Visual acuity in children with low grade gliomas of the visual pathway: implications for patient care and clinical research

Low grade gliomas affecting the visual pathway, commonly referred to as optic pathway gliomas (OPGs), have a relatively high survival rate but can cause significant vision loss. While previous treatment outcomes for tumors of the central nervous system have focused primarily on changes in tumor size or patient survival, more recently preservation of vision has also become a primary objective when treating these tumors. Visual acuity (VA) is the most testable and reliable visual parameter in young children with OPGs. Unfortunately, standardized VA assessments have neither been employed to make treatment decisions nor used as primary outcomes in clinical trials. The lack of a standardized VA assessment has also hindered the ability to interpret and compare results between studies. It is essential that all members of the multidisciplinary care team (i.e., pediatric neuro-oncologist, neurologist, neurosurgeon, and ophthalmologist) can accurately interpret VA results and properly use them to guide management decisions. Specifically, determining what constitutes a significant change in VA and the factors that may influence these results should be incorporated into collective team recommendations. This review describes the VA assessment in children with OPGs and proposes a standardized VA testing protocol for future pediatric OPG clinical treatment trials.