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What causes
glaucoma?
Our eyes constantly produce a clear fluid called aqueous humor
(Fig 1 & Fig 2), which bathes and nourishes its different
parts (this is different from tears). Normally the fluid drains
out of the eye through a 'drainage canal' located in the 'angle'
of the eye (Fig 2), the junction between the cornea and the
iris. In persons with glaucoma, the fluid does not drain out
as freely as it should, thus increasing the pressure inside
the eye, known as intraocular pressure (IOP).
The optic nerve carries all sensations from the retina to
the brain; the part of the optic nerve that is inside the
eye is called the optic disc. Raised IOP damages the optic
disc.
Glaucoma can sometimes occur with a statistically "normal"
IOP. Hence the vulnerability of the optic disc is another
factor that needs to be considered. Accordingly, the diagnosis
of glaucoma requires more than the mere measurement of intraocular
pressure.
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