Automated Perimetry and Laser Polarimetry in the Assessment of Nerve Fibers Involvement in Pituitary Adenoma

Purpose To point out the nerve fibers involvement in patients suffering from pituitary adenomas submitted to transphenoidal surgery. Methods 26 patients (50+/-17,9 ys) were selected and submitted to a complete ophthalmic examination before (baseline visit) and after surgery. The post-intervention examinations were scheduled at 1, 3, and 6 months. The adenomas were classified according to Hardy classification. A kinetic test (HFA-II, stimulus I/4) was performed as a screening and in case of abnormal outcomes a static test 24-2 or 30-2 was carried out to better determine the visual field (VF) defect. The retinal nerve fiber layer (RNFL) was evaluated by GDx-VCC. Results 3 adenomas were classified as micro and 23 as macro: the dimensions and the extrasellar extension were very eterogeneous. At baseline visit, none patients suffering from microadenoma presented VF or RNFL damages: these data were confirmed at 1, 3, and 6 months examinations. Among the macroadenomas, at baseline, 16 subjects presented normal VF while 22 had normal GDx; 6 presented bitemporal hemianopia at VF, one of them bilateral and 2 of them had mono-lateral GDx alteration; a mono-lateral defect of VF was recorded in 3 patients, 2 of them had abnormal GDx. Six months later, 5 patients out of 6 with bilateral VF defect performed a normal VF examination, 2 and 1 of them presented abnormal GDx, bilateral and mono-lateral respectively. Conclusion The nerve fiber involvement can be pointed out only for macroadenomas with extrasellar extension classified as 2/C but a strict correlation between the clinical defect and anatomical tumor’s characteristics cannot be determined.Our data suggest that the nerve fibers involvement is mainly due to compression: the compression doesn’t cause immediately a nerve fiber loss as demonstrated by complete postoperative recovery of VF. The Gdx is able to point out persistent fiber losses in patients with recurrent disease and therefore prolonged fiber compression.