Cataract, leading cause of blindness’

In this interview with ARUKAINO UMUKORO, an ophthalmologist at the Lagos University Teaching Hospital, Dr. Adetunji Adenekan, talks about  eye defects and their treatments

 What are the major eye defects?

The major eye defects are cataract, refractive errors/low vision, glaucoma, age-related macular degeneration, retinopathies and trauma (injury). Before, there used to be diseases such as trachoma and onchocerciasis. But it is not so common today because of the awareness and treatment programmes established by government and non-governmental organisations over the years. Diabetes could lead to complication in the eyes, which could affect the vision or result in blindness.

 What is glaucoma?

Glaucoma is a disease that affects the optic nerve function of an individual. The optic nerve is just like an electric cable wire that carries light from the metre to the point source. That’s how the optic nerve works. It sends messages to the brain and this is interpreted by the brain and transmitted back. If there is a problem with the optic nerve, vision is often affected. There are other neurodegenerative diseases that affect the eyes. Of course, the eye is an extension of the brain, and when there is damage to the optic nerve, it affects the visual pathway and transmission of impulses to the brain. Glaucoma is an issue we take seriously because it is the commonest cause of irreversible blindness. There are other issues such as psycho-social disorders such as depression that may results from visual loss. Glaucoma is associated with increased pressure in the eye. There are different classifications and causes of glaucoma. This is done so as to be able to initiate the proper treatment. The aim is to reduce the progression of the disease and prevent blindness.

 What are the causes of glaucoma?

There are different classification and causes of glaucoma. It may be classified into primary and secondary glaucoma, congenital and acquired glaucoma, open or close angle glaucoma. Primary glaucoma can be linked to risk factors such as genetics, race, family history, corneal thickness, myopia and so on.  For example, there are genetically pre-determined people that would be susceptible to glaucoma. Research has shown that there are some genes responsible for some certain types of glaucoma. So, individuals that carry these genes are susceptible to glaucoma. Apart from that, there are other risk factors like ocular pressure. For example, when there is normal or increased pressure within the eye. And when there is a build-up of pressure in the eye, it affects blood supply and transport of nutrients to the eye. So, the nerve cells begin to die.

Also, some people that have thin corneas are prone to it. Race is also a factor; certain types of glaucoma are more common among blacks or in other places such as Asia. Often times, it is not about causes of primary glaucoma per se, it is about the risk factors. Secondary glaucoma could be caused by an injury, or an injury that affects where the fluid in the eye is being produced or drained. There must be a balance between production and drainage and where there is no balance; there is build up of eye pressure. Also, people could develop glaucoma following eye surgeries, use some drugs such as steroids or from injuries and develop glaucoma later. Sometimes, some people come to the hospital with redness in the eye. We take this seriously because it could be glaucoma in the making.

 What is cataract?

Cataract is actually the opacification of the natural lens in the eye due to changes in the lens itself. It is the clouding of the lens which leads to reduced vision. The reduced vision happens because this opacification hinders light from passing and being focused on the retina at the back of the eye. The natural lens is a transparent structure that is in-between the eye. When light passes through the eyes, two things happen: The cornea bends the light, which is called refraction of light. The cornea does two-thirds of this. The remaining one-third is done by the lens. So, if the one-third is not well done, it begins to affect one’s vision. Those with cataract have problems with walking, reading and changes in contrast of colours or coping with the intensity of light. There are changes in the substances of the lens as one grows older. Ultraviolet light or sun rays get absorbed by the lens and over time begin to change the structure of the lens. The protein structure of the lens also begins to change as it reduces over time. This affects the clarity of the eye vision. Thus, ageing is the most common cause of cataract.

 What is the statistics for the number of people with cataract in Nigeria?

The recent statistics was the data in 2007 by the National Blindness and Visual Impairment survey, which was done with collaboration from local and international organisations and the government. The data estimated that generally about 0.78 per cent of Nigerians are said to be blind, and that cataract causes about 42.9 per cent of the magnitude of blindness. The data is still nationally accepted, even though others have done pockets of research. Cataract is the major cause of blindness worldwide. This is followed by refractive errors. Many people don’t realise they can see better than they do now, until they go for an eye test and they are prescribed to use eye glasses.

 A few years ago, the minister of health said about four million Nigerians have eye defects. What is the current figure?

The situation has not really changed much, even though we are doing all we can to create more awareness. Some of the causes of blindness are actually reversible. Even the irreversible ones can be prevented with early treatment. But for problems such as cataract, which causes the largest proportion of blindness, the major cause is due to aging, apart from other causes such as trauma, metabolic problems. In this area, more awareness needs to be created. Currently, the government is sponsoring initiatives and programmes focused on restoring sight to such people, by sponsoring free surgeries. Most people do not know they have glaucoma until it is far-gone.

