Discovering systemic drugs that affect glaucoma risk
Anthony Khawaja, a consultant ophthalmic surgeon at Moorfields, has led a study revealing new insights about the association between a subset of glaucoma and some antidepressants.
Primary open angle glaucoma (POAG) is a subset of glaucoma which is a group of diseases that damage the eye’s optic nerve and can result in vision loss and blindness. POAG is a progressive condition and is the most common cause of irreversible blindness worldwide.
What is glaucoma?
Glaucoma is a when damage to the optic nerve causes sight loss. It is usually caused by the pressure inside your eye rising too high.
Your eye is full of fluid, which helps it to keep its shape and function properly. If too much fluid builds up inside the eye, the pressure rises and squeezes the optic nerve at the back of the eye.
This can cause damage to your optic nerve - a bundle of over a million nerve fibres that carry signals between your eye and your brain.
Pressure might build up in the eye when:
- fluid is stopped from draining away;
- extra fluid is produced after an eye injury or infection - this is called ‘secondary glaucoma’;
- there is an abnormality in the shape of the eye in children - this is called ‘congenital glaucoma’.
Glaucoma tends to develop slowly over many years. As there is currently no cure for glaucoma, treatment focuses on early diagnosis, careful monitoring and regular treatment to help prevent further sight loss.
9 in 10
Over 90 per cent of people diagnosed with glaucoma today who get the treatment they need will retain useful sight for the rest of their lives
It is not currently possible to repair the optic nerve once it has been damaged, so any vision lost to glaucoma cannot be recovered. If left untreated, glaucoma can lead to blindness.
There are usually no symptoms of a rising pressure in the eye until sight loss occurs, so regular eye tests are the best way to help spot the condition early.
The study revealed a striking association between common classes of antidepressant medication known as ‘selective serotonin reuptake inhibitors’ (SSRI) and POAG, where SSRIs were associated with a 30 per cent reduced risk in the condition.
It also showed that some types of blood pressure medication, such as calcium channel blockers, were associated with a 26 per cent increased risk of POAG.
Looking to the future
These findings could significantly change the way glaucoma patients are managed, particularly those with existing depression or high blood pressure.
This research could mean that a trial of how SSRIs could be used to slow progression of disease in POAG could happen in the future and shows the need for other potential mechanisms driving this disease.