Anna Brouwer

13 General introduction, aims and scope 1 Complications of uveitis Many complications can occur due to uveitis. Depending on the specific cause of uveitis, the incidence of these complications varies. Complications that can occur on the anterior segment of the eye include: cataracts, band keratopathy, corneal decompensation, ciliary body dysfunction, posterior synechiae and a pupillary occlusion. 29,30 Complications to the posterior segment include cystoid macula edema (CME), glaucoma, vasculitis, retinal detachments, subretinal fibrosis, retinal neovascularization, retinal scarring, retinal atrophy and sometimes even phthisis bulbi. 29–32 Several retinal changes can occur as well, which may result in retinal dystrophy like changes such as thinning of the retina, macula edema, and thinned vessels. 33–35 These changes canmake it quite difficult to distinguish uveitis from retinal dystrophies. 18 But because uveitis can also lead to retinal atrophy, it would be useful to find early signs of retinal damage at a stage when it is still reversible. 32,36 Monitoring uveitis activity and severity Uveitis is monitored usingmultiple tests and examinations. What exact work-up is done, depends on the type and severity of uveitis. Generally it includes a best corrected visual acuity (BCVA), slit-lamp examination and funduscopy. 20 The amount of inflammatory cells in both the anterior chamber and vitreous are graded according to the Standardisation of Uveitis Nomenclature (SUN) criteria. The amount of leakage of proteins due to the inflammation is graded in the anterior chamber as flare, and in the vitreous as vitreous haze. 1 Ancillary tests that use imaging include optical coherence tomography (OCT), fluorescein angiography (FA) and indocyanine green angiography (ICG). The OCT is used to assess the structure of the retinal layers. It uses differences in interference between tissues to create images with a much higher resolution than ultrasound: OCT scans show the structure of the retinal layers in a manner which resembles histology. Figure 2 gives an overview of the different retinal layers which can be identified on OCT and their relation to histology. Invasive imaging techniques that are frequently used include FA and ICG to identify vascular leakage or vascular occlusions. FA is used to evaluate the retinal vasculature, whereas ICG is used to visualize pathology in the choroid, the vascular layer beneath the retina. 37 A frequentlyusedphysiological test is visual fieldanalysis (VF). It is used tomonitor and diagnose glaucoma, a frequent complication of uveitis, neuro-ophthalmologic disorders, but it can also be used to monitor progressive visual field loss in birdshot uveitis. Lastly, functional tests that are sometimes used are the electroretinogram (ERG) and visually evoked potentials (VEP).