The normally clear lens of the eye becomes opaque, causing hazy and indistinct vision. It affects 20% of people by the age of 60. As we get older, cataracts (loss of transparency of the lenses in the eyes) are the most common cause of impaired vision. Cataracts form due to changes in the delicate protein fibres within the lens, in the way that an egg white goes solid when we cook it.
With increasing loss of transparency, the clarity and detail of what we see gets progressively less. Cataracts usually occur in both eyes, but one eye is nearly always more severely affected than the other.
Almost everyone over the age of 65 has cataracts to some degree, but they’re usually minor and often confined to the edge of the lens where they don’t interfere with sight. Most people over the age of 75 experience some visual impairment due to cataracts.
Risk for Growing Cataracts
Increases with Age
Cataracts are increasingly common as people age; for example, among men in 1996, the speed of cataracts was 17.3 per 1,000 individuals in the United States for those ages 45-64 years of age. The speed drastically improved to 109.3 per 1,000 men for individual’s ages 65-74 years and rose yet again to 189.6 per 1000 individuals for those who age 75 and older.
Among girls, the speed of cataracts was 29 per 1000 for those ages 45-64 in 1996. It rose to 186.4 for those ages 65-74 and still farther to 203.9 per 1,000 girls age 75 and older. Certainly, girls in America have a higher risk of developing cataracts than guys.
Other Risk Factors
Individuals with diabetes are also especially at risk for developing cataracts. Some potential causes of cataracts are eye injuries or exposures to radiation or hazardous materials. Other risk factors for developing cataracts are smoking or an excessive exposure to sun. On the other hand, the cause of cataracts is frequently unknown. The National Eye Institute, part of the National Institutes of Health, is studying whether some minerals or vitamins may be effective in retarding the development of cataracts or in preventing them from forming completely. Results should be accessible in several years.
Causes of Cataracts
Light passes through the cornea, lens and fluid in the eyes with great efficiency, but eventually the clarity of the lens deteriorates. Exposure to daylight over many decades may be the main cause of the condition, probably because ultraviolet light changes the protein within the lens.
Diabetics are at greater risk of cataracts, developing them ten to fifteen years earlier than otherwise expected (see Diabetes). Those who take steroids by mouth, for example for rheumatoid arthritis, run a significant risk – perhaps up to 75% – of developing cataracts. They should be checked regularly by a doctor to detect cataracts early.
Injury that has penetrated to the lens will leave scarring. There are a few rare congenital or biochemical causes of cataracts that might be suspected if cataracts appear at an unusually early age.
You needn’t be fearful of getting cataracts – they are so common that they could almost be considered part of the normal ageing process.
- Exposure to the ultraviolet radiation in strong sunshine increases the risk, and cataracts are more common in tropical countries than in Europe or North America. They occur more often in those who spend most of their lives outdoors, especially if the eyes are unprotected.
- Exposure to other types of radiation, including infrared radiation and X-rays, may cause cataracts to form.
- Cataracts may be caused by direct injury to the eye, and are almost inevitable if a foreign particle, such as a shard of metal or glass, gets into the lens.
- Cataracts are common in people with diabetes and may develop early if the diabetes isn’t well controlled and blood-sugar levels get very high.
- The formation of cataracts is promoted by long-term treatment with corticosteroid drugs, poisoning by substances such as naphthalene (found in mothballs) or ergot (formed in stored grain contaminated by a certain type of fungus).
- Mixing sunshine and the herbal antidepressant St John’s wort may lead to cataracts. Hypericin, the active ingredient in St John’s wort, reacts with visible and ultraviolet light to produce free radicals that damage the lens. Once proteins are damaged they produce cloudiness in the lens, forming a cataract. Hypericin does not cause any protein damage when kept in the dark, so at the very least, those taking St John’s wort should wear hats and wraparound sunglasses.
Symptoms of Cataracts
When cataracts first grow, there may be no symptoms, or the individual may experience just a little clouding in the field of vision. As the disorder advances, it becomes increasingly more challenging for the person to see through the muddy picture of the cataract. Most individuals who have dismissed the issue up to that stage will seek help when their eyesight becomes seriously reduced.
A number of people do experience several early warning symptoms. By way of example, the man with cataracts may discover that sun looks more glaring than it did previously. Oncoming headlights of a car at night might appear way too bright or have a deformed look. Colours may additionally appear more boring than before.
The effect of a cataract is similar to looking through frosted glass. Light is scattered so that the edges of objects look blurred. Bright light causes a glare and objects are indistinct unless brought very close to the eyes, and even then may be fuzzy. As well as loss of clarity there is deterioration of colour vision, which again can be reproduced by looking through frosted glass. Lesser degrees of cataract can be indicated by a non-specific change in vision and difficulties with close work. Changing the prescription of glasses makes no difference.
- Cataracts are entirely painless.
- The onset of visual symptoms is almost imperceptible, and progress is nearly always very slow.
- The main symptom is blurring of vision and shortsightedness, which gradually becomes worse. So a person who was previously longsighted may be able to read without using their reading glasses.
- Colours become distorted, with dulling of blues and accentuation of reds, yellow and oranges; the full perception of colour is dramatically restored after surgery.
- Beware! Night driving can be impaired. Often the lens opacity causes scattering of light rays and, even at a fairly early stage, may seriously affect night driving.
Cataracts seen through an ophthalmoscope appear as a white opacity to the bright light. The usual tests of visual acuity will show how much vision has been affected in order to judge how urgently surgery might be required.
Treatment of Cataracts
Once a cataract has developed, changes to the lens are irreversible. Nowadays, the need to have thick glasses can be avoided by replacing the removed lens with a tiny plastic implant that is fixed permanently in the eye during surgery. Cataract surgery gives excellent results
in most cases.
Cataract surgery is a highly developed and delicate branch of ophthalmology that can, in most cases, restore good vision. Surgery involves removing the opaque lens, usually by very fine dissection, from its attachments. Increasingly, surgeons do this by a technique that liquefies the lens so it can be sucked out, causing less disruption to surrounding structures. An artificial lens is replaced within the capsule that contained the natural lens (a lens implant).
Unlike the natural lens, which can of course vary focus, the replacement lens is a fixed focus. Therefore you may need glasses in order to deal with distant or close vision, but you will notice that your overall vision will be restored to its normal clarity and normal colour.
Cataract surgery is a relatively safe procedure that is usually done under local anaesthetic. Any surgery carries a risk of infection or bleeding. For this reason, if you have cataracts in both eyes, surgeons will normally defer dealing with the second eye until after full recovery from the first operation.
A cataract is an opaque region in the lens of the eye causing loss of vision. During cataract surgery, the affected lens is removed and replaced with an artificial lens using microsurgical techniques. The operation is usually performed under local anaesthetic, and you will probably be able to go home the same day.
The lens is first softened by an ultrasound probe and then the softened tissue is extracted. The back of the natural lens capsule is left in place, and an artificial lens is placed inside it. The incision in the cornea is either closed with surgical stitches or will gradually heal on Its own
Some Commonly Asked Questions
What are ‘ripe cataracts’?
This was a term that meant cataracts bad enough to justify surgery and the heavy cataract glasses that were inevitably necessary following surgery.
Will I need thick-lensed glasses?
These date from when cataract surgery removed the lens and did not replace it. Therefore the only way to achieve focusing was by using very thick lenses. Thanks to lens implants, these type of glasses are now rarely required.
Warning: Never use aromatherapy oils near the eyes. Eye surgery is the only effective treatment for cataracts, although complementary therapies do play a supportive role.
Chakra balancing – there is evidence that cataracts may become less opaque for a few days following treatment but this is not yet proven.
Nutritional therapy – boosting the intake of antioxidant vitamins (A, C and E) can aid prevention. Yoga and massage are both therapies that are beneficial postoperatively. Other therapies to try: see Stress.