Table of Contents

What Glaucoma Means

Glaucoma or Papahewa is a disease of the eye that affects 2% (2 out of 100 people) in New Zealand over 40 years of age.

It is irreversible blindness resulting from specific damage to the optic nerve. The role of the optic nerve is important as it connects the eye, which focuses and senses light, to the brain, which processes the information from the eye and gives us perception of vision.

 

What is Glaucoma

What Types of Glaucoma are there

Glaucoma can come in different forms; the following are common1:

  • Primary Open Angle Glaucoma (POAG) – most common2
  • Acute (sudden) Angle Closure Glaucoma (AACG) – emergency3
  • Chronic (long-standing) Primary Angle Closure Glaucoma (PACG)
  • Pigment Dispersion Syndrome
  • Pseudoexfoliation Syndrome

What's Glaucoma Symptoms

Most forms of glaucoma carry no symptoms in the early stage of the disease and can only be detected with routine eye exams.

The reason for this is that with most forms of glaucoma, the disease is progressive. This means that the symptoms take a long time to develop, making it difficult to notice any changes in vision.

Vision loss typically begins in the far periphery of vision. If vision loss is present, especially if it is slow and progressive, the brain has the ability to fill in the area where vision loss is experienced.

Regular eye exams are able to detect the presence of all forms of glaucoma, hence the importance. In addition to this, early exams allows baseline testing to be compared to future exams.

A form of glaucoma known as Acute Angle Closure Glaucoma has very obvious and sudden symptoms which include:

  • Severe pain and headaches
  • Vomiting and nausea
  • Haloes around lights
  • Reddening of eyes
  • Blurred vision

What causes Glaucoma

Glaucoma results in damage to the optic nerve – the connection of the eye and the brain.

High eye pressure results in damage to the physical structure of the optic nerve resulting in death of the nerve cells that travel from the eye to the brain or the pressure can reduce blood flow so the optic nerve gets less nourishment resulting in some cells dying.

A number of different factors can cause pressure to increase. This could be due to the drainage angle of the eye being blocked by the pupil or debris in the eye which cause the pressure to increase4.

Who is at Risk of Glaucoma

Individual who have higher risk of glaucoma may have the following factors5:

  • Age over the years of 40
  • Family history of glaucoma with first degree relatives (parents, siblings and children)
  • Race with individuals with Asian origin more to likely to develop PACG
  • High myopia
  • Hyperopia
  • Sleep Apnoea
  • Long-term Steroid medication

How Glaucoma is Diagnosed

In the public’s eye, the ‘pressure test’ is the hallmark test that represents glaucoma. However, high intraocular pressure (eye pressure greater than 21 mmHg) is not a definitive sign for glaucoma. Those with normal eye pressure can still develop glaucoma and only one out of ten who have high eye pressure develop glaucoma6. Glaucoma is a difficult disease to diagnose requiring consideration of multiple tests. Common tests in addition to a standard eye exam include:
  • Applanation tonometry: this uses a small probe that touches the cornea (the front layer of your eye) or a puff of air
  • Pachymetry: a small probe is used to measure the thickness of the cornea
  • Visual field test: this measures any field of vision loss due to glaucoma
  • Optical Coherence Tomography (OCT): this uses light to provide a three-dimensional scan of the optic nerve, which is the structure that is damaged by Glaucoma
  • Gonioscopy: this is a small lens put on to the front of the eye to determine if the drainage system of the eye is blocked
  • Dilation: this allows better analysis and photography of the optic nerve

Glaucoma Treatments

Most treatment methods for glaucoma involve decreasing intraocular (eye) pressure. These treatments are permanent and require constant monitoring by an eye professional who specialises in glaucoma. These treatments include:

  • Medication: eye drops or a combination of different drops are taken at least once a day in order to reduce the eye pressure
  • Surgery: different types of procedures act to eye pressure
References
  1. Types of Glaucoma – Glaucoma NZ[]
  2. Primary Open Angle Glaucoma- Questions and Answers – Glaucoma NZ[]
  3. Acute Angle Closure Glaucoma (ACG)- Glaucoma NZ[]
  4. The Pathophysiology and Treatment of Glaucoma – RN. Weinreb, T Aung et al.[]
  5. Glaucoma history and risk factors – CW McMonnies[]
  6. The Ocular Hypertension Treatment Study: a randomized trial determines that topical ocular hypotensive medication delays or prevents the onset of primary open-angle glaucoma. – MA Kass, DK Heuer et al.[]

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