Glaucoma

Glaucoma is a debilitating eye disease that causes progressive optic nerve damage, resulting in permanent peripheral vision loss and eventually central vision loss. Glaucoma is called 'the silent thief of sight' as 50% of a patient's retinal nerves can be damaged irreparably before any vision loss is noticed. Glaucoma is one of the main conditions an optometrist checks for at your eye examination. Early detection is key as this allows appropriate treatment before too much vision is lost. This condition highlights why it is so important to have a routine eye examination at least every two years.

What is Glaucoma?

The glaucomas are a range of eye diseases that cause optic nerve damage and can result in permanent vision loss. The optic nerve transmits images from the retina to be processed in the brain so that we can see. In glaucoma, the pressure of the fluid in the eye damages the optic nerve over time, leading to loss of function. Glaucoma is most commonly due to high intra-ocular pressure but it can occur with normal eye pressure in eyes that are more susceptable to damage. This is called normal tension glaucoma.

Glaucoma typically progresses slowly over time and patients are not aware of high pressure in their eyes. However, some patients may have a sudden increase of pressure if the area of the eye that drains fluid, called the anterior-chamber angle, closes suddenly. This will cause aching in the eye, blurry or hazy vision around lights, and sometimes nausea and vomiting. Emergency care is needed to lower the pressure and prevent permanent vision loss. Individuals at risk of this acute angle-closure glaucoma will often be referred for a prophylactic laser treatment to create a 'safety valve' in the iris tissue to prevent this pressure rise occuring.

Typically, it is the outermost parts of your vision that are affected first in glaucoma (ie. your peripheral vision). In most cases, this vision loss is not detected by the sufferer until the advanced stages, when both their central and peripheral vision is affected. If the entire nerve is destroyed, complete blindness results. It is estimated that around 300,000 Australians have glaucoma, with half going undiagnosed. The direct medical costs of glaucoma are almost $150 million annually.

A simulation of the effect on your peripheral vision with worsening glaucoma

How is Glaucoma diagnosed?

There is a significant increased risk of developing glaucoma if you have a family history of glaucoma, diabetes, migraine, short sightedness (myopia), eye injuries, high blood pressure or past or present use of cortisone drugs (steroids). If you have a family member who has glaucoma, you have approximately four times greater likelihood of developing the disease. It is crucial for people with glaucoma to speak to their families about this silent and progressive eye condition so they understand the necessity of regular eye examinations. In nearly all cases of glaucoma, there are no noticeable symptoms detected by the individual. In rare instances of glaucoma, patients may note blurred vision, coloured rings around lights, loss of side vision and/or pain and redness of the eye.

Regular eye examinations are the best way to detect glaucoma. There is not just one test, but a range of different measurements used to diagnose and treat glaucoma including:

  • Measuring your eye pressure (which is the main risk factor for glaucoma if it is too high for your eye) and corneal thickness
  • Inspecting the drainage angle of your eye
  • Evaluating or scanning your optic nerve and retina (this is done with an OCT scan, retinal photography and examination through the slitlamp)
  • Testing the visual field of each eye with an automated visual field test

The information from these tests provides an indication of the presence or stage of this potentially blinding disease. Not all of these tests are necessary for every person, nor at every visit.

The retinal photo of a patient with glaucoma showing loss of their optic nerve tissue

How is Glaucoma treated?

Glaucoma can be managed effectively. Early detection is the key, as this increases options for treatment that can significantly slow the progression of the disease. Treatment options include eye drops, laser and surgery. Both optometrists at Innovative Eye Care can prescribe the eye drops used to treat glaucoma. If you are prescribed glaucoma eye drops, these need to be used correctly every day to decrease the chance of worsening of the condition. Visit our page on using eye drops correctly for more information on this. Ongoing examinations at least every year are required to ensure your glaucoma is stable.

An OCT scan analysis showing glaucoma of the right eye. Note the thinner (blue) part of the retina damged by the condition. The left eye is normal at this point in time.