What is Glaucoma?
Glaucoma is an eye disease that causes loss of sight by damaging a part of the eye called the optic nerve. When Glaucoma damages your optic nerve, you begin to loose patches of vision, usually side vision [peripheral vision]. Over time, Glaucoma may also damage straight ahead [central] vision. Many people who get glaucoma donít even know that they have the disease. If left untreated, it can lead to gradual vision loss and over a period of time total blindness.
Normal Vision & Glaucoma
The transparent part of an eye located in front is known as cornea. An extra layer called the conjunctiva also covers the front part of the eye. The back of the eye is called retina. The retina changes light signals into electric signals. These electric signals are sent through the optic nerve to the brain, which translates these signals into the image we see.
The eye has the anterior chamber and a back or posterior chamber. A clear fluid called aqueous humor collects in the anterior chamber of your eye. The fluid then gets drained through a spongy meshwork in an area called the Ďangleí.
If the fluid does not get drained on regular basis, it builds up in the anterior chamber. When the fluid builds up, tension and pressure inside the eye increase.
This increase in pressure causes damage to the eye and the optic nerve resulting in the condition called glaucoma, which if left untreated can lead to blindness.
Types of glaucoma
There are six types of glaucoma.
- Open angle glaucoma
Low tension or Normal tension glaucoma
Closed angle glaucoma
Chronic Angle closure glaucoma
- Open angle Glaucoma
In this type of glaucoma, pressure in eyes increase gradually. Open angle glaucoma is the most common type of disease.
Low tension or Normal tension glaucoma
In low tension or normal tension glaucoma, the symptoms do not occur slowly, as in open angle glaucoma. Pressure in the eyes may increase without warning.
Closed angle Glaucoma
Closed angle Glaucoma is medical emergency. This type of glaucoma produces a sudden increase in eye pressure. Symptoms include severe pain and nausea, redness of the eye and blurred vision. Without immediate treatment, blindness may occur in 1-2 days. Usually, prompt surgery can clear blockage and save eye sight.
Chronic angle closure glaucoma
The term, chronic angle closure glaucoma, refers to an eye
With a high intraocular eye pressure. The anterior chamber is narrow and closed in places by adhesions so that the iris cannot free itself. This could be a result of previous intraocular inflammation. Eye medication to reduce the intraocular eye pressure can be given and, if this is not sufficient, then laser surgery called iridotomy is performed.
Congenital glaucoma affects children who are born with eye defects that slow normal fluid drainage. However, with surgery these children have chance of clear vision.
Secondary glaucoma occurs due to the complications related to other medical condition such as:-
- Eye surgery
Certain eye tumors
Untreated hypertension or high blood pressure
Untreated diabetes or high blood sugar in the blood
Prolonged use corticosteroids medication
- Symptoms of glaucoma
In the early stages, glaucoma may have no symptoms. However, in a few people eye pain and headache can occur.
Without treatment, people with glaucoma may find that they suddenly have no side vision or peripheral vision. It may seem though as they are looking through a tunnel vision. Without treatment, patients with glaucoma may continue to lose vision until blindness results.
Knowing the risks
The following factors can put you at a higher risk of getting glaucoma:
Age after 40 years
Untreated high blood pressure or Hypertension
Untreated high blood sugar or Diabetes
A family history of glaucoma
Shortsightedness or Myopia
Prolonged use of corticosteroid drops, tablets or ointments
- Tests and Diagnosis
An early Diagnosis of glaucoma is vital to prevent vision loss or blindness. Only a detailed examination can help detect the disease.
Tests for detecting glaucoma include:-
- Visual acuity
- Visual field test or perimetry
Visual acuity test:-In the test, your doctor will use an eye and chart to evaluate how well you see at various distances.
Tonometry:-This is a simple, painless procedure with which your doctor measures your intraocular pressure Goldmann applanation tonometer, or Pneumotonometer (non-contact) after numbing your eyes with drops.
Gonioscopy:-This test is done to determine the angle at which the fluid in the eye drains out. A special lens ( gonioscope ) is placed in your eyes to inspect the drainage angle.
PACHYMETRY WITH CORNEAL THICKNESS CORRECTION FACTOR
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