Glaucoma is not a single disease entity but a group of conditions characterized by damage to the optic nerve (detected by pathological cupping of the optic disc) and loss of the field of vision. The two main types are primary open-angle glaucoma and primary angle-closure glaucoma. Primary open-angle glaucoma is more frequent in whites and Afro-Caribbeans, while primary angle-closure glaucoma is more common in South-East Asia. Glaucoma is uncommon among persons under the age of 40, but the prevalence increases with age. Other risk factors include raised pressure inside the eye (intraocular pressure), a positive family history and belonging to a susceptible ethnic group. Primary open-angle glaucoma cannot be prevented, but acute attacks of primary angle-closure glaucoma and more chronic forms of the disease can be prevented by early detection, followed by laser treatment or surgery to the iris. As the early stages of both types of glaucoma are often asymptomatic, patients often present late, particularly in developing countries. Once vision has been lost, regardless of the type of glaucoma, it cannot be restored.

Current situation
WHO has estimated that 4.5 million people are blind due to glaucoma. Published projections indicate that 4.5 million people will be blind due to open-angle glaucoma and 3.9 million due to primary angleclosure glaucoma in 2010 (37). Furthermore, about 60.5 million people will have glaucoma by the year 2010 (44.7 million with open-angle glaucoma and 15.7 million with angle-closure glaucoma). Given the ageing of the world’s population, this number may increase to almost 80 million by 2020. The published projections also indicate that nearly half of the bilateral blindness attributable to glaucoma by 2020 will be caused by angle-closure glaucoma (11.2 million people).

Primary open-angle glaucoma can be managed by long-term use of eyedrops to reduce intraocular pressure or surgery (e.g. trabeculectomy) and should be followed up by long-term monitoring of the visual field, optic disc and intraocular pressure. Detection of eyes at risk of angle closure by assessment of anterior chamber depth or the configuration of the drainage angle of the eye, followed by treatment with laser or surgery to produce an iridotomy or iridectomy can prevent progression to angle-closure glaucoma. Treatment of established primary angle-closure glaucoma requires surgery or medication to reduce intraocular pressure, followed by long-term monitoring.