To put it in simple terms, Glaucoma is a chronic visually incapacitating disease that primarily damages and destroys the nerve cells in the retina that is responsible for relaying information about the person's visual field to the brain via the optic nerve. This damage is brought about by a combination of increased intra ocular pressure and/or a compromise of the blood supply to the nerve fibers constituting the optic nerve.
The 'Menace of glaucoma"
The disease called Glaucoma is especially dangerous to the continued health of the eye for the following reasons:
- The visual impairment produced by glaucoma is 'irreversible' unlike that which occurs in cataract, which is reversible with surgery. The main aim of treatment in glaucoma therefore is to preserve the undamaged optic nerve function.
- In the vast majority of patients suffering from this disease -close to 60% it remains asymptomatic. Patients therefore are unaware that they are suffering from glaucoma unless they are subjected to a thorough eye examination.
- About one to two of every hundred individuals are probably suffering from glaucoma. This is a huge number considering the total population. Studies have shown that less than 30% of patients who are suffering from glaucoma are aware that they have the condition, which means that the majority of glaucoma patients are unfortunately unaware.. This sad state of affairs is more common in rural areas.
The 'Good News' about glaucoma
If detected early then the disease can be successfully and adequately controlled by potent topical medications, which need to be used just once or twice a day.
If the patient diligently uses the prescribed medications and subject themselves to 4-6 monthly examinations - this crippling disease can be halted in its tracks.
Only a very small percentage of patients, less than 10% will need surgery and that too only in advanced disease.
Why does Glaucoma occur?
At this current point of time we are not fully aware of the reason causing 'primary' glaucoma. However several chromosomal and genetic factors, including an infection caused by an organism called H.pylori have been implicated.
What has been established beyond any doubt is that primary glaucoma has a genetic predisposition, hence all family members of a patient with established glaucoma should undergo diagnostic tests to rule out this disease after the age of forty.
Is Glaucoma a single disease?
The Glaucoma’s are a group of diseases whose common morbidity is optic nerve damage and impairment of the visual fields.
The two main types of glaucoma are called - Open angle type and Narrow angle type.
The main difference between these two lies in the pathology and the early manifestations.
In Narrow angle glaucoma the outflow passages of the aqueous humor (the fluid circulating in the anterior chamber of the eye) are narrowed down. This could be due an anatomical defect of the eye or if the anterior-posterior length of the eyeball is very short. This type of glaucoma is very symptomatic. It may produce eye pain, sometimes so severe that it may cause vomiting and a massive headache. It can cause 'haloes' to be seen around lights. Performing a 'laser iridotomy' is indicated in the initial stages of the disease. This laser procedure creates an opening in the iris and usually neutralizes the causative mechanism propagating this disease at least in the early stages of this condition.
The other type of glaucoma which is more common (about 60-70%) is the open angle type. This condition occurs because the drainage channels although open is functionally compromised. This type of glaucoma is largely asymptomatic. It is usually picked up only when the patient is subjected to a comprehensive eye examination.
In addition we have the 'Secondary' glaucomas. These glaucomas are not hereditary. They can occur in one eye or both eyes. They may be brought on by 'trauma' to the eyes, indiscriminate use of topical or systemic steroids, surgical procedures on the eye, inflammation within the eye called 'Uveitis" and a host of other causes.
Although the age of onset of most 'Primary' glaucomas is usually beyond 40 years, Glaucoma can even be present in some children at birth- called 'Congenital glaucoma' or can occur in early teens called ''developmental glaucomas". By and large these variations in glaucoma presentation are rather rare.
How will i know if i am suffering from Glaucoma?
You may be at a higher risk for developing glaucoma if:
- Your close relative is suffering from glaucoma.
- You are a high myope- a refractive error also known as 'short sight'.
- You are using steroids for a considerably long time either in the form of drops or tablets.
- You need to frequently change your reading glasses - at intervals of 4-6 months.
- You are suffering from intermittent headaches, which are usually associated with eye pain and appreciation of 'haloes' or coloured spectral rings around lights.
- You are a diabetic.
The diagnosis of whether glaucoma exists in your eye or not is usually clinched by performing a series of tests. These include:
- Measuring the intra ocular pressure, by a method known as 'applanation tonometry'.
- "Pachymetry"- this measures the cornel thickness. This thickness measurement is important, as it will influence the interpretation of the intra ocular pressure measurements.
- Performing "Gonioscopy" - which is a contact lens method of studying the anatomical structure of your drainage passages or channels. This test will enable the surgeon to classify your glaucoma into the 'Open' or 'Narrow' angle type.
- A 'Visual Field' examination. This will help to detect and quantify the damage to the visual field. This test is also performed periodically to assess progression of the disease.
- Optic disc photography - to study the structural damage sustained by your optic nerve as a result of glaucoma.
These are the 'basic' minimum battery of tests that need to be performed to establish the presence of, initiate treatment and formulate a follow up strategy in patients with glaucoma.
Occasionally in certain doubtful or borderline cases, certain other tests may be ordered. These are the OCT of the retinal nerve fibre layer, GDx or the HRT tests.
Will treatment cure my Glaucoma?
Most glaucomas cannot be cured. However they can be controlled and progression or worsening can be arrested by medical treatment with eye drops, laser treatments and/or surgical intervention.
What should I do if i have Glaucoma?
With newer potent medications and accurate diagnostic modalities the progression of glaucoma can be curtailed effectively.
All you have to do is to be regular with your eye drops and your follow up schedule with your treating physician.
Awareness is the first step. Resolve is the second. The final step is peace in the knowledge that with todays modern technology and with a good understanding and collaboration between the patient and the treating physician the 'silent thief of vision' will be prevented from robbing from us the most precious gift given to us by god.
- 'Our Vision'
Prof S.Venkatesh, msdipnb fico frcs (glasg.)
CMO, VECH - chrompet
Glaucoma Services Offered : The Glaucoma Screening Week
Glaucoma has been called " the silent thief of vision" because more often than not it may exist in patients without any symptoms at all. This is why a routine screening for glaucoma in all people above the age of 40 is of paramount importance.
If you have a close relative with glaucoma , high myopia ( short sighted ness) or long standing diabetes, you could be at greater risk of having glaucoma.
Avail week long free glaucoma screening at the eye clinic.
All patients will be screened for:
- The intra ocular pressure - by applanation tonometry.
- Gonioscopy : a procedure that analyses the fluid drainage pathways of the interior of the eye.
- A thorough fundus examination. Wherein the optic disc will be meticulously examined for evidence of glaucoma damage.
Any patient who turns out to be a suspect with these screening test, may have to undergo further specialized examination like visual field testing (HFA) , and an OCT test to assess the retinal nerve fibre layer.
Patients who turn out to be positive for glaucoma will subsequntly be counselled about medications, laser therapy or surgery depending upon the quantum of damage to their optic nerves or in the visual fields.
" service to mankind is the first step towards self realisation"