How can a patient tell if they have glaucoma? In most cases, they can’t! Four out of five patients have a form of open angle glaucoma which does not typically produce any pain sensation or other symptoms in early and even moderately advanced glaucoma.
Patients with untreated glaucoma develop progressive optic nerve damage painlessly. As the optic nerve damage occurs slowly over time, we can. This loss occurs so slowly and far enough away from the center of your visual field that patients rarely perceive the loss in function. However, we can measure this loss in the clinic with a visual field test by measuring places in the peripheral vision, typically towards the nose or just above or below center vision, that subtly lose the ability to detect low levels of light.
In its earlier stages, open angle glaucoma doesn’t noticeably affect the patient’s daily functioning. In fact, a patient can have severe glaucoma, and his or her visual acuity can still measure a crisp 20/20. The central field of vision, which we use to read a book, distinguish a face, make out the scoreboard, or read a street sign remains intact until the late stage of the disease.
A patient can have up to 50% of the optic nerve damaged before we can detect visual field loss in the clinic. Even then, many of these patients are unaware of visual symptoms. The more advanced the glaucoma is at diagnosis the more likely the patient will experience noticeable loss of visual function in their lifetime. Regular eye exams in adulthood are the only way to avoid this scenario.
Angle closure glaucoma, which accounts for one out of five glaucoma cases in the U.S., can cause symptoms. If the drainage angle closes acutely (acute angle closure glaucoma), patients can experience a variety of symptoms: eye pain or headache (usually on just one side), which can be severe enough to cause nausea and vomiting, as well as eye redness, dilated pupil, blurry vision, and colored rainbows around lights. This is a medical emergency which requires immediate attention by an eye doctor to prevent permanent eye structural damage and vision loss. Fortunately, acute angle closure is less common in the U.S.. Once again, regular eye exams can detect a predisposition to this problem and treatment can be undertaken to prevent it before symptoms and damage ensue.
Take home lesson: Even if your vision is fine, schedule a regular eye exam with Stiles Eyecare Excellence.