Glaucoma

Read in Hindi

Types
Stages
Symptoms
Causes And Risk Factors
Prevention
Diagnosis
Treatment
Lifestyle/management
Prognosis And Complications
Alternative Treatments
References.

Glaucoma is a disease that is the result of a number of mechanisms that produce increased pressure within the eye. This elevated eye pressure causes damage to the optic nerve over time. Unfortunately, the damage caused by glaucoma to the optic nerve is irreversible. There are no symptoms associated with most forms of glaucoma, which is why it is also referred to as the ‘silent thief of vision’.

The eye is a vital organ in our body. Like a camera, the eye captures information about shape, colour and movement, and relays it to the brain. The brain then processes this information to enable us to ‘see’ the world.

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Types

Glaucoma can be broadly classified into four main categories based on the effect of the internal fluid pressure on the eye, the optic nerve and any defect in the passage of the fluid:

Glaucoma since birth or congenital glaucoma

Open angle glaucoma

Closed angle glaucoma

Secondary glaucoma

Stages

Glaucoma can be divided into four stages as per the ICD-10 classification (International Classification of Diseases):

Stage1: Mild or early-stage glaucoma – glaucoma-like abnormalities are seen in the optic nerve, but any visual field abnormalities are absent.

Stage 2: Glaucoma-like abnormalities seen in the optic nerve and one hemifield (a half) of the eye.

Stage 3: Advanced stage – glaucoma-like abnormalities are seen in the optic nerve and in both hemifields of the eye.

Stage 4: Indeterminate stage – the patient is incapable of being tested and visual field testing cannot be interpreted.

Symptoms

There are no symptoms associated with most forms of glaucoma, which is why it is also referred to as the ‘silent thief of vision’. In some uncommon forms of the condition, the eye pressure can rise over a short time to a high level and the patient may experience eye pain, redness of the eye and halos around light. They may also experience nausea and vomiting during such an attack which may be caused by being in dim light for a considerable time, e.g. watching a movie. The patient may experience peripheral (side) loss of vision, which may gradually lead to tunnel vision (appearance of looking through a tunnel). Otherwise, most of the varieties of glaucoma may only cause a slowly progressive reduction in the area that a person can see. This happens from outside (peripheral vision) to inside (inner aspects of the eye) and may not be recognised by most patients, as the visual acuity may still remain intact.

Causes And Risk Factors

Causes

The cause of glaucoma is idiopathic (unknown). There have been attempts to explain the causes with a few theories. These theories revolve around improper drainage of the eye fluid, improper blood supply to the eye or increased intraocular pressure (pressure within the eye). All these theories are used to explain the resulting damage to the optic nerve.

Risk Factors

The following factors can pose a higher risk of getting glaucoma:

Age – after the 6th decade

Family history – if anyone in the family has it, then your risk of getting it increases

Certain diseases – certain medical conditions like high blood pressure, diabetes and heart ailments increase the risk of getting glaucoma.

Eye injuries – any physical trauma to the eye can result in increased eye pressure.

Eye-related risk factors – The eye’s structure such as a thin cornea or heightened sensitivity of the optic nerve can increase the risk of an individual getting glaucoma. Medical conditions like tumours of the eye, retinal detachment or inflammation of the eye are some other factors predisposing an individual to glaucoma. Being near-sighted can also pose a risk of glaucoma.

Corticosteroid overuse – excess corticosteroid use (namely hydrocortisone, prednisone, or cortisone) can predispose an individual to glaucoma.

Prevention

There is no way to prevent glaucoma. However, in order to avoid complications like loss of vision, the best way is to detect it early, treat it promptly and monitor it regularly. For early detection of glaucoma, the best method would be to get regular eye examinations. It is suggested that individuals between the age of 18-60 years should get an eye examination done once in two years, while individuals after the 6th decade of life should get an annual eye examination done.

Diagnosis

Known as the silent killer of vision, glaucoma can be diagnosed based on the symptoms, which mainly includes changes in vision. To ascertain symptoms a patient’s history, their family history or an account of other contributing factors may be taken. Your ophthalmologist might check eye pressure (intraocular pressure) and also estimate the damage to the optic nerve to detect the condition. The tests that are commonly advised include:

Visual acuity test – to identify if vision is affected

Tonometry – to measure eye pressure

Pachymetry – to identify the thickness of the cornea. Individuals with thicker corneas are more predisposed to glaucoma.

Perimetry or visual field testing – to identify the extent of loss of vision

Optical Coherence Tomography – to detect changes in the optic nerve over time

Gonioscopy – to observe the drainage of the eye.

Serial tonometry – to identify any changes in the eye pressure at different times of the day

Treatment

The damage caused by glaucoma cannot be reversed. Treatment of glaucoma is aimed at preventing further damage to the eye nerve. The whole purpose of treatment is to keep the eye pressure under control to prevent further loss of vision. More importantly, as the goal of all the treatment modalities is the same, i.e. to control the eye pressure, one method doesn’t surpass the other. For example, surgery for glaucoma may not necessarily score over the use of eye drops and none of them can cure the disease. Each treatment has its own pros and cons.

The treatment for glaucoma involves eye drops, tablets, laser procedures, eye operations or a combination of methods:

Eye drops: Anti-glaucoma eye drops mainly reduce the secretion of eye fluid and thereby reduce the eye pressure. Eye drops may cause a burning or stinging sensation upon application. This is often due to the antibacterial agent present in the drop solution and not due to the drug itself. While it can be uncomfortable, the discomfort lasts for only a few seconds. It is important that you take your medication exactly as it is prescribed if you are to control your eye pressure. For example, drops which are prescribed two times a day usually have ‘duration of action’ of twelve hours. By taking these drops two times spaced through your waking hours, e.g. at 7 am and 7 pm (with maximum variation of 15-30 minutes either way) you ensure that you are covered by the drug´s effectiveness for a full 24-hour period.

Since eye drops are absorbed into the bloodstream, it is important that you tell your doctor about other diseases you might be suffering from and all other medications you are currently taking. Ask your doctor if the medications you are taking together are safe. To minimize absorption into the bloodstream and maximize the amount of drug absorbed into the eye, close your eyes for one to two minutes after administering your drops and press lightly against the nasal corner of your eyelids to close the tear duct that drains into the nose. It is very important to not to miss even a single dose of any medication otherwise the eye pressure can fluctuate between the drop applications and continue to damage the eye nerve.

Tablets: Sometimes, drops are not enough to control the eye pressure. In that case, oral medications may be prescribed in addition to the drops. They do have more side effects compared to the eye drops. Therefore, they are usually prescribed for a short period to control the eye pressure.

Laser procedures: These procedures are advised in certain types of glaucoma. The most common laser procedure performed for angle-closure glaucoma is called laser iridotomy. This procedure takes between one and three minutes, is painless, and is performed on an outpatient basis. The laser beam (a high energy light beam) is directed in the eye. This laser beam leads to certain biological and chemical changes within the eye, which results in better drainage of fluid from the eye, via the ophthalmic drainage meshwork. You can resume normal activities in a short time following the procedure. Your doctor will check your eye pressure one hour later. Your doctor will also determine which anti-glaucoma medications are necessary for you after the procedure. The possible complications of the laser procedure are minimal and rare.

Surgery: The most common anti-glaucoma operation is called trabeculectomy. In this procedure, the surgeon removes a small section of the eye wall to facilitate drainage of the eye fluid. This procedure, done on an outpatient basis, is usually done after giving an anaesthetic injection around the eye. The doctor will see you on the day after the operation to check your vision and eye pressure. Although trabeculectomy is a relatively safe surgery, complications do occur. Therefore, the surgery is judiciously advised. After trabeculectomy, most patients are able to discontinue all anti-glaucoma medications. A few patients may require additional surgery.

The process of managing glaucoma doesn’t end by treating the patients alone. Glaucoma appears to run in families. The tendency for developing glaucoma may be inherited. Therefore, it is advisable to take your close relatives for glaucoma check-ups.

Lifestyle/management

Apart from medication and surgery, altering one’s lifestyle can reduce complications such as the loss of vision due to glaucoma. The following lifestyle modifications can be incorporated:

Regular exercise can reduce vision loss.

Meditation which reduces cortisol (a stress hormone), can help in reducing eye pressure.

Including fruits and green leafy vegetables in one’s diet can reduce the glaucoma risk by 20% to 30%.

Avoid smoking

Maintaining an optimal body weight can reduce the risk of diabetes which predisposes an individual to glaucoma.

Prognosis And Complications

Prognosis

With adequate and prompt treatment, glaucoma can be treated and complications such as the loss of vision can be prevented. In cases of acute glaucoma, early treatment can restore your eyesight to pre-glaucoma status. However, if neglected, you may experience loss of vision in the affected eye within two days of ignoring the problem.

Complications

Visual impairment and blindness can occur if glaucoma is not treated promptly and correctly.

Alternative Treatments

Meditation, acupuncture and exercise have been found to reduce intraocular pressure and visual field acuity to a small extent. These alternative treatment modalities can also help keep stress at bay and maintain healthy body weight to reduce glaucoma complications.