Abstract Purpose Surgery in patients with non-functioning pituitary macroadenomas (NFMA) is effective in ameliorating visual function. The urgency for decompression, and preferred timing of surgery related to the preoperative severity of dysfunction is unknown. Methods Systematic review for evidence to provide clinical guidance for timing of surgical decompression of the optic chiasm, and a cohort study of 30 NFMA patients, in whom mean deviation (MD), and severity of visual dysfunction was assessed. Results Systematic review 44 studies were included with a total of 4789 patients. Postoperatively, visual field defects improved in 87.0% of patients, stabilized in 12.8% and worsened in 1.0%. Specific protocols regarding timing of surgery were not reported. Only seven studies (16.7%) reported on either the duration of visual symptoms, or diagnostic, or treatment delay. Cohort study 30 NFMA patients (50% female, 60 eyes, mean age 58.5 ± 14.8 years), had a median MD of − 5.3 decibel (IQR − 3.1 to − 10.1). MD was strongly correlated with clinical severity (r = − 0.94, P < 0.0001), and were used for severity of defects cut-off values: (1) normal > − 2 dB, (2) mild − 2 dB to − 4 dB, (3) moderate − 4 to − 8 dB, (4) severe − 8 to − 17 dB, (5) very severe < − 17 dB. Conclusion Surgical decompression is highly effective in improving visual function. Uniform, quantitative grading of visual dysfunction was lacking. MD is a promising quantitative outcome measure. We provide recommendations for the evaluation of timing of surgery, considering severity of visual impairment, which will need further validation based on expert clinical practice.