Visual field defects in non-functioning pituitary adenomas.

PURPOSE: To report the prevalence and pattern of visual field loss in non-functioning pituitary adenomas and to study the relationship between the tumour size and severity of field defects. METHODS: Ninety-three patients with histologically confirmed pituitary adenomas, non-functional on hormonal assessment, underwent a complete ophthalmic assessment and automated perimetry using the HFA 30-2 programme. Defects with quadrantanopic or hemianopic characteristics, defined using criteria on the threshold/pattern deviation plots were considered typical. Typical defects were graded as mild, moderate and severe. All other defects were considered atypical. A neuroradiologist measured tumour size on a CT or MRI Scan. The Chi-square test for trend was used to test association of tumour volume with severity of typical defects. RESULTS: Eighty-eight (94.6%) of the 93 patients had a field defect. Typical field defects were seen in 69 (74.2%) patients and atypical in 19 (20.4%). A severe typical defect involving at least 3 quadrants in one or both eyes was the most common (24 patients or 25.80%). All 31 patients (33.3%) with a tumour size greater than 20 cc had field defects. Severity of field defect increased with tumour volume (Chi-square test for trends significant p = 0.0096). CONCLUSIONS: Field defects occurred in 95% of patients with non-functioning pituitary macroadenoma. A severe visual field loss involving at least 3 quadrants in one or both eyes was the most common. 20% of patients had atypical field defects. Severity of field defects increased with tumour volume.