Everyone knows what “Hypertension” is – too high a blood pressure throughout the veins and arteries that if not treated or reduced can lead to stroke or heart failure.
But what about “Ocular Hypertension”?
Well hypertension preceded by the word “ocular” means something to do with the eye, and in fact it can be simply thought of as “high pressure in the eye”.
Although there may be some minor correlation between high blood pressure in the body and high eye blood pressure, ocular hypertension is generally treated as a disorder of the eye alone.
How is eye pressure measured?
Firstly the pressure in the eye has a term to describe it – Intraocular Pressure – IOP for short.
IOP is measured during routine eye examinations by an optometrist, and it’s quite probable that if you’ve just had an examination you didn’t even suspect that it was in fact being measured!
Typically during an examination your head is held perfectly still by resting your chin and forehead on a pad, and a quick short puff of air is blown at your open eye. A pre-calibrated sensor measures the indentation response in the eye to give the pressure.
Intra Ocular Pressure should be within the range of 10 to 20 mm Hg (which is relatively low when compared to the values of body blood pressure such as 80 to 120 mm Hg under different heart actions).
There are other methods of measuring IOP, the field of measurement going under the name of tonometry and the various devices being called tonometers.
To enable quick on the spot assessments some tonometers are purposely made easier to use than the static and cumbersome ones used in optometrists rooms – they act a bit like a pressure pen.
What is the problem if IOP is too high?
THE major concern is that elevated intraocular pressure could be the indicator for the development of glaucoma, so much so in fact that some optometrists and ophthalmologists like to use the term “glaucoma suspect” instead of saying “ocular hypertension”.
Glaucoma is a serious eye disease in which the optic nerve becomes damaged with inherent vision loss and possible blindness. Intraocular pressure, if it becomes too high because the aqueous fluid in the eye cannot drain away, can increase to unacceptable levels.
It is essential then, even if there are no signs of glaucoma, that IOP be reduced.
What can be done to treat ocular hypertension by reducing IOP?
The two main ways of treating ocular hypertension are:
• Eye drops – quite often more than one type are administered, so don’t be alarmed if this happens.
If both eyes are exhibiting ocular hypertension it’s a good idea for the optometrist or ophthalmologist to have the patient use the drops in only one eye – in that way the response can be more readily assessed and if positive then both eyes can be treated.
• Laser Surgery – great strides have been made in recent years in using laser surgery to carry out simple and effective procedures when compared to conventional surgery.
One fairly simple laser surgery procedure called selective laser trabeculoplasy (SLT) gently burns and unblocks the drainage system of the eye called the trabecular meshwork.