Anna Brouwer

Abstract Purpose To identify possible correlations between structural changes on optical coherence tomography (OCT) and functional abnormalities on electroretinography (ERG) in uveitis patients. A characteristic ERG abnormality in uveitis is a prolonged cone b-wave implicit time (cone b-IT). We investigated the relationship between a prolonged cone b-IT and retinal layer thickness on OCT. Differences in thickness were expected to occur in the retinal layers which contain the bipolar cells: the inner plexiform layer (IPL), inner nuclear layer (INL), and outer plexiform layer (OPL). Methods OCT scans of 189 uveitis patients (333 eyes) were segmented with Iowa reference algorithms software. Differences in mean thickness were analyzed of ten retinal layers per region of the ETDRS grid between non-uveitis eyes and uveitis eyes with and without a prolonged cone b-IT on ERG. Spearman’s rho correlation coefficients were also analyzed. Results The IPL was significantly thinner (p < 0.05,regions 2, 3, 5-9) in eyes with a prolonged cone b-IT, whereas the INL was significantly thicker (p < 0.05, regions 1 - 6). No differences were observed in the OPL. However, the correlation coefficients between implicit times and retinal layer thickness were weak (Spearman’s rho 0.103 - 0.388, p < 0.05). Vitritis, FA score, and age were also weakly correlated to thickness. Conclusions There is a weak correlation between a prolonged cone b-IT on ERG and a thickening of the INL and thinning of the IPL. Other clinical factors including age and uveitis activity showed similar weak correlations to thickness. Therefore, differences in retinal thickness alone do not fully explain a prolonged cone b-IT. 94 Chapter 4