Glaucoma

What is Glaucoma ?

Glaucoma is a disease where the pressure inside eye becomes high damaging the nerve fibers forming the optic nerve. This nerve carries the visual information from eye to brain and therefore any damage to the nerve fibers causes defects in the visual area we see around and decreased vision which may even progress to blindness if not treated in time. Normally eye has a certain pressure—10 to 21 mmHg (like a balloon filled with water) which is required for the eye to function in a healthy way. This pressure is created by a fluid called aqueous humor that is being continuously formed and drained out from the eye throughout life. Any disturbance in maintaining this delicate balance leads to high pressure, which in turn damages the nerve fibers.

The main problem in picking up this SILENT disease is that mostly it does not have symptoms in early stages and by the time patients report with visual complaints, the damages which have occurred in the eye are irreversible. Most of the cases are picked up on a routine eye examination by an eye doctor. The disease can be controlled if detected early enough. The cure of glaucoma means to keep the eye pressure within normal range and stop further deterioration by means of eye drops, laser or surgery.

To avoid fears & misconceptions about the disease this section helps you in understanding the disease better. Following are some of the frequently asked questions by patients.

What are the symptoms of glaucoma ?

The presentation of glaucoma varies depending on the type of glaucoma :

OPEN ANGLE GLAUCOMA is the silent chronic variety. It does not have any symptom in early stages and is most often picked up during a routine eye examination by the eye surgeon. Later there can be a feeling of heaviness in & around eyes, headache, frequent change in spectacle number or even inability to see certain areas in the field of vision around us.
NARROW ANGLE GLAUCOMA can cause acute pain, redness, headache or seeing colored rings around bulb light. This group of glaucoma patients can have a sudden attack of very high pressure leading to redness, pain and marked diminution of vision.
SECONDARY GLAUCOMA can occur due to various causes like injury, inflammation, tumors of eye, hemorrhage, drugs like steroids etc. They can present with any of above symptoms.
CONGENITAL GLAUCOMA is a condition where the exit channels are poorly formed since birth. Due to high pressure the cornea becomes opaque and eye may gradually enlarge. Child presents with either decreased vision, glare, watering or enlarged eye, and requires immediate treatment.

Who are the people more at risk of glaucoma ?

Diabetics
Spectacle wearers- Myopia/ Hypermetropia
Steroid users
Family history of glaucoma
Thyroid diseases
Other eye diseases eg. uveitis, vitreous hemorrhage, major eye surgery etc.
Eye injury

What tests are done to diagnose glaucoma ?

It is not enough to record only eye pressure to diagnose glaucoma. Once a patient has suspicion of having glaucoma, we study the angles of eye, optic nerve and visual fields. All these have to be looked at together to establish a complete picture of the type and nature of glaucoma. In our glaucoma clinic, the basic work up of a patient includes :

Applanation Tonometry : Most accurate method to measure intraocular pressure.
Ophthalmoscopy : To assess the changes in the anterior visible portion of optic nerve, seen through the pupil.
Gonioscopy : To study the details of exit channels for eye fluid situated at the angle of anterior chamber.
Computerized Perimetry : To detect loss in visual field corresponding to the nerve fibre damage. This is a very sophisticated test, which shows the changes in both qualitative & quantitative manner and is very crucial for the further treatment course and to study the progression of disease.
Disc & Nerve fibre layer evalauation : Fundus photographs/ OCT/ HRT/ GDX-taken to assess the changes in optic nerve head and retinal nerve fibre layer for detailed objective analysis and further comparisons.

Above tests need careful analytical assessment for baseline treatment and future management. Because glaucoma is a progressive disease, a long-term careful follow up is required where these tests are repeated and compared to the previous reports. If any progression in the damage is noted, then the treatment is modified.

How does high pressure affect vision ?

High pressure leads to poor blood circulation damaging nerve fibers forming the optic nerve that carries visual impulses from eye to brain. Initially there are corresponding areas of loss in visual field and gradually progress to marked decrease in vision.

What is the treatment for glaucoma ?

The treatment is aimed to keep eye pressure in normal range. For any individual the normal or "target pressure" is different, which is decided by the eye doctor after studying the reports of all above mentioned tests. The lowering of eye pressure is achieved by eye drops or medicines alone or in combination with laser procedure. If the eye pressure is not controlled by above, surgery is required. The modality of treatment is decided by factors like type & stage of glaucoma, damage already done at the time of presentation, response to prior treatment, patients ability to put medication regularly etc.

How do eye drops/medicines treat glaucoma ?

The first attempt to control glaucoma is made with eye drops alone or combination with oral pills. These medicines act by lowering the eye pressure either by decreasing the production of aquous fluid within the eye or by improving the outflow through drainage channels. Various combinations of eye drops may be given to control the eye pressure depending on the type of glaucoma and systemic condition. To be effective these medicines have to be put at regular intervals as advised by the doctor and never be stopped without consulting him. A time to time evaluation of eye pressure and other tests are crucial to monitor the glaucoma status.

What is the role of laser in glaucoma ?

Laser surgery may be effective for some types of glaucoma. In open angle variety, trabeculoplasty is done where the drainage angles are treated by laser to increase the outflow of aquous fluid and lower eye pressure. In narrow angle glaucoma, a hole is made in the iris -peripheral iridotomy, to restore the flow of aquous fluid and open up the drainage angles. These are done as OPD procedures.

What is the surgery done for glaucoma ?

It is a microscopic filtering surgery- Trabeculectomy where a small drainage channel is created for the fluid to leave the eye and thus lower the eye pressure. It is done under local anesthesia and you need to be in hospital for a couple of hours only. Usually the surgery is done when eye pressures are not controlled by medicines and laser or in advanced glaucoma.

Do I need to change anything in my lifestyle ?

No, you can continue your routine lifestyle. A word of caution- avoid excess caffeine intake and certain yoga practices (like kapalbhati and headstands) which may further increase the eye pressure.

What is the follow up for glaucoma treatment ?

The follow up for glaucoma patient is usually life long. It is not only very important to be regular with medication but also with follow up. The usual protocol is to call patients once in every 3 or 4 months for eye pressure check and repeat the investigations (like perimetry) annually to make sure that glaucoma is well controlled.

If I have glaucoma, will I be able to enjoy good vision throughout my life? ?

Yes surely, the success of your treatment depends on early diagnosis, timely intervention and regular follow ups. The key to prevent the worsening of glaucoma is regular treatment and follow-up.

Note : Everybody over forty years of age should get there eye pressures checked once every two years, specially if they have family history of glaucoma or are diabetics.

EYE SPECIALIST