Hi there!
The exact reason why myopia causes glaucoma is not known. One possible hypothesis is that when you have very high myopia, your eyeball becomes stretched and the tissue supporting the nerve in the eye is weaker so you are at more risk of nerve damage from high pressures (or even pressures in the "normal" range). Reduced blood flow to the optic nerve in highly myopic eyes could be another reason. However, these are all hypotheses which have yet to be proven.
What we do know from a study conducted in Singapore, is that glaucoma affects around 3 per cent of people over the age of 40 and the risk increases with age. In addition, the risk of getting glaucoma among Chinese Singaporeans with myopia, as compared to those without myopia, are as follows:
- Mild myopia (less than 300 degrees) = 2 times more likely to get glaucoma
- Moderate myopia (300 to 600 degrees) = 5 times more likely to get glaucoma
- Severe myopia (more than 600 degrees) = 15 times more likely to get glaucoma
In addition, Chinese people with a family history of glaucoma were nearly 8 times more likely to develop it later in life.
Hence, if you have myopia or a family history of glaucoma (or both), do get screened for glaucoma. It is very important to remember that the majority of cases of glaucoma are without symptoms in the early to intermediate stages of the disease. The blurring of vision, when experience, is often a late symptom and is irreversible.
Hope this helps!
Regards,
DQ
