PURPOSE: To examine early postoperative wound healing in rabbit corneas that had LASIK flaps formed with three different models (15 KHz, 30 KhZ, and 60 KHz) of a femtosecond laser compared with flaps formed with a microkeratome. METHODS: Thirty-nine rabbit eyes were randomized to receive either no surgery or corneal flaps formed with one of the lasers or the microkeratome. Sixteen eyes also had lamellar cuts with no side cuts with the 30 KHz laser. Animals were sacrificed and corneas processed as frozen sections or fixed for transmission electron microscopy. Frozen sections were evaluated with the TUNEL assay to detect apoptosis, immunocytochemistry for Ki67 to detect cell mitosis, and immunocytochemistry for CD11b to detect mononuclear cells. RESULTS: Rabbit corneas that had flaps formed with the 15 KHz laser had significantly more stromal cell death, greater stromal cell proliferation, and greater monocyte influx in the central and peripheral cornea at 24 hours after surgery than corneas that had flaps formed with the 30 KHz or 60 KHz laser or the microkeratome. Results of the 60 KHz laser and microkeratome were not significantly different for any of the parameters at 24 hours, except for mitotic stromal cells at the flap margin. Transmission electron microscopy revealed that the primary mode of stromal cell death at 24 hours after laser ablation was necrosis. CONCLUSIONS: Stromal cell necrosis associated with femtosecond laser flap formation likely contributes to greater inflammation after LASIK performed with the femtosecond laser, especially with higher energy levels that result in greater keratocyte cell death. [J Refract Surg. 2007;23:667-676.]

Refractive surgery is a popular method used to reduce or eliminate dependence on glasses and contact lenses. Corneal haze is one of the common complications observed after photorefractive keratectmomy (PRK). The objective of this study was to develop an in vivo mouse model that consistently produces moderate to severe corneal haze in the anterior stroma of the mouse cornea after excimer laser treatment to study myofibroblast biology and corneal wound healing in a genetically defined model. Regular-or irregular-phototherapeutic keratectomy (PTK) was performed on black C57BL/6 mice with the Summit Apex excimer laser (Alcon, Ft. Worth, TX). Different numbers of laser pulses (45; ablation depth ~10 μm) were fired on the central cornea, after scraping the epithelium prior to excimer laser ablation. Irregularity was generated by positioning a fine mesh screen in the path of laser after firing 50% of the pulses. Eyes were collected 1, 2, 3 or 4 weeks after the procedure. Haze formation was gauged with slit lamp biomicroscopy. Immunocytochemistry was used to determine number of myofibroblasts in the mouse cornea using antibodies specific for the myofibroblast marker alpha-smooth muscle actin (SMA). The numbers of SMA-positive cells/400X microscopic were determined by counting within the stroma. Statistical analysis was performed using analysis of variance (AVOVA) with the Bonferonni-Dunn adjustment for