Anna Brouwer

The uveitis diagnosis was based on the Standardization of Uveitis Nomenclature (SUN) criteria 11 and made by an ophthalmologist specialized in uveitis. Electroretinograms and their medical charts were retrospectively reviewed. This study was conducted in compliance with the ethical principles of the declaration of Helsinki. Ethical approval was requested and obtained from the Medical Ethical Research Committee of the UMC Utrecht. Depending on the age of the patients, we obtained consent from the patients themselves, or their parents, or both. ERG analysis ERGs were measured incorporating the International Society for Clinical Electrophysiology of Vision (ISCEV) standards. 12 Dawson-Trick-Litzkow (DTL) electrodes were used as corneal electrodes. An Espion E3 system with ColorDome Stimulator (Diagnosys LLC, Cambridge, UK) was used for flash stimulation. We measured an extended ISCEV series, consisting of stimulus strengths that increase with approximately 0.5 log units and range from 0.0001 - 30.0 cds/m 2 for the dark-adapted ERG (DA; rod and combined rod/cone) and from 0.3 - 10.0 cds/m 2 for the light-adapted ERG (LA; cone), including a 30 Hz flicker response (LA; cone). The ERGs of patients were compared to healthy controls with the same age range as uveitis patients (5 - 22 years) (N = 50). These ERGs were measured with the same equipment and protocols and provided by the Rotterdam Eye Hospital and Bartiméus (Bartiméus Diagnostic Centre for complex visual disorders, Zeist). An ERG was considered abnormal if amplitudes were below the 2.5 th percentile, or implicit times were above the 97.5 th percentile, or both. We categorized the ERG abnormalities based on the measuring conditions ((LA 0.3 - 10.0 cds/m 2 (cone response), 30 Hz flicker response (cone response), DA 0.0001 - 0.01 cds/m 2 (rod response) or DA 3.0 - 30.0 cds/m 2 (combined rod cone response)) and which part of the response was abnormal (a-wave, b-wave, amplitudes or implicit times). We did not classify DA 0.03 - 1.0 cds/m 2 , as stimulus strengths lay between rod and combined rod-cone responses. All ERGs could be used for analyses. It is our experience that in a child-friendly environment, it is possible to measure an ERG properly, even in small children. Clinical parameters Medical records were reviewed for age, gender, medical history and age at onset of uveitis (defined as age at the date of diagnosis by a (referring) ophthalmologist). Using the outpatient visit closest to ERG measurement, with a maximum of 2.5 months, we recorded for each eye: laterality and localization of uveitis, best corrected visual acuity 112 Chapter 5