Editor's Note: Glaucoma Subspecialty Day 2014, held during this year's American Academy of Ophthalmology (AAO) meeting, focused on the integration of new technologies and approaches into daily practice. Douglas J. Rhee, MD, and Shuchi B. Patel, MD, convened afterward to discuss some of the session highlights for Medscape readers.
Reliable Visual Fields
Dr Rhee: Hello. My name is Douglas Rhee, and I am chair of ophthalmology at Case Western Reserve University. Joining me is Dr Shuchi Patel, assistant professor and director of the glaucoma service at Loyola University in Chicago. We'll be discussing the recent AAO meeting, and some of the practical tips that came out of it.
Let's start with a particularly good session on visual fields. What did you find interesting about that session?
Dr Patel: It was a great session. General ophthalmologists as well as glaucoma specialists use visual field testing for diagnosing and monitoring for the progression of glaucoma, so it's a key instrument for us. It can be difficult to achieve reliable—and reproducible—visual field results. Tips on how to improve the reliability of visual fields are always useful, including how we can have patients participate and help to give us those reliable data.
Dr Rhee: It's hard at the later stages of disease, isn't it?
Dr Patel: We get a lot of generalized depression. Patients have difficulty with fixation because their vision is poor, and then the test results are unreliable. It's very difficult to use them to follow progression.
Dr Rhee: What were some of the tips that you thought were very helpful?
Dr Patel: One is that there are other options if you are using a visual field test, in terms of the stimulus size and intensity. Changing it from the standard Stim3 to a Stim5 will make the spot size significantly larger—up to 64 mm in size. It makes it easier for patients with poor vision to be able to respond to the stimulus. It was a great idea to get a better test result.
Another tip was that if patients have a central scotoma or other retinal pathology that prevents them from having good fixation (which can also lead to a poor visual field), have them use a central diamond for fixation so that they have a larger area to fixate on and do a reliable test.
Yet another good tip was to remember that every test does not have to be a 24-2. We can change to a 30-2, or in situations where we are really constricted, go down to a 10-2. Those tips can make more reliable fields and more reproducible fields to monitor for progression.
Dr Rhee: I completely agree. Those are wonderful tips for the glaucoma specialists and comprehensive ophthalmologists.
When I switch over to a 10-2 (for a patient with a very narrow central visual field) or if I switch to a Stim5, within about a week I do a back-to-back comparison. I have whatever test they had been getting before to see whether there is progression, and then I have the new test to establish a new baseline. Otherwise, it's hard to compare a Stim3 with a Stim5 done a year ago and say whether there has been any progression. I establish a new baseline. Is that something that you also would recommend?
Dr Patel: It's a great idea. Sometimes I do both on the same day, but it can be stressful for patients to do that much testing. Bringing them back in a short period to repeat is probably a better idea.
Dr Rhee: I tell patients that I am not going to do two visual field tests at once, but we want to be able to use this test and make it easier for them to take the test, so I need them to come back in a week or two. If their pressures are stable, I'm not worried that they are going to progress in that timeframe.