Exploratory Study of the Association between the Severity of Idiopathic Intracranial Hypertension and Electroretinogram Photopic Negative Response Amplitude Obtained Using a Handheld Device.

Antony Raharja,Mathura Indusegaran,Omar A Mahroo,Isabelle Chow,Shaun M Leo,Christopher J Hammond,Sui H Wong

doi:10.3390/life11050437

Abstract

The photopic negative response (PhNR) is a negative component of the photopic flash electroretinogram that follows the b-wave and is thought to arise from the retinal ganglion cells. Reduction in its amplitude in idiopathic intracranial hypertension (IIH) has been previously documented using formal electroretinography. This study explored the use of a handheld device (RETeval, LKC technologies, Gaithersburg, MD, USA) in 72 IIH patients of varying stages and severity (and seven controls) and investigated associations between PhNR parameters and disease severity. PhNR amplitudes at 72 ms (P72) and p-ratio (ratio to b-wave peak value) differed significantly across groups, with a trend towards smaller amplitudes in those with severe IIH, defined as papilloedema with Modified Frisén Scale (MFS) ≥ 3, retinal nerve fibre layer (RNFL) ≥ 150 μm or atrophic papilloedema (p = 0.0048 and p = 0.018 for P72 and p-ratio, respectively). PhNR parameters did not correlate with MFS, RNFL thickness, standard automated perimetry mean deviation or macular ganglion cell layer volume. This study suggests that PhNR measurement using a handheld device is feasible and could potentially augment the assessment of disease severity in IIH. The clinical utility of PhNR monitoring in IIH patients requires further investigation.

Highlights

Idiopathic intracranial hypertension (IIH), known as pseudotumor cerebri (PTC), is a neuro-ophthalmic condition in which raised intracranial pressure causes axoplasmic stasis in retinal ganglion cells (RGCs) by mechanical compression, leading to clinical papilloedema [1]
We explored the correlation between photopic negative response (PhNR) parameters and visual parameters, and clinical parameters (BMI, lumbar puncture opening pressure and duration of symptoms)
Our study showed that PhNR amplitudes are significantly smaller in severe IIH patients compared to controls, indicating that RGCs’ function may be impaired in severe papilloedema or optic atrophy caused by IIH

Summary

Introduction

Idiopathic intracranial hypertension (IIH), known as pseudotumor cerebri (PTC), is a neuro-ophthalmic condition in which raised intracranial pressure causes axoplasmic stasis in retinal ganglion cells (RGCs) by mechanical compression, leading to clinical papilloedema [1]. It predominantly affects obese women of child-bearing age, and its incidence has been significantly increasing in recent years in association with the obesity epidemic [2,3]. An objective assessment tool could be helpful to improve stratification of IIH patients to identify those at risk of visual loss

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Conclusion