Open angle glaucoma 09/09/2013
Glaucoma is an eye disorder that is generally characterised by a pathological increase in intraocular pressure due to a lack of drainage of the aqueous humour, although this is not the only reason, and its common ultimate condition is an optical neuropathy characterised by the progressive loss of optic nerve fibres and changes in its appearance.
The number of people presenting this illness is high as its incidence ranges from 1.5 % to 2 % among those over forty years of age. It's one of the main causes of irreversible blindness in the world.
Glaucoma has different risk factors but one of the main ones is high intraocular pressure, although there is no exact correlation between glaucoma and intraocular pressure as some people may develop the illness with intraocular pressure levels considered normal while, on the other hand, high rates of pressure are detected without any glaucomatous repercussions occurring in the eye.
One typical consequence of glaucoma is the loss of visual field, detected using a campimeter. Loss of vision due to glaucoma first affects the peripheral part of the visual field. If the illness is not treated, the visual field will gradually and increasingly shrink, the central part will darken and, finally, it will degenerate into total blindness in the affected eye.
The vision lost due to glaucoma is irreversible but the right treatment can prevent this or at least reduce its progression.
Open angle glaucoma
The iris-cornea angle is normal. Progression is slow and there are no apparent symptoms but vision gradually deteriorates; that's why this kind of glaucoma is often called "the silent thief of sight".
Depending on its cause, open angle glaucoma is classified as:
Primary. If there's no other illness causing it. Simple chronic glaucoma comes under this category, the most frequent form of the illness.
Secondary. When it is caused by another illness. The following come under this category:
— Neovascular glaucoma, via the formation of new vessels in the iris.
— Phacolytic glaucoma, due to a long-term cataract.
— Pseudoexfoliation glaucoma.
— Ghost cell glaucoma, due to a vitreous haemorrhage.
— Inflammatory glaucoma, caused by an inflammation inside the eye.
— Post-operative glaucoma.
— Glaucoma due to trauma. After eye injury, there may be a haemorrhage in the anterior chamber, or hyphaema, which results in ocular hypertension because the aqueous humour cannot be reabsorbed in the trabecular meshwork.
— Lens-induced glaucoma, caused by the bad positioning of the crystalline lens.
— Steroid-induced glaucoma, caused by the therapeutic use of cortisone or its derivatives over a prolonged period of time.