Longitudinal comparison of RNFL and mGCC thickness as predictors of assessing functional visual impairment in papilledema secondary to idiopathic intracranial hypertension

Background: Idiopathic intracranial hypertension (IIH) is marked by elevated intracranial pressure, which is evidenced by papilledema and imaging results, occurring without a discernible causal factor and the main objective of this study is to evaluate and compare the predictive value of retinal nerve fiber layer (RNFL) and macular ganglion cell complex (mGCC) thickness for best corrected visual acuity (BCVA), visual field index (VFI), pattern standard deviation (PSD) outcomes across three visits in both eyes. Methods: Retrospective analysis conducted on 69 idiopathic intracranial hypertension patients over 3 visits at 0, 1, 3 months with examination of RNFL, mGCC thickness from optical coherence tomography (OCT) and BCVA, VFI, PSD from HVF 30-2 analysis. Linear regression models assessed the relationship between RNFL and mGCC thickness with VFI, PSD, BCVA. Predictive strength was evaluated using adjusted R2 and regression coefficients. Results: RNFL thickness consistently demonstrated higher adjusted R2 values and stronger coefficients for predicting VFI, PSD, BCVA compared to mGCC. In the first visit RNFL predicted BCVA with an adjusted R2 Value of 0.51 in right eye and 0.31 in left eye outperforming mGCC. Conclusion: Longitudinal analysis reaffirms that, RNFL and mGCC thickness demonstrate significant associations with functional visual outcomes, while mGCC consistently shows stronger correlation with BCVA and comparable or slightly better predictive strength for PSD, particularly in second and third visits. RNFL remains a reliable predictor of VFI. mGCC may serve as more sensitive marker for central visual function, while RNFL maintains its robustness in broader functional assessments. Bilateral, sustained trends strengthen the evidence for integrating the structural parameters in clinical evaluation with mGCC, potentially offering insights into disease progression. Both markers should be considered complementary in longitudinal monitoring of papilledema.