SLP has outcome-predictive potential in NAION

Fort Lauderdale, FL-Scanning laser polarimetry (SLP) seems to have good ability to predict the visual field and retinal nerve fiber loss outcomes compared with evaluation of images over time in patients with nonarteritic ischemic optic neuropathy (NAION). The SLP results are not correlated with optical coherence tomography (OCT) outcomes, according to Mark J. Kupersmith, MD.

Dr. Kupersmith and his colleagues were looking for ways to model the optic nerve in acute injury that would be valuable when there is a therapeutic intervention available. Dr. Kupersmith is affiliated with the Department of Neuro-Ophthalmology, Roosevelt Hospital and New York Eye and Ear Infirmary, New York.

Using the commercially available scanning laser polarimeter (Carl Zeiss Meditec), the investigators postulated that, given the dependence of SLP on intact axonal microtubules and membranes and neurofilaments, SLP might show something different in an acute injury. Any parameter that was lower than the 5th percentile of the data in the fellow unaffected eye or from the age-matched database from different instruments was considered abnormal. Twenty-seven patients were included.

A representative case showed that SLP anticipated a progressive problem at baseline and showed a decreased superior field. At 1 month, the visual field had markedly deteriorated; at 3 months it was the same. In contrast, OCT at 3 months showed thinning that was almost within the normal range.

“SLP seems to be very helpful for predicting baseline injury,” Dr. Kupersmith said.
Of the 27 quadrants that were abnormal at baseline, 25 remained abnormal at 3 months follow-up, and all had substantial field defects.

“SLP is predictive and as good as looking at images long range,” he said. “Baseline SLP does not correlate with OCT outcomes. Acute segmental retardation correlates fairly well with the baseline field and the outcome of the visual fields. SLP clearly is complementary to OCT. SLP may serve as a biomarker for showing permanent injury at presentation, which will be very useful when therapies become available.”

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