Ophthalmology. Retina
OBJECTIVE: To describe the histological findings 7 weeks and 18 months after subretinal implantation of the PRIMA photovoltaic array in eyes with geographic atrophy.
DESIGN: Comparative case series SUBJECTS: and controls: Four globes of two deceased study participants from the prospective PRIMAvera study were analyzed.
METHODS: The subretinal implant was removed after horizontal sectioning of the globe. Serial sections were performed and stained with hematoxylin-eosin, Masson trichrome as well as periodic acid Schiff for histopathologic analysis. Selected sections were immunohistochemically stained for CD68, CD163, GFAP, CD31, CK18, ARR3, RPBMS, and TRPM1. Both study and fellow eyes were analyzed.
MAIN OUTCOME MEASURES: The histopathological analysis focused on the anatomical implant localization, wound healing processes, potential inflammatory reactions adjacent to the implant and at the retinotomy site, the development of retinal gliosis and retinal atrophy as well as a potential encapsulation.
RESULTS: Both implants could be removed in toto without obvious retinal trauma. Histologically, the implants were located at the level of the outer plexiform layer, as intended, close to the inner nuclear layer. A tissue layer was identified beneath the implant, consisting of a basement membrane deposit and cellular components. A small rupture of Bruch's membrane was detected (in the globe with an 18 months follow-up) associated with localized subretinal fibrosis. At the implant-retina interface, there was only a minimal tissue response without pseudocapsule formation. Furthermore, no significant inflammatory response was detected. The retina overlying the implant was comparable to the fellow eyes in most areas, with limited focal atrophy of the inner retina 18 months after PRIMA implantation. At the retinotomy site, a full thickness scar was noted with mild atrophic changes in the implant insertion area.
CONCLUSIONS: The wireless subretinal PRIMA implant demonstrated good biocompatibility with no significant encapsulation or surrounding inflammatory response. At seven weeks and eighteen months after implantation, retina overlying the implant was viable and layered as in control areas. Histopathologic analysis following innovative surgical techniques can provide important information in addition to in vivo findings.
Copyright © 2026 American Academy of Ophthalmology, Inc. Published by Elsevier Inc. All rights reserved.
PMID: 42250602