Impact of Navigation-Assisted Transsphenoidal Surgery on Residual Tumor Volume and Retinal Nerve Fiber Layer Thickness in Pituitary Adenoma

Aim: Predicting visual outcomes following transsphenoidal surgery for pituitary adenoma remains challenging. Intraoperative neuronavigation is occasionally used during pituitary surgery; however, its effect on visual outcomes is not fully understood. This study aimed to investigate the impact of navigation-assisted transsphenoidal surgery on postoperative residual tumor volume and retinal nerve fiber layer (RNFL) changes. Methods: A retrospective analysis was performed on 27 consecutive patients who underwent microscopic transsphenoidal surgery for pituitary adenoma. Patients were divided into two groups: Group 1 (non-navigation-assisted) and Group 2 (navigation-assisted). Postoperative residual tumor volume and RNFL thickness changes were compared between groups. Results: Group 1 consisted of 17 patients (63%) with a mean preoperative tumor volume of 4.84 ± 1.24 cm³, while Group 2 included 10 patients (37%) with a mean preoperative volume of 8.91 ± 1.18 cm³. The postoperative residual volume was significantly higher in Group 1 (3.06 ± 0.78 cm³) compared with Group 2 (1.12 ± 0.26 cm³; p  = 0.031). Although RNFL thinning was observed postoperatively in both groups, navigation-assisted surgery did not result in statistically significant differences in RNFL thickness. Conclusion: Navigation-assisted transsphenoidal surgery enables significantly greater tumor volume reduction without substantially altering postoperative RNFL thickness. These findings suggest that neuronavigation improves surgical precision and extent of resection while maintaining visual structural integrity.