DEC 18, 2018
This study compares measurements of papilledema using fundus photography, OCT and Frisén score in patients with idiopathic intracranial hypertension (IIH).
The authors reviewed images from 126 participants in the idiopathic intracranial hypertension treatment trial (IIHTT) who were randomized to acetazolamide or placebo. The disc area and Frisén grade were measured from fundus photographs, while the volume of the optic nerve head (ONH) was derived from OCT images with segmentation between the internal limiting membrane and the retinal pigment epithelium.
The disc area and ONH volume were positively correlated at baseline (R=0.77; P<0.001). At 6 and 12 months, the acetazolamide group had a weaker correlation between ONH volume and disc area than the placebo group. While the Frisén score correlated with disc area and ONH volume at baseline, by 6 months that relationship was only significant in the placebo group.
At 12 months, there was no consistent relationship between Frisén score with disc area or ONH volume in either group.
Not all subjects within the IIHTT had OCT images. Only 58% of patients remained in the study at 12 months, which could have introduced some inadvertent sampling bias. In addition, visual function was not evaluated against Frisén scale, disc area or ONH volume, so investigators did not assess which of these better correlated with treatment success.
This study suggests that the Frisén score may not be a good measure of treatment effect because it did not correlate with quantitative measures of papilledema—including disc area and ONH volume—in patients treated with acetazolamide. In addition, the correlation between ONH and photograph-derived disc area is weakened in patients treated with acetazolamide. While this study showed that Frisén score, disc area and ONH volume are not correlated in treated IIH patients, it has yet to be determined which of these variables are most clinically meaningful.