Myth: people with glaucoma always have high eye pressure
Any population has a range of eye pressures (IOPs) into which most members fit. In Australia the range is usually between 10 and 20 mm Hg (mm Hg is the same measurement used to measure blood pressure). This range is regarded as ‘usual’ or ‘normal’.
Until the late 1980s definitions of glaucoma included ‘eye pressure above normal’ but a large proportion of glaucoma sufferers may not show a raised IOP (only one-third in Australia but 90% in Japan) and there are more individuals with IOP greater than ‘usual’ without glaucoma than there are people with IOP greater than ‘normal’ with glaucoma.
Those with elevated IOP but no discernible structural or functional damage are regarded as ‘ocular hypertensives’ with increased risk of developing glaucoma. Eyes with ‘usual’ IOP with disc and/or visual field damage are diagnosed as having glaucoma and are sometimes sub-diagnosed as having ‘normal-pressure’ glaucoma. Although their IOPs lie within the normal range, these patients also benefit when their pressure is reduced.
IOP is only a risk factor, so ask your eye healthcare professional about your optic nerves and visual fields as well for the ‘full picture’!
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