Glaucoma – Part I
While glaucoma may be considered a common disease of aging, it can occur in anyone and result in potentially career-ending impairment or loss of sight, especially if left untreated. For those whose livelihood depends on good eyesight, including dentists and physicians, a diagnosis of glaucoma can be particularly overwhelming. As we’ve discussed before, filing disability claims based on vision-related conditions is possible, but presents a unique set of challenges.
In this post we will look at the different types of glaucoma and common symptoms.
What Is It?
Glaucoma is a group of eye conditions that damage the optic nerve, which is crucial for good vision. The damage is often caused by abnormally high pressure in the eye. Normally there is a balance between the amount of aqueous humor that is produced in and that leaves the eye but when the eye doesn’t drain properly or is otherwise blocked, excess fluid can back up and increase intraocular pressure (IOP). There are several forms of glaucoma, the most common include:
- Open-angle glaucoma: the most common form (70-90%). The drainage angle formed by the cornea and iris remains open, but the trabecular meshwork is partially blocked, which causes pressure in the eye to gradually increase. The pressure then damages the optic nerve. The changes often happen so slowly that vision may be lost before someone is even aware of a problem.
- Angle-closure glaucoma: also called closed-angle glaucoma, occurs when the iris bulges forward and narrows or blocks the drainage angle formed by the cornea and iris. Therefore, fluid can’t circulate through the eye and pressure increases. This type can be acute (a medical emergency) or chronic and happen gradually. Blindness more often occurs from this than open-angle glaucoma and is largely inherited.
In adults, these chronic forms of glaucoma can be caused by:
- Having high internal eye pressure
- Age (over 40)
- Race (Asian, Black, Hispanic)
- Family history
- Certain other medical conditions (notably: diabetes, heart disease, high blood pressure, sickle cell anemia)
- Corneas that are thin at the center
- Extreme near or farsightedness
- Eye injury or certain types of eye surgery
- Taking corticosteroid medications (especially in the form of eye drops) for extended periods of time
- Gradual loss of peripheral vision, typically in both eyes (open-angled)
- Patchy blind spots either in peripheral or central vision, often in both eyes (open-angled)
- Tunnel vision in advanced stages (open-angled)
- Chronic angle-closure glaucoma: similar slow progression, but 30% will have an attack of acute angle-closure
- Acute angle-closure symptoms include: severe headaches, eye pain, nausea and vomiting, blurred vision, halos around lights, eye redness
- Sometimes patients report sight difficulty (e.g. with reading) before acuity is measurably worse
An eye doctor will likely conduct several tests to assess the health of the eye–including eye pressure and the optic nerve–to determine whether glaucoma is present and, if so, how far it has progressed.
- Tonometry test – examines inner eye pressure
- Ophthalmoscopy (dilated eye exam) – to determine the shape and color of the optic nerve
- Perimetry (visual field test) – tests the complete field of vision
- Gonioscopy – looks at the angle in the eye where the iris meets the cornea
- Pachymetry – examines the thickness of the cornea
- In advanced stages, only a small central area of vision is left, eventually the damage to the optic nerve can be severe enough to cause blindness
- Those with moderate or severe glaucoma also describe looking through a fog, which extends into central vision
- Depth perception is affected
- Untreated glaucoma will eventually cause blindness, sometimes within several years – but treated the odds of going blind are considered low
- However, even with treatment, 15% of people with glaucoma will go blind in at least one eye within 20 years
The rate of progression will depend on a variety of factors including age, overall health of the eye and amount of time elapsed before starting treatment. In the next post we will discuss common treatments for glaucoma and what a diagnosis could mean for a professional suffering from vision impairment.
These posts are for informative purposes only and should not be used as a substitute for consultation with and diagnosis by a medical professional. If you are experiencing any of the symptoms described above and have yet to consult with a doctor, do not use this resource to self-diagnose. Please contact your doctor immediately and schedule an appointment to be evaluated for your symptoms.
Glaucoma Research Foundation
American Academy of Ophthalmology
National Eye Institute
Glaucoma Service Foundation