Open-angle glaucoma

Glaucoma is the main cause of irreversible blindness in the world; open-angle glaucoma is the most common type.

Frequently presents asymptomatically and may be identified on routine ophthalmic examination.

Intra-ocular pressure (IOP) is most often elevated, but it may be normal.

Optic disc cupping is diagnostic.

Untreated glaucoma may lead to irreversible loss of peripheral vision and, later, of central vision.

Glaucoma is a neurodegenerative condition in which elevated IOP occurs primarily due to dysfunctional aqueous humour outflow. IOP is the primary modifiable risk factor.

Aqueous humour is a nutrient-rich fluid that constantly flows through the eye. It is created in the ciliary body, passes through the pupil into the the anterior chamber (a small area between the iris and cornea) and then into the anterior chamber angle (at the periphery of the chamber) where it travels through the trabecular meshwork and into blood vessels.

Open-angle glaucoma is characterised by an anatomically open angle with a dysfunctional and slowed outflow. Although the mechanism causing the blockage is unclear, it increases the IOP. The initial clinical presentation is of retinal ganglion cell damage, followed by peripheral vision loss in early disease and central vision loss in late disease.[1]Weinreb RN, Leung CK, Crowston JG, et al. Primary open-angle glaucoma. Nat Rev Dis Primers. 2016 Sep 22;2:16067. http://www.ncbi.nlm.nih.gov/pubmed/27654570?tool=bestpractice.com