Introduction 1 2 3 5 3 5 6 10 6 7 9 10 11 12 13 13 14 6 12 Patients and methods Patient selection Compression of the optic chiasm on MRI by the pituitary tumor prior to surgery Transsphenoidal surgery for non-functioning pituitary macroadenoma (diameter > 1 cm) for decompression of the optic chiasm Assessment of visual acuity at least once before surgery, and at least twice in the first year after surgery The availability of two postsurgical MR scans, within a time frame of maximal 3 months of the ophtalmological assessments We did not restrict the inclusion criteria to patients with visual field defects, but also included patients with clear compression of the optic chiasm without decreased visual function, for two reasons. First, we were interested in the pattern of change in visual function prior to surgery. Second, it is, at least theoretically, possible that in patients with compression of the optic chiasm, surgical treatment may decrease visual function. To overcome the potential effect of postoperative tumor-regrowth on visual outcome, patients were excluded from analysis if the 1 year post-operative scans revealed growth of residual tumor. For complete assessment, we reviewed the patient records of all departments involved in the treatment of NFMA (Endocrinology, Neurosurgery, Ophthalmology). Endocrine (pituitary function) and ophthalmologic data (visual acuity and visual fields) were assessed before surgery, 3 and 12 months after surgery. An MRI was performed before surgery, 3–6 months and 12–15 months after surgery. Transsphenoidal surgery was performed by one of two neurosurgeons 15 16 Definitions 17 0, A, B, C D,E 0-E  0-E In all patients, visual acuity was scored on a scale between 0 and 1.25. Visual field defects were scored semi-quantitative and classified as mild, moderate or severe. Visual field defects were classified as mild, if there were peripheral defects in only one quadrant. Defects were classified as moderate if the upper quadrants were affected, whereas in combined upper and lower quadrant field defects, these were classified as severe. Growth hormone (GH) deficiency was defined as an insufficient rise in GH levels (absolute value < 3 μg/l) after stimulation during an insulin tolerance test (ITT). When secondary amenorrhoea was present for more than 1 year premenopausal women were defined as LH/FSH deficient. Postmenopausal women were defined as LH/FSH deficient, when gonadotropin levels were below the normal post-menopausal range (LH < 10 U/l, FSH < 30 U/l). In men, LH/FSH deficiency was defined, as a testosterone level below the reference range (8.0 nmol/l). TSH deficiency was defined as a total or free T4 level below the reference range. ACTH deficiency was defined as a basal cortisol level at 8.00 AM of <0.12 μmol/l and/or an insufficient increase in cortisol levels (absolute value < 0.55 μmol/l) after an ITT. Statistical analysis t P Results 1 Table 1 Patient characteristics before transsphenoidal surgery Male/female 22/21 Age (years ± SD) 56 ± 14 Visual acuity  Right eye (mean ± SD) 0.65 ± 0.37 Left eye (mean ± SD) 0.60 ± 0.32 Visual field defects Severe 60% Moderate 17% Mild 14% None 9% Pituitary function GH deficiency 76% LH/FSH deficiency 69% ACTH deficiency 43% TSH deficiency 36% Panhypopituitarism 23% MRI characteristics Suprasellar extension 100% Infrasellar/parasellar extension 42% 1 n n Surgical treatment n n n n Three months postoperative assessment of visual function After transsphenoidal operation in patients with preoperative visual field defects improvement was observed in 60% and normalization of the visual fields in 30%. In 1 patient there was a slight increase in visual field defects. 1 P P Fig. 1 n  One-year postoperative assessment of visual function One year after initial surgical therapy visual field defects showed continuous improvement in 36% of patients, compared to early postoperative results. In 80% of them, this improvement was accompanied by continuous improvement of visual acuity. n 1 P P Discussion The main aims of surgery in non-functioning pituitary macroadenoma are restoration of visual acuity and visual field defects by decompression of the optic chiasm. Nonetheless, our data indicate that there is no necessity for immediate decompression, since postponement of surgery for several weeks did not result in deterioration of visual acuity. Moreover, in this series of 43 patients, we demonstrated a continuing improvement of visual acuity until 1 year after transsphenoidal surgery. 9 13 14 4 9 18 19 18 19 20 21 12 11 12 12 13 13 6 10 12 13 12 22 23 13 24 In conclusion, this study demonstrates that the improvement of visual acuity, after transsphenoidal treatment for non-functioning pituitary macroadenomas, consists of both an early and a delayed phase of recovery. After initial post-surgical recovery, a progressive delayed improvement of visual acuity at least until 1 year after transsphenoidal surgery, is likely to occur.