There are several types of glaucoma all of which 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 gradually 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 on its own, 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 here, the ‘drainage’ canal is closed by the iris.
The third type is developmental glaucoma, which may be further divided into congenital glaucoma (occurs in infants from the time of birth) and juvenile glaucoma (occurs in children and young adults).
Glaucoma or high IOP may also be secondary and occur due to other causes such as the use of steroid drops without prescription. Such drops should never be used without monitoring the intraocular pressure.
