Peripapillary comet lesions and comet rain in PXE-related retinopathy

Purpose To study peripapillary comet lesions (PCL) in Italian patients affected with pseudoxanthoma elasticum (PXE). Methods Retrospective review of fundoscopic and swept-source (SS) optical coherence tomography (OCT) images of patients with PXE examined at the Regional Reference Center for Hereditary Retinal Degenerations at the Careggi Teaching Hospital of Florence from 2012 to 2017. Results From 148 eyes of 74 patients affected with PXE, we identified 24 eyes of 14 patients (11 were female) with a mean age of 39 years (range, 20–58 years) characterized by peripapillary comet lesions. Of these 24 eyes, 15 eyes (of 10 patients) were characterized by comet rain. The smallest comet lesion at the OCT examination appeared as a focal roundish hyper-reflective alteration at the level of the outer retinal segments and RPE-Bruch’s membrane complex; the larger lesions appeared as circular and ovoid structures with hyper-reflective borders in the outer nuclear layer. Conclusion The comet lesion formation process involves the outer layers of the retina and RPE/Bruch’s membrane complex. It consists of a degenerative/rearrangement process of the photoreceptors which occurs in an area of focal altered RPE/Bruch’s membrane resembling the outer retinal tubulation.