The objective of the study was to evaluate the preoperative visual field defect, the postoperative outcome and the possible prognostic factors in patients with pituitary macroadenoma, using a quantitative method (the mean deviation = MD), and to review the literature. A total of 73 patients, operated trough trans-sphenoidal approach, were selected, and data in single eyes were analysed by calculating the frequency and the degree of postoperative improvement (relative improvement). The visual field defect improved in 95.7% of eyes: The recovery was complete in 48.9% and partial in 46.8%. Multivariate logistic regression showed that factors, independently predictive for complete recovery, were as follows: low preoperative MD absolute value (p = 0.008), low cranio-caudal diameter of tumour (p = 0.02) and young age (p = 0.0001). The mean relative improvement in visual field defect (dMD%) was correlated with the preoperative visual acuity (p = 0.0001) and inversely related with the preoperative MD (p = 0.007) and the age (p = 0.017). The relative improvement was higher in tumours with a smaller cranio-caudal diameter (p = 0.0185). In conclusion, using a quantitative method, we can measure the degree of the postoperative visual field defect improvement. Predictive factors for a complete recovery were good preoperative visual function, young age and low cranio-caudal tumour.