 Are there particular kinds of food and fruit that help to improve vision?

Yes, there are. Eating a wide range of fruit and vegetables is essential for protecting your eyes and keeping them healthy. Brightly coloured foods are rich in carotenoids and tend to also be high in lutein and zeaxanthin, all of which help to protect the retina and maintain eye health. Foods rich in vitamins A, C and E also play an important role. These fruits include spinach, cabbage, cauliflower, carrots, sweet corn, sweet peppers, tomatoes, strawberries and citrus fruits.

 How regular should people go for eye tests?

For someone whose eyes are relatively normal, it is advised to go for an eye check-up annually. In countries where things work better, it should be done annually; for children, it could be done monthly, depending on whether the child was born normally or there were problems at birth. One should not just assume that the eyes are always in a good state because one does not see the eyes except he or she looks in the mirror. It is advised to go for yearly check-ups as part of the general medical check-up. From that, the doctors could pick anything that may be wrong with the eyes. Eyesight is important in life.

 Who are those that should use eye glasses and in what situation should it be used?

Some people use eye glasses as fashion accessories and it has become fashionable to wear them. Others wear sunscreen glasses, but what you see most people wear are just dark glasses. Anybody can wear fashionable glasses. But medically speaking, those who should wear glasses are those who have refractive errors, low vision, or maybe had a surgery done before on the eyes. Although it is advisable that everyone in the hot climate should have sunscreen glasses to protect one from exposure to ultraviolet rays from the sun, which usually affects the eyes in one way or the other. Also, eye glasses are sometimes recommended even when one doesn’t have refractive errors, because they can serve as protection for the eyes against harsh weather. But the content of that type of glasses is different from those recommended to correct refractive errors. Hospitals with good optical services should be able to provide these.

 What causes short-sightedness and long-sightedness?

Short-sightedness, which is also called myopia, is a common eye condition that causes distant objects to appear blurred, while close objects can be seen clearly.  It is a refractive eye condition; that is, it occurs when problems with the eye’s structure affect how light enters the eye. In layman’s term, we say the eye is too powerful that it bends light so powerfully, affecting images formed from the light rays. Short-sightedness is usually caused by a combination of genetic and environmental factors, which could cause a disorder in the normal growth of the eye. Long-sightedness, which is also called hyperopia, means that the eye power is low compared to normal. People with long-sightedness are usually able to see distant objects clearly, but they can’t see nearby objects clearly.

There is also astigmatism, which happens when there are different refractive powers in different parts of the eyes like the cornea or lens. These are the three major causes of refractive errors. Other refractive errors could be due to aging as mentioned earlier, which would also require the use of eye glasses to correct the vision.

 Does using glasses cure eye defects?

‘Cure’ is a wrong term used by many. Recommended eye glasses are used to correct one’s vision. There are tests carried out to ascertain the type of glasses to be used. But for children, it could differ because the refractive status of children changes as they grow older. Refractive surgeries could be done also for adults if it goes beyond using glasses to correct them. In such cases, surgery is done on the cornea or lens. Thus, it depends on the problem. Eye defects can generally be corrected using glasses or through surgery when it is at an advanced stage. Not everyone requires a surgery to correct the vision. An eye test will determine if someone needs glasses or not. It depends on whatever state the person’s refraction is. It also depends on the type of job a person does. For example, a pilot cannot afford to have poor eyesight. But a carpenter can manage.

 How good are the optical services in Nigerian hospitals?

There are centres now with these facilities, especially private hospitals. But in the public hospitals, facilities are being improved upon. There is clamour for improvement of these facilities because blindness affects the economy and the workforce. And over the years, there has been improvement in facilities for eye treatment across different regions in the country. But there also needs to be an increase in the number of personnel to carry out such treatment. At a time, there were few ophthalmologists, compared to other fields, but the number is increasing, although it is still not enough. I don’t have the correct figures, but we are still far from where we should be in terms of the number of personnel.

 What is your advice to Nigerians regarding eye care and treatment?

While there has been an increase in awareness concerning eye problems, Nigerians should take advantage of the different programmes to get themselves checked. For those who cannot afford to go to private hospitals, such facilities also exist in government hospitals, which also have the personnel that can assist in such cases, especially when it relates to cataract, which is the leading cause of blindness. Everyone should visit the nearest hospital and get their eyes checked if they have not done so.