Surveying old, new diagnostic tests for pediatric neuro-ophthalmic cases

Reviewed by R. Michael Siatkowski, MD

Diagnostic technology in pediatric neuro-ophthalmology has made tremendous advances in the past 25 years, according to R. Michael Siatkowski, MD.

“We’re close to an easy-to-use, handheld optical coherence tomography (OCT) device for the operating room, but it still needs to be cheaper, lighter, and able to adapt to eye changes in the first 3 years of life,” said Dr. Siatkowski, the David W. Parke II, MD Professor; vice chairman for academic affairs, and residency program director, Dean McGee Eye Institute, University of Oklahoma, Oklahoma City. 

“It also has to have higher-quality analytics,” he added. “You don’t want to spend a lot of time doing calculations by hand afterward.”

OCT pearls

Dr. Siatkowski shared two pearls for OCT use: 

•  When switching machines, perform at least two studies on each machine before making the conversion.

•  Watch out for what he calls the papilledema trap, in which surgeons rely only on results seen on OCT to gauge progress in a patient. Progressive decrease in nerve fiber layer thickness may reflect improvement in papilledema, but can also be a sign of worsening optic atrophy, he noted.

Always consider the patient’s history, exam, fundus results, and other factors before making a clinical judgment.

Fundus imaging advances are also frequently used. Dr. Siatkowski said he favors the use of autofluorescence because it is easier to view changes, such as Plaquenil-induced toxicity.

One testing modality that may still be misused is electrophysiology, he noted.

“It has its role,” Dr. Siatkowski said. “If the results are clearly abnormal, you can make a confident diagnosis. In most cases, the exam itself should tell if the patient is clinically abnormal, so the added diagnostic value is less. The hard part is when results are somewhat abnormal.”

It can be difficult to tell how much is weighted on disease versus patient cooperation versus testing circumstances. To get best results from electrophysiology, clinics need professionals who are seasoned at performing the tests and who have done enough of them in children to have a normative database.

“If you don’t have this, you can run into a lot of problems,” said Dr. Siatkowski, noting this may result in conflicting information. “Sometimes, if you can’t do these tests well, you’re better off with a detailed history and physical or referring to a place with more extensive experience.”

Dr. Siatkowski also uses orbital echography.

“It’s not new, but new A-scan evaluation of the optic nerve is very helpful,” he said, adding that the 30° test is particularly helpful.

Optic nerve sheath diameter

Optic nerve sheath diameter

If the optic nerve sheath diameter is enlarged, but decreases by 15% or 20% when the eye is abducted 30°, this indicates that subarachnoid fluid is being pushed posteriorly, as in optic neuritis or papilledema. If the optic nerve sheath diameter is enlarged but does not decrease on abduction, this indicates a tumor or some sort of infiltration, according to Dr. Siatkowski.

Neuroimaging also has reached advances in the past 25 years, he said.

Due to radiation concerns in children, he believes that computed tomography should be avoided unless absolutely urgent, as magnetic resonance imaging is still good for bone, orbit, and soft tissue.

It is important to use gadolinium unless there is allergy or renal disease. The use of gadolinium provides a greater chance of spotting masses, where the infused study clearly demonstrates a mass lesion that was missed on the non-contrast study.

Genetic testing is increasingly performed today. Commercially available testing is sometimes the quickest and cheapest option, such as for dominant optic neuropathy, he noted.

Dr. Siatkowski recommended that ophthalmologists stay familiar with functional visual loss testing and teach others in the profession how to use it, because it is commonly seen in children.

Some testing devices that have been around a long time and remain useful include the ophthalmoscope, retinoscopy, neutral density filters, and Frenzel goggles.

Finally, Dr. Siatkowski stressed the importance of doing a thorough history and exam. “It’s still the gold standard and well worth your time,” he said. 

R. Michael Siatkowski, MD

e:RMichael-Siatkowski@dmei.org

This article was adapted from Dr. Siatkowski’s presentation at the 2016 meeting of the American Academy of Ophthalmology. Dr. Siatkowski has no related disclosures.