Glaucoma is one of the most common eye diseases, affecting about 1.9% of people over the age of 40. Glaucoma is a slow, chronic disease of the optic nerve that often presents in a very subtle fashion. This disease will affect your peripheral vision first before it causes a loss of visual clarity.
Many patients may not be aware of any changes until significant damage is done. These features make glaucoma a difficult disease to diagnose for both the patient and the physician, which is why we utilize several tests to help determine whether a patient truly has glaucoma and, if so, to what extent the disease has damaged the optic nerve.
Patients are often referred to an ophthalmologist for a glaucoma evaluation. The normal range for intraocular pressure is about 8-22 mmHg; however, some patients may experience glaucoma even within a “normal range”. An elevated intraocular pressure will often set off a red flag for further investigation into whether a patient is developing glaucoma.
Glaucoma is closely tied to the eye’s pressure and the treatment for this disease is linked to lowering the eye pressure. The patient’s cornea, the clear front window of the eye, can cause variations in the intraocular pressure measurements.
One important reading during a glaucoma evaluation is the corneal thickness. When the corneal thickness is thin, patients are at a higher risk of glaucoma as their intraocular pressure readings tend to be falsely low. On the other hand, many patients are referred for elevated intraocular pressure but only have a thick cornea, which has led to false elevated eye pressure readings.
Numerous tests are employed to help evaluate the presence and severity of glaucoma. One important test is optical coherence tomography (OCT), which takes a quick scanning picture of the optic nerve. This test provides a quantitative measurement to track the disease over time.
Visual field testing is utilized to measure the functional damage from glaucoma. This test is critical to help track progression of the disease over time.
Another test is examination under a slit lamp microscope. Gonioscopy utilizes a special lens to visualize the anterior chamber angle to determine if there is any physical obstruction causing glaucoma. The physician will also examine the health and appearance of the optic nerve under the microscope.
The physician will put together all of these tests to ensure the patient is on the appropriate treatment regimen to help minimize any disease progression.