NF1 and neoplasm: In the subgroup of individuals with NF-1, median tumor volumes in patients with evidence of impaired VA at the time of diagnosis similarly showed a significant difference as compared to patients without evidence of impaired VA (17.9 vs 2.3 cm3, p = 0.025), while no significant difference could be shown in individuals with non-NF-1 OPG (19.7 vs 7.9 cm3, p = 0.30, see Fig. 2B).