Ganglion cell complex and retinal nerve fiber layer thickness in predicting visual outcome in brain tumors after surgery.

BACKGROUND

Anterior visual pathway lesions can cause severe visual loss. Optical coherence tomography (OCT) can detect ganglion cell complex (GCC) thinning, even with normal retinal nerve fiber layer (RNFL) thickness and subtle visual field changes.

AIM: To determine the proportion of eyes with RNFL and GCC thinning and their association with visual parameters in patients with brain tumors undergoing surgery.

METHODS

A prospective study was conducted on 37 patients (69 eyes) with peri-chiasmatic and chiasmatic brain tumors undergoing surgical decompression between February 2019 and June 2020 at a tertiary care institute. A comprehensive neuro-ophthalmological work-up, demographic and clinical profile documentation, and six-month postoperative follow-up weredone. Statistical analysis was significant at P < 0.05.

RESULTS

Mean age was 35.14 ± 11.98 years. The best and worst visual outcomes were associated with the craniopharyngioma and meningioma groups, respectively (P = 0.008). There was an increase in the proportion of eyes with RNFL damage in the inferior quadrant (P = 0.02). Maximum GCC thickness thinning was associated with severe visual impairment. The odds of having blindness in eyes with RNFL (inferior) and GCC loss were 0.96 (P = 0.003) and 0.95 (P = 0.03), respectively. GCC thickness showed a clinically positive correlation with visual acuity (r = -0.48, P < 0.001) and field defect (r = -0.27, P = 0.04) at six months postoperatively. The preoperative GCC thickness and the final postoperative visual outcome were plotted in an empirical ROC curve with area under the curve = 0.754. The cut-off value of RNFL (inferior) and GCC, beyond which blindness could be prevented, was 73 µm and 58 µm, respectively.

CONCLUSION

In chiasmal compression, RNFL and GCC thickness measurements using OCT can be a useful prognostic indicator for assessing visual recovery. An eye with structural damage, with significant RNFL and GCC loss, is a predictive factor of blindness. A minimum preoperative RNFL and GCC thickness of 73 µm and 58 µm, respectively, can preserve vision after surgery.