Prime editing for ocular gene therapy and disease modeling: a narrative review of advances, delivery, and translational readiness.

Prime editing is a versatile "search-and-replace" genome-editing technology that enables precise and flexible genome correction of genetic sequences by reverse-transcribing an RNA template encoded at the 3' end of a prime editing guide RNA (pegRNA). It supports the introduction of nucleotide substitutions, and insertions or/and deletions (indels) in living cells without requiring double-stranded DNA breaks or exogenous donor templates. Since its introduction in 2019, prime editing has advanced rapidly-from the first-generation prime editor (PE1) to PE7 and other next-generation variants-with editing efficiencies increasing from 0.7 to 5.5 % to more than 50 % in vitro. Optimization strategies including engineering of the Cas9 and reverse transcriptase domains, refinement of pegRNA architecture, recruitment of auxiliary proteins, and modulation of DNA repair pathways have substantially enhanced editing efficiency, product purity, and target scope across diverse cell types and tissues. These developments are particularly relevant to ophthalmology, where many blinding disorders arise from point mutations or small indels ideally suited for prime editing-based correction. Recent work in retinal cells and animal models has demonstrated the growing feasibility of prime editing to treat inherited retinal diseases, modulate pathological angiogenesis, and achieve precise gene repair in post-mitotic photoreceptors and retinal pigment epithelial cells. As delivery vectors and newer PE variants improve, prime editing is a plausible next-generation platform for a wide range of ocular diseases.