Visual outcomes after chemotherapy for optic pathway glioma in children with and without neurofibromatosis type 1: results of the International Society of Paediatric Oncology (SIOP) Low-Grade Glioma 2004 trial UK cohort.

Aims: To report visual acuity (VA) outcomes following chemotherapy for optic pathway glioma (OPG) in children with or without neurofibromatosis type-1 (NF1) and to analyse associated risk factors.

Methods: A prospective, multicentre, cohort study involving 155 children treated between September 2004 and December 2012. Initial and final VA was used for per-eye and per-subject analysis. Correlation tests were performed to determine whether initial VA predicted final VA. Logistic regression was used to determine whether age and tumour location were associated risk factors.

Results: 90 children had complete ophthalmological data. At initiation of chemotherapy, 26% and 49% of eyes with NF1-OPG and sporadic OPG, respectively, had VA of ≥0.7 log of the minimum angle of resolution (logMAR). At final visit, per eye, 49% had ≤0.2, 23% had 0.30-0.60 and 28% had VA≥0.70 logMAR in the NF1-OPG group. In the sporadic OPG group, per eye, 32% had ≤0.2, 11% had VA 0.30-0.60 and 57% had ≥0.70 logMAR. Children with sporadic OPG, per eye, were significantly less likely to have VA outcomes ≤0.60 logMAR compared with children with NF1-OPG (OR=0.30; 95% CI 0.16 to 0.56; P<0.0001). Per subject, VA improved in 24%, remained stable in 35% and worsened in 41% of children with NF1-OPG and improved in 18%, remained stable in 43% and worsened in 39% of children with sporadic OPG.

Conclusions: Children with and without NF1 demonstrated the same rate of VA improvement, stabilisation or worsening; however, children with sporadic OPG had a poorer VA outcome. Better initial VA, older age, absence of postchiasm tumour and presence of NF1 were associated with improved or stable VA outcomes.