DEFINITION: Disruption to the internal eye fluid or increased resistance to the external flow results in internal pressure more than the eye can tolerate and thereby a group of diseases characterised by irreversible damage to the optic nerve.

Figure 1. Appearance of the normal optic disc (left) and glaucomatous optic disc (right).

SYMPTOMS AND FINDINGS: In open angle type glaucoma, the disease gives no indications until the advanced stage at which vision loss develops. The progressive course of the disease is generally slow and initially the patient is not aware of impairments in the field of vision.

In acute closed angle type glaucoma the prevention of internal eye fluid circulation results in high levels of internal eye pressure. In these cases, clouded vision, coloured circles around light, severe pain in and around the eye, redness of the eye and nausea and vomiting may be seen. In congenital glaucoma cases, there are findings of watering of the eyes, large diameter cornea and loss of clarity.

Figure 2. Optical coherence tomography imaging of a patient diagnosed with glaucoma.  Areas flagged as yellow or red, indicate that they are reduced in thickness.

CAUSES AND RISK FACTORS: The risk factors in primary open angle glaucoma are advanced age, negro ethnicity, positive family history, diabetes, low blood pressure and myopia.

The risk factors in primary closed angle glaucoma are advanced age, Caucasian ethnicity, positive family history and female gender.

In addition glaucoma may develop associated with eye trauma, infection inside the eye, steroid use, contact lenses, neovascularisation of the iris and structural changes of the anterior segment of the eye.

TESTS AND DIAGNOSIS: Following biomicroscopy measurement of internal eye pressure, optic disc and gonioscopic angle examination, diagnosis is made by the visual field test and analysis of the optic nerve fibres by tomography.

Figure 3. A demonstration of visual field progression in glaucoma.

TREATMENT: Medical treatment is extremely successful in primary open angle glaucoma. For those who do not respond to laser trabeculoplasty in addition to medical therapy, trabeculectomy surgery may be applied.

Surgical treatment is necessary for primary closed angle glaucoma. Prior to surgery, medical therapy, laser iridoplasty and laser iridotomy may be applied. 

In secondary glaucoma, medical therapy or surgery may be applied according to the underlying disease.