Visual outcome including visual field defects after treatment of paediatric optic pathway glioma: A nationwide cohort study

PURPOSE: To examine long-term visual impairment and visual field examination (VF) after diverse treatments for paediatric optic pathway glioma (OPG), and to determine prognostic factors for long-term severe visual impairment or blindness.

METHODS: A nationwide retrospective cohort study (1995-2018) was performed on paediatric OPGs that received various (successive) therapies. The analysis of severe VI or blindness was represented by the outcome of both BCVA and VF testing. Prognostic factors for long-term severe VI or blindness were identified.

RESULTS: Data on BCVA and VF were available in 117 of 136 children (86.0%) who received treatment. After a median follow-up of 8.3 years (range: 0.1-23.8 years) after the start of treatment, severe VI or blindness (>1.0 LogMAR) was observed in both eyes in 18.8% of 117 patients and in 34.6% of 234 included eyes. This impairment was more common in sporadic OPGs. Monocular VF defects were present in 80.0% of a subgroup of 110 eyes (47.0%), predominantly represented by hemianopia in 69.3% and various scotomas in 28.4%. Independent prognostic factors for severe VI or blindness included starting therapy under the age of 2 years and hypothalamic involvement of the OPG.

CONCLUSION: In this study, long-term binocular severe VI or blindness appeared in almost one in five patients and in one in three eyes after diverse treatment for paediatric OPG. Visual field data were available in only one in two children; VF defects were present in four out of five eyes. Children starting therapy under the age of 2 years were particularly at risk for long-term severe VI or blindness. Future prospective studies need to include VF analysis as an outcome parameter and should analyse treatment effects on both monocular and binocular BCVA.