Abstract AIMS Preservation of functional integrity is a core goal of glioblastoma surgery. Visual field deficits can significantly impact quality of life and patient function. Both tumour and surgical effects may affect visual function in these patients. The objective of this Study was to evaluate the effect of visual field deficits on HRQoL in the preoperative and early postoperative period (prior to chemoradiotherapy). METHOD 48 patients with glioblastoma received preoperative, early postoperative (withon 1 week) and delayed postoperative testing (6 weeks) for visual function usinga combination of the OCS-Bridge neurocognitive screening tool and formal visual field testing. Patients also completed the EORTC QLQ C30 with BN-20 and VFQ-25 visual function questionaires at the same timepoints. Statistical tests were performed using R Statistical Software (v4.1.2; R Core Team 2021). RESULTS The proportion of patients with visual field deficits at preoperative, early postoperative and late early postoperative timepoints were 20 (41.7%), 28 (58.3%) and 24 (50%) respectively. Most patients without a preoperative deficit did not have an early 17/20 85% or late postoperative deficit 19/24 79.1%. The proportion of patients with deficits at early and late postoperative timepoints was significantly higher in patients with preoperative deficits compared to patients without preoperative deficits, (Chi square p = 0.004) and (p = 0.008) respectively. There was no significant differences between HRQoL measures between timepoints or between patients with deficits at any timepoint compared to patients without deficits. CONCLUSION Postoperative visual field deficits are related to preoperative tumour-effects rather than surgery. Patients can be counselled that while they do not recover following surgery, it is not associated with significant reductions in HRQoL. Patients with preoperative visual field deficits may be considered for resection without significant worry about the preservation of visual field function since these deficits do not recover postoperatively.