All about glaucoma in World Glaucoma Week

It's World Glaucoma Week and while anyone can be affected by glaucoma, certain people are at higher risk and should get their eyes checked once a year, says consultant ophthalmologist Dr Tristian Mann.

The optic nerve, which is crucial for good vision as it transmits visual information from the eye to the brain, can be impaired by a group of eye conditions known as glaucoma.

Though glaucoma can occur even with normal eye pressure, damage to the optic nerve is commonly associated with high eye pressure.

So, who does it affect and who is more at risk?

While glaucoma can occur at any age, it mainly affects people beyond 40 years. It can also be found in children.

Glaucoma is a condition wherein an increased intraocular pressure damages the optic nerve, thereby affecting vision. In the normal eye, the rate of production of aqueous (the fluid that nourishes the front part of the eye) matches the rate of its drainage, thereby maintaining optimal pressure inside the eye.

However, with age, disease, trauma or other factors, the channels carrying this fluid may get blocked, increasing the pressure inside the eye.

This increased pressure damages the optic nerve, which sends visual messages to the brain. Working silently, glaucoma damages the outer or peripheral vision first while maintaining the central vision.

Glaucoma is called the silent thief of sight because there may be no symptoms in the early stages of the disease. By the time glaucoma is detected, the patient may have already suffered extensive peripheral vision damage which can no longer be restored.

It is the leading cause of blindness in the United States, and a study presented at the World Ophthalmological Congress in 2008 projected India as the next glaucoma capital.

You are at risk, if you:

• • Are aged 45 or above
  • Have a family history of glaucoma
  • Have health conditions such as diabetes, hypertension or thyroid disease
  • Suffer from myopia or near-sightedness

If you have any of these risk factors, it’s really important that you go for regular eye tests at your optometrist.

There are two major types of glaucoma:

• • Chronic or Primary Open-Angle Glaucoma (POAG) This is the most common form. Damage to vision is gradual and generally painless.

• • Closed or Acute Angle-Closure Glaucoma: In the closed or acute form, the intraocular pressure increases rapidly due to a sudden and severe block of fluid drainage within the eye. Significant symptoms indicating the presence of acute glaucoma appear immediately. This condition must be treated quickly by an ophthalmologist otherwise blindness may occur.

Symptoms of glaucoma:

• • Inability to adjust the eyes to darkened rooms, such as theatres
  • Poor night vision
  • Frequent changes in glasses prescription
  • Gradual loss of peripheral vision
  • Blurred vision
  • Feeling of a patchy visual loss in the eye
  • Seeing rainbow-coloured halos around lights
  • Severe eye pain, facial pain, nausea and vomiting
  • Red eye

Treatment

Glaucoma cannot be cured, but it can be controlled to slow down or stop any further damage to the optic nerve. This can only be done through disciplined and regular treatment, which is life-long.

• • Medical management is using eye drops. Eye drops should be taken exactly as prescribed, using the right drop in the correct eye at the right time in the right way.

• • Surgical management includes a procedure where an opening is made to create a new drainage pathway for the fluid to leave the eye easily.

• • Management by lasers includes procedures such as trabeculoplasty, in which a laser is used to open the trabecular meshwork drainage area; iridotomy, in which a tiny hole is made in the iris, allowing the fluid to flow more freely; and cyclophotocoagulation, in which a laser beam treats areas of the ciliary body, reducing the production of fluid.

There is no proven way to prevent glaucoma but regular check-ups can help detect the disease in its early stages.