Macular exudate in idiopathic intracranial hypertension affects outer retina and visual acuity.

Background: Optical coherence tomography (OCT) is suggested as a potential tool for retinal biomarkers in idiopathic intracranial hypertension (IIH). We explored how macular exudate (ME) affects retinal structure in IIH and investigated its relationship with their clinical features.

Methods: Patients diagnosed with IIH and matched controls were enrolled. ME detection was done on fundus photography; swept-source OCT was used to image and measure the retinal sublayer thicknesses, including the retinal nerve fibre layer, ganglion cell-inner plexiform layer (GCIPL), inner nuclear layer (INL) and outer retinal layer (ORL). IIH patients underwent lumbar puncture where intracranial pressure (ICP) was assessed.

Results: 195 eyes from 98 IIH patients (42 eyes had ME) and 224 eyes from 112 controls were included. IIH patients had thicker INL and ORL compared with controls (both p<0.001) while IIH eyes with ME had thicker INL and ORL thicknesses compared with eyes without ME (both p<0.05). In IIH patients, the retinal sublayer thicknesses correlated with their ICP levels, and GCIPL thickness correlated with visual acuity (VA). Furthermore, ME was associated with higher ICP, worse papilledema and lower VA (all p<0.001).

Conclusion: ME affects retinal thickness in IIH patients and is associated with more severe clinical features in IIH. OCT may provide biomarkers informative of clinical changes in IIH. Further longitudinal studies are needed to explore the evolution of ME and its relationship to VA and retinal structure.