Microbiopsy in healthy rabbit corneas. A long-term study

Corneal biopsies are important in diagnosing multiple corneal diseases. They were previously performed by way of keratectomy, a method that causes corneal opacity and topographic changes due to scarring. Microbiopsy is a new way to perform corneal biopsies. Before microbiopsy may be performed on human corneas, the safety of this procedure has to be proved concerning clinical development, histological changes and topographic changes after multiple biopsies.

The healthy right cornea of 24 rabbits was punctured. 12 microtrephinations in 4 different symmetric patterns were performed. The clinical development of the bioptic sites as well as the topographic changes were observed over 5 months. After enucleation, serial sections of the corneas were analysed histologically.

Out of 294 performed biopsies, 291 samples could be collected. 4 perforations occurred. The initial epithelial defect closed within 3 days. A pale stromal scar remained. The histological analysis of these scars showed a facette underlined by a dense hypocellular fibrous layer and a typical star-shaped figure consisting of a loose hypercellular stromal tissue. Only dioptric power of corneas with circle-pattern showed a statistically significant decrease.

Micropuncture is a safe and efficient bioptic procedure. Even 12 micropunctures do not lead to significant changes of dioptric power in most patterns. Further studies are necessary to evaluate the reproducibility of refractive changes by circle patterns and corrections of astigmatisms.