When we talk of eye diseases, many of us are aware about cataract, refractive errors and even diabetic retinopathy. How many of us know about a disease which causes gradual dimness of vision and eventually blindness if undetected or untreated, gives no warning signs to the patient and therefore easily missed unless we undergo a proper eye examination?
Yes, we are talking about glaucoma, the disease which is the number one cause of irreversible blindness in India and worldwide, and the numbers are rising day by day. In 2010, the number of people with glaucoma worldwide was 60.5 million and in 2020, the numbers will increase to 79.6 million. In India, approximately 12 million people are suffering from glaucoma.
WHAT IS GLAUCOMA?
Glaucoma is a progressive disease of the optic nerve which constricts the visual fields. So the area that we can normally see with our eyes open is gradually reduced from the sides and if not diagnosed or treated, can eventually cause blindness in one or both eyes. It is usually (but not always) associated with an increase in eye pressure. Eye pressure is different from blood pressure. Normal range of eye pressure is between 10 -21 mm Hg.
WHAT CAUSES GLAUCOMA?
Glaucoma is not a single disease but there are many types. By far, primary glaucomas are most common wherein genetic factors play a role. Secondary glaucomas can be associated with steroid use, neovascular glaucoma , uveitic glaucoma, following eye injury or eye surgery. Anatomically, they can be open-angle or angle-closure types of glaucomas depending on the appearance of a particular anatomical part of the eye, called the angle of the anterior chamber.
IS THERE ANY AGE FACTOR?
Glaucoma can affect people of all ages, though the prevalence increases with age. Even newborn babies and toddlers can have a particular type of glaucoma called congenital/developmental glaucoma and young adults can develop another type called juvenile open angle glaucoma.
HOW DOES THE PATIENT KNOW THAT HE/SHE HAS GLAUCOMA?
This is the most tragic part of the disease. There are no warning signs, there is only gradual painless dimness of vision from the sides. Because the central vision is preserved till the very late stages of the disease, the patient is not aware that he has a potentially blinding disease. It is usually during a routine eye check-up to an eye specialist (Ophthalmologist) that the disease is detected. However, there may be dramatic presentations in some types of glaucomas. Some people see coloured halos. In primary congenital glaucoma, the eyeball size is abnormally enlarged, becomes hazy, and there is watering and light intolerance. In acute attack of angle-closure glaucoma, the eye suddenly becomes red and painful with severe dimness of vision, there may be headache and vomiting.
WHAT IS THE TREATMENT?
The aim of treatment is to reduce the eye pressure and preserve whatever visual function the patient has at the time of diagnosis. Treatment is best done by Glaucoma specialists or Ophthalmologists specially trained in glaucoma. Before initiating treatment, the glaucoma specialist performs a comprehensive eye examination including slit-lamp examination, eye pressure check-up (by applanation tonometry), angle evaluation (gonioscopy), visual field assessment (automated perimetry), central corneal thickness (pachymetry) and imaging studies (like OCT).
There are three treatment modalities: medical, lasers and surgical. Medical treatment with anti-glaucoma eye drops are usually the first line of treatment. YAG laser is the first treatment in angle-closure glaucomas. For glaucomas in children, the only treatment is a highly specialised and delicate surgery, called combined trabeculotomy with trabeculectomy, available in select centres. In any glaucoma, when the eye pressure is not adequately controlled with eye drops, there is a need for glaucoma surgery. The commonly performed surgery is called trabeculectomy. Specialized glaucoma implants are used in difficult cases. Cataract surgery in glaucoma needs special care.
BE AWARE OF GLAUCOMA.
Get a complete eye check-up done by an ophthalmologist after the age of forty even if you do not have any eye problem. A complete check-up means all the tests discussed above including eye pressure and not merely the glass power check-up. If any of your blood relatives has glaucoma, get this done on a priority basis. Those who are steroids in any form or have high glass-power should also get their eyes checked. If you are a glaucoma suspect or diagnosed with glaucoma, follow your doctor’s instructions carefully and follow-up regularly. Remember what ever vision is lost due to glaucoma is permanent but useful vision can be preserved lifelong with early diagnosis and treatment. The biggest problem with glaucoma is lack of awareness, 50-90% of people with glaucoma are not aware that they have the disease. Please be aware and spread the word of awareness.