GLAUCOMA

Can you guess who is at risk of developing glaucoma?

Only doctors can diagnose glaucoma
at its early stage. Glaucoma is a relatively common eye disease that can progress to blindness if untreated. It is a silent thief of sight, which experts warn can affect the young and old, the healthy and the sick, even though many people are not paying attention to its detection and treatment, reports Sade Oguntola.

It was a simple question posed to a group of members of a church during a medical outreach in Ilorin. The crowd of people at the programme listening to the experts’ talk were over 500. It was, however, amazing that many of them were not aware of glaucoma as a disease, or the fact that some people go blind if this eye problem was not detected early.

Glaucoma – often called “the sneak thief of sight”, because it can strike without pain or other symptoms – is one of the leading causes of blindness in many countries of the world, including Nigeria. This is a group of eye disorders that occur when internal pressure in the eye increases enough to cause damage to the optic nerve (the nerve that’s responsible for vision) in the back of the eye. Its exact causes are unknown, but potential risk factors include smoking at age above 60, being black skinned, and having family members with glaucoma and high blood pressure.

However, more than four million Nigerians are not aware that glaucoma is an eye disease that is the second commonest cause of blindness in the country, after cataract, according to Dr. Adeyinka Ashaye, President, Nigerian Glaucoma Society and consultant ophthalmologist, University College Hospital, (UCH), Ibadan, Oyo State.

Despite being the leading cause of irreversible blindness worldwide and one that often produces no symptoms until the affected person starts noticing that he or she could not see clearly again, she said “it is pathetic that by estimate, half of the people in North America and 90 per cent of those in developing countries affected by glaucoma do not know they have it, and when it is left undetected or untreated, it can lead to irreversible blindness.”

Explaining why some people develop glaucoma, she said, “a healthy eye produces fluids, called aqueous humor, at the same rate at which it drains. However, when the drainage system is blocked and the fluid cannot drain at the normal rate, it increases the pressure within the eye.

According to her, such an increased pressure in the eye, referred to as intraocular pressure, is one reason for some cases of glaucoma in some individuals. It also explains why the optic nerve responsible for transmitting pictures from the eye to the brain becomes gradually damaged and eventually results in blindness.

Meanwhile, she stated that glaucoma can affect anyone at any age and so there is the need for people generally to have regular eye tests, especially when getting older, when one has a family history of glaucoma, formerly had an eye injury, wears eye glasses or have other medical conditions such as diabetes and hypertension.

There are several variations of glaucoma, but primary open-angle is the most common. Generally affecting the elderly, it occurs when fluid in the eye doesn’t properly drain out. Left undetected, glaucoma can cause irreversible loss of vision and severe damage to the nerve fibers of the optic nerve.

Congenital glaucoma is very rare and affects babies, with 80 per cent of the cases diagnosed by the age of one. Children born with this disease have narrow angles or some other defects in the drainage system of the eye. Congenital glaucoma occurs more often in boys than girls.

Pigmentary glaucoma, another rare form of the disease, occurs when pigment from the iris clogs the draining angles and prevents fluid from leaving the eye. Over time, the inflammatory response to the blocked angle causes damage to the drainage system. Pigmentary glaucoma affects mostly white males in their mid-30s to mid-40s. In addition, secondary glaucoma develops after an injury to the eye. Injury, infection, inflammation, diabetes, tumors or an enlarged cataract can precipitate secondary glaucoma.

Nevertheless, Dr. Asaye said, there are means of detecting glaucoma during an eye test.”What the specialist does is to measure the intraocular pressure and evaluate the drainage angle of the eye as well as the condition of the optic nerve.”

She emphasised that these tests were also to be demanded for by people requesting for new eye glasses, so that if there is any problem, it can be detected early and appropriate treatment commenced to prevent damage to the eye’s nerve cells, thus preventing loss of vision.

According to Dr. Asaye, even though several factors had been found to increase an individual’s chance of getting glaucoma, elevated intraocular pressure is currently the only treatable risk factor for this eye disease.

Dr. Gboyega Ajayi, an ophthalmologist at Ojulowo Eye Clinic, Veterinary, Mokola, Ibadan, said it was fact that people may think that because they have a normal vision, all is well, whereas they are yet closer to being blind than they can imagine.

Explaining further, he said that there are three functions of the eye. The first is the ability to see objects and recognise them, which is what the visual acuity chart measures. The second is the ability to perceive colours, which is called colour vision. The third is visual field, which is a little more complex. Visual field is often described as “an island of vision in a sea of blindness”. People with poor visual field find it hard seeing objects to the side and out of the corner of the eye

He pointed out that some eyes might have good visual acuity and yet could almost be blind because something is wrong with their visual field, adding that the commonest thing that accounted for poor visual field was glaucoma.

But, there is hope. New medications, treatments, technology and research are now helping the millions of people afflicted with glaucoma. Getting the facts about glaucoma is the first and most important step. In a case where glaucoma is detected, Dr. Asaye said, “it is important to treat the eye disease aggressively with the most effective products, such as a prescription eye drop that can provide maximum reduction of the increased intraocular pressure in its long term. However, in some cases, surgery can also help.”

Such things as people complaining of reading glasses getting weak after it was changed about three months ago or complaints of seeing rainbows or haloes around lights should not be overlooked as normal, given that they may be suggestive of glaucoma.

According to Dr. Ajayi, promptly reporting for eye test is more important for people already using corrective lenses, who might assume they just need a different lense prescription, when they really have a more serious problem.

According to him, with eye diseases and disorders, as with most health issues, early detection and treatment are often the key to avoiding permanent problems.