Abstract
Purpose: :
Patients with idiopathic intracranial hypertension (IIH) have been found to demonstrate shorter globe lengths compared to controls using computed tomography (Madill & Connor, 2005). We also noted anecdotally that optic discs of IIH patients with resolved papilloedema tend to remain mildly elevated and appear crowded. We therefore decided to investigate whether patients with IIH could have small crowded optic discs prior to the development of papilloedema.
Methods: :
We analysed optic nerve head parameters using the Stratus OCT Optic Nerve Head Analysis in nine cases with IIH or resolved IIH (Frisen grade 0 or 2) (mean age = 45) and nine age-matched control subjects (mean age = 43). We choose the scleral canal diameter as being most representative of disc diameter prior to papilloedema development. To increase accuracy, we measured the canal width manually from the OCT images.
Results: :
The disc diameters of patients with IIH were significantly larger than controls in right eyes (t-test for independent samples, p<0.05) and showed a trend in the left eyes (t-test for independent samples, p<0.3). The mean disc diameter measured 2.32 mm (SD = 0.29) in IIH and 2.01 mm (SD = 0.38) in controls.
Conclusions: :
This pilot study shows that in patients with IIH there is no evidence for small crowded optic nerves prior to the development of papilloedema, despite the relatively short axial globe length in these individuals. The IIH cohort in fact demonstrated significantly larger optic discs than controls.
Keywords: neuro-ophthalmology: optic nerve • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • optic disc