Optico-Chiasmatic Distortions in Pituitary Adenomas: Correlation Between Postoperative Morphological Reversal and Follow-Up Functional Visual Recovery.

Objective: To objectively correlate distortions of optic apparatus morphology in patients with pituitary adenomas undergoing trans-sphenoidal surgery.

Methods: In this retrospective analysis, visual acuity (VA), visual field (VF), and total visual (TV) function were objectively scored in patients selected from an institutional cohort of pituitary adenomas. The following imaging measures of optico-chiasmatic morphology were recorded preoperatively, and at 3 months after surgery: chiasm area, mid-chiasm height (CH), optic nerve-canal bending angle (BA), and optic nerve kinking angle (ONKA). Receiver operator characteristic analysis was performed to establish optimal thresholds for achieving a "normal" TV score of 200 at 1-year follow-up.

Results: Seventy-one eyes were individually studied. VA, VF, and TV scores significantly improved after surgery, both at the 3-month and at the 1-year follow-up visits (P < 0.001). Cranio-caudal tumor dimension was significantly associated with VA, VF, and TV scores, both preoperatively and postoperatively. There were significant changes in CH (P < 0.001), BA (P < 0.001), and ONKA (P < 0.001) at 3 months after surgery, but not in chiasm area (P = 0.061). Baseline VA, VF, and TV scores were positively correlated with preoperative CH and ONKA, while VF and TV scores also demonstrated significant negative correlations with preoperative BA. VF scores at 1-year follow-up were significantly correlated with preoperative and change in BA values, as well as with preoperative and change in ONKA values. Receiver operator characteristic analysis revealed that only the preoperative ONKA was found to have acceptable discrimination (area under the curve >0.7) for predicting "normal" TV score. Chiasm sag was noted in 45.8% of patients at 1-year follow-up, but was not associated with delayed visual deterioration in any case.

Conclusions: Anatomic realignment of the optic apparatus 3 months following trans-sphenoidal surgery predicts VF scores, but not VA or TV scores at 1-year follow-up. Patients with preoperative ONKA values of more than 139.3° have a 76% chance of achieving normal TV scores 1 year after surgery. Postoperative chiasm sag appears to be clinically irrelevant at short-term follow-up.