Skip to main content
Home » Eye health » Glaucoma: How does it occur and evolve?
Vision and Eye Health 2019

Glaucoma: How does it occur and evolve?

iStock / Getty Images Plus / nd3000

WGA Education Committee

World Glaucoma Association

Glaucoma is the leading cause of irreversible blindness globally. Visual loss from glaucoma can be prevented with an early diagnosis and treatment.

The eye contains a fluid known as aqueous humour that provides nourishment to its internal structures.

This fluid is produced behind the iris (coloured portion of the eye) and then is drained out through a sieve-like structure called the trabecular meshwork at the front part of the eye.

In some eyes, abnormalities in the drainage system lead to impairment of the normal aqueous humour outflow, and intraocular pressure (IOP) increases.

This high IOP may damage the optic nerve head in the back part of the eye and impair the communication between the eye and the part of the brain responsible for the vision.

In other cases, IOP may be relatively normal, but glaucoma occurs anyway because of the inability of the eye to handle mechanical stress where the nerve fibres leave the eye, or because of poor blood supply to these same nerve fibres.

Glaucomatous optic disc

In glaucoma, the optic nerve gets damaged. A portion of the optic nerve may be assessed during an eye exam, where it can be seen as a round structure (optic disc), with the pink or reddish section representing the neural tissue, which takes the visual information to the brain.

The whitish central part represents absence of neural tissue, and it is called the ‘cup’. Some amount of cupping is normal, but excessive cupping, or an increase in the amount of cupping over time, suggests glaucoma. There are many blood vessels that emerge from the optic disc to the retina.

Glaucoma causes loss of the neural reddish tissue and there is progressive cupping of the optic disc – enlargement of the whitish central part.

How does glaucoma evolve?

The great majority of glaucoma cases evolve silently, as patients may not notice vision loss until it is significant and present in both eyes, or may assume that vision loss is correctable, as it is for other conditions such as cataract.

When the disease is at advanced stages, most patients will then perceive visual abnormalities. Glaucomatous damage to the optic nerve is irreversible, so what is lost cannot be recovered.

The asymptomatic early stages of disease and irreversible nature of the glaucoma makes it one of the main causes of blindness worldwide.

Glaucoma does not have a cure, however, this disease can be treated and the worsening of glaucomatous damage can be limited or even stopped.

Thus, an early detection associated to an appropriate treatment and follow-up can preserve your vision throughout your lifetime.

If one has glaucoma, what are the important things that can be done by the patient and his/her family members?

  • Glaucoma patients must take eye drops on a daily basis and follow up lifelong with an ophthalmologist at least once/twice a year to evaluate for any worsening of disease;
  • Family members – and especially siblings of glaucoma patients – must be screened annually for glaucoma;
  • Any form of steroid therapy (oral, inhalational, injectable etc) can elevate IOP in glaucoma patients and should be avoided or given under strict vigilance;
  • All systemic diseases like diabetes, hypertension and cardiovascular disease should be well controlled in consultation with a qualified physician and drug interactions with glaucoma medications should be checked;
  • Patients who are on anti-hypertensive medicines should avoid having a very low blood pressure, as low blood pressure may be harmful for glaucoma;
  • Glaucoma patients can do all physical exercise (particularly aerobic exercise), which may protect against glaucoma. Yoga is acceptable but one should avoid exercises with head down postures like shirshasana/sarvangasana (yoga positions) as these can cause an increase in Intraocular pressure;
  • Meditation and relaxation exercises can help reduce IOP and also decrease the stress and anxiety in glaucoma patients.
Next article