Types of glaucoma
Chronic Open Angle glaucoma:
This is the most common form of glaucoma and its risks increases with age.
The drainage angle of the eye becomes less efficient with time and the pressure within the eye gradually increases, causing damage to the optic nerve.
Typically, open angle glaucoma has no symptoms in the early stages, and vision remains normal. As the optic nerve becomes more damaged, blank spots begin to appear in the visual field. A person will not typically notice these blank spots until the optic nerve is significantly damaged and these spots become large. If all the optic nerve fibers die, blindness results.
Narrow angle glaucoma:
In this case, the iris (the colored part of the eye) may initially be too close to the angle, leaving a narrower area for the fluid to drain. Often, this type of glaucoma develops in farsighted people with small eyes.
In some people, the angle may slowly get narrower over time, then all of a sudden completely close off, abruptly blocking the flow of aqueous fluid (becoming angle closure glaucoma) and leading to increased intraocular pressure or optic nerve damage. This situation can happen in people with a dense cataract that as it grows, starts pushing on the iris and making the angle narrower.
Acute angle closure glaucoma:
In acute angle-closure glaucoma there is a sudden increase in IOP due to the buildup of aqueous fluid. This condition is considered an emergency because optic nerve damage and vision loss can occur within hours of the problem. Symptoms can include blurred vision, nausea, vomiting, seeing halos around lights, headaches, and severe eye pain.
Normal tension glaucoma:
Even people with "normal" IOP can experience vision loss from glaucoma. In this type of glaucoma, the optic nerve is damaged even though the IOP is considered normal. Normal tension glaucoma is not well understood, but we do know that lowering IOP has been shown to slow progression of this form of glaucoma.
Some secondary types
Pseudoexfoliation glaucoma or PXE glaucoma: This is a type of glaucoma that may develop on people with a condition known as Pseudoexfoliation (PXE). It is characterized by the presence of granular material at the margin of the pupil and throughout the anterior chamber of the eye (the area between the iris and the cornea) that can cause blockage in the drainage angle and causing in turn the typical increase in IOP. This type of glaucoma is very aggressive, but at the same time responds very well to trabeculoplasty treatment.
This rare form of glaucoma is caused by pigment deposited from the iris that clogs the draining angle, preventing aqueous humor from leaving the eye. Over time, the inflammatory response to the blocked angle damages the drainage system.
This is a very dangerous type of glaucoma in which blood vessels start growing at the angle and the iris, which can lead to acute angle closure. It is mainly seen in, but not limited to, patients with severe diabetic retinopathy and if not treated promptly can cause total loss of vision and a painful eye that in some cases may have to be removed.