Intrastromal Keratotomy With Femtosecond Laser Avoids Profibrotic Tgf-Beta 1 Induction

PURPOSE. To examine expression of the profibrotic cytokine TGF-beta 1 after selective intrastromal corneal injury with the use of a femtosecond laser.METHODS. Rabbits underwent monocular intrastromal keratotomy at a preoperatively determined corneal depth of 160 to 200 mu m with the use of a femtosecond laser. Femtosecond laser-induced TGF-beta 1 expression was compared in nonoperated control eyes and eyes treated with photorefractive keratectomy (PRK). Follow-up examinations were performed 1, 3, 7, and 28 days after surgery. TGF-beta 1 protein was identified by immunofluorescence labeling. With the use of laser-capture microdissection, epithelial, stromal, and endothelial cell layers were collected, and changes in TGF-beta 1 mRNA expression were quantified with quantitative RT-PCR.RESULTS. TGF-beta 1 mRNA and protein expression did not significantly increase after intrastromal femtosecond laser keratotomy. In contrast, TGF-beta 1 was induced in corneal epithelial and stromal cells after PRK and showed up to 23-fold higher TGF-beta 1 mRNA levels compared with control corneas. The increase of TGF-beta 1 mRNA levels after PRK was accompanied by increased TGF-beta 1 protein production.CONCLUSIONS. Isolated stromal injury with a femtosecond laser does not result in induction of the profibrotic cytokine TGF-beta 1. Because TGF-beta 1 has been implicated in a fibrotic response of the corneal stroma to injury, absence of TGF-beta 1 induction argues for a favorable wound-healing response. These findings support highly selective intrastromal procedures in refractive surgery. (Invest Ophthalmol Vis Sci. 2009; 50:3688-3695) DOI:10.1167/iovs.08-2699