|Optovue iVue’s SD-OCT offers the benefits of faster scans, giving the clinician significantly more data in less time.|
Thanks to innovative instrumentation, managing glaucoma patients is easier than ever.
Technological advances have improved the way we diagnose and monitor disease, especially when it comes to glaucoma management. A decade ago, we had time domain optical coherence technology (TD-OCT) for monitoring retinal nerve fiber layer (NFL) thickness in our glaucoma patients. This technology revolutionized the way we managed the condition, but was not without its limitations.
Although we could view the retina in a way that we never had been able to in the past, the level of precision, along with the slow measurement time of TD-OCT technology, made the quality of the images highly dependent on the person performing the test.
As with most technologies, OCT has rapidly progressed to become a gold standard in both diagnosing and managing glaucoma. Spectral domain OCT instruments (SD-OCT) from companies such as Carl Zeiss Meditec, Inc., Heidelberg Engineering, Inc., Optovue Inc, and Topcon Medical Systems, Inc., offer the benefits of higher resolution and faster scans, giving the clinician significantly more data in less time.
Here is how SD-OCT has shaped the landscape in managing our glaucoma patients:
Retinal nerve fiber layer thickness: Monitoring NFL thickness around the optic nerve has become the standard of care for glaucoma suspects and patients diagnosed with glaucoma. The data is presented with most technologies in a temporal-superior-nasal-inferior-temporal (TSNIT) graph where the patient’s NFL thickness is compared to the normal range for those in their age group. The true benefit of this technology is measuring for changes over time.
Ganglion cell complex (GCC): This is measured in the macular region and often correlates with decreases seen in NFL thickness around the optic nerve. There are certain cases where there will be changes seen in the GCC in the macular region before the changes are seen at the NFL around the optic nerve head. We would suggest more thoroughly testing the central 10Â° of a patient’s visual field if there is decreased NFL thickness.
Corneal thickness: This was traditionally done with ultrasound technology and sometimes caused a higher reading due to the measurement being taken on an angle. With current SD-OCT technology, however, the central corneal thickness can be measured more accurately.
Visualizing the angle: Along with measuring corneal thickness, this perspective allows you to view the angle created between the cornea and the iris, revealing whether the angle may be narrow, and thus, an additional risk factor. It’s important to note that though the angle can be visualized with this view, it should not be considered a replacement for gonioscopy, but rather a supplemental measurement.
With the advances that now exist””and continue to improve””it’s becoming clear this technology is quickly becoming part of the standard of care to manage glaucoma patients.
Mile Brujic practices at Premier Vision Group in Bowling Green, OH; David Kading practices at Specialty Eyecare Group with locations in Seattle and Kirkland, WA.
WHERE TO FIND IT:
Carl Zeiss Meditec, Inc.
Heidelberg Engineering, Inc.
Topcon Medical Systems, Inc.