Cataracts are the most common cause of blindness – Guest column by Dr Vivek M Singh
Our guest columnist this week is a consultant ophthalmologist at Hyderabad’s L. V. Prasad Eye Institute. Dr Singh talks about the high prevalence of cataracts in India and ways to cope with the crisis.
Cataract is derived from the Latin word Cataracta, meaning ‘waterfall’. In ophthalmology, the word cataract is used for clouding or whitening of the lens, which leads to blurring of vision.
The human eye behaves like a camera, where the rays of light pass through the optically clear parts of the eye to fall on the retina. The normal human crystalline lens is transparent so that light can pass freely through the lens onto the retina. The retina, in turn, processes the visual impulse and sends it to the brain to comprehend. The transparency is maintained by the systematic arrangement of the collagen fibrils within the lens.
As age advances, the protein within the lens denatures, loses its transparency and becomes opaque. Apart from advancing age, other common causes of cataract are systemic illnesses like diabetes, use of steroids in any form, malnutrition, trauma, long-standing inflammation in the eye, smoking, long-duration exposure of Ultraviolet radiation, congenital and genetic.
Cataract can affect any age group, but most commonly affects people above 60 years of age. Patients with cataracts usually complain of gradual and progressive blurring of vision. Colours do not appear as bright and sharp as they used to. Other commonly experienced symptoms are double vision, glare and halos which can create problems while driving at night.
Cataracts can lead to blindness if left untreated and allowed to progress. As per data available from the World Health Organisation (WHO), cataract is the leading cause of bilateral blindness across the globe. It is responsible for about 48% of the causes of total blindness.
There is no proven medical management of cataracts. Certain lifestyle modifications such as using UV radiation protective eye gear, avoiding smoking, and keeping illnesses like diabetes under check can delay or even prevent the onset. Once the cataract develops, it can progress to cause visual symptoms. This can be dealt with by performing cataract surgery. However, not all patients who develop cataract needs surgery as the rate of progression differs from one person to another. On the contrary, there are certain varieties of cataract which can cause incapacitating glare and may need early cataract surgery.
In the early stages, the symptoms can be tackled with glasses and contact lenses. As the cataract advances, the visual quality worsens even with glasses. Cataract surgery is essentially the removal of the pathological lens and replacing it with an artificial lens. This lens is called an Intra-ocular lens (IOL) and occupies the same place in the eye as the natural lens. This is a one-time procedure and is for a lifetime. In some patients, a layer can grow behind the IOL which requires cleaning. This can be done in the regular OPD.
Cataracts are preventable
As per the International Agency for the Prevention of Blindness (IAPB), there are around 2.2 billion people in the world with vision impairment. Of these, one billion people have an impairment that could have been avoided or treated. The prevalence of vision impairment and blindness is higher in developing and under-privileged countries.
In India, the prevalence of blindness is as high as 1.5%. cataract and uncorrected refractive errors account for 80% blindness in India. The magnitude could be higher and the main reason is patient to eye care personnel ratio. Most eye care providers are based in cities, while 75% of the population is in rural India. This makes access to eye care services difficult. Vulnerable groups are unable to travel to towns or cities for treatment. These include women, the elderly, and people with disabilities, among others. To deal with a problem of this magnitude, eye care has to be integrated into the health care services with a primary focus on the people rather than the disease itself.