Purpose
To study progression of visual field loss in serial Humphrey Visual Fields (HVF) by pointwise linear regression analysis of luminance sensitivity against time, over long term follow up in a large series of patients with Birdshot chorioretinopathy (BCR).
Methods
Retrospective review of charts and HVF of all HLA A29 positive BCR patients, diagnosed in accordance with the diagnostic criteria laid out by the International Consensus Conference on BCR and seen at Moorfields Eye Hospital from 1999 to 2012. All reliable white on white SITA Standard/ SITA Fast 24-2/ 30-2 HVF available for eyes with 3 or more reliable field tests were uploaded on the progressor software for analysis. Studies were excluded from analysis if they failed reliability criteria of < 33% fixation losses and < 20% false positive and < 20 % false negative responses or if the patient had coexistent pathology in the visual pathway that may have contributed to visual field defects. Progression was defined as a significant regression slope (p<0.05) showing >/= 1 dB per year sensitivity loss for non edge points and >/= 2dB per year for edge points (beyond 15 degrees eccentricity).
Results
133 HVF from 31 eyes of 17 patients were included in the analysis. 10 patients were female. All were white. Mean time interval between the first and the last field test in each series was 54.47 months. Median time interval was 44 months (Interquartile range 27-61months). 23 eyes (74%) had more than 3 reliable fields. There was evidence of progressive field loss in 5 eyes of 3 patients (18% patients, 16% eyes) of which 2 patients had received and one had declined systemic treatment for BCR. The only other untreated patient maintained stable visual fields over an 85 month follow up. The mean slope of global sensitivity change in eyes with stable fields was 0.59+/- 1.80 db/yr, range -0.23 to 3.32 db/yr.
Conclusions
In this series of patients with BCR, there was good concordance between the progression status of a subject’s left and right eyes. Non-progressing eyes had a positive mean slope which we interpret as learning effect. Only a small percentage of patients showed significant white on white progressive visual field loss, suggesting that with treatment, most visual fields can be preserved over the long term. However, not all untreated patients will necessarily suffer progressive field loss.
Keywords: 746 uveitis-clinical/animal model •
758 visual fields •
451 chorioretinitis