ABSTRACT
OBJECTIVE: The aims of this study were to investigate the quantitative relationship between pituitary macroadenoma size and degree of visual impairment, and assess visual improvement after surgical resection of the tumor. METHODS: The medical records of patients with pituitary adenoma, who had undergone trans-sphenoidal adenectomy between January 2009 and January 2011, were reviewed. Patients underwent an ocular examination and brain MRI before and after surgery. The visual impairment score (VIS) was derived by combining the scores of best-corrected visual acuity and visual field. The relationship between VIS and tumor size/tumor type/position of the optic chiasm was assessed. RESULTS: Seventy-eight patients were included (41 male, 37 female). Thirty-two (41%) patients experienced blurred vision or visual field defect as an initial symptom. Receiver operating characteristic curve analysis showed that tumors <2.2 cm tended to cause minimal or no visual impairment. Statistical analysis showed that 1) poor preoperative vision is related to tumor size, displacement of the optic chiasm in the sagittal view on MRI and optic atrophy, and 2) poorer visual prognosis is associated with greater preoperative VIS. In multivariate analysis the only factor significantly related to VIS improvement was increasing pituitary adenoma size, which predicted decreased improvement. CONCLUSION: Results from this study show that pituitary adenomas larger than 2 cm cause defects in vision while adenomas 2 cm or smaller do not cause significant visual impairment. Patients with a large macroadenoma or giant adenoma should undergo surgical resection as soon as possible to prevent permanent visual loss.