While angle-closure is less common than open-angle glaucoma, it usually causes more vision loss if it is not treated properly. This article discusses angle-closure suspects, that is, persons who have not yet developed angle-closure, but have features that make it more likely to occur later. The risk factors among angle-closure suspects are different from suspects for open-angle glaucoma.
What is the angle and what is angle closure?
The angle is the space between the clear part of the eye (cornea) and the colored part (iris), close to their meeting point near the white eye wall (sclera). The angle contains the trabecular meshwork ™, which is the main structure that drains fluid out of the eye. The angle can be viewed by doctors with a simple office test called gonioscopy.
The earliest stage of angle closure is the ‘angle closure suspect.’ In these persons, the iris blocks the view of the TM during gonioscopy for at least half of the angle, but the eye pressure (IOP) is normal and the optic nerve is healthy. In the next stage, ‘angle closure,’ there are signs of damage to the TM such as elevated IOP or scar tissue in the angle, but the optic nerve is still healthy. Elevated IOP in angle closure can happen either suddenly and painfully in an acute angle-closure attack, or more commonly, it develops gradually and silently. When elevated IOP causes optic nerve damage, the disease stage is called ‘angle-closure glaucoma’. There are many more ‘angle-closure suspects’ than persons with ‘angle closure’ or ‘angle-closure glaucoma.’
The standard treatment for angle closure is to prevent iris blocking the TM drainage by making a laser hole in the iris—called iridotomy. Laser iridotomy is recommended for those with ‘angle closure’ and ‘angle-closure glaucoma.’ For ‘angle closure suspects’ laser iridotomy is helpful as a preventive treatment, but these eyes may also do well with a ‘wait and watch’ approach. Recently, a large clinical trial in Chinese angle-closure suspects found that very few untreated eyes worsened over 6 years of follow-up. However, this low risk was reduced by half in eyes treated with laser iridotomy.
Currently, there is no definitive way to identify which angle-closure suspect will develop angle closure disease in the future. So, doctors attempt to estimate this risk by evaluating a series of other factors.
Factors increasing angle-closure risk:
- Smaller eyes (far-sightedness)
- Older age
- Asian and Indian ethnicity
- Having a blood relative with angle-closure glaucoma
- Behavior of the iris and choroid
The standard exam findings and other personal factors of each angle-closure suspect are taken into account by the doctor in presenting the risk and benefit of preventive laser iridotomy. In angle-closure suspects who have a cataract (clouding of the lens), surgery to remove the cataract is an alternative treatment instead of laser iridotomy.
Posted on April 14, 2022
Harry A. Quigley, MD.
Dr. Quigley is the A. Edward Maumenee Professor and Director of the Glaucoma Center of Excellence at the Wilmer Eye Institute at Johns Hopkins, in Baltimore, Maryland. He has participated in glaucoma studies worldwide and published over 4,500 peer-reviewed articles.