Glaucoma is the second leading cause of blindness in the world, with open-angle glaucoma being the most common type.
Frequently presents asymptomatically and can be identified on routine ophthalmic examination.
Intraocular pressure is most often elevated, but may be normal in some cases.
Optic disk cupping is diagnostic.
May lead to irreversible loss of peripheral vision and, later, of central vision if untreated.
Glaucoma is a neurodegenerative condition primarily due to dysfunction in outflow of the nutrient-rich fluid, aqueous humor that constantly flows through the eye. Aqueous humor, created in the ciliary body, passes through the pupil into the small area between the iris and the cornea, called the anterior chamber. The fluid then flows into the periphery of the chamber known as the anterior chamber angle. This angle is where the fluid travels through the trabecular meshwork and into blood vessels. Open-angle glaucoma is characterized by an anatomically open angle but with an obstructed and slowed drainage system outflow. The mechanism of blockage is unclear. An increase in intraocular pressure results, characterized by retinal ganglion cell damage, then peripheral vision loss in early disease and central vision loss in late disease.
History and exam
Key diagnostic factors
- cup-to-disk ratio >0.4
- notching of optic nerve cup
- peripheral vision loss
- increased intraocular pressure
- loss of nerve fiber layer
- retinal hemorrhage
- intraocular pressure >23 mmHg
- age >50 years
- family history of glaucoma
- black ethnicity
- diabetes mellitus
1st investigations to order
- direct ophthalmoscopy
- indirect ophthalmoscopy
- slit-lamp biomicroscopy
- visual field testing
Investigations to consider
- photographs of the optic nerve head
- nerve fiber layer analysis
- optical coherence tomography scanning
elevated intraocular pressure and/or visual and retinal changes
- Normal/low-tension glaucoma
- Closed-angle glaucoma
- High myopia
- ICO guidelines for glaucoma eye care
- Comprehensive adult eye and vision examination
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