Role of ultrasonographic optic nerve sheath diameter in the diagnosis and follow-up of papilledema and its correlation with Frisén's severity grading

Purpose: The aim of this study was to compare the ultrasonographic optic nerve sheath diameter (ONSD) in different grades of papilledema and in controls and to evaluate ONSD in atrophic papilledema/optic atrophy when raised ICP was suspected. Methods: Prospective cross-sectional case–control study. Following an ocular examination, papilledema was graded clinically using modified Frisén's grading. An ultrasonographic cross section of the retrobulbar optic nerve was obtained with a posterior transverse scan. Independent t-test and analysis of variance were the statistical tools used in the study. Results: The study included 55 cases and 55 age- and gender-matched controls; mean (± standard deviation) age was 37.17 (±11.25) years and male: female ratio was 49:61. There was a statistically significant difference in the mean ultrasonographic ONSD between cases [4.89 (±0.65) mm] and controls [3.12 (±0.22) mm] (P < 0.001). There was a significant difference in the mean ONSD across Frisén's grades of papilledema (P < 0.001). The mean ONSD in atrophic papilledema was 6.2 (±0.75) mm. Conclusion: In the presence of symptoms, ultrasonographic ONSD >4 mm is diagnostic of papilledema. Ultrasonographic ONSD correlates well with the severity of papilledema and can be used to follow-up patients with chronically elevated ICP. It is useful in detecting raised ICP in the presence of optic atrophy and to distinguish true papilledema from pseudopapilledema.