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.
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 susceptible 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 occurring.
Typically, it is the outermost part of your vision (peripheral vision) that is affected first in glaucoma. 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.
CAPTION: A simulation of the effect on your peripheral vision with worsening glaucoma.
Regular eye examinations are the best way to detect glaucoma. 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 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 peripheral vision and/or pain and redness of the eye.
CAPTION: The retinal photo of a patient with glaucoma showing loss of their optic nerve tissue.
There is not just one test, but a range of different measurements used to diagnose and treat glaucoma including measuring eye pressure and corneal thickness, and testing the visual field of each eye with perimetry.
These days, we have advanced technology at our disposal that grants our optometrists a more detailed look at your eyes. This is especially significant for glaucoma patients as it allows for more accurate diagnosis, more acute progression monitoring, and more personalised treatment. Our Heidelberg Spectralis gives insight into multiple indicators of glaucoma, including anterior chamber angle, retinal nerve fibre layer thickness, minimum rim width thickness, hemisphere thickness asymmetry, and ganglion cell layer thickness.
CAPTION: Scans taken by the Heidelberg Spectralis OCT that reveals indications of glaucoma, including hemisphere thickness asymmetry, neuroretinal fibre layer thickness and anterior chamber depth.
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.
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. 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.
CAPTION: 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.