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Types of
glaucoma
There are several types of glaucoma, all of them can increase
IOP and damage the optic nerve.
In open angle glaucoma, an increase in resistance to the outflow
in the canal causes a rise in the IOP. This type develops
slowly and the symptoms may not be obvious till the damage
has occurred. The patient may lose peripheral vision, leaving
only central or 'tunnel' vision. This occurs more among people
above 45 years of age.
In angle closure glaucoma there is a relative block to the
flow of fluid, which causes raised pressure. This occurs more
among long-sighted people. In the rarer acute cases, the symptoms
are dramatic and may include severe pain in the eye, headache,
nausea, reduced vision, and seeing rainbow coloured rings
around lights. Stress, anxiety, and reading may also precipitate
an attack, which may resolve spontaneously but recur after
some time.
The more common variety of angle closure glaucoma is chronic
angle closure. This behaves similar to open angle glaucoma
but the 'drainage' canal is closed by the iris.
The third type is developmental glaucoma, which may be further
divided into congenital glaucoma (in infants from birth) and
juvenile glaucoma (in children and young adults).
Glaucoma or high IOP may also be secondary, due to other causes,
such as use of steroid drops without prescription. Such drops
should never be used without monitoring the intraocular pressure.
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