Glaucoma describes a whole group of diseases affecting the eye, but all share the common fact that they cause the pressure within the eye (intraocular pressure) to increase to unhealthy levels in the affected person. Most types of glaucoma are chronic and are present for the patient's lifetime. Some types of glaucoma occur suddenly, but most develop slowly, over months or years. Appropriate treatment for glaucoma will prevent loss of sight in majority of patients whose condition is detected early.
What Is Glaucoma?
In normal eyes a clear transparent fluid called 'Aqueous humor' is secreted inside the eye and continuously drained via microscopic outflow channels into the blood circulation. If this outflow of fluid is blocked due to any reason, the pressure inside the eye builds up and causes damage to the eye. Glaucoma is a spectrum of diseases where the optic nerve is damaged most commonly due to increase in intraocular pressure.
How does Glaucoma affect the eyes?
The normal human eye functions like a camera. When we look at any object the image falls on the neurosensory retina and is carried to the brain via the optic nerve. The optic nerve is like an electrical cable with more than a million wires. Increase in intraocular pressure damages these wires (optic nerve fibers) causing their death, resulting in blind spots in the field of vision. When the disease is advanced, it can cause total blindness.
What are the types of Glaucoma?
Glaucoma can be divided into many types depending on the mechanism:
- Chronic simple glaucoma/ open angle glaucoma
- Acute/ closed angle glaucoma
- Secondary glaucoma
- Congenital glaucoma
Symptoms vary according to the type of Glaucoma.
Chronic simple glaucoma/open angle glaucoma
Acute closed angle glaucoma
- 'No symptoms' and usually diagnosed on routine examination of eyes, hence called "Silent thief of sight"
- Progressive loss of vision
- Mild headaches, discomfort around the eyes
- Blurring of side vision, difficulty in crossing roads
- Frequent change of eye glasses with no significant improvement in vision
- Coloured haloes around light
In certain individuals the angle from where the fluid from inside drains out is narrow and can get blocked resulting in sudden increase in pressure, giving rise to symptoms like
- Severe eye pain, headache and facial pain
- Sudden blurring of vision
- Rainbow haloes around light
- Nauseas and vomiting
When increase in pressure occurs due to some other disease in the eyes like inflammation, tumor, hyper mature cataract, bleeding trauma, use of corticosteroids etc., then it is known as secondary glaucoma.
This type of glaucoma is present from birth and it occurs due to abnormal drainage channels in the eye. Congenital glaucoma has the following symptoms:
- Excessive watering from the eyes
- Abnormal sensitivity to light
- Cornea may become cloudy to enlarged resulting in poor vision
How is Glaucoma diagnosed?
Glaucoma can be diagnosed with routine examination or when a patient visits the doctor for the above described symptoms.
Diagnosis is confirmed by
- Tonometry/ eye pressure check up: Normal eye pressure is 12 - 21 mm of Hg. A rise in intra ocular pressure is highest risk factor for glaucoma.
- Slit lamp examination & gonioscopy for checking the angles (drainage area) and other signs of glaucoma.
- Optic nerve examination: By a special lens to check the nerve loss.
- Pachymetry: Corneal thickness measurement to check for corrected intra ocular pressure.
- Perimetry or computerized visual field testing: To check the subtle defect in field of vision which we are not aware of in routine day to day life.
- Optical Coherence Tomography (OCT): A kind of scan of the optic nerve to evaluate nerve fiber layer thickness and also presence and extent of glaucomatous damage.
- Fundus Photography: The photography of the optic nerve to check for progression or stability of glaucoma over years.
What is the treatment for Glaucoma?
The treatment option depends upon the type of glaucoma, extent of damage, effectiveness of medical treatment, patients compliance, etc.
Various treatment options can be:
- Medical To use medication which either decreases the fluid formation inside the eye or increases its drainage or both. Usually once started the drops need to be put throughout life.
- Laser iridotomy In narrow angle glaucoma, a small hole is made in the iris by laser to create additional filtration channels for fluid.
- Surgical trabeculectomy Surgically an alternative drainage channel is created.
How do I know if the treatment is effective?
Your doctor will call you for periodic check ups to do a detailed glaucoma evaluation which includes intraocular pressure, fields, nerve evaluation, etc., to pick any progression. The treatment is adjusted according to the results.
Can I get the surgery done and treat glaucoma for once, rather than undergoing lifelong treatment?
Surgery comes with its own effectivity (90%), side effects and complications. Moreover, many times even after surgery you may need to use medication. Your doctor will be the best judge to advise you about your options.
What happens if glaucoma is not diagnosed in time or not treated?
Often patients go to the doctor very late, when excessive damage to optic nerve has already happened. That is why routine examination is emphasized in people over the age of 40 years. In such a scenario, further damage to the optic nerve can only be stopped by medication. Whatever damage/ death of optic nerve fibers have occurred can not be reversed. If glaucoma is not treated in time it keeps constricting visual fields leading to a very small central island of vision and eventual blindness.
eye pressure is normal, still by doctor tells me I have Glaucoma.
Glaucoma is a complex disease. There is a term called "Low Tension Glaucoma", where the optic nerve is vulnerable to damage even with normal eye pressure and which needs treatment. Similarly, there is a condition called "ocular hypertension" where the pressures are high but still there is no damage to the optic nerve.
Am I likely to develop Glaucoma?
You may be at risk of glaucoma, if you have any of these risk factors.
- Age factor: The incidence of glaucoma is more after 40 years of age and increases with every passing decade
- High intra ocular pressure or ocular hypertension
- Family History of glaucoma: In parents and siblings
- Diabetes, Hypertension, Myopia
- Using Steroid drops over a long period of time or in patients currently on oral steroids
Your Glaucoma Guide
- Sometimes only one pressure reading is not sufficient. It may be repeated or recorded throughout the day
- Once diagnosed with glaucoma you will need periodic check ups with your eye doctor
- You can have glaucoma even with normal pressure and vice-a-versa, i.e., have high pressure and still not have glaucoma
- You need to put anti-glaucoma drops regularly and preferably at the same time
- Progression or affectivity of treatment is checked by pressure check up, fields, OCT and other modalities
- The affectivity of anti-glaucoma drugs or anti-glaucoma surgery may decrease over time, therefore continuous monitoring is required