Normal eye pressure in the general population averages around 16 mmHg, ranging from 12 mmHg to 20 mmHg. Vision loss occurs if pressure rises above 25 mmHg for long periods.^8,9

The term ocular hypertension (OHT) is used if the pressure is consistently above 21 mmHg in an eye which is otherwise healthy. It does not automatically mean vision is at risk, but it should be monitored with regular eye health checks. If damage is detected and treatment becomes necessary, it can be started early on when it will have the most impact.^9,10

If OHT is untreated, POAG develops in around 10% of patients within five years. Factors increasing the risk of glaucoma developing from OHT include age (especially once over 40), a family history of glaucoma, very short-sightedness (high myopia), or a thin cornea. OHT is estimated to occur in 4.5-9% of the population aged over 40.^10,11