Neuro-ophthalmology continues to advance with improvements in imaging, diagnostics

The rapid development of technology available to neuro-ophthalmologists greatly changed patient care during the past 20 years.

Issue: November 1, 2002

ByBarrett Katz, MD, MBA

It is interesting to look back at the last two decades and see how issues affecting ophthalmology and neuro-ophthalmology have changed.

Buried within the September 1982 issue of Ophthalmology, a Graduate Medical Education National Advisory Committee report to the secretary of the Department of Health and Human Services spoke to the estimated expected oversupply of ophthalmologists by the year 1990. Interestingly enough, it was predicted in that report that there would be 10,000 ophthalmologists needed for the nation’s health care while there would be closer to 15,000 ophthalmologists working in this country. Understandably, it was surmised that over half of their workload would be in refractions. It was uniformly agreed upon by the assembled panel that medical school training programs should decrease the number of residents trained in ophthalmology.

Changes within the specialty

What about practice issues? The effectiveness of office perimetry was discussed, and the value of electrophysiology testing available to the ophthalmologist was debated. Scanning techniques, even 20 years ago, continued to amaze us. In 1980, the Goldmann perimeter was the gold standard of the sophisticated and modern office. Automated perimetry was knocking at the door, offering promises of taking the technician out of the patient/machine interface.

We worried then about when to do a visual evoked response and when to do an electroretinogram (ERG). In 1982, the computed tomogram was widely available and was dramatically changing the practice of clinical neuro-ophthalmology and neuroimaging. Nuclear magnetic resonance scanning was available in fewer select centers; positron emission tomography (PET) scan and single-photon emission computed tomography technology was lunchtime conversation. Ophthalmologists worried which test to do, and to what avail.

Which diagnoses were ophthalmologists worried about missing in neuro-ophthalmology 20 years ago? Then, as now, it was temporal arteritis, perhaps ethambutol-induced optic neuropathy, occasionally the remote effects of carcinoma.

What treatment modalities did we use then that we have since discarded? Perhaps most impressively, 20 years ago the average ophthalmologist commonly treated acute optic neuritis with oral steroids. Now we know better; we know that oral steroids increase the risk of a second attack, that IV steroids may lower that risk and that immunomodulatory therapies administered prophylactically may decrease the risk of a patient with optic neuritis going on to develop multiple sclerosis.

Perhaps the most dramatic change over the last two decades has been the rapid advance of technology available to the neuro-ophthalmologist in taking care of patients. No-where is this most compelling than in neuroradiology. It is probably true that Moore’s Law applies in clinical imaging, which is to say that every 18 months the size of a chip decreases and the speed of the computer behind it increases dramatically.

The resolution of the MRIs of the brain rivals images of dissections. An MR angiogram is performed routinely with minimal risk, and some argue that an MR angiogram suffices to rule out an aneurysm. Fat suppression of an orbital MR scan defines exquisite anatomy previously unavailable to the clinician. Multifocal ERG testing helps differentiate between optic nerve disease and retinal disease. Functional MR promises to take our understanding of the central nervous system and its extraordinarily complex organization to new levels, and offers promises of clinical advances.

Molecular biology has forced us to reorganize how we think about disease processes, and allowed us to give entities better names with better organizational hierarchy. Mitochondrial disease, genetic mapping, proteonomics and polymerase chain reaction probe analyses have allowed us to dig and drill deeper into underlying pathophysiology of neuro-ophthalmic disturbance. We now look for genetic markers for unique phenotypes, and await the day when such genetic descriptions will allow for interventional therapeutic success.

Vascular diseases of the eye are now called retinal strokes. We think about the ocular declaration of cerebrovascular disease, while treatment for them remains a constant challenge. Glaucoma has become just another optic neuropathy, as the primary thrust of its treatment moves to neuroprotection. The protection of sick axons has become a major business and key focus in neurosciences research.

New therapies for neurosurgeons are available: radiation for optic sheath meningioma, interventional neuroradiology for aneurysms and carotid cavernous fistulas, Gamma knife stereotactic microsurgery for vascular formations. The popularity of carotid endarterectomy is waxing, while that of sheath fenestration is waning.

For Your Information:

Barrett Katz, MD, MBA, is a professor of ophthalmology, neurology and neurosurgery and chair of the ophthalmology department at The George Washington University. He can be reached at 2150 Pennsylvania Ave. NW, Washington, DC 20037; (202) 741-2825; fax: (202) 741-2821; e-mail: bkatz@mfa.gwu.edu

Future advances

What will the next decades bring us? Likely, advances will continue in the following areas:

Neuroimaging, allowing tests to have better resolution, and images to be acquired in less time.

Continued intravascular manipulation of vascular lesions, so that neurosurgery moves more towards a conservative endovascular approach to operations.

New approaches for glaucoma, as it becomes more a question of protecting neural tissue.

Molecular biology continues to show us how varying genotypes can present with differing phenotypes.

Neuroplasticity of the central nervous system will likely be seen as much more plastic than heretofore accepted.

Stroke therapy will advance; also, as we make progress into the treatment of hemispherical disease, the analogies of treating strokes that affect the retina and optic nerve — from central retinal artery occlusion to anterior ischemic optic neuropathy — will offer promise for us and our patients.

Functional MR will begin to bring together our neuroanatomic understanding of the visual brain and the neurophysiology that underlies central processing of visual information.

PET scanning will become clinically relevant as it becomes more widely available.

Ultimately, however, a good history and thorough physical examination in the final analysis will continue to be the most compelling segment of a patient’s evaluation, and we must keep this in mind as we move forward in these other arenas.