Diagnosing Glaucoma

Dr. Guy Eakin: Hi! I'm Dr. Guy Eakin, Vice President of Scientific Affairs for the BrightFocus Foundation. Today I'm talking about glaucoma, the leading cause of irreversible vision loss and ultimately blindness. In this segment, I'm going to talk about how glaucoma is diagnosed. If you are at high risk of developing glaucoma, your doctor will often perform several tests to determine whether or not the optic nerve has been damaged. During the eye examination, the doctor will check several readings and these will include a number of different things and often your eye doctor will want to take more than one reading, so that they can determine what the pressure is at different times of the day. Since eye pressure can vary from day to day and even from hour to hour, these comparative readings are much more likely to give your doctor an accurate picture of your overall eye pressure. However, if the cornea or the clear covering of your eye is thin because of genetics or of prior surgeries, this pressure reading can be artificially low. LASIK, which is the surgical procedure intended to reduce a person's dependence on glasses, can cause the cornea to become thinner than normal, so if you have had LASIK or a similar procedure, be sure to inform your doctor.

Dr. Donald Zack: So usually, when a patient comes to see a glaucoma doctor, one of the things we'll do is do a functional test of their vision. He may use a visual field test which is basically like a video game. It's a big ball and the computer will shine lights in different places in the patient's visual field and then the patient's holding a little control, little button, whenever they see the light, they push the button and the machine will shine the light in different places and will also shine different intensities. So it measures not only whether the patient can see the dot in a particular area, but how sensitive they are. This allows us to measure, as I mentioned the visual field. That's very important, because in glaucoma, vision loss usually is not the sensual high acuity vision in the middle, but it's a side vision. And we see the vision gets smaller and smaller. We'll also measure the patient's visual acuity using a standard reading chart like 20/20, 20/30, 20/40. We also use a lamp exam to measure those general mechanical and those general structures of the eye. Then we'll use an applanation or the tonometer to measure the eye pressure in the eye. Then we'll dilate the eye and we'll look in back to look at the optic nerve. And the optic nerve or the optic disk is basically like a cable, it takes information from the eye to the brain and that's what ultimately gets damaged in glaucoma. We'll also use a special kind of lens to look at the side part of the eye called the angle. Those are really most of the tests that we generally do.

Dr. Guy Eakin: All of these tests are painless and noninvasive. To learn more about glaucoma, check out the other videos in this series, including how to treat glaucoma.