Pigment Loss and Pseudo-Albinism in Birdshot Chorioretinitis

Objectives To describe a rare phenotype of birdshot chorioretinitis (BSCR) characterized by diffuse retinal depigmentation and to evaluate its impact on visual outcomes. Methods This observational study included patients from the CO-BIRD cohort (NCT05153057) with ultra-widefield fundus imaging. Retinal depigmentation was graded using the albinism scale by Kruijt et al. (grades 0–3). Eyes with grade ≥ 2 in at least one image were included. Best-corrected visual acuity (BCVA), Humphrey 30 − 2 mean deviation (MD) and pattern standard deviation (PSD), and National Eye Institute Visual Function Questionnaire – 39-item (VFQ-39) were recorded. Incidence of macular oedema (MO), optic disc oedema (ODO), and choroidal neovascularization (CNV) was assessed. Results Among 1016 eyes (508 patients), 52 eyes (26 patients, 5.1%) had depigmentation grade ≥ 2; 22 eyes (2.2%) reached grade 3. Fifteen years after symptom onset, BCVA worse than 0.7 logMAR occurred in 42.1% of grade 3 versus 5.0% of grade 2 eyes ( p  = 0.014). VFQ-39 scores were similarly reduced in both groups. Grade 3 was associated with lower ODO risk (HR = 0.38; p = 0.028) and a non-significant MO risk reduction. CNV occurred only in grade 3 (40.9%). Grade 3 was linked to worse BCVA ( p  = 0.012) and higher PSD ( p  = 0.011). Compared with previously published CO-BIRD data, grade 3 showed faster BCVA decline ( p  = 0.044) and greater cumulative loss ( p  = 0.001). Conclusion Diffuse retinal depigmentation resembling albinism is an uncommon but severe BSCR phenotype associated with poorer visual outcomes.