Can myopia increase the risk of glaucoma?
Myopia is one of the leading causes of sight impairment across the globe, with, according to some predictions, half of the world’s population likely to be affected by 2050. Glaucoma is the second leading cause of blindness worldwide, with Moorfields Eye Hospital  commenting that it affects two per cent of over 40s in the UK.
So are myopia and glaucoma completely separate eye conditions, and will the incidence of one affect the chances of developing the other? Well, yes, myopia and glaucoma are very different conditions. Myopia (commonly referred to as short-sightedness here in the UK) generally occurs when the eyeball grows too far, resulting in images being focused in front of the retina. In time as the retina is stretched, this can lead to retinal tears and other damage in the eye, which can further affect sight. Primary open-angle glaucoma (POAG), the most common type of glaucoma, generally arises when the pressure inside the eye is too high, resulting in damage to the optic nerve. However, in some cases, glaucoma can arise when eye pressures are closer to normal.
Glaucoma and myopia can arise completely independently of each other. However, studies have shown that the risk of developing glaucoma increases depending on the level of myopia.
One review reported in the British Journal of Ophthalmology  concluded that high myopia was a major risk factor for the development of POAG, with a 7.3-fold risk increase compared to non-myopic eyes.
Studies are still ongoing as to why high levels of myopia are more likely to lead to the development of glaucoma. But it is thought that the myopic elongation of the eye can lead to structural and physiological changes, which increase the susceptibility to other conditions.
However, there is another problem. A 2017 article in the Review of Ophthalmology  highlighted the difficulty faced by practitioners in that: “Highly myopic eyes often resemble glaucomatous eyes, so if pressure is normal, diagnosis can be challenging.” The article also comments that it can be difficult to isolate optic changes due to glaucoma in those individuals who have high myopia.
Being able to distinguish between the two conditions is vital if appropriate treatments and management plans are to be put in place. Quite simply, opticians can’t afford to wait and see if a patient’s sight deteriorates in a way which is more indicative of glaucoma because by then, the sight loss may well be irreversible. That is where effective screening tools can come into their own, enabling an early and accurate diagnosis which might just help to save an individual’s sight.
Occuity is working on the PM1, the world's only non-contact, handheld pachymeter, to allow both clinicians and technicians to take a corneal centre thickness measurement quickly and easily. The PM1 will support the earlier, faster, and more accurate screening of glaucoma, allowing patients to prevent vision loss through timely diagnosis and appropriate treatment.