Glaucoma is a medical condition in which loss of vision (eyesight) can result from excessively high pressure in the eyeball. Pressure within the eye is measured using a technique called oculoplethysmography which is important for detecting the possibility of glaucoma.
Glaucoma is classified as either primary glaucoma or secondary glaucoma:
Primary Glaucoma refers to high pressure in the eyeball in the absence of any other ocular (eye) disease or condition and takes one of two forms:
- Acute Glaucoma (also known as angle-closure glaucoma) applies when the increase in eye pressure occurs suddenly when the angle between the cornea and iris is reduced such that the aqueous humour might drain from the eye. This is often painful and accompanied by blurred vision.
- Chronic Simple Glaucoma (also known as open-angle glaucoma) is more common and applies when the increase in eye pressure is gradual and usually painless. In this case the reduction in quality of vision may also happen gradually and so be less obvious to the patient. This can sometimes happen in the cases of people whose eyes do not have higher than usual pressure, in which case it is referred to as "low-tension glaucoma".
Secondary Glaucoma refers to the situation in which another disorder of the eye / visual system acts to impair the normal (healthy) circulation of the aqueous humour causing the pressure inside the eye to increase.
The main aim when treating glaucoma is usually to reduce the pressure inside the eyeball(s), which is called the intraocular pressure. Methods commonly used to achieve this include the use of eye drops and, if necessary, surgery.
More about Ophthalmology:
This section includes short definitions
of many diseases, disorders, and conditions of the eyes and visual system.
For definitions of other terms in this category, choose from the list to the left (but note that this is not a complete/exhaustive list).
Other related pages include
- A diagram of the eye
- Definitions and descriptions of the parts of the eye
- A concise description of the human retina
- Definitions of parts of the retina
- Clinical and surgical procedures re. eyes and human visual system
For further information see also our pages of books about ophthalmology.