Abstract
Purpose:
To characterize multifocal electroretinogram (mfERG) findings in patients with birdshot chorioretinopathy (BCR) over the clinical course of the disease. A retrospective chart review was conducted to compare findings on mfERG to clinical indicators of uveitis activity, Goldmann visual field (GVF) findings, and structural findings on spectral domain optical coherence tomography (sdOCT) throughout the clinical course of BCR.
Methods:
A review of 14 eyes of 7 patients presenting to the uveitis service at the University of Ottawa Eye Institute with BCR and documented mfERG, GVF, sdOCT, and clinical exam between September 2010 and December 2013. Time since diagnosis, pharmacological therapy, best corrected visual acuity (BCVA), anterior chamber and vitreous cell grading, mfERG ring ratios, GVF maps, and structural changes on sdOCT were recorded from each clinical appointment and compared over the duration of follow-up.
Results:
Mean age at presentation was 55 years (range 41-71 years). There were five females and two males, all Caucasian. Average duration of follow-up was 29.4 months. All patients developed electroretinal dysfunction of the cone system within the central 30 degrees detected on mfERG regardless of the morphology of choroidal lesions. In 4 of 7 patients, mfERG abnormalities preceded detectable changes in the degree of inflammation, BCVA, GVF, and macular thickness on sdOCT. In one patient, the onset of mfERG findings coincided with abnormal clinical, GVF, and sdOCT findings. Two patients were referred late in the disease course and their mfERG results were abnormal from baseline.Four patients were treated with cyclosporine and prednisone, two patients were treated with mycophenolate mofetil, and one with adalimumab. All patients showed an improvement of at least one line in Snellen visual acuity from baseline.
Conclusions:
This is the first report in the literature illustrating the potential utility of mfERG in detecting declining retinal function earlier in the course of BCR than is otherwise detected by history, clinical indicators of uveitis activity, GVF, or macular thickness on sdOCT. Further prospective trials are required to determine if use of mfERG to detect early functional decline in the retina may assist clinicians in initiating immune modulatory therapy or optimizing treatment to improve patient outcomes in the treatment of BCR.