Introduction: Optical coherence tomography has become a standard component in the neuro-ophthalmological assessment of patients with pituitary tumors. In particular, preoperative structural measurement of the anterior visual pathway has been shown to be predictive of early post-operative visual recovery patients with compressive neuropathy. However, the course of long-term outcome remains heterogeneous with a subset of patients experiencing progressive dysfunction even after complete decompression of the optic apparatus. The purpose of this study was to characterize the long-term structural changes of the anterior visual pathway in patients who underwent pituitary tumor resection.
Methods: 22 patients (10F: 12M) with diagnosis of symptomatic pituitary macroadenomas underwent a neuro-ophthalmic evaluation and spectral-domain optical coherence tomography (OCT) testing pre-operatively, and up to 3 years after surgery. Retinal nerve fiber layer thickness (RNFLT) and ganglion cell layer thickness (GCLT) were compared between patients with normalized visual function versus persistent visual field deficits after surgery (mean deviation< -5.0 decibels).
Results: Preoperative RNFLT and GCLT between the two patient groups were significantly different with patients with persistent deficit having thinner RNFL and GCLT (84.1um vs 71.8um; p<0.01, 72.1um vs 62.6um; p<0.01). There was progressive thinning of the RNFL in patients with persistent deficit at long-term follow-up (1-3 years postop) with trend towards significance (71.8um vs 65.2um; p=0.06). Furthermore, these patients had significant decrease in GCLT at long-term follow-up (62.6um vs 52.2um; p=0.04). Contrastingly, patients with normalized visual field function exhibited stable RNFLT and GCLT (84.1um vs 81.7um; p=0.18, 72.1um vs 70.9um; p=0.29 respectively).
Conclusions: There are long-term structural changes seen in the anterior visual pathway in patients with ongoing visual dysfunction even after complete decompression of the optic apparatus. This argues for the notion of threshold effect in compressive neuropathy even after decompression where irreversible and progressive injury occur preventing functional recovery.
Patient Care: Understanding the long-term structural changes seen in the anterior visual pathway in patients with compressive neuropathy from pituitary tumors may provide information that can influence the management of these patients (such as timing of surgery, and management of asymptomatic cases) and their prognosis.
Learning Objectives: 1. To understand the utility of optical coherence tomography (OCT) in assessing patients with pituitary tumors.
2. To describe the variability in post-operative visual recovery in patients with pituitary tumors; including following the complete decompression of the optic chasm.