Visual prognostic value of optical coherence tomography and photopic negative response in chiasmal compression

Abstract

PURPOSE: To investigate the potential of the optical coherence tomography (OCT) measurement of retinal nerve fiber layer (RNFL) thickness and ganglion cell complex (GCC) area and photopic negative response (PhNR) for predicting postoperative visual outcome in chiasmal compression, prospectively. METHODS: Eighteen eyes of 18 patients undergoing chiasmal decompression surgery were prospectively assessed before, and 3 months after surgery with standard automated perimetry (SAP), OCT, and PhNR. Preoperative measurements were compared with 20 eyes of 20 age-matched controls. Spearman's correlation and regression analyses were conducted to evaluate the relationship between preoperative RNFL thickness, GCC area, PhNR/b-wave amplitude ratio, postoperative mean deviation (MD) and temporal visual field sensitivity (1/Lambert). RESULTS: Preoperative measurements of RNFL thickness, GCC area, and PhNR/b-wave amplitude ratio were reduced significantly in patients compared with normal controls. Preoperative RNFL thickness of the temporal quadrant, GCC area, and PhNR/b-wave amplitude ratio were correlated significantly with postoperative MD and temporal visual field sensitivity (1/Lambert). CONCLUSIONS: An eye with the more demonstrable structural deterioration, as shown by reduced RNFL thickness and GCC area, and retinal ganglion cell dysfunction as shown by decreased PhNR/b-wave amplitude ratio was associated with the worse visual fields outcome. RNFL thickness and GCC area measurements using OCT and PhNR/b-wave amplitude ratio could be a useful prognostic indicator in the preoperative assessment of chiasmal compression.