Correlation of peripapillary nerve fiber layer thickness with visual outcomes after decompression surgery in subclinical and clinical thyroid-related compressive optic neuropathy

Abstract

Purpose: To assess the correlation of peripapillary retinal nerve fiber layer (PRNFL) thickness with visual recovery in compressive optic neuropathy (CON) in patients with thyroid eye disease (TED). Methods: Twenty-three eyes of 13 consecutive patients with TED-related CON were prospectively recruited. Assessment of PRNFL by means of spectral domain optical coherence tomography (SD-OCT), visual field (VF) parameters, color vision, and visual acuity in logMAR were compared before and 6 months after decompression surgery in the operated eye for each patient, which in ten cases included both eyes. Decompression surgery was performed as medial and inferior wall decompression sparing the orbital strut by the same surgeon. Results: There was a significant correlation between the preoperative PRNFL average thickness and postoperative improvement in visual acuity among all patients (P = 0.048). This correlation was found to be significant in clinically non-edematous optic neuropathy cases (P = 0.023) but not in edematous optic neuropathy (P = 0.23). There was significant correlation between PRNFL thickness and improvement of postoperative mean deviation (MD) and pattern standard deviation (PSD) parameters in VF studies and in color vision scores (P = 0.005, P = 0.02, P = 0.01, respectively). Average PRNFL thickness and quadrantal PRNFL were all significantly reduced after decompression surgery in all of the cases (P = 0.024). Conclusions: PRNFL thickness measured by SD-OCT is correlated with visual recovery after decompression surgery in TED-related CON. In eyes with severe VF defect (MD worse than −10 dB), the ones with higher preoperative PRNFL thicknesses (>65 μm) had more improvement in MD compared with those with thin PRNFL measures (<60 μm). Keywords: Retinal nerve fiber layer thickness, Optical coherence tomography, Decompression surgery, Thyroid eye disease, Compressive optic neuropathy