What is Glaucoma ?
Glaucoma is a general term used to describe damage to the optic nerve usually caused by high eye pressure. Whenever we look at an object the image of that object falls on the retina (Neurosensory layer of the eye). From this it is carried to the brain via the optic nerve.
Glaucoma causes damages to the optic nerve fibres (wires in the cable). If the entire nerves is destroyed- blindness results.
How does it happen?
In the normal eye, a clear transparent fluid called aqueous humor is secreted and drained continuously out via microscopic channels. If because of some reason te channels are blocked or there is an obstruction in the drainage mechanism, the fluid starts accumulatin with the eye and the pressure starts building up which if not controlled causes damage to the optic nerve of the eye.
Type of Glaucoma
1:- Chronic simple glaucoma or open angle glaucoma :
It is a long standing slowly progressive disease process and can cause visual loss so quietly that the patient is unware of the trouble till the final stage of the disease. The angle is usually open and the obstruction in the fluid circulation is usually in the drainage channels.
If not checked in time this form of glaucoma is reported to cause painless, progressive and total blindness.
Following are symptoms of this type of glaucoma
- Gradual dimness of vision with blurred vision
- Mid chronic headaches
- Reduction in peripheral vision
- Coloured haloes around light.
2:- Acute/ Closed angle Glaucoma
as the name suggests, its onset is quite sudden. In certain individuals, the angle from where the fluid drains from the eye is genetically narrow. Its can be blocked suddenly due to many reasons resulting in sudden increase in eye pressure
Following are the symptoms of acute/ closed angle glaucoma
- Severe pain in the eye with headache
- Sudden blurring of vision
- Cloudy vision with coloured haloes seen around the lights
- Red eye
3:- Congenital Glaucoma :
Occur in children born with defective drainage channels. Following are the symptoms
- Excessive watering
- Abnormal sensitivity to normal light
- Cornea appears cloudy and is abnormally large in size.
4 :- Secondary Glaucoma:
the Intraocular pressure in the eye can increase secondary pressure due to
- any other eye disease
- injury for e.g. blunt fist injury
- overuse of certain drugs like ‘steroids’
- any systemic disease e.g. Diabetes
- Intraocular Pressure (IOP): this is the pressure within the eyeball which is usually between 10-21mmhg. Sometimes a single recording cannot confirm or rule out diagnosis of glaucoma. In such case it needs to be repeated. If elevated pressure is confirmed, further tests need to be done to establish the diagnosis of glaucoma.
- Gonioscopy: This is the test by which the drainage area from where the aqueous fluid is drainded is examined by a special lens. This area is known as the angle. In case some abnormality is found in the angle, steps can be taken to correct the defect and restore normal fluid circulation in the globe.
- Pachymetry: This is to evaluate the central corneal thickness. This may influence the recording of pressure with the eyeball.
- Perimetry/ Visual field: This test is done to evaluate the field of vision. It is conducted on a computerized machine which is able to pick up defects. Repeat test periodically are also necessary to pick up any deterioration so that timely treatment may be given
- Ophthalmoscopy: done to view the optic nerve head changes that are characteristic of glaucoma.
- HRT (Heidelberg retinal tomography): one of the latest tolls used to diagnose and follow the progression of glaucoma.
Treatment modalities available are
- Medical: This consist of eye drops which have to be put into the eye on daily basis. Glaucoma medications are required for long periods: usually life long.
- Laser iridotomy : Done for acute or narrow angle glaucoma with hole. A hole or opening is made in the iris to relieve the blockage of the drainage channels
- Laser trabeculoplasty: Useful in the open angle glaucoma case. Here the layer is used to open the blocked passages in the eye
- Surgery/ Trabeculectomy : It is the operation where an additional channel is created surgically to drain the excess fluids bypassing abnormally blocked channel. It is useful for most types of glaucoma.
- Strong family history of glaucoma
- Diabetes/ hypertension
- Far sightedness/ plus number
Best defense against glaucoma s REGULAR eye check up specially after the age of 40.
Risk factor for glaucoma are
Never use any medication without an eye doctor approval. Continuous use of drop like STEROIDS can cause glaucoma.
Once diagnosed glaucoma patient needs PERIODIC EYE CHECK UP.