Development of an Ex Vivo Model of Focal Corneal Desiccation to Investigate the Pathophysiology of Corneal Dellen and Ulcers.

Purpose: To determine the maximum extent of corneal thinning induced solely by dehydration and to establish the threshold at which corneal lysis begins, thereby refining therapeutic indications, with the aim of improving clinical management.

Methods: Dehydration was induced in 28 corneas, after 4 ex vivo experimental models. Corneal thickness was regularly measured using swept-source optical coherence tomography (OCT). Histological analysis was performed on 14 of the corneas, with computer-based counting of collagen lamellae. The remaining 14 corneas were rehydrated and remeasured using OCT.

Results: Regardless of the model, all corneas exhibited sectoral thinning, clinically resembling corneal dellen. With the most efficient dehydration model, the average minimum pachymetry was 102 ± 30 μm, with minimal values down as low as 49 μm. Computerized histological analysis confirmed that this thinning reflected a greater density of collagen lamellae and not a real loss of collagen. After rehydration, OCT showed a resolution of corneal thinning in all cases.

Conclusions: Corneal dellen thinning reflects the compaction of collagen fibers secondary to localized dehydration. Dehydration alone thinned the cornea to an average of 102 μm, and in some cases, it became as low as 49 μm. Above this threshold, corneal rehydration is sufficient to achieve full recovery.