Detection of mild papilloedema in posterior uveitis using spectral domain optical coherence tomography

Objective To compare two methods for diagnosing mild papilloedema (PO) using peripapillary total retinal (PTR) and retinal nerve fibre layer (RNFL) thickness measurement by spectral domain optical coherence tomography (OCT) in patients suffering from posterior uveitis. Methods 17 eyes in 17 patients with PO caused by posterior uveitis, 15 eyes in 15 patients with uveitis but with no PO based on slit lamp analysis were studied. High-quality OCT fundus images were analysed and graded by three masked observers using the Modified Frisen Scale. Eyes with PO were divided into two subgroups: mild (n= 15) and moderate-severe PO (n= 2). Two measurement methods were evaluated and compared: RNFL and PTR thickness measurements centred on the optic disc. Thickness values were calculated overall and for each quadrant and compared between groups. The main outcome measures were RNFL and PTR thickness, and thickness variation between control and affected patients for both protocols. Results Average RNFL and PTR thickness in the moderate-severe PO, mild PO and control groups were 274.5 +/- 54.45 mm, 134 +/- 31.69 mm, 97.4 +/- 14.43 mm and 722.25 +/- 29.34 mm, 437.53 +/- 84.47 mm, 327.8 +/- 25.92 mm, respectively. Mild PO differed from the control groups according to both the RNLF (p= 0.0006) and the PTR (p= 0.0002) measurements. The average thickness variation between control and mild PO was significantly different between RNFL and PTR measurements: 36.6 mm vs 109.73 mm (p< 0.0001), respectively. Conclusions PTR thickness measurement increases the sensitivity of detection of mild PO and could be useful for diagnosing and monitoring papillitis. A new protocol should be developed to measure PTR in the same 3.5 mm disc as the RNFL measurement.