Glaucoma is the leading cause of irreversible blindness in the world and in India. An estimated 80 million people worldwide have glaucoma and in India There are about 11.2 million people with glaucoma. What is alarming is that half of the patients are not even aware that they have glaucoma.
What is glaucoma?
Glaucoma is a group of disorders affecting the nerve of the eye. The nerve of the eye (optic nerve) forms a very important component of visual function. Whatever visual images are captured by the eye has to be relayed to the brain through the optic nerve. In glaucoma the optic nerve gets damaged and causes irreversible blindness.
But how does the optic nerve get damaged in glaucoma.
The eye produces a fluid called as aqueous humour. The aqueous has to continuously drain out through a structure known as angles of the eye. In Patients with glaucoma due to various reasons the drainage system gets blocked and as a result the aqueous gets accumulated in the eye. This causes the pressure of the eye to increase. The optic nerve is pressure sensitive and any rise in eye pressure above the normal limits causes the nerve to dysfunction.
Who is at risk of developing glaucoma?
Anybody above the age of 45 years can develop glaucoma. Increased eye pressure is one of the main risk factors for developing glaucoma. Other risk factors include a positive family history of glaucoma, steroid use, high myopes, systemic disorders like diabetes and hypertension, nocturnal dips in blood pressure and sleep apnoea.
How does glaucoma affect the vision?
In the initial stages of glaucoma, the peripheral vision of the patient is the first to get affected. As the disease progresses the peripheral loss of vision becomes more significant and there is progressive constriction of the field of vision. In the advanced stages the patient is left with a very small area of vision in the centre and this is called as tunnel vision. This can progress to complete loss of vision and blindness if glaucoma is not arrested in this stage.
Very few people present with other symptoms like headache and eye ache, light sensitivity, haloes, nausea and vomiting. In majority of the cases the patient is asymptomatic until the disease progresses to the advanced stage. That is the reason glaucoma is known as a silent thief of sight as the patient loses his eye sight without knowing it.
Why is glaucoma dangerous?
In majority of the cases the optic nerve damage progresses but it happens gradually and steadily. The damage might take many years to progress. Because of the gradual course of the disease patients are usually asymptomatic and turns up at the eye clinic with complains only when he or she is left with a narrow field of vision.
How is glaucoma diagnosed?
Diagnosing Glaucoma is easy and can be diagnosed based on clinical examination, eye pressure measurement, and other additional tests like perimetry (peripheral vision test) and OCT (retinal scan).
What can be done to prevent blindness from glaucoma?
Glaucoma cannot be reversed. It can only be arrested once it is diagnosed. The best way to prevent loss of vision is to diagnose glaucoma in the mildest form. And because in the mildest form patients are not symptomatic, every individual above the age of 45 years should get his or her eyes examined at least once in a year irrespective of presence of any symptoms or not. This is the only way it can be diagnosed in the earliest stage of the disease and treatment can be initiated at the earliest. Once treatment is initiated glaucoma gets arrested at that stage and no further deterioration usually occurs.
How is glaucoma treated?
Glaucoma is usually managed conservatively. Medical management is the mainstay of treatment. There are various medicines (usually in the form of drops) which help to reduce the pressure of the eye. Based on the staging of the disease and severity, drops are usually prescribed in different combinations and usually that is the only treatment required to arrest it.
Sometimes lasers are used as a substitute to medicines or if the medicines do not work.
In advanced stages of glaucoma or when medicines do not help to arrest progression surgery is usually performed. There are different types of surgeries performed for glaucoma and all are aimed at reducing the eye pressure.
What needs to be remembered is that treatment for glaucoma is lifelong and compliance is key. Since the treatment does not actually reverse the disease many a times patients discontinue the treatment without consulting the doctor and as a result end up losing their eye sight.
Prognosis of glaucoma
The aim of treating patients with glaucoma is for them to be able to maintain their quality of life and live as normally as possible. Patients with glaucoma have a normal life expectancy and with treatment can carry out activities as they did before the diagnosis. If diagnosed early the prognosis is generally very good as long as the patient’s compliance with regards to the treatment is good and follows up regularly with the glaucoma specialist.
It is very important that the patients understand that treatment goal is to prevent the glaucoma from getting worse and that in no way will it improve the already damaged nerve and the lost vision and that the treatment is going to be lifelong and in no way can he or she stop the treatment as this can end up with dire consequences.
