Relationship between changes in retinal nerve fiber layer thickness measured by SD-OCT and changes in visual field parameters in birdshot chorioretinopathy

Purpose To describe the structure-function relationship in birdshot chorioretinopathy (BSCR) using visual field data and peri-papillary retinal nerve fiber thickness (RNFL). Methods A total of 21 patients (34 eyes) with BSCR were evaluated prospectively from 2014 to 2018 (IMAGE-EYE cohort). Functional tests included measurement of visual acuity and visual field (30-2 SITA standard). Anatomical tests included fluorescein angiography, indocyanine green angiography, and spectral domain optical coherence tomography. Results Most of the patients were female (57%) with a mean age of 62 +/- 8 years. Mean follow-up was 2.3 +/- 0.6 years. Structural examination results were significantly modified in contrast to functional test results, with a significant reduction in mean RNFL (2.49 mu m, p < 0.01), temporal RNFL (- 1.68 mu m; p = 0.03) and lower nasal RNFL (- 2.83 mu m; p = 0.003). A significant linear relationship was found (p = 0.001) between the visual field deficit (mean deviation (MD)) and the Napierian logarithm of the mean RNFL thickness. Conclusion We found a subtle structural deterioration of the optic nerve (RNFL) during the follow-up, but not of the visual field. The significant relationship between structural (RNFL thickness) and functional measures (mean deviation) also supports the idea that RNFL thickness measurements could be useful for the mid-term monitoring of BSCR patients.