What is Glaucoma?
Glaucoma is a progressive, vision threatening disease that is commonly asymptomatic until severe stages. It is the third leading cause of irreversible blindness in the United States. Unfortunately, up to fifty percent of glaucoma remains undiagnosed. The most common type of glaucoma, known as Primary Open Angle Glaucoma (POAG) occurs when high eye pressure (intraocular pressure or IOP) damages the optic nerve fibers. High IOP is the #1 risk factor for developing glaucoma and the only factor we can modify with medications or surgeries. Glaucoma is more prevalent in the older population, and there is a higher incidence in Black and Latino populations. There is also a genetic link in glaucoma. Patients with siblings or parents with POAG are more likely to develop POAG.
Types of Glaucoma
There are four major types of glaucoma – open-angle, angle-closure, congenital, and secondary. The part of the eye between the iris and the cornea is filled with a clear fluid called aqueous humor. This fluid is created by a structure called the ciliary body and is drained through channels where the iris and cornea meet, also known as the anterior chamber angle. When fluid does not drain properly, it causes pressure to build up in the eye. This increased pressure damages the optic nerve which can lead to glaucoma.
Open-angle glaucoma is the most common type of glaucoma. The increase in IOP happens very gradually over time, therefore it is often asymptomatic until severe damage occurs. There is a slow loss of peripheral vision, also known as tunnel vision. Unfortunately, the optic nerve damage and resulting visual field loss is permanent.
Closed-angle glaucoma occurs when the anterior chamber angle is suddenly blocked, and fluid cannot drain. Acute closed-angle glaucoma is an emergency. Some symptoms may include sudden, severe pain in one eye, decreased or cloudy vision, nausea and vomiting, or a red eye.
Secondary glaucoma occurs due to another cause, and can also be classified as open- or closed-angle glaucoma. Some causes include medications such as corticosteroids, eye diseases (like uveitis), diabetes, or eye injury. Symptoms are most commonly related to the underlying cause.
Congenital glaucoma is present at birth. It is caused by improper eye development, and tends to run in families. Symptoms may include cloudiness or enlargement of the eye, sensitivity to light, or tearing.
Testing
There are multiple tests involved in monitoring glaucoma. The first imaging instrument we use is the Optos camera which takes a two dimensional photo of the optic nerve. This imaging is taken on nearly every patient at Optique. We also check intraocular pressure at every exam. If your doctor determines that your optic nerves look suspicious for glaucoma or if your intraocular pressure is considered elevated, further testing is performed at a follow up appointment. At this visit, we use an Optical Coherence Tomographer (OCT) which quantifies the thickness of the retinal nerve fibers that make up the optic nerve as well as constructs a three dimensional image of the eye. We perform peripheral vision testing utilizing a virtual reality headset, allowing us to determine our patient’s visual field and if it is impacted by glaucoma. Additional testing we utilize include pachymetry which measures the thickness of the cornea, and gonioscopy which measures the angle that drains the fluid of the eye. We will then repeat these tests anywhere from a 6-month to 12-month basis and compare values from each visit to determine individual risk for development or progression of glaucoma.
Management
At Optique, we diligently monitor intraocular pressure, optic nerve thickness, peripheral vision, among other factors to assess your risk of developing or progressing glaucoma. If treatment is needed, we will thoroughly educate you on your options including surgical intervention and topical drop therapy and prescribe the best option for you. Glaucoma is a sight threatening condition that can result in tunnel vision if left untreated. It is critical that every patient receives an annual eye examination to assess ocular health, including additional testing for glaucoma if your optometrist deems necessary.
