Many people must have heard about “glaucoma” as an eye ailment, but very few know about the disease, much less that it is irreversible. Losing one’s vision can be devastating and continuous trauma, specially if one gets to know that the disease is irreversible.
Glaucoma is a disease of the eyes that can lead to vision loss or blindness due to damage to the optic nerve. Experts say that glaucoma is the leading cause of visual loss affecting the quality of life of millions of people in the world. Glaucoma affects around 67 million people worldwide.
Experts estimate that half of these may not know they have glaucoma because symptoms may not occur during the early stages of disease. Around 40 per cent of the optic nerve, which carries information from the eye to the brain, can be damaged before one notices vision loss.
Experts at a seminar conducted last year in Rawalpindi, under the aegis of Al-Shifa Eye Trust Hospital, experts told the participants that “Glaucoma is the second leading cause of blindness globally after Cataract, responsible for around 12.3% of blindness worldwide. There are an estimated 60 million people worldwide with glaucoma and an estimated 8.4 million people who are blind from this disease. These numbers are expected to increase to 80 million and 11.2 million respectively by the year 2020. Majority of people affected from glaucoma in developing countries are unaware that they have the disease and visual impairment.”
Experts said that according to an estimate nearly 50-90% of true glaucoma patients remain undiagnosed (the rate of undiagnosed glaucoma cases in developing countries is 90% in contrast to 40-60 % in developed countries). Nearly half of the patients diagnosed of having glaucoma had already visited an ophthalmologist and remained undiagnosed.
Asians constitute the largest population group affected representing 47% of the total people with all types of glaucoma and 87% of primary angle-closure glaucoma. Glaucoma as a blinding eye disease presents serious challenges in Pakistan. The results from the two blindness surveys reveal that the prevalence of glaucoma as a cause of blindness has effectively doubled from 3.9% to 7.1% in all causes of blindness.”
Similarly, a research conducted by P S Mahar, M Aamir Shahzad, done on the topic, “Glacoma burden in a public sector hospital”, at Isra Postgraduate Institute of Ophthalmology, Al – Ibrahim Eye Hospital, Malir, Karachi, showed: “A total of 80,767 patients were seen in the hospital with different eye problems. The number of patients referred to the glaucoma division was analyzed and 447 patients were confirmed with the diagnosis of glaucoma (0.55%). Their demography showed 287 (64.2%) patients were male and 160(35.8%) were female. Age distribution showed 383 (85.7%) patients were 40 years or older. Primary glaucoma was seen in 345 (77.2%) patients, out of which 186 (41.6%) had primary open angle glaucoma (POAG) and 137 (30.67%) had chronic angle closure glaucoma (CACG). Secondary glaucomas were seen in 102 (22.8%) patients.”
The study concluded that Primary open angle glaucoma was still the most prevalent type of glaucoma seen in the clinic but chronic angle closure glaucoma also involved a significant number of patients. Most patients presented very late when their central vision was compromised or their glaucoma was detected at an early stage due to eye examination carried out due to some other ocular complaint. Intensive medical and surgical treatment was shown to control the disease in most of the patients.”
In order to understand how glaucoma can occur, we must first understand the anatomy of the eye.
The eye is a very complex and important organ of our body. Each eye produces a fluid known as the aqueous humor that, under normal circumstances, should drain from the eye through canals inside the eye in order to maintain a healthy eye pressure. If the production of aqueous humor is normal, but the drainage is not in pace with the fluid’s production, the fluid pressure inside the eyes (known as intraocular pressure, or IOP) can increase, leading to some types of glaucoma.
Glaucoma can lead to vision loss or blindness by causing damage to the optic nerve. The optic nerve is the nerve that transmits the visual signals from the eyes to the brain, which is what allows us to see.
There are multiple types of glaucoma, with three of the most common types described below:
Open angle glaucoma:
- This is the most common form
- Here, the eye’s drainage canals become blocked, but not completely, hence being called “open angle”
- IOP increases as the fluid drains too slowly
- Sometimes patients might have no signs or symptoms but can gradually lose their vision if this type of glaucoma is not treated in time
- It usually responds well to medication, especially if caught early and treated
Closed angle glaucoma:
- Also called acute or narrow angle glaucoma
- Much rarer and the IOP rises very quickly, rather than gradually over time
- Occurs when the opening of the drainage canal gets covered or completely blocked by the iris, which is in close proximity to the canal opening. The iris will change shape if the pupil (the black part of the eye) responds to changes in the amount of light present by widening or narrowing. If the iris covers the canal due to the pupil’s movement, it will obliterate the drainage angle and cause fluid to build up.
- Signs and symptoms of closed angle glaucoma occur suddenly and may include headaches, intense eye pain, nausea and vomiting, rainbows or halos around lights at night, and very blurred vision
- Closed angle glaucoma is a medical emergency and should be treated immediately to prevent permanent vision loss
Normal tension glaucoma:
- Also known as low-tension or normal-pressure glaucoma because here the IOP is within normal range but the optic nerve is damaged due to some reason other than pressure build up
- Risk factors include: positive family history, low blood pressure, being female, and having a history of systemic heart disease, such as irregular heart rhythm
- The initial signs can be loss of vision starting from the periphery (or side) appearing as if you are looking through a tube. It is often called the “silent thief of sight” since there might be no initial signs and symptoms of glaucoma unless considerable loss of sight is observed
There are, however, a variety of physical and psychological aids that can help glaucoma patients and their families.
According to Dr Farah Akhtar of Al-Shifa Trust Hospital Rawalpindi, “The management of glaucoma is a challenge for both patient and ophthalmologist as the progression of visual loss can be halted by treatment, but the damage already done cannot be reversed. Untreated glaucoma leads to blindness.”
She further said that “The vision lost due to glaucoma cannot be regained. Hwoevre,the patients who ultimately do well are those who see the changes as a challenge, not some form of punishment. Glaucoma progresses insidiously. Peripheral vision is lost first in early stages of disease and may not even be noticed by the patient. Central vision is spared until late stages of disease. Severe loss of vision can usually be prevented if glaucoma is detected early and enough lowering of intraocular pressure is achieved.
She said that unfortunately, a small number of patients may suffer irreversible vision loss even with adequate treatment; they should be referred for low-vision rehabilitation and social services.
Patients suffering due to Glaucoma need great support both from the family and the society. A system which mainstreams these patients in the society by giving them the necessary care, will be called a good social system. And we need such a system in our society.