Integrated Diagnostic Tools for Glaucoma Management
By C. Gustavo De Moraes, MD, MPH
The best tools we have to diagnose glaucoma and track progression over time are visual fields and OCT. They are both quick tests, often performed by technicians at baseline and follow-up visits, with the goal of identifying defects and correlating those areas with structural and functional abnormalities.
Integrating the two results has always been challenging, however. In the past, we would print the visual field and OCT and compare them on paper or view one on screen and the other on paper, looking for areas where the tests correlate. The clearer the correlation, the more certain we were that the patient had glaucoma or progression. This process allowed us to identify and monitor disease, but it was far from ideal.
About a year ago, my colleagues and I began using a system that integrates visual field and OCT testing, allowing us to see both test results in high resolution side by side on the same screen, while also analyzing their spatial correlation. This is a big change, and one that I’ve seen has four important functions.
Comparative analysis: Normative database comparisons for both OCT and visual fields gives us the probability that the values at any location on the test indicate a problem. As soon as testing is complete, we can look at the color-coded probability maps and easily see significant defects and the correlation between structure and function. The system allows us to click on specific regions (e.g., superior or inferior) to zoom in on the matching area for both tests.
Greater detail: With side-by-side, high-definition comparisons, we can be much more certain of our diagnosis, even for small changes. With other methods, certainty depends on the severity of the defect, but now we can identify very early defects with greater certainty, so we can treat patients sooner to preserve vision.
Long-term tracking: Over the course of many years, each patient with diagnosed or suspected glaucoma accrues many tests. The system helps us manage these tests, and the analysis improves over time as we collect more quality data.
Efficiency: Since we began using the integrated system, decision making has become easier and faster, with greater certainty. We have a better flow and less wait time for patients. I now spend more time educating my patients, answering questions, and showing them what’s happening to their eyes, using the structure and function maps as a visual aid.
Figure 1. Left panel: 24-2 SITA Standard visual field of the right eye of a patient referred as a glaucoma suspect. Right panel: OCT mapping of the same eye. Note that the OCT shows a superior defect (red arrows) that match the inferior part of the visual field (black arrows). However, the conventional visual field output flags the eye as "within normal limits" (red rectangle). The side-by-side spatial correlation between the visual field and OCT increases the likelihood that the patient actually has glaucoma.
C. Gustavo De Moraes, MD, MPH, is an associate professor of ophthalmology and medical director of clinical trials at Columbia University Medical Center Edward S. Harkness Eye Institute, New York Presbyterian Hospital, and Harlem Hospital.