Glaucoma is the damage of the optic nerve in the eye, which can be caused by high eye pressure. The optic nerve is a bundle of nerve fibres that help transmit visual information from your retina out of the eyeball and into the brain. Glaucomatous damage can be observed at the optic disc, also known as the optic nerve head, at the back of the eye where the fibres leave the eye ball.
Glaucomatous changes can be seen through fundus photography (/eye-examination), although further and more detailed tests will need to be done for any suspect or higher-risk cases.
Glaucoma is often described as the silent thief of sight, as there are no obvious symptoms until at an advanced stage where irreversible vision field loss is pronounced, leaving behind a ‘tunnel of vision’.
Most cases of glaucoma do not result in obvious symptoms and changes can be very gradual. Hence, glaucoma is sometimes only detected only in advanced changes where where the field of vision is limited to a tunnel. As vision loss from glaucoma cannot be reversed, early detection is ideal. Untreated glaucoma will eventually lead to blindness.
Our eyes continuously produce and drain fluids. A chronic or acute problem with the drainage can cause eye pressure to be raised, leading to glaucoma. However, glaucoma can also happen in eyes with normal pressures.
Open Angle Glaucoma
A higher-than-normal eye pressure slowly causes damage to the optic nerve, caused by a slow drainage of fluid from the eye. There are usually no initial apparent symptoms.
Angle Closure Glaucoma
The drainage of fluid from the eye is blocked, causing a sudden increase in eye pressure. This usually causes eye pain, nausea, red eyes, and blurry vision, and is a medical emergency.
Normal Tension Glaucoma
The optic nerve is damaged even though the eye pressure is normal. The exact cause is still unknown but an affected blood flow to the optic nerve is suggested as a possible cause.
Glaucoma can also be secondary to other factors, such as trauma, or due to growth of new blood vessels affecting drainage of fluid from the eye.
Risk factors for developing glaucoma include a family history, being of older age, having high myopia, or on corticosteroid medications. A recent paper (Vaghefi, 2021) highlighted that resistance exercise increases the pressure in the eye which is potentially a significant risk for glaucoma.