Ocular hypertension means there is increased pressure of the clear fluid inside the eye.
Ocular hypertension increases a person's risk of developing glaucoma. Ocular hypertension affects around 3-5% of people over 40. Around 1 in 10 people with untreated ocular hypertension go on to develop glaucoma.
Eye pressure is also called intraocular pressure (IOP) and is measured with a special tonometry device. Pressure is recorded in millimetres of mercury (mmHg).
Normal eye pressure ranges from 10 to 21 mmHg. Ocular hypertension is defined as an eye pressure of greater than 21 mmHg on two consecutive occasions without glaucoma changes being present.
The optometrist or ophthalmologist will verify the eye pressure findings with a procedure called pachymetry to measure the corneal thickness with an ultrasound probe.
Having a thinner cornea can give false low eye pressure readings, but a thicker cornea can give false high eye pressure readings.
Further vision tests, monitoring or specialist referrals may be recommended.
Ocular hypertension causes
High pressure inside the eye is usually due to problems with production of fluid in the eye – called aqueous humour – or drainage problems with ducts being blocked.
If fluid builds up and the natural pressure valves in the eye don’t work, pressure is put on the optic nerve and can damage it over time.
Ocular hypertension symptoms
Pressure often builds up over time, so symptoms may not be noticed until it has done lasting damage to a person's eyesight.
Treatment for ocular hypertension
A common treatment for high pressure in the eye is special drops to reduce intraocular pressure.
In some cases, laser surgery and general eye surgery is needed, including to unblock drainage ducts.
Once eye pressure is brought back to normal levels, the risk of developing glaucoma is greatly reduced, but this will continue to be monitored to look for pressure changes and any vision changes.
Ocular hypertension cannot be prevented, but good general health and regular eye examinations can help reduce the risks of its complications developing.