Anna Brouwer

Chapter 3 80 It is important to note that most of the eyes did not show significant ERG changes. In 78 eyes (80%) the implicit time was stable, of which 25 eyes had a prolonged implicit time. Almost two third of these (16 eyes) had no signs of an active inflammation during the follow-up ERG. Supplemental tables 2 and 3 give an overview of the different aspects of the FA score. There were no differences in these individually scored aspects of the FA between eyes with a different ERG outcome. Supplemental table 4 shows the correlation matrix between statistically significant clinical factors, duration of uveitis, age, and treatment. Although many factors are statistically significant, all of the associations are weak (rho < 0.5). Discussion This study highlights that a prolongation of the implicit time of the cone b-wave occurs early on in the non-infectious uveitis and often persists. Only in a minority of cases, it can improve or deteriorate in the course of the disease. Improvement was mostly seen in eyes in which the inflammation became more quiescent, whereas a worsening was seen in eyes with a persistent inflammation. The delayed cone b-wave is probably due to an impaired photo-transmission to the bipolar cells. It remains speculative if this ERG abnormality is the first sign of evolving photoreceptor damage. Although these findings indicate that it is important to treat the inflammation in uveitis adequately and early, we found no differences between the groups based on type of treatment. This might be due to several factors including variation between treatment strategies, as well as the effects of responders versus non-responders. In eyes with an improved ERG, the inflammation in the anterior chamber had become quiescent. The majority of these patients had a panuveitis. It is likely that the improvement of the inflammation in the anterior chamber was associated with an improvement of the posterior segment, which should be the subject of further studies. In most eyes the ERG abnormalities were irreversible, even without signs of active inflammation at the time of the follow-up ERG. Because we measured the first ERG in the first year of onset of disease, it indicates that the retinal damage can occur early on in the disease process. Patients with an abnormal first ERG started systemic treatment on average later than those with a normal first ERG. Furthermore, patients with an improved ERG were using systemic medication more often at the time of the follow-up ERG compared to the first ERG. Although these results showed a trend, the differences were not significant. One explanation could be that the patients in this study may represent a group with a more severe disease course, because this study was performed in a tertiary referral centre.