What is primary angle closure / primary angle closure glaucoma?
The shape of the outer edge of the iris and the drainage channel for the fluid inside the eye (a space known as ‘the angle’) varies from person to person. This space is normally open, so that the fluid can drain freely, but if the edge of the iris and the drainage channel comes into contact from time to time, the patient is described as a primary angle closure suspect (PACS). There are no abnormal attachments between the iris and drainage channel, there is no rise in eye pressure or evidence that damage to the optic nerve has been caused through raised eye pressure in the past. A condition called primary angle closure (PAC) is present if the eye pressure is raised and/or adhesions between the iris and the drainage channel are present, but there is no damage to the optic nerve (the nerve of sight). If there is damage to the optic nerve caused by rises in eye pressure, the condition is described as primary angle closure glaucoma (PACG). In this country, this form of glaucoma is rarer than primary open angle glaucoma (POAG), but it carries a greater risk of damage to vision. This condition affects women more often than men, is commoner in long-sighted people and people of East Asian ancestry, and becomes more likely to occur as people age. Certain drugs and eye operations can also cause the drainage angle to close.
A sudden complete closure of the angle (known as acute angle closure crisis, AAC), which usually affects just one eye, causes rapidly progressing impairment of vision, redness of the eye, and pain in and around the eye which may be so severe as to cause nausea and vomiting. The eye pressure may be very high, because the fluid continues to be formed within the eye but cannot drain away. Various other changes will be seen in the eye by the examining optometrist.
How is primary angle closure / primary angle closure glaucoma managed?
An acute attack of angle closure is an emergency which needs same-day referral to the ophthalmologist. There are drugs that the optometrist can use as first aid. The ophthalmologist will also prescribe drugs and may advise laser treatment (‘YAG laser’) to create a tiny hole in the iris (the coloured part of the eye) through which the fluid can drain. Treatment to the edge of the iris using a different kind of laser (argon laser peripheral iridoplasty) may also be advised. Later, further surgery may be recommended.
If at a routine eye examination there are signs that there have been earlier, milder attacks of angle closure, or if it appears that a patient could develop PACG, the referral can be urgent.