Discrepancy between fundus autofluorescence abnormality and visual field loss in Bietti crystalline dystrophy

Purpose: We aimed to explore the potential benefits of retinal pigment epithelium (RPE) replacement therapy in patients with Bietti crystalline dystrophy (BCD) by assessing the disease pathology with the distinctive relationship between fundus autofluorescence (FAF) abnormality and visual field defect (VFD). Methods: Sixteen eyes from 16 patients with BCD and 16 eyes from 16 patients with RHO-associated retinitis pigmentosa (RHO-RP) were included. FAF, optical coherence tomography, and Goldmann perimetry results were retrospectively reviewed and assessed using image analyses. Results: In patients with BCD, the FAF abnormality area was not correlated with the overall VFD area, and median overall VFD area (57.5%) was smaller than FAF abnormality area (98.5%). In contrast, the ellipsoid zone (EZ) width was significantly correlated with the central VF area (r=0.806, p<0.001). In patients with RHO-RP, the FAF abnormality area and the EZ width was significantly correlated with the overall VF defect area (r=0.833, p<0.001) and the central VF area (r=0.887, p<0.001), respectively. Conclusion: The FAF abnormality shown in patients with BCD involves the RPE degeneration without complete loss of photoreceptors or visual function. These results suggest that BCD patients are good candidates for RPE replacement therapy for preservation of residual visual function.