Anna Brouwer

3 73 ERG abnormalities in non-infectious uveitis often persist To determine how many ms the implicit time needed for change to be defined as significantly changed, we used data of a previous study where we measured a LA ERG twice in 200 uveitis patients, to assess the effects of DTL position on the ERG. 12 The DTL position had an effect on amplitudes, but not on implicit times of the ERG. Because this study was in essence a repeated measurement study, we used the difference in implicit time between the two ERGs of each eye to determine a normal repeatability distribution. We defined improvement as a reduction in cone b- wave implicit time of ≥ 2 SD of this distribution (2.7, 1.7, 1.6 and 1.3 ms for the 0.3, 1.0, 3.0 and 10.0 cds/m 2 flashes respectively) in at least two consecutive flash strengths. We defined worsening as an increase in implicit time with ≥ 2 SD in at least two consecutive flash strengths. We defined the ERG as stable if the implicit time of the first and second ERG was within 95% of the repeatability distribution (< 2 SD). Figure 1 shows examples of a patient with a worsened implicit time (A) and of a patient with an improved implicit time of the cone b-wave (B). Because the focus of this manuscript is on the implicit time of the cone b-wave of the ERG, the terms stable, improved, or worsened ERG mean a stable, improved, or worsened implicit time of the cone b-wave, respectively. Clinical parameters Medical records were reviewed for age, gender, medical history, uveitis diagnosis, and anatomical localization of uveitis. On each of the two outpatient clinical visits we recorded for each eye the BCVA and graded uveitis activity according to the SUN criteria. 13 We also noted the presence of possible media opacities and other factors which might influence the ERG such as: posterior synechiae, corneal clarity, lens clarity, vitreous haze, and pupil size. Also, we recorded per patient if they were treated at the time of ERG recording with systemic steroids, disease modifying anti-rheumatic drugs (DMARDS) (i.e. methotrexate (MTX), azathioprine, mycophenolate mofetil, mycophenolate sodium, or cyclosporine) or biologicals (adalimumab or infliximab). We scored fluorescein angiograms (FA) which were performed within 3 months to the time of ERG recordings as an indication of the severity of inflammation. FAs were scored by an experienced ophthalmologist (JdB) who was blinded regarding the ERG results, using the Fluorescein angiographic scoring system of the Angiography Scoring for Uveitis Working Group (ASUWOG). 14 This FA scoring system scores individual aspects of an FA, which are added up to a final FA score. This FA score, which is the summation of each of these individual sub-scores helps to quantify the magnitude of retinal inflammation. In our previous study, eyes with a higher FA score