Immunohistochemical study of corneal inflammation after femtosecond laser clear corneal incisions or manual surgery

Abstract

To use immunohistochemical staining to evaluate corneal inflammation and apoptosis induced after femtosecond laser incisions or manual incisions. Ophthalmology Clinic, University G.d'Annunzio, Chieti, Italy. Experimental study. Ninety human cadaver corneas were cut manually or with the femtosecond laser at different energies and analyzed by immunohistochemistry after 5minutes or 4hours. The corneas were divided into 5 groups: untreated (Group 1), cut manually (Group 2), and treated with the femtosecond laser with increasing energies (Groups 3 to 5; 3.0μJ, 6.0μJ, and 15.0μJ, respectively). At 5minutes, increased expression of interleukin (IL)-18 was observed in the femtosecond laser groups compared with the manual group (P<.01). Interferon gamma (IFNγ) positivity was significantly higher in Groups 4 and 5 than in Group 2 and between Groups 3 and 4 (P<.05). The terminal uridine deoxynucleotidyl nick end-labeling (TUNEL) positivity increased with higher energy (Group 2 versus Group 4 and Group 2 versus Group 5; P<.05). After 4hours, IFNγ positivity was higher in Group 5 than in Group 2 (P=.0021) and between Group 5 and Groups 3 and 4 (P<.05). No sign of IL-18 positivity was found after 4hours in any sample. Group 5 showed significant higher TUNEL positivity than all other groups (P<.0001). The femtosecond laser technique at high energies induced a higher corneal inflammatory response and a higher corneal cell apoptosis than the manual technique. None of the authors has a financial or proprietary interest in any material or method mentioned.