These can be sub-categorised as follows
Primary open-angle glaucoma
In this type of glaucoma drainage channel of the eye is open and large enough for drainage to occur. Yet the drainage does not occur as there is a problem in the eye's drainage system. It is similar to having a broad pipe that gets blocked internally, thus not allowing fluid to flow through. This type is prevalent in India and affects people after 50. Therefore, it is essential to get your eye pressure, and optic nerve examined regularly after 50. In certain conditions, it may occur earlier than 50 years. These conditions refer to predisposing conditions.
Some of the predisposing conditions:
Diabetes
Family history wherein one or more 1st or 2nd-degree family members suffer from a similar condition.
High myopia or a very high number for distance vision.
This condition is usually treated medically by eye drops that help lower eye pressure by increasing fluid drainage out of the eye. In certain advanced cases, glaucoma surgery becomes necessary to lower eye pressure.
You can read more about primary open-angle glaucoma.
Primary closed-angle glaucoma
In this type of glaucoma, the eye's drainage channel is narrow due to which fluid does not exit the eye, similar to having a thin pipe that doesn't allow fluid to flow through it. This type of glaucoma is commonly seen in India. It occurs more commonly in females. This glaucoma typically happens at the age of 40 years.
Some of the predisposing conditions:
Family history where one or more 1st or 2nd-degree family members suffer from a similar condition.
High Hyperopia – Which is a high plus number in your glasses
This condition, in most cases, is easily treated by a laser procedure that broadens the drainage channel, which is known as laser iridotomy. In some more advanced cases, medications or surgery may be the line of management.
In patients with a cataract, removing the cataract also helps broaden the drainage channel.
Secondary glaucoma
These are conditions that cause the pressure in the eye to increase indirectly and hence cause glaucoma. It can do so by damaging the drainage channel or blocking it.
Some common examples are:
Bleeding in the eye due to trauma. The drainage channel gets blocked due to trauma
Blunt trauma to the eye, which causes direct damage to the drainage channel of the eye
Inflammation in the eye or uveitis. Inflammatory cells block the drainage channel.
Mature cataract. When a cataract advances to a level where it matures, it swells in size and blocks the drainage channel.
Steroid Induced Glaucoma: Long term use of steroids causes a rise in eye pressure. Sometimes this raised eye pressure does not reduce even after stopping the steroids. One may also need surgery to treat glaucoma—trabeculectomy or even a tube shunt glaucoma surgery.
What happens when a person has Glaucoma?
The eye's optic nerve is like an electric cable, which has many tiny wires inside it, known as nerve fibres, which pick up information from all the parts of the retina. All the nerve fibre signals together help give a wide field of vision.
Now, what happens when the eye pressure increases. The increased pressure presses upon these delicate nerve fibres and kills them. The longer the eye pressure is high, the more nerve fibres die. As each nerve fibre handles a part of the visual field, that part of the field of vision gets lost when they die. When 90% or more nerve fibres get damaged, it hampers a patient's central vision.
This combination of raised eye pressure, optic nerve damage and reduced field of vision is glaucoma.
Who is at risk of developing Glaucoma?
As mentioned earlier, some of the risk factors of glaucoma are:
People with a family history of glaucoma. Anyone with 1st or 2nd-degree family members with glaucoma should get checked for the condition.
Patients with diabetes. Diabetic patients can lead to primary open-angle glaucoma.
Patients with high spectacle power. High myopia and high hyperopia both cause glaucoma.
Anyone with a history of trauma
Anyone with a recent surgery in the eye. Any eye surgery can cause a disturbance in the eye's fluid drainage and cause eye pressure to increase.
People with advanced cataracts. As the cataract can swell and block the drainage channel of the eye.
What does a person with Glaucoma feel? What are Glaucoma symptoms?
Glaucoma is a silent disease. Many of our patients don't realise that they have glaucoma till the very end where their central vision starts getting affected. Unfortunately, nothing can help to revive vision at that point.
In glaucoma patients, there is a loss of peripheral field of vision. The visual field becomes smaller and smaller as the damage to the nerve increases. In the advanced stages, the patients have tunnel vision; like the view we get when we look out when driving through a tunnel.
This disease remains silent in the early part of the condition. Hence, we council all predisposed or in the high-risk group of having the disease to get a thorough glaucoma evaluation. Nothing is more important than detecting it early.
In cases where the eye pressure becomes very high, patients may feel pain or pressure over the eye and forehead. Some may even have red eyes.
Some patients may complain of decreased vision in dim light.