Original article
Retinal Nerve Fiber Layer Thickness in Children With Optic Pathway Gliomas

https://doi.org/10.1016/j.ajo.2010.08.046Get rights and content

Purpose

To determine the relationship of high-contrast visual acuity (VA) and low-contrast letter acuity with retinal nerve fiber layer (RNFL) thickness in children with optic pathway gliomas.

Design

Cross-sectional convenience sample, with prospective data collection, from a tertiary care children's hospital of patients with optic pathway gliomas associated with neurofibromatosis type 1, sporadic optic pathway gliomas, and neurofibromatosis type 1 without optic pathway gliomas.

Methods

Patients underwent best-corrected VA testing using surrounded H, O, T, V optotypes and low-contrast letter acuity (5%, 2.5%, and 1.25% low-contrast Sloan letter charts). Mean RNFL thickness (micrometers) was measured by a Stratus optical coherence tomography device (Carl Zeiss Meditec) using the fast RNFL thickness protocol. Eyes were classified as having abnormal vision if they had high-contrast VA of more than 0.1 logarithm of the minimal angle of resolution units or visual field loss. The association of subject age, glioma location, and RNFL thickness with both VA and low-contrast letter acuity scores was evaluated by 1-way analysis of variance and linear regression, using the generalized estimating equation approach to account for within-patient intereye correlations.

Results

Eighty-nine eyes of patients with optic pathway gliomas were included, and 41 were classified as having abnormal VA or visual field loss. Reduced RNFL thickness was associated significantly with higher logarithm of the minimal angle of resolution scores for both VA (P < .001) and all low-contrast letter acuity charts (P < .001) when accounting for age and glioma location.

Conclusions

Eyes of most children with optic pathway gliomas and decreased RNFL thickness had abnormal VA or visual field loss.

Section snippets

Patients

A cross-sectional convenience sample with prospective data collection identified candidate subjects between 6 and 21 years of age during their routine clinical visits to the neuro-ophthalmology or neuro-oncology clinics at Children's Hospital of Philadelphia from July 2009 through January 2010. Children between 6 and 17 years of age required parental or guardian informed consent and, when appropriate, child assent before study enrollment. Participants 18 to 21 years of age provided their own

Results

Sixty-two patients (124 study eyes) were enrolled and attempted to complete the study procedures. OCT imaging was unsuccessful for both eyes in 3 patients and for 1 eye in 7 patients because of patient cooperation, immobile eye, or facial plexiform fibroma impeding the OCT. During the study, one patient originally diagnosed to have NF1 was found to have an as-yet unidentified genetic mutation, and this child's data were not included in the analysis. Therefore, 58 patients contributed 109 eyes

Discussion

This study demonstrated that most children with optic pathway gliomas and decreased RNFL thickness have abnormal VA, VF loss, or both. Some children with decreased RNFL thickness had normal high-contrast VA, but abnormal VF results. Interestingly, other children were found to have normal VA and normal VFs despite a significantly decreased RNFL thickness—possibly suggesting that VA or VF loss may not have been detected with current techniques or that the child has yet to manifest symptoms.

Robert A. Avery recently completed his Neuro-ophthalmology fellowship at the Children's Hospital of Philadelphia/University of Pennsylvania and a Master's degree in Clinical Epidemiology at the University of Pennsylvania, Philadelphia, Pennsylvania. In July 2010, Dr. Avery joined the faculty of the Department of Neurology and the Gilbert Family Neurofibromatosis Institute at Children's National Medical Center in Washington DC where he has a dedicated pediatric neuro-ophthalmology practice and

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    • Cited by (0)

    Robert A. Avery recently completed his Neuro-ophthalmology fellowship at the Children's Hospital of Philadelphia/University of Pennsylvania and a Master's degree in Clinical Epidemiology at the University of Pennsylvania, Philadelphia, Pennsylvania. In July 2010, Dr. Avery joined the faculty of the Department of Neurology and the Gilbert Family Neurofibromatosis Institute at Children's National Medical Center in Washington DC where he has a dedicated pediatric neuro-ophthalmology practice and clinical research program.

    Laura J. Balcer, MD, MSCE, is a Professor of Neurology, Ophthalmology and Epidemiology at the University Pennsylvania School of Medicine, Philadelphia, Pennsylvania. She is the director of the Multiple Sclerosis Division in the Department of Neurology. Dr. Balcer's primary research focus is on the identification and development of visual and ocular imaging outcome measures for Multiple Sclerosis clinical trials.

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