Detection of mild papilloedema using spectral domain optical coherence tomography

Objective To propose a method of diagnosis of mild papilloedema (PO) using peripapillary total retinal (PTR) thickness measurement by spectral domain optical coherence tomography (OCT). Methods 24 eyes in 24 patients with PO caused by increased intracranial pressure and 22 eyes in 22 normal subjects were studied. OCT high-quality fundus images were analysed and graded by three masked observers using the Modified Frisen Scale. Eyes with PO were divided into two subgroups: those with mild PO (n = 18) and those with moderate-severe PO (n = 6). Two methods of measurements were evaluated and compared: retinal nerve fibre layer (RNFL) thickness measurements using standard optic disc cube 200 x 200 acquisition protocol and PTR thickness measurements using the 'macular' cube 512 x 128 acquisition protocol centred on the optic disc. Thickness values were calculated globally and for each quadrant (temporal, superior, nasal, inferior) and compared among the three groups (control, mild PO, moderate-severe PO). The main outcome measures were RNFL and PTR thickness. Results Average RNFL and PTR thickness in the moderate-severe PO, mild PO and control groups were 299.3 +/- 10.9, 112.4 +/- 6.3, 96 +/- 5.7 and 804.5 +/- 17, 463.1 +/- 9.8 and 332.4 +/- 8.9 mu m, respectively. Moderate-severe PO differed from mild PO and control groups using both RNLF thicknesses and PTR thicknesses measurements. Mild PO did not differ from controls using RNLF thickness measurement (p = 0.17), but was statistically different using PTR thickness measurement (p < 0.001). Conclusion PTR thickness measurement increases the sensitivity of detection of mild PO compared with conventional RNFL measurement. This new way of using OCT may be useful for clinicians to detect mild PO.