Optical Coherence Tomography (OCT) Features of Inactive Multifocal Choroiditis with Panuveitis and Punctate Inner Choroidopathy (MFCPU/PIC) Lesions

Abstract Purpose To identify optical coherence tomography (OCT) biomarkers of inactive multifocal choroiditis with panuveitis and punctate inner choroidopathy (MFCPU/PIC) and to compare them with atrophic chorioretinal scars secondary to inflammatory and infectious mimickers. Design Cross-sectional observational study. Subjects Fifty-nine patients with inactive chorioretinal atrophic lesions, including 27 patients (57 lesions) with MFCPU/PIC and 32 patients (49 lesions) with non-MFCPU/PIC etiologies (sarcoidosis, tuberculosis, syphilis, serpiginous choroiditis, APMPPE, birdshot chorioretinopathy, and ocular toxoplasmosis), evaluated at Luigi Sacco Hospital (Milan, Italy). Methods All patients underwent multimodal imaging including color fundus photography, near-infrared reflectance, fundus autofluorescence, and spectral-domain OCT (SD-OCT), with additional high-resolution OCT (HR-OCT). Lesions were randomly sampled (maximum three per eye). Quantitative OCT measurements included retinal pigment epithelium atrophy size (RPE-AS), Bruch's membrane defect size (BrM-HS), and choroidal thickness coefficient (CTC). Structural alterations across retinal layers were graded. Regression models with cluster-robust standard errors were used to account for intra-patient clustering. Main Outcome Measures Frequency of Bruch's membrane (BrM) disruption and inner retinal layer herniation; relationship between RPE-AS and BrM-HS; choroidal involvement; agreement between SD-OCT and HR-OCT. Results BrM disruption was observed in 94.7% of MFCPU/PIC lesions compared with 6.1% of controls (p < 0.001), remaining strongly associated with MFCPU/PIC independently from age and RPE-AS. Inner nuclear layer (INL) herniation was significantly more frequent in MFCPU/PIC lesions (57.9% vs 4.3%, p < 0.001). RPE atrophy was present in all lesions, while BrM defects were consistently smaller and concentrically localized within areas of RPE atrophy. RPE-AS and BrM-HS were positively correlated (β = 0.36, p = 0.002). MFCPU/PIC lesions demonstrated lower CTC values (p < 0.001) and more frequent focal choroidal excavation. Agreement between SD-OCT and HR-OCT was good (κ = 0.60), with no added diagnostic yield of HR-OCT. Conclusions Bruch's membrane disruption and inner retinal layer herniation into focal choroidal excavation are highly characteristic OCT features of inactive MFCPU/PIC. These findings may facilitate diagnosis in the absence of active inflammation and support a distinctive lytic inflammatory mechanism involving the outer retina, BrM, and choroid.