Glaucoma is an optic nerve disease characterised by increase in intraocular pressure, gradual loss of visual fields, and loss of optic nerve cells. There are a number of optic nerve diseases that affect the human eye, but glaucoma has the highest prevalence, especially, among black people. Glaucoma is an insidious disease because of its asymptomatic nature; it creeps into your field of vision silently like a thief, and takes away your precious sight.
In embryology, the optic nerve is known to have emanated from the brain; and its cells are akin to that of the brain cells. Brain cells are notoriously difficult to regenerate after they are lost and this makes brain injury or brain diseases difficult to cure or manage. The nervous system has two parts: the central nervous system and the peripheral nervous system. The central nervous system consists mainly of the brain and the spinal cord, while the peripheral nervous system consists mainly of the cranial and spinal nerves. Cranial nerves arise from the brain while spinal nerves arise from the spine. Cranial nerves are some 12 very important nerves that connect your brain to different parts of your head, neck and trunk.
The optic nerve is the second cranial nerve and its function is to carry visual information from the eye to the brain; then, the brain processes the information to produce beautiful images of the objects that you view. Glaucoma affects the second cranial nerve – i.e., the optic nerve; gradually destroying the nerve cells and eventually causing blindness. The process of optic nerve cell loss is very slow and quiet, but with extremely devastating outcomes – low vision, blindness, disability and economic hardships.
Currently, there are over 232,500 Ghanaians who are blind from several causes. About 19.4% of this blind population lost their sight through glaucoma – an estimated 45,105 people. An estimated 500,000 Ghanaians over age 40 are living with the disease. The burden of glaucoma is quite huge and can lead to financial constraints for people who do not have any form of medical insurance that pays for the cost of anti-glaucoma medications. And because the disease is prevalent among older people, especially pensioners, it takes a toll on them.
There are two main kinds of glaucoma: primary glaucoma and secondary glaucoma. Primary glaucoma has no known cause although it is largely linked with genetics. Secondary glaucoma is mostly acquired through trauma, certain eye diseases that block the drainage angle, certain medications like corticosteroids, and as a sequela to surgical complications.
Glaucoma may damage your optic nerve through sustained high intraocular pressure (eye pressure) or force on the optic nerve, oxidative stress (abnormally high levels of free radicals in the body), and poor perfusion of the optic nerves.
Even though the cause of the disease is poorly understood, a person may be at risk of getting the disease if he has a family history of the disease, is over age 40, has a past or present history of trauma, is of African ancestry, and has refractive error e.g., very high myopia or hyperopia.
The disease can only be diagnosed if a thorough eye examination is conducted. Most glaucoma patients are picked up through routine eye examinations or screenings. The asymptomatic and insidious nature of the disease makes it difficult for a lot of people to get early diagnosis. Early diagnosis is key to blindness prevention. Because optic nerve cells, the primary target of the disease, do not easily regenerate when they die, it makes it very difficult to recover vision loss through glaucoma.
That notwithstanding, promoting healthy eating habits e.g., eating a lot fruits and vegetables rich in vitamins A, C, E, and antioxidants, regular eye check-ups (at least once a year), becoming aware of the risk factors and taking the necessary steps to mitigate them, and strictly adhering to treatment protocols, may help prevent low vision and blindness in either or both eyes.
Although there are tonnes of research into the causes and cure of the disease, none have proven successful yet, but stem-cell therapy is showing some promise. The current treatment options available to people who are diagnosed of glaucoma include medications in the form of drops and tablets, surgery, and laser.
In summary, glaucoma is a chronic idiopathic, asymptomatic visually debilitating disease that affects the optic nerve (the 2nd cranial nerve) and eventually causes blindness in either one or both eyes. Annual routine eye examination is a very important step to mitigating the disease and the burden of blindness from the disease.
The writer is an Eye Unit Head at HealthNet, Accra. He can be reached on Tel: 0243252414, 0540124974 and 0268606026