GDx, OCT, HRT—these imaging devices are familiar to ophthalmologists, perhaps too familiar. Some glaucoma specialists argue that ophthalmologists have become so fascinated by high technology that they are overlooking how much information can be gleaned from a brief, routine clinical examination. It’s time, they say, to refocus attention on a good old-fashioned clinical evaluation of the optic nerve.

In the words of Robert D. Fechtner, MD, professor of ophthalmology at the University of Medicine & Dentistry of New Jersey: “We get so enamored of technology in ophthalmology that we can overlook some of the fundamentals.”

The Technologies
Developed over the past 15 years, imaging technologies designed to detect early glaucomatous optic nerve damage and monitor for change include confocal laser scanning tomography (HRT), nerve fiber layer polarimetry (GDx nerve fiber analyzer) and optical coherence tomography (OCT), among others. They permit quantitative measurement of optic disc and retinal nerve fiber layer structure, providing accurate, reproducible information about the optic nerve topography and the surrounding nerve fiber layer.

But they cannot quantify other irregularities of the optic nerve head such as disc hemorrhage, optic disc pallor and peripapillary atrophy, according to David S. Greenfield, MD, associate professor of ophthalmology at Bascom Palmer. What’s more, according to Dr. Fechtner, the imaging devices could miss early signs of glaucoma.

Drs. Fechtner and Greenfield, along with other glaucoma specialists who advocate a return to the basics, contend that high-tech devices are used too often in place of a clinical examination and photography.

A Study Raises Concerns
Their concerns are based on more than casual observations or hunches. Several of them cited a study, headed by Allen M. Fremont, MD, PhD, that assessed conformance to the Academy’s Preferred Practice Pattern for patients with primary open-angle glaucoma. The study, reported in Archives of Ophthalmology, concluded that “care is falling short on several key aspects” of the PPPs.¹ According to the study, only 53 percent of 395 working-age patients with POAG received an optic nerve head photograph or drawing.

“It’s data such as these that make one wonder whether we are forgetting to examine and document the appearance of the optic nerve clinically,” Dr. Greenfield said. The data suggest to him that these examinations are not happening.

Technology Is Easy
Why isn’t it happening? Jeffrey M. Liebmann, MD, said that most doctors rely heavily on the various technologies to help make a diagnosis of glaucoma because it is easy to do. Take perimetry, for example. While it may be easy to use, it can overlook early warning signs of glaucoma.

“Glaucoma is a disease of the nerve that leads to visual field loss. But by the time patients experience visual field loss there has already been a fair amount of nerve damage,” explained Dr. Liebmann, clinical professor of ophthalmology at New York University and director of glaucoma services at Manhattan Eye, Ear and Throat Hospital and New York University Medical Center.

“Visual field loss is not early glaucoma,” continued Dr. Liebmann, who warns against depending upon the field alone for diagnosis. “When you have achromatic visual field loss you’ve already had a fair amount of nerve damage. The key is to try to make a diagnosis by looking at the optic nerve before the patient has field loss.”

The range of normal for the optic nerve appearance is huge, Dr. Fechtner notes. “So it’s going to be very difficult for a machine to find the subtly abnormal nerve.”

On the other hand, a clinical evaluation of the area of thinning of the nerve fiber layer or a disc hemorrhage might enable you to detect signs of trouble early, he said.

Refocusing on the Basics
Dr. Fechtner believes ophthalmologists should become less reliant on the imaging technology. “I’m warning not to use those [devices] instead of a careful examination. The technology complements what we can see. It doesn’t replace it,” he said. “What I would like to see happen is for clinicians to re-educate themselves about how to examine the optic nerve.”

Dr. Greenfield agrees. “I have access to them all [imaging devices] and use them all, but I don’t use them as a replacement for optic nerve examination or photography. They are not a replacement for a careful exam of the optic nerve and documentation of the optic nerve appearance with stereoscopic photography,” he said. Rather,
he sees these technologies as a clinical adjunct to the stereoscopic photograph, which he called “the existing structural gold standard.”

None of this is new, Dr. Liebmann said. “It’s refocusing. We need to refocus our attention on the optic nerve.”

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1 Arch Ophthalmol 2003;121(6):777–783.

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Drs. Fechtner, Greenfield and Liebmann have or currently receive research support from Carl Zeiss Meditec. Dr. Greenfield is a consultant to Carl Zeiss Meditec. Dr. Liebmann receives research support from Heidelberg Instruments.