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.
What do we know about glaucoma in India?
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.
Why is glaucoma hard to catch?
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.
How is glaucoma diagnosed?
Glaucoma has no clear, outward signs and requires special tests to identify it. An expert will examine the front of the eye and check eye pressure with a device called a tonometer. To understand the actual cause of glaucoma, they will perform a gonioscopy to view the angle at which the fluid drains out of the eye and maintains the pressure inside. Then, the expert will examine the optic disc at the back of the eye. This test is important to identify glaucoma and the extent of damage if it is present because such damage is one of the first identifiable signs of glaucoma.
Patients with glaucoma lose their peripheral vision, so a perimetry test is conducted to evaluate their field of vision and establish the extent of loss. Imaging technologies like optical coherence tonometry give micrometer-scale images of the eye’s interior, which can help experts identify alterations and damage, sometimes earlier than a perimetry test might spot a field defect.
Once a person is diagnosed with glaucoma, treatment strategies include eye-drops, lasers, and surgery depending on the type and stage of glaucoma. A patient may need to move from one to the other to achieve long-term control over their lifetime. Vision lost to glaucoma is irrecoverable, so treatment only stops further loss. This means the vision for people who are treated doesn’t improve with treatment.
The condition has no clear signs when it begins and any damage to the eye is irreparable.
Is there a comprehensive solution?
The best strategy is to diagnose glaucoma early. There is evidence that community screening can help ensure equitable access to glaucoma care, especially for women and the elderly, who, in the eye care context, tend to miss out on care. Networks of ‘vision’ centres, i.e. primary eye-care centres, with teleophthalmology support can take basic screening and monitoring close to those in need.
Adults older than 40 years, especially those with a family history of glaucoma, must get a comprehensive eye exam every year, including an examination of the retina and the optic nerve. If and when it is identified, people will need long-term monitoring and management.
Those prescribed eye drops may need to take them every day for the rest of their lives. The cost of treatment – daily medicines, laser treatments, surgeries – will keep eating into their finances. The long-term pressures of glaucoma management may be overwhelming for most individuals, so tackling the condition will require both individual and community action.
Dr Sirisha Senthil is the head of the Glaucoma service at the L.V. Prasad Eye Institute. Tejah Balantrapu is associate director, Science, Health Data, and Story-telling, at the L.V. Prasad Eye Institute.
- 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.
- Glaucoma is a set of conditions that damage the optic nerve and cause peripheral vision loss, leading to blindness
- The best strategy is to diagnose glaucoma early. There is evidence that community screening can help ensure equitable access to glaucoma care, especially for women and the elderly, who, in the eye care context, tend to miss out on care
Published - March 17, 2023 03:05 pm IST
