Assessment Of Endothelial Cell Loss Within Transplant Preparation For Posterior Lamellar Keratoplasty

To assess the extent of endothelial cell loss as a result of preparing an ultra-thin transplant for posterior lamellar keratoplasty.

This study was conducted at the Federal Center in the Cheboksary branch of the S.N. Fedorov Scientific and Technical Complex "Microsurgery of the Eye," Russia, from January 2023 to January 2025. The hospital serves a population of approximately 600,000 people in an urban environment.

Donor human corneoscleral discs with viable endothelium preserved in the Borzenka-Moroz base medium were used for the experiment execution. Two groups of four pairs of donor corneas were formed. Group 1: corneal transplants for posterior lamellar keratoplasty, cut from the endothelial side with the usage of a femtosecond laser “Visum”  (Optosystems, Troitsk); intact corneoscleral discs of the same donors served as the control. Group 2: donor corneas, on which the laser interface was applanated for 20 seconds from the endothelial side without femtolaser exposure; paired intact corneoscleral discs of the same donors were used as the control.

Identification of live and dead endothelial cells was carried out with the usage of the fluorescent dyes Calcein Violet 450 (ThermoFisher Scientific) and Propidium Iodide (Sigma Aldrich) and a fluorescence microscope. Live and dead cells from the obtained images were counted by means of the program ImageJ. 

Endothelial loss resulting from the preparation of a 130 μm thick transplant amounted to 11.4%. In the group within which only laser interface applanation was performed, this indicator was 12.8%. No statistically significant differences were found between the groups (p>0.05).

The results of the study have demonstrated the absence of damaging energy impact of the femtosecond laser "Visum" on the endothelium within the formation process of a 130 μm thick transplant from the posterior corneal surface. The key reason leading to the death of the endothelium was the mechanical impact at the moment of its applanation.