Uveitis

Abstract

Optical coherence tomography (OCT) provides fast, non-contact and reproducible high-resolution imaging of the posterior pole. With improving resolution down to 1 µm and the ability to clearly define anatomical layers, OCT plays an ever-increasing role in the management of uveitis. Diagnostically, the ability to observe alteration in the reflectivity, thickness and retinal architecture is invaluable in understanding the pathophysiology of some uveitic conditions. Whilst there are general agreements on anatomical layer and nomenclature of the inner retinal layers, the same is less so for the outer retinal layers. In 2014, the IN OCT group produced a consensus statement on the four distinct hyper-reflective outer retinal bands (Staurenghi et al. 2014). From the outermost to the innermost are the retinal pigment epithelium (RPE)/Bruch’s membrane complex, the interdigitation zone (IZ), the ellipsoid zone (EZ) and the external limiting membrane (ELM) (Staurenghi et al. 2014). The term ‘zone’ is used when tissues within a region cannot be clearly delineated with current technology. With enhanced depth imaging, choroidal vasculature and thickness can also be both qualitatively and quantitatively measured. This is particularly helpful in uveitic conditions such as Vogt-Koyanagi-Harada (VKH) syndrome, sympathetic ophthalmia (SO), Behcet’s disease and choroidal granuloma.