Integration of Perforated Subretinal Prostheses With Retinal Tissue

Area of Science:

• Ophthalmology
• Biomaterials Science
• Regenerative Medicine

Background:

• Subretinal implants are a promising strategy for vision restoration.
• Understanding implant biocompatibility is crucial for successful retinal integration.
• Photoreceptor degeneration impacts retinal tissue response to implants.

Purpose of the Study:

• To evaluate the biocompatibility of subretinal implants with varying perforation widths in rat and pig retinas.
• To assess the long-term integration and tissue response to different implant designs.
• To determine optimal implant features for retinas with photoreceptor degeneration.

Main Methods:

• Four subretinal implant designs were tested in transgenic rats (TgP23H-1) and wild-type pigs.
• Implants included solid inactive polymer arrays (IPA) and IPAs/bipolar photovoltaic arrays (bPVA) with 5- or 10-μm perforations.
• Surgical implantation, optical coherence tomography, fluorescein angiography, and light microscopy were used for evaluation.

Main Results:

• Retinal vasculature remained normal across all implant designs and species.
• In TgP23H-1 rats, 10-μm perforations led to inner nuclear layer (INL) cell migration and thinning, increased pseudo-rosette formation, and fibrosis.
• Solid or 5-μm perforated implants, and bPVAs, showed better biocompatibility with less INL migration and fibrosis in TgP23H-1 rats. Pig retinas showed less migration but more fibrosis with perforated implants.

Conclusions:

• Solid implants or those with 5-μm perforations demonstrate superior biocompatibility in retinas experiencing photoreceptor degeneration.
• Implant perforation width significantly influences cellular response and tissue integration.
• Careful design of subretinal implants is essential for minimizing adverse tissue reactions and maximizing therapeutic potential.