Optic disc vessel density changes after shunt surgery in idiopathic intracranial hypertension

Abstract

Aim: To detect the change in optic disc vessel density in patients with idiopathic intracranial hypertension (IIH) after shunt surgery.

Patients and method: Twenty-one patients with IIH underwent shunt surgery. Patients were subjected to full ophthalmic and neurological examinations. Optic disc vessel density was measured using optical coherence tomography angiography (OCT-A) before and two months after surgery.

Results: The age of patients ranged from 27 to 48 years old, with a mean of (34.85 ± 6.87). Visual acuity ranged between 0.2 and 0.9 by log Mar, with a mean of (0.64±o.20). The mean deviation (MD) of the perimeter ranged from -22.9 to 0 dB, with a mean of (-9.77 ± 7.23 dB). With respect to the grade of papilledema, 15 eyes (35.7%) were of grade II, 21 eyes (50.0%) were of grade III, and 6 eyes (14.3%) were grade IV. Intracranial pressure measured by lumbar puncture (LP) prior to surgery ranged from 30 to 40 cm, with a mean of 35.43 cm. Except for right transverse sinus hypoplasia in 6 patients (28.6%), MRV was normal. In 15 patients (71.4%), lumboperitoneal shunt was performed, while ventriculoperitoneal shunt was performed in 6 patients (28.6%). After surgery, the optical disc vessel density was decreased in all patients. This decrease was highly significant for the whole image, the inner disc, the peripapillary, superior, and inferior hemispheres. Moreover, this reduction affected both optic disc microvasculature (referred to as capillary vessel density) and macro vasculature (also known as all vessel density). There were positive correlations between the CSF opening pressures and the preoperative optic disc vessel density of the whole image and inside disc with a P-value (0.002, 0.009), respectively. In addition, there was a positive correlation between the opening CSF pressures and the reduction in whole image vessel density after surgery with a P-value of 0.000.

Conclusion: Optic disc vessel density decreased after shunt surgery in patients with IIH. Consequently, optic disc vessel density can be used as a biomarker for the reduction of CSF opening pressure.

Keywords: Idiopathic intracranial hypertension; OCTA; Optic disc vessel density; Shunt surgery.