making it easier to remove. This step is called ” phacoemulsification “.
- In most people, the lens is then replaced by an artificial lens , introduced into the lens envelope. The introduced lens is chosen according to the patient. Depending on the case, the lens can correct myopia, hyperopia, astigmatism and presbyopia.
|Two types of artificial lenses
– Rigid lenses made of polymethylmethacrylate (PMMA). They have been used since the 1950s, but have not undergone any innovation since the 1990s. They are reliable, but require a large aperture (5.5 mm) to introduce them into the eye. They can correct myopia and hyperopia.
– Soft , soft or collapsible lenses , made of acrylic or silicone. They can be bent at 3, so that the incision in the eye is 3 times smaller. They offer better night vision. Cataracts are less likely to re-declare (see below). Some soft lenses can correct astigmatism, presbyopia or both. However, they are not suitable for everyone. Discuss with your ophthalmologist.
- The person who undergoes this surgerycan expect a complete cure within 1 month. At first, some people have the impression that the world literally explodes in color and the intensity of their perceptions is almost painful. In fact, the brain has offset the reduction in light impulses by amplifying the signals responsible for color. It may take some time for the brain to get used to the new, improved view. It may be that driving is not possible for a few weeks.
- However, sometimes a cataractappears months or years after surgery. This cataract is caused by opacification of the lens envelope left in place at the time of surgery. This occurs in 5% to 40% of surgeries, depending on the type of lens used. Even if people experience symptoms similar to their initial cataract, this problem can be corrected easily and quickly with a simple laser intervention.
- For some congenital cataracts, surgery must be done within the first few weeks after birth to allow good vision development.