Hydrogel implants for refractive keratoplasty: corneal morphology

Current refractive correction methods rely on either donor corneal tissue or synthetic materials. While donor tissue remains standard, synthetic alternatives like hydrogels offer potential advantages in customization. However, long-term integration of these materials within the cornea remains uncertain. Prior studies have shown that foreign bodies can trigger fibroblast activity, which may disrupt corneal clarity. The cornea's transparency depends on precise cellular organization, and any disruption could lead to visual impairment. No prior work had resolved whether hydrogels could maintain this structure without adverse effects. This uncertainty motivated investigations into the biocompatibility of hydrogels in refractive procedures. The need to evaluate long-term tissue responses led to the development of this study.

This investigation aimed to assess the biocompatibility of hydrogel implants in refractive keratoplasty. Specifically, the study sought to determine whether hydrogel lenticules could integrate safely within the corneal stroma. The researchers focused on evaluating fibroblast activity and overall tissue morphology. They hypothesized that nonreactive hydrogels might avoid triggering abnormal cellular responses. The goal was to establish whether these implants could maintain corneal transparency. The study also aimed to compare results between rabbit and primate models. By analyzing morphological changes, the team sought to predict clinical viability. The ultimate aim was to provide evidence for the potential use of hydrogels in refractive surgery.

The study used Permalens hydrogel to fabricate lenticules with specific dimensions. Each lenticule was 6 mm in diameter and 0.24 mm thick. These were implanted into rabbit corneas through intracorneal pockets. The surgical procedure involved creating precise pockets within the stroma. Post-implantation, the corneas were monitored for eleven months. Light and electron microscopy were used to examine tissue responses. Researchers analyzed fibroblast activity at the hydrogel-stroma interface. They also assessed the presence of keratocytes and overall ultrastructural integrity.

Microscopy revealed scattered zones of abnormal fibroblast activity at the posterior interface. However, the anterior lining showed a single cell layer of keratocytes. No irregularities were found that could cause light scattering. The remaining ultrastructure remained normal and undisturbed. In primate models, no such fibroblast activity was observed. These results suggest limited adverse reactions in rabbits. The absence of significant morphological changes supports hydrogel integration. The findings indicate that hydrogels may be suitable for refractive keratoplasty.

The authors propose that hydrogels could serve as viable implants in refractive keratoplasty. The data suggests that these materials may integrate without causing major tissue disruption. Limited fibroblast activity in rabbits does not preclude clinical use. Primate studies showed no similar adverse effects, supporting further investigation. The results indicate that hydrogels may maintain corneal transparency. The study implies that these implants could offer an alternative to donor tissue. However, the authors caution that long-term effects remain to be fully established. These findings support the potential of hydrogels in refractive surgery.