What is Glaucoma?
Pressure begins to build up within the eyeball when drainage of circulating fluid within the eye is reduced (normal IOP =10-21 mm Hg).
The cause of the lesser drainage is malfunctioning of drainage channels.
Glaucoma is a disease in which Damage to the optic nerve usually caused by high intraocular pressure. Optic nerve damage causes loss of these transmitting fibres to the brain. Loss of nerve fibres leads to development of blind spots in vision.
People seldom notice these blind areas in the side vision until considerable optic nerve damage has occurred. If the entire nerve is destroyed, blindness results.
Some frequently asked doubts about Glaucoma:
Structure of the Eye
The human eye resembles a camera. Cornea and lens are focussing devices .retina captures the image and transmits it via optic nerve to the brain. It acts similar to and electric cable from camera to the PC. The brain interprets whatever we are seeing.
Symptoms and Signs
Different types of glaucoma have different symptoms:
- Chronic Glaucoma :
Chronic glaucoma can causes headaches, discomfort around the eyes, blurring of side vision, difficulty in crossing roads, frequent change of spectacles, haloes around lights, etc.
- Acute Glaucoma :
Sudden painful blurring of vision and throbbing headache. Patients may suffer from nausea and vomiting. If this emergency isn’t treated quickly and adequately, blindness may ensue.
Diagnosis of Glaucoma
To definitely say that a person has glaucoma requires several tests, and many times these need to be repeated over time before confirming the diagnosis.
- Intraocular Pressure:it is the pressure inside the eyeball, which is usually 10-21 mm Hg. The intraocular pressure should be measured at different times of the day.
- Gonioscopy: This is a test by which the drainage area, from where the aqueous fluid from the eye is drained, is examined by a special lens.
- Pachymetry: This is a test to measure the central corneal thickness which may influence the recording of intraocular pressure
- Perimetry:perimetry is a test to evaluate the field of vision. It is conducted in a dark room on a computerised machine which is able to pick-up even subtle defects. Repeat tests are done to note any deterioration, so that timely treatment is offered.
- Photography of the Optic Nerve: The optic nerve can bedocumented on a photo with a Fundus Camera.
- OCT:Optical Coherence Tomography is among the modern tools to diagnose and to follow the progression of glaucoma.
Incidence of Blindness due to glaucoma in India is estimated from 0.5% to 4%. It is commonly seen in patients suffering from diabetes, hypertension and other vascular diseases. The risk of developing glaucoma is more after 35-40 years of age.
Family history or genetic basis is the single most important risk factor.
Who is a ‘Glaucoma Suspect’?
An individual with 1 or more positive findings
- Family history
- Intraocular pressure recordedmore than 21 – 22 mm of Hg.
- Optic disc changes on OCT.
- glaucomatous field defects on perimetry.
These individuals are as glaucoma patients when reports suggest progressive changes. These patients need regular follow up to diagnose and treat the glaucoma.
How is Glaucoma Treated?
Once the diagnosis of glaucoma is confirmed, the chief aim of treatment is:
- To keep the intraocular pressure at a level causing no damage to the optic nerve.
- Progressive analysis of the optic nerve and visual fields.
Treatment Modalities Available :