Purpose:
To investigate the association between fluorescein leakage on fundus fluorescein angiography (FFA) and electroretinography (ERG) parameters in a cohort of patients with Birdshot chorioretinopathy (BCR).
Methods:
Retrospective cross sectional study. The case notes, fluorescein angiograms and electroretinograms of all patients with the diagnosis of BCR seen in the Uveitis Service at Moorfields Eye Hospital between May 2010 and October 2011 were reviewed. Fluorescein angiograms were scored using the angiographic scoring system for uveitis proposed by the Angiography Scoring for Uveitis Working Group (ASUWOG). All electroretinograms were performed using protocols to incorporate the International Society for Clinical Electrophysiology of Vision (ISCEV) standard electroretinograms. The relationship between FFA scores and contemporaneous ERG parameters was assessed using Spearman’s Rank Correlation.
Results:
Fifty one Patients met published research criteria for the diagnosis of Birdshot chorioretinopathy as proposed by an International Consensus Conference (Lake Arrowhead, California, October 2002) and were HLA A29 positive. All were white, 30 were female and 21 were male. The mean age at onset of symptoms referable to BCR was 51.73 years (median age 53 years; range 30-82 years). 43 patients had contemporaneous FFA and ERG. Fluorescein leakage at the posterior pole was scored for both eyes of all patients, four quadrant peripheral frames were also available and were scored for 27 right eyes and 26 left eyes. Complete ERG data was available for all eyes. We found strong evidence of an association between the severity of fluorescein leakage and the 30 Hz peak time (Right eye ρ=0.4708, P =0.0017, Left eye ρ=0.6081, P=0.0000), the light adapted single flash b wave peak time (Right eye ρ=0.4294, P=0.0045, Left eye ρ=0.5510, P=0.0001) and the dark adapted bright flash a wave peak time (Right eye ρ=0.3723, P=0.0152, Left eye ρ=0.3963, P=0.0085). Whilst associations appeared plausible for other parameters, the correlations were not statistically significant.
Conclusions:
In this large series of patients with Birdshot chorioretinopathy, a strong association was found between the severity of retinal vascular leakage on angiography and functional impairment, as measured by electroretinography abnormalities. On the basis of this correlation, it is hypothesized that aggressive treatment of retinal vascular leakage in the early stages of the disease maybe warranted to reverse electrophysiological abnormalities and to preserve retinal function.
Keywords: uveitis-clinical/animal model • electroretinography: clinical • chorioretinitis