Glaucoma

What are the causes and symptoms of glaucoma?

Doctors have not yet completely identified the pathology of the condition.

But amongst the observed causes, increased pressure in the eye was the cause for the damage of the optic nerve followed by vision deterioration. 

Once the optic nerve gets damaged, the result is the formation of blind spots in the vision of the person impacted.

Aqueous humor (fluid in the eye) follows throughout the eye. This fluid is constantly drained through a meshwork of tissue called the trabecular meshwork. It meets at the angle of the iris and cornea.

When the fluid is produced in excessive quantities the drainage system renders ineffective. The rate of the fluid draining from the inside of the eye is hindered, thus resulting in pressure that builds inside of the eye. 

Scientists have identified genes responsible for building high pressure in the eye and optic nerve damage. Thus, it tends to be inherited and may run in families.

What are the types of Glaucoma ?

• Open-angle glaucoma:

Open-angle glaucoma is the most commonly observed glaucoma. It results from the partial blockage of the trabecular meshwork.

The drainage angle formed by the cornea and iris in this type of glaucoma is intact. This results in the build-up of pressure in the eye, finally damaging the optic nerve.

The affected person may lose sight even before realizing the onset of the condition. Regular preventive checkups may enable early diagnosis and management of the condition.

• Angle-closure glaucoma:

Angle-closure glaucoma, or closed-angle glaucoma, results from the bulging of the iris. 

This narrows the drainage angle between the cornea and iris. This hinders the circulation of the fluid, increasing the eye pressure.

This condition can occur suddenly (acute angle-closure glaucoma) or progressively (chronic angle-closure glaucoma). Acute angle-closure glaucoma must be treated as a medical emergency.

• Normal-tension glaucoma:

In Normal-tension glaucoma, the fluid pressure in the eye is normal. The exact reason for this glaucoma is unknown.

The damage to the optic nerve could be due to less blood supply, or a sensitive optic nerve. 

Less blood supply could be because of atherosclerosis (fatty deposits called plaque in the arteries) or other conditions that hinder normal blood circulation.

• Glaucoma in children:

Glaucoma can be present at birth or a child may develop glaucoma within the first few years of life. 

The observed causes have been certain medical conditions or blocked drainage of the eye fluid, leading to pressure on the optic nerve and thus damage. 

• Pigmentary glaucoma:

The pigment molecules of the iris that block the drainage channels in this kind of glaucoma, hamper the eye fluid drainage.

The pigment molecules can be stirred up by rigorous body activities such as jogging. These disturbed molecules may now go and settle in the meshwork leading to fluctuations in the eye pressure.

What are the symptoms of Glaucoma?

The type and stage of glaucoma determine its symptoms:

• Patchy blind spots in the central or peripheral vision (mostly both eyes)

• Tunnel vision (advanced stages)

Acute angle-closure glaucoma:

• Eye pain

• Blurred vision

• Severe headache

• Halos around lights

• Nausea and vomiting

• Eye redness

Glaucoma will lead to blindness; if untreated. Despite treatment, 15% of patients suffer from blindness because of glaucoma in at least one eye within 20 years of commencement of treatment.

How to diagnose Glaucoma?

The doctor relies on medical history and any family history while evaluating for glaucoma. For a condition like glaucoma, it is best to be evaluated by an eye specialist (ophthalmologist). 

The ophthalmologist while confirming glaucoma does numerous other assessments in addition to the past health and physical examination. These evaluations include:

Structure of the eye:

It is assessed by techniques such as slit lamp examination, ophthalmoscopy, optic coherence tomography, and gonioscopy

Vision:

This test evaluates the sharpness of the vision and loss of side and/or central vision if any using the perimeter technique.

Eye pressure:

The technique of tonometry measures the fluid pressure inside of the eye (intraocular pressure).

The thickness of cornea:

Along with the measurement of intraocular pressure, cornea thickness quite effectively allows defining the patient's risk for glaucoma. 

Pachymetry is a technique, which helps measure the thickness of the cornea. 

Once glaucoma is diagnosed, the above-described evaluations continue at regular intervals to ensure optimal utilization of the vision the patient has and to help preserve the quality of life. The doctor may perform a low-vision assessment for the same.

What are the Treatment options for Glaucoma ?

Treatment of glaucoma aims to prevent pressure on the optic nerve and hence to prevent the loss of vision. 

This can be effectively achieved by maintaining intraocular pressure. Depending upon the stage of diagnoses, the doctor may suggest the following course of action:

Medicines:

This is conservative management, where the doctor prescribes either medicated eye drops or tablets to reduce the intraocular pressure. The doctor may also use a combination.

Surgery:

The surgery depends on the type of glaucoma.

If Glaucoma caused by slow or blocked drainage channels is leading to increased pressure in the eye; the doctor may consider ablating the excessive fluid-producing glands.

Angle-closure glaucoma is approached differently.

This is treated as a medical emergency and requires the pressure built up by the fluid to be reduced immediately.

The doctor may try medicines first. But if the patient does not respond with immediate effect, the doctor may resort to iridotomy. 

This is a laser protocol that makes small holes in the iris of the eye. These holes in the iris facilitate fluid movement, thus relieving intraocular pressure.