Silent thief of sight
Glaucoma is the most serious eyesight threatening condition of the eye. It usually manifests as a painless gradual loss of vision. The lost vision can never be recovered. However, medical or surgical treatment can prevent or retard further loss of vision.
Many a times it can be confused with a cataract which also manifests as a painless gradual loss of vision. The difference is that in the case of cataract, the loss of vision is fully recoverable by means of a simple surgery called Phaco. Our eyes contain a clear fluid called aqueous humour, which is continuously produced in the eye to bath and nourish the structures inside it. The fluid normally drains out of the eye through drainage canals in a fine mesh work located around the edge of the iris (the colored part of the eye that surrounds the pupil). In people with glaucoma the fluid fails to drain due to some defect and thus increases the pressure inside the eyes called raised Intraocular Pressure (IOP) (or Tension).
In most cases of glaucoma, the patient is not aware of the gradual loss of sight until vision is significantly impaired.However, if glaucoma progresses without adequate treatment, the following symptoms may occur in some individuals:
- Pain around the eyes when coming out from darkness (e.g., as soon as the person comes out of a cinema hall)
- Colored halo rings seen around light bulbs especially in the mornings and nights
- Frequent change of reading glasses, headaches, pain and redness of the eyes
- Reduced vision in dim illumination and during nights
- Gradual decrease of side vision with progression of glaucoma
Types Of Glaucoma
1. Open Angle Glaucoma
It happens when the eye’s drainage canals become clogged over time. The inner eye pressure (also called intraocular pressure or IOP) rises because the correct amount of fluid can’t drain out of the eye. With open angle glaucoma, the entrances to the drainage canals are clear and open. The clogging problem occurs further inside the drainage canals, similar to a clogged pipe below the drain in a sink. Most people have no symptoms and no early warning signs. If open angle glaucoma is not diagnosed and treated, it can cause a gradual loss of vision. This type of glaucoma develops slowly and sometimes without noticeable sight loss for many years. It usually responds well to medication, especially if caught early and treated. This form of glaucoma is more common in Caucasians.
2. Angle Closure Glaucoma
This type of glaucoma is also known as acute glaucoma or narrow angle glaucoma. It is more common in Asian and is very different from open angle glaucoma in that the eye pressure usually rises very quickly.This happens when the entrance to the drainage canals are very norrow or covered over, like a sink with something covering the drain. Symptoms of angle closure glaucoma may include headaches, eye pain, nausea, rainbows around lights at night, and very blurred vision.
Few other rarer forms of Glaucoma
Low-tension or normal-tension glaucoma:
In this type of glaucoma, the optic nerve is damaged even though intraocular pressure (IOP) is not very high. Lowering eye pressure at least 30 percent through medicines slows the disease in some people. A comprehensive medical history is important in identifying other potential risk factors, such as low blood pressure, that contribute to low-tension glaucoma. If no risk factors are identified, the treatment options for low-tension glaucoma are the same as for open-angle glaucoma.
Children are born with a defect in the angle of the eye that slows the normal drainage of fluid. These children usually have obvious symptoms, such as cloudy eyes, sensitivity to light, and excessive tearing. Conventional surgery typically is the suggested treatment, because medicines may have unknown effects in infants and be difficult to administer. Surgery is safe and effective. If surgery is done promptly, these children usually have an excellent chance of having good vision.
These can develop as complications of other medical conditions. These types of glaucomas are sometimes associated with eye surgery or advanced cataracts, eye injuries, certain eye tumors, or uveitis (eye inflammation). Pigmentary glaucoma occurs when pigment from the iris flakes off and blocks the meshwork, slowing fluid drainage. A severe form, called neovascular glaucoma, is linked to diabetes. Corticosteroid drugs used to treat eye inflammations and other diseases can trigger glaucoma in some people. Treatment includes medicines, laser surgery, or conventional surgery.