Anna Brouwer

131 6 JIA uveitis: a typical anterior uveitis, but the retinal function can be affected Dear editor, Juvenile idiopathic arthritis (JIA) associated uveitis is typically described as a chronic anterior uveitis. We would like to present 8 patients with longstanding JIA uveitis (aged between 17 - 40 years) with suspicional retinal thinning on optical coherence tomography (OCT), of whom we additionally measured a full-field electroretinogram (ERG). In 10 of the 16 uveitis eyes we observed ERG abnormalities (Figure 1). These ERG abnormalities indicate that although the inflammation in JIA is mainly located in the anterior part of the eye, the retina can be affected as well. To the best of our knowledge, this is the first report that describes that the ERG can be affected in this particular type of uveitis. The ERGs were measured according to an extended international society for clinical electrophysiology of vision (ISCEV) protocol. This protocol incorporates the ISCEV standards, but includes more flash strengths than the standard ISCEV protocol. The flash strengths increase with approximately 0.5 log units steps and range from 0.0001 - 30.0 cds/m 2 (12 flash strengths) for the dark-adapted ERG (DA) and from 0.3 - 10.0 cds/m 2 (4 flash strengths) for the light-adapted ERG (LA) and include a 30 Hz flicker response. Dawson-Trick-Litzkow (DTL) electrodes were used as corneal active electrodes, and an Espion E3 system with Colordome stimulator (Diagnosys LLC, Cambridge, UK) for flash stimulation. Our reference values were previously described. 1 The type of ERG abnormalities varied among patients. Table 1 gives an overview of the ERGresults.Weobserved abnormalities in all parts of the ERG: both in amplitudes and implicit times, in a-waves, b-waves and the 30 Hz flicker response. Abnormalities occurred in both the dark adapted (DA) and the light adapted (LA) ERG. The only ERG parameter which showed no abnormalities was the implicit time of the rod b-wave indicating that the rod response might be less affected than the cone response in JIA uveitis. In some eyes the amplitudes were severely diminished, whereas in others the implicit times were mainly prolonged. The most frequent ERG abnormality was a prolonged cone a-wave, which was abnormal in eight eyes. These findings highlight that different aspects of retinal function can be affected in JIA uveitis, which is in line with other forms of uveitis where ERG abnormalities may be observed in all aspects of the ERG, but the light adapted ERG is most frequently affected. 1 We previously reported a characteristic type of ERG abnormality in non- infectious uveitis: a prolonged cone b-wave, which was associated with the severity of inflammation, but in these studies no patients with JIA uveitis were included. 1,2 The ERGs of the current JIA patients showed a prolonged cone b-wave in 6 eyes. Recently we observed that the prolonged cone b-wave can improve in other forms of uveitis, particularly in eyes where the inflammation in the anterior chamber becomes less