Glaucoma is a complex group of diseases and can be caused by a number of different things — from ocular hypertension and cataracts to diabetes and genetics. It’s typically split into two types: primary and secondary.

In order to help you understand glaucoma and its potential causes a little better, we’ve put together some information for you to look through. You’ll find information about the link between glaucoma causes and other conditions such as diabetes, whether or not glaucoma is preventable, and how it can develop in children.

You can find more information about glaucoma diagnosis and glaucoma treatment here. Or visit our glaucoma hub for more information on glaucoma symptoms.

What causes glaucoma?

The eyeball contains a fluid called aqueous humour, which is constantly produced by the eye, with any excess drained though tiny channels and tubes. When the fluid cannot drain properly, this causes the pressure inside the eye (intraocular pressure) to rise.

 Glaucoma typically develops when this increased pressure damages the optic nerve (which connects the eye to the brain) and the nerve fibres in the retina (the light-sensitive layer at the back of the eye). 

In acute glaucoma cases this pressure rises rapidly to higher levels, causing pain.

Glaucoma risk factors

Anyone can develop glaucoma, but there are several risk factors which make glaucoma more likely. These include:

  • A family history of glaucoma – there’s at least a four-times higher risk of developing glaucoma if a close blood relative has it1
  • Age – chronic glaucoma affects up to two in every 100 people over 40, and around five in every 100 people over 80
  • Higher levels of short sightedness (myopia) in the chronic form, but also in the acute form of long-sightedness (hyperopia)
  • Consistently raised pressure in the eye, called ocular hypertension (OHT)
  • People of African-Caribbean origin have about a four-times higher risk of developing chronic forms of glaucoma compared to those of European origin.2 Acute glaucoma is much less common, but people of east Asian origin are more at risk of getting this type of glaucoma compared with those from other ethnic groups
  • Diabetes – people with diabetes may be at a higher risk of developing glaucoma
  • Blood pressure – very high blood pressure can lead to increase pressure in the eye. Low blood pressure can reduce the blood supply to the optic nerve

Read more articles about glaucoma diagnosis


1, 2. Glaucoma UK (2021). What is glaucoma? Available at: [accessed August 2021]