The term ‘cataract’ is derived from the Latin word ‘cataracta’ meaning ‘waterfall’. A cataract refers to clouding of the eye’s natural lens. This clouding or opacity of the lens causes vision to suffer. Usually, cataract develops gradually as part of the normal ageing process.
What is cataract?
A cataract is a clouding that develops in the lens of the eye or in its envelope (lens capsule). Light rays travel into our eyes through the pupil and are focused through the lens onto the retina, the light-sensitive cell layer at the back of the eye. The lens must be clear in order to focus light properly onto the retina. This clouding or opacity of the lens causes vision to suffer.
Usually, cataract develops gradually as part of the normal ageing process, but can occasionally occur rapidly. Many people are in fact unaware that they have cataract because the changes in their vision have been so gradual. Cataract commonly affects both eyes, but it is not uncommon for cataract in one eye to advance more rapidly. Cataract is very common, affecting roughly 60 per cent of people over the age of 60. Cataract typically progresses slowly and causes loss of vision, and are potentially blinding, if left untreated.
When was it documented historically?
The ancient Indian physician Sushruta first described anatomy of the eye, cataract and cataract surgery in Sanskrit medical literature ‘Sushrut Samhita’ in 600 BC. The Romans were pioneers in the health arena, particularly regarding eye care. The first references to cataract and its in ‘De Medicinae’, the work of the Latin encyclopaedist Aulus Cornelius Celsus in the 1st century AD. In the 9th century AD, Ammar ibn Ali, an ophthalmologist based in Egypt, wrote in his ‘Choice of Eye Diseases’, about his invention of the hypodermic hollow needle, and how he discovered the technique of cataract extraction with it through suction, on a patient.
How does cataract develop?
Cataract is an extremely common disease of the eye, and most cataracts are a result of the ageing process. Other factors that may lead to development of cataract at an earlier age include excessive ultraviolet light exposure, diabetes, smoking, or prolonged use of certain drugs, such as oral, topical, or inhaled steroids. Other medications that may be associated with cataract include the long-term use of statins (lipid lowering drug) and phenothiazines.
Oxidative stress is also believed to play a role in the development of nuclear cataract, which is the most common type of age-related cataracts. Local diseases of the eye e.g. iridocyclitis, retinal detachment, retinitis pigmentosa, may also contribute to cataract formation (complicated cataract). Strong, blunt or penetrating injury to the eye may also cause cataract.
Can cataract formation be prevented?
There is no scientifically proven prevention for cataract. However, wearing UV (ultraviolet) protected glasses may delay the development of cataracts. In addition to wearing UV sunglasses, a hat with a brim to block ultraviolet sunlight may help to delay cataracts. It has also been suggested that regular intake of antioxidants (such as vitamins A, C and E) may retard the process of cataract development.
How early can cataract develop?
Cataracts may occur even in a newborn child or children under ten years of age. This is termed as congenital cataract and developmental cataract respectively.
What are the symptoms of cataract?
Cataracts usually develop slowly. Common symptoms of cataracts are blurred vision, glare of light, double vision and faded colours. Most symptoms of cataract develop occur so gradually that patients are unaware of it until they have gross loss of vision. Early symptoms can only be detected by an eye specialist. Frequent prescription changes in your glasses’ power and poor vision at night may also be signs that you are suffering from cataract.
How is cataract diagnosed?
Your eye specialist may mention during a routine eye examination that you are suffering from early cataract even if you are not yet experiencing disturbing visual symptoms. During a comprehensive, dilated eye exam (where your pupil is widened with eye drops), your eye specialist will examine and test your eyes to make a cataract diagnosis. Your eye specialist will closely examine the cornea, iris, lens and the space between the iris and cornea. With this special microscope, the eye specialist is able to examine your eye in detail, making it easier to spot abnormalities. When your eye is dilated, the pupils are wide open so the doctor can clearly see the back of the eye. Using the slit lamp and/or an instrument called an ophthalmoscope, the doctor looks for signs of cataract. Your ophthalmologist will also look for signs of glaucoma and other potential problems in the retina and optic nerve to assess visual recovery after surgery. Each eye is tested individually for the ability to see letters of varying sizes.
Can cataract be treated without surgery?
Since most cataracts are part of the normal ageing process, they cannot be reversed. There are no medications or eye drops that will make cataract go away. New eyeglasses, brighter lighting, anti-glare sunglasses or magnifying lenses can help initially. However, surgery is the only and ultimate option. It involves removing the cloudy lens and replacing it with an artificial lens.
When is a cataract operation necessary?
A cataract may not need to be removed right away if your lifestyle isn’t significantly affected. In some cases, simply changing your eyeglass prescription may help to improve your vision. Contrary to popular belief, a cataract does not have to be ‘ripe’ to be removed. However, once you are diagnosed with a cataract, your eye specialist needs to monitor your vision regularly for any changes.
What can happen if a cataract is not removed on time?
If the cataract is allowed to remain even after it is mature, i.e. totally white and opaque, then it will ultimately burst inside the eye.