Ocular hypertension is when the pressure inside the eye (intraocular pressure or IOP) is higher than normal.

With ocular hypertension, the front of the eye does not drain fluid properly. This causes eye pressure to build up. Higher than normal eye pressure can cause glaucoma. Glaucoma is a disease where eye pressure damages the optic nerve, causing vision loss.

A cataract is a clouding or opacity of the lens inside the eye. It causes gradual blurring of vision and often glare.

Inside your eye, behind the iris and pupil is a lens. In a normal eye, this lens is clear. It helps focus light rays onto the back of the eye (the retina), which sends messages to the brain allowing us to see.

When cataract develops, the lens becomes cloudy and prevents the light rays from passing on to the retina. The picture that the retina receives becomes dull and fuzzy.

Cataract usually forms slowly and most people experience a gradual blurring of vision.

A transient ischaemic attack (TIA) or ‘mini-stroke’ is caused by a temporary disruption in the blood supply to part of the brain.

The disruption in blood supply results in a lack of oxygen to the brain.

This can cause sudden symptoms similar to a stroke, such as speech and visual disturbance, and numbness or weakness in the face, arms and legs.

But a TIA does not last as long as a stroke. The effects last a few minutes to a few hours and fully resolve within 24 hours.