Glaucoma is not a single disease entity, but refers to a group of eye conditions which share certain common features.
Most eye surgeons agree that to make a diagnosis of glaucoma, the following features should be present:
Higher than normal eye pressure
Evidence of damage to the optic nerve
Change in appearance of the optic nerve which shows damage
Damage to the visual field of the eye which can be demonstrated by performing certain tests on the patient.
Blindness due to glaucoma is irreversible, unlike other eye diseases such as cataracts or retinal detachments,
where some amount of vision can be restored after successful surgery. The only way to prevent blindness from glaucoma is early
detection of glaucoma and treatment.
There have been many classification schemes for glaucoma. The most widely used classification system relies
on the appearance of the drainage angle of the anterior chamber. Using special viewing lenses to see the drainage angle of
the anterior chamber, the eye surgeon can tell if the drainage angle is open, narrow or closed.
Broadly speaking, all glaucomas can be classified into either open angle or closed angle glaucomas. The open and
closed angle glaucomas are further divided into 'primary' or 'secondary'.
'Primary' glaucomas
Refer to glaucomas of undetermined cause and not due to complications of known eye or systemic diseases.
Primary glaucomas usually affect both eyes and may be inherited. The most common type of glaucoma in the world is Primary Open Angle Glaucoma.
'Secondary' glaucomas
Refer to glaucomas caused by eye or systemic diseases such as diabetes, trauma, medication, inflammation,
complicated cataracts, congenital developmental abnormalities etc. Secondary glaucomas are not so common. Secondary glaucomas are usually
unilateral and familial occurrence is less common.
There is a special group of glaucomas called developmental glaucoma.
Developmental glaucomas
Affect infants, children and young adults. Developmental glaucomas can be subdivided into primary infantile glaucoma,
juvenile glaucoma, secondary glaucoma and glaucoma associated with congenital anomalies/systemic disorders.
