In vitro immunohistochemical and morphological observations of penetrating corneal incisions created by a femtosecond laser used for assisted intraocular lens surgery.

PURPOSE: To compare inflammatory cell response and morphological aspects of femtosecond laser-created corneal incisions.

SETTING: Department of Ophthalmology, Goethe-University, Frankfurt am Main, Germany.

DESIGN: Experimental study.

METHODS: In 16 of 22 human corneoscleral buttons, clear corneal tunnel incisions were created using a femtosecond laser (Lensx) with 7 μJ laser pulse energy on the outer periphery and manually using a phaco knife on the respective opposite side (180 degrees). In 6 corneas, no treatment was performed (controls). Corneas were then kept in organ culture for 12 or 48 hours, and the inflammatory reaction was evaluated using standard immunofluorescence analyses for monocytes (CD11b) and for dendritic cells (HLA-DR). For morphological analyses and apoptosis, van Gieson staining and terminal deoxynucleotidyl transferase deoxy-UTP-nick end labeling was performed.

RESULTS: There were no statistically significant differences in inflammatory cell response between femtosecond laser corneal incisions and manually performed incisions. Apoptosis was significantly more pronounced in the femtosecond incisions. The ratio of dendritic cells between femtosecond incisions and manual incisions was 1:2 (12 hours and 48 hours; P=.07), the ratio of monocytes was 1:2 (12 hours and 48 hours; P=.08), and the ratio of apoptotic cells was 1:5 (12 hours) and 1:6 (48 hours) (P=.02). Femtosecond laser incisions showed a more sawtooth-like cutting edge than manual incisions.

CONCLUSIONS: Femtosecond laser-created corneal incisions in human corneas showed no differences in inflammatory cell response but a significantly higher cell death rate than manually performed incisions, indicating an upregulated postoperative wound-healing response.

FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosures are listed after the references.