For adults born without irises, progressive corneal clouding — aniridia-related keratopathy — has historically offered little beyond palliative care or high-risk conventional transplants that frequently fail. A tissue-engineered approach that simultaneously addresses two cellular deficits in the cornea could meaningfully shift the treatment calculus for this rare but vision-destroying condition.
A single-arm, open-label trial conducted at a London tertiary center enrolled nine adults with congenital aniridia and advanced aniridia-related keratopathy between 2022 and 2024. Participants received surgical transplantation of RAFT-OS, a good-manufacturing-practice-produced collagen scaffold seeded with both allogeneic limbal epithelial stem cells and stromal keratocytes. The primary endpoints were safety and ocular surface normalization measured by the Ocular Surface Score at three and twelve months post-transplant. Secondary endpoints captured best-corrected visual acuity via ETDRS charts alongside patient-reported quality-of-life measures through the VFQ-25 and RAND-36. Untreated fellow eyes served as internal natural history comparators over the twelve-month follow-up window.
What makes this trial scientifically notable is its dual-cell architecture. Prior limbal stem cell transplant strategies have largely addressed only the epithelial compartment, leaving the stromal microenvironment — which provides critical scaffolding and paracrine signaling — to deteriorate independently. By co-delivering keratocytes within a bioengineered collagen matrix, the RAFT-OS construct attempts to reconstitute both layers simultaneously, a mechanistic advance over single-lineage approaches. The collagen scaffold itself may also reduce the immune challenge that undermines conventional donor grafts in this immunologically compromised tissue. That said, with only nine participants, no randomized control arm, and a twelve-month horizon, causal efficacy claims remain premature. Aniridia-related keratopathy also progresses slowly and variably, meaning longer observation windows will be essential. This trial is best read as a carefully designed feasibility and safety signal — incremental but credible groundwork for a future adequately powered randomized study.