Optical coherence tomography in papilledema: A probe into the intracranial pressure correlation

Purpose:To study the optic nerve head characteristics on optical coherence tomography (OCT) in patients with papilledema and correlate them with intracranial pressure (ICP).Methods:A retrospective hospital-based study of 46 eyes of 23 patients with bilateral optic disc edema secondary to increased ICP. The clinical profile and the OCT features in terms of retinal nerve fiber layer thickness (RNFL), ganglion cell inner plexiform layer (GCIPL) thickness, and enhanced depth imaging (EDI) B scan images of the optic nerve head were studied and correlated with the ICP.Results:Papilledema was secondary to idiopathic intracranial hypertension (IIH) (n = 20), obstructive hydrocephalus (n = 2), and communicating hydrocephalus (n = 1). The mean ICP in 20 IIH patients was 347 mmH2O. The ICP and RNFL thickness in all four quadrants were found to be weakly positively correlated: superior RNFL r (38) = 0.17, P = 0.30, and nasal RNFL r (38) = 0.30, P = 0.05, inferior RNFL r (38) = 0.29, P = 0.07, and temporal RNFL, r (38) = -0.001, P = 0.99. The GCIPL layer thickness and the ICP were weakly negatively correlated in all sectors: superior (38) = -0.23, P = 0.16, superonasal, r (38) = -0.07, P = 0.67, inferonasal r (38) = -0.08, P = 0.64, inferior r (38) = -0.21, P = 0.19, inferotemporal r (38) = -0.23, P = 0.17, superotemporal, r (38) -0.21, P = 0.20. Descriptive features on the B scan, such as peripapillary hyperreflective ovoid mass-like structures and microcystic spaces, were observed most commonly with an ICP of 251-350 mmH2O, and the hyperreflective dots in the RNFL layer and Bruch's membrane inward denting were observed more commonly with an ICP of 351-450 mmH2O.Conclusion:The RNFL thickness in all four quadrants had a weak positive correlation, and the GCIPL layer had a weak negative correlation with the ICP. The EDI descriptive features on OCT may vary with ICP.