Explained | Why is glaucoma such a pain to catch?

March 12-18 is World Glaucoma Week, observed to increase awareness of this serious threat to our vision.

People with glaucoma go blind gradually, and then suddenly. March 12-18 is World Glaucoma Week, observed to increase awareness of this serious threat to our vision. Glaucoma has no clear symptoms until its late stages, requires complex diagnostic skills to be identified, and is often masked by other eye conditions. All this makes glaucoma a complex condition to identify early.

The Indian eye health system has had remarkable successes in the last few decades. According to the latest data from the Ministry of Health and Family Welfare (from 2019), the prevalence of vision impairment in the adult population has decreased across the country over two decades. Tackling cataract and refractive errors – among the most cost-effective health interventions – is key to this success.

However, the top five causes of blindness in India also include glaucoma, a chronic and age-related eye condition that has no cure. It is a cause of irreversible sight loss in adults that needs to be taken seriously, and is difficult to identify in the community. Estimates for the number of people with blindness due to glaucoma in India range from 230,000 in adults over 50 in 2019 to 1.1 million people (the latter estimate is from 2010). Worldwide, glaucoma is the second leading cause of irreversible blindness in adults older than 50 years, or around 3.6 million people. Some 76 million people have glaucoma around the world. 

A key problem with our sense of glaucoma’s prevalence is that the number of cases in India is likely being undercounted. About half of all people with glaucoma go undiagnosed in high-income countries. In developing countries, more than 90% who need medical attention for their glaucoma don’t have access to it. There are several reasons for this situation, each of which points to the complexity of developing effective pathways to screen, diagnose, and manage this lifelong condition.

Glaucoma is a set of conditions that damage the optic nerve and cause peripheral vision loss, leading to blindness. Vision can’t be restored once it is lost in this way because the death of the retinal ganglion cells, and the loss of their axons to the optic nerve, are permanent. (These retinal cells are located at the back of one’s eye.)

People with glaucoma have no inkling of the damage to their optic nerve until there is vision loss, by when it is too late to catch the condition.

Glaucoma has complex causes. Many genes are involved, as are several environmental factors in its onset and progression. (The prolonged use of steroid eye drops without a prescription or beyond the prescribed time is also a common practice: such misuse can also lead to glaucoma.) Glaucoma has also been linked to age, especially among people older than 40 years. It is also heritable.