Glaucoma: some myths and facts

By Dr Neeraj Jain, MD, DNB, MNAMS  (Ophthalmology)
Most people can recite the warning signs of diabetes. Just about everyone knows the risk factors for heart disease. But how many people know the facts about glaucoma? Here I would like to discuss some most common myths which I encounter every day. I hope this will help everyone to understand glaucoma better.
Myth: I have great vision. I see 20/20! I don’t even wear glasses. I couldn’t have glaucoma.

Most of the time glaucoma is diagnosed by an ophthalmologist to a totally unaware patient. Most forms of glaucoma have no symptoms or cause no change in vision until late in the course of the disease.

Once vision has been lost due to glaucoma (permanent damage to the optic nerve), sight cannot be regained. That is why early detection and treatment before vision loss occurs is so vital.
Myth: only old people get the glaucoma

Glaucoma can affect any age group from the new-born to the elderly, though increasing age is one of the high-risk factors. Approximately 1 in 10,000 babies are born with glaucoma, either because of a defect in the development of the drainage system of the eye or because of a congenital disease of the eye or of the body.

It is not uncommon to find children between the ages of four and ten suffering from glaucoma which is called juvenile glaucoma. People who inherit glaucoma generally develop it in their early forties. Incidences of glaucoma increases further with advancing age.

Myth: Glaucoma is
always inherited

Family history is a strong risk factor for glaucoma, but an absence of family history does not mean a person is risk-free.

An individual’s risk for glaucoma is increased by any and all of the following factors: elevated intraocular pressure; age over forty-five; Asian or African descent; diabetes; nearsightedness; high blood pressure; significant eye injury; and long-term use of cortisone or steroids.

In the presence of a family history of glaucoma, everyone in the family – from the children upwards should be sure to get regular eye exams.
Myth: all people have the same risk for glaucoma

Africans and Asians are at particularly high risk for developing glaucoma and these two races comprise about 70-80% of the total Guyanese population.

Glaucoma also manifests itself differently in various ethnic groups. For instance, on average, Africans develop glaucoma ten years earlier than Caucasians. According to statistics Africans who are between forty-five and sixty-five years of age and have glaucoma are fourteen to seventeen times more likely to go blind than their Caucasian counterparts. The possibility of a poor response to medication and the failure of surgery is very high in the African race.
Myth: high blood pressure increases
the intra-ocular pressure (IOP)

Sometimes it is a tough task to explain to the patient that intra-ocular pressure and blood pressure are two different things. Controlling blood pressure does not mean that IOP will be controlled. Those who have normal blood pressure may get glaucoma, while patients with high blood pressure have an increased risk of getting glaucoma.

Interestingly, low blood pressure is strongly associated with some forms of glaucoma, such as normal-tension glaucoma (NTG).

Myth: All people with glaucoma
have elevated intra-ocular pressure (IOP)

Many people believe that glaucoma is a disease characterized and defined by elevated IOP. Actually, elevated IOP is a risk factor for glaucoma and is not the disease itself. The common factor among all types of glaucoma is damage to the optic nerve rather than elevated IOP.

There are more than forty different types of glaucoma, and not all of them are associated with elevated IOP.
Myth: The target IOP should be the same for everyone

The target IOP is calculated on the basis of baseline intra-ocular pressure, the optic nerve damage and the type of glaucoma. There is no one specific number that has been found to be the level at which a person’s eye is safe from glaucoma-related damage. Some people require an IOP of between 8 and 10 mmHg while others can tolerate an IOP that is above 21 mmHg. Your doctor must be the one to choose your unique IOP target level.
Myth: my IOP is fluctuating, so
something is wrong with the medicine

Most of the time, patients come to the clinic at different times during the day and find their pressure reading is different. Actually, IOP varies throughout the entire twenty-four hour period, and these variations are very important for glaucoma management. Patients with greater-than-normal variations in diurnal and nocturnal (daytime and night-time) IOP are more likely to have progression of their glaucoma.

Myth: Smoking is good
for glaucoma

Some patients started smoking marijuana on the basis of some articles in the paper that marijuana helps glaucoma. It is true that clinical studies have shown that marijuana can lower intra-ocular pressure in individuals both with and without glaucoma.

The active ingredient in marijuana has been shown to reduce blood flow to the eye. This reduced blood flow leads to a decrease in IOP. We now understand that adequate blood flow to the optic nerve is a critical factor in maintaining optic nerve health. Thus, the harmful effect of reducing blood flow to the eye negates the beneficial effect of lowering the IOP.

Cigarette smoking is harmful and a person should think in terms of quitting in an attempt to save their sight.

Myth: If I have a cataract and
glaucoma, I can’tget surgery

If a glaucoma patient is in need of cataract surgery, the doctor has three options: cataract surgery alone; staged surgeries (surgeries for the two conditions performed at different times); and combined cataract-glaucoma surgery.
Myth: Glaucoma always leads to blindness

This statement is one of the most dangerous of all the glaucoma myths.  Nearly 90 per cent of all glaucoma-related blindness can be prevented with proper treatment. The key is timely diagnosis, regular medication and timely surgical intervention.

If everyone has regular eye screenings and all glaucoma patients are diagnosed in a timely fashion, are able to obtain the appropriate treatment advice, and follow all the doctor’s instructions regarding medication, lifestyle changes, and – if necessary – surgery, there is a good chance that the sneak thief of sight can be stopped and blindness avoided.