Anna Brouwer

Summary Types of ERG abnormalities and clinical associations The aim of this thesis was to investigate if, and how the ERG can be affected in uveitis. But also, we wanted to investigate if the disease duration would influence the ERG. We discovered that the retinal function was worse in uveitis patients in all parameters of the ERG compared to healthy controls ( Chapter 2 ). Amplitudes were lower, and implicit times were longer in in the rod, cone and combined rod/ cone responses. Also, both a-waves and b-waves were affected. However, the most characteristic type of ERG abnormality that we observed in uveitis patients was the prolonged implicit time of the cone b-wave (cone b-IT). This prolonged cone b-IT is associated with the severity of the inflammation in both present and past ( Chapter 2 ). Interestingly, the duration of uveitis was not associated with ERG abnormalities in any way because an ERG can already be abnormal in the first year of inflammation. This is contrary to what we expected at the start of this thesis. We also investigated if a different anatomical localization of uveitis led to a different amount of ERG abnormalities ( Chapter 2 ), but this proved not to be the case. This entails that even in eyes with an anterior uveitis, where the primary location of the inflammation is in another anatomical compartment than the retina, the ERG can be abnormal. It illustrates that the consequences of inflammation in the eye due to uveitis may be broader than we think. Onemay speculate that this was to be expected, because cystoidmacula edema (CME) is a frequent complication in in anterior uveitis. However, the macula accounts only for a small part to the full-field ERG. 1 An abnormal macular function alone will not result in an abnormal full-field ERG. Therefore, the presence of CME alone cannot explain the abnormal ERGs that we observed in eyes with anterior uveitis. We also investigated possible differences in ERG abnormalities between the different uveitis diagnoses, but we found no such difference. The retinal function can be affected in all the types of uveitis that were investigated in this thesis. The ERG in childhood uveitis In Chapter 5 we investigated ERGs of patients with childhood uveitis that were performed to exclude a retinal dystrophy. 2 The findings of Chapter 5 highlight that the ERG can be abnormal in childhood uveitis, but to a much lesser extent than in patients with a retinal dystrophy. 160 Chapter 8