WHAT IS GLAUCOMA?

Glaucoma is a disease of the nerve for vision (optic nerve) caused by increased pressure in the eye.

HOW DOES GLAUCOMA OCCUR?
Glaucoma : The inside of the eye contains a fluid, which is being produced and drained out of the eye constantly. It is drained through a sieve like structure situated at the angle between the transparent cornea and the brown coloured iris. When the drainage mechanism becomes ineffective, the pressure in the eye (intra-ocular pressure) increases leading to optic nerve damage.

WHAT ARE THE EFFECTS OF GLAUCOMA?
Glaucoma can lead to permanent loss of vision. Initially, the loss of vision starts from periphery and progressively affects the central vision. The central visual acuity is affected only in the advanced stage.

Progressive loss of visual field with corresponding loss optic nerve damage
Progressive loss of visual field with corresponding loss optic nerve damage

ARE ALL THE GLAUCOMAS SAME?
No, there are many types of glaucoma. Some of these are:

Open angle glaucoma, in which, despite of open drainage angle, the drainage does not occur
Angle closure (closed angle) glaucoma, in which, the angle itself is closed preventing fluid drainage
Secondary glaucoma, which occurs due to other eye disease or treatment
Glaucoma3

HOW DO I KNOW WHETHER I HAVE GLAUCOMA?
95% patients with glaucoma do not have any sypmtoms. Glaucoma is a silent disease that cannot be detected or felt by the patient since central vision remains unaffected till the late stages of the disease. Hence it is rightly called as the ‘sneak thief of sight’. It is usually detected during a routine eye checkup.

WHEN SHOULD I GO FOR EYE CHECKUP?
Everyone over the age of 40 years should have a detailed eye check up, at least when one needs reading glasses. Hence it is advisable to not stop with visiting an optician alone.
Those who have additional risk factors should undergo an early evaluation.

WHAT ARE THE RISK FACTORS ASSOCIATED WITH GLAUCOMA?
If you

have blood relatives with glaucoma
have diabetes mellitus, hypertension, or thyroid disease
are near sighted
are on treatment with steroids (in the form of tablets, skin ointments, inhalers, eye drops)
have a history of trauma
You will need an early check up if you have any of the above symptoms.

WHAT ARE THE TESTS I NEED TO UNDERGO?
Tests help in finding out the presence of glaucoma and also its progression in the subsequent follow ups.
These tests include;

Tonometry: To measure the pressure in the eye
Gonioscopy: To assess the drainage angle
Ophthalmoscopy: To view the optic nerve
Pachymetry: To check the thickness of cornea
Perimetry: To assess the field of vision
All these tests are painless.

WHAT IS THE TREATMENT?
Glaucoma is a treatable disease that needs early detection as the damage is not reversible. The treatment can include medicines, laser or surgery.
The medicines either decrease the production of the fluid or increase the drainage of the fluid so as to keep the eye pressure under control as determined by your doctor. You may need lifelong treatment as per the instructions given by doctor.
Lasers are used in the treatment of glaucoma to increase the flow of fluid.
When medical or laser treatment fails, you may need surgery.

DOES TREATMENT RESTORE THE LOST VISION?
Treatment of glaucoma aims at preserving the existing vision; it does not restore the vision that is already lost. Therefore, early detection and treatment are very important.

SPECIALIZED TESTS FOR GLAUCOMA
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INSTRUMENTS USED FOR DIAGNOSIS OF GLAUCOMA
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FLOWCHART FOR INITIAL EVALUATION OF A GLAUCOMA PATIENT
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Department of Glaucoma at Narayana Nethralaya is equipped with the latest diagnostic facilities including,

Perimeters – Humphrey Visual Field Analyser, VFA Octopus and Humphrey Matrix.
Retinal Nerve Fiber Layer Analysers
– Optical Coherence Tomography (OCT)
– GDX
– Heidelberg Retinal Tomogram (HRT-3)
Ultrasound Pachymetry.
Ultrasound Biomicroscopy.
Anterior Segment OCT (AS-OCT).
Newer Tonometers – Tonopen, I-Care, Dynamic Contour Tonometer, ORA.

Article by

Narayana Hospitals
Bangalore