Prognostic Value of Retinal Nerve Fiber Layer and Ganglion Cell Complex after Optic Chiasmal Decompression

Abstract

This paper is an attempt to ascertain the role of the optical coherence tomography by measuring the retinal nerve fiber layer thickness and ganglion cell complex area to predict postoperative visual outcome after chiasmal decompression. 16 eyes scheduled for chiasmal decompression surgery were assessed before and 3 months after surgery with standard automated perimetry and OCT (optical coherence tomography). Preoperative RNFL (retinal nerve fibre layer) thickness and GCC (ganglion cell complex) area were compared with 20 normal control eyes. 13 cases were operated by microscopic assisted endoscopic endonasal transsphenoidal approach; the remaining 3 cases were operated transcranially. Spearman’s correlation analysis was used to evaluate the relationship between preoperative RNFL thickness, GCC area, postoperative mean deviation and temporal visual field sensitivity (1/Lambert). Preoperative measurements of RNFL thickness and all GCC area were significantly reduced in the patients compared with normal control. 3 months postoperative evaluation showed improvement of the visual field, but reduction in global and sectorial RNFL thickness except for nasal sector. Moreover, absolute postoperative (not pre-post change) visual field parameters were significantly correlated to preoperative RNFL (P = 0.00399 for mean deviation, P = 0.0023 for temporal sensitivity), GCC thickness (P = 0.00736 for mean deviation, P = 0.0469 for temporal sensitivity), with FLV (focal loss value) (P = 0.0012 for mean deviation, P = 0.0021 for temporal sensitivity) showed a higher correlation. Reduced RNFL thickness mainly, and GCC area minimally, were associated with the worst visual field outcome. FLV is a new prognostic value.