Pigment loss and pseudo-albinism in Birdshot chorioretinitis
摘要
To describe a rare phenotype of birdshot chorioretinitis (BSCR) characterised by diffuse retinal depigmentation and to evaluate its relationship with disease chronicity and visual outcomes.
MethodsThis observational study included patients from the CO-BIRD cohort with ultra-widefield fundus imaging. Retinal depigmentation was graded using the albinism scale by Kruijt et al. (grades 0–3). Eyes with a grade ≥ 2 in at least one image were included. Disease activity and severity were assessed using best-corrected visual acuity (BCVA), vision-related quality of life (VFQ-25), visual field testing and multimodal imaging.
ResultsAmong 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-25 scores were similarly reduced in both groups. Grade 3 was associated with a lower risk of optic disc oedema (HR = 0.38; p = 0.028) and a non-significant reduction in macular oedema risk. Choroidal neovascularisation occurred only in grade 3 (40.9%). Grade 3 was linked to worse BCVA (p = 0.012), higher pattern standard deviation (p = 0.011), and a history of active disease. Compared with previously published CO-BIRD data, grade 3 showed faster BCVA decline (p = 0.044) and greater cumulative loss (p = 0.001).
ConclusionDiffuse retinal depigmentation resembling albinism is an uncommon but severe expression of BSCR, indicative of chronic disease and associated with poorer visual outcomes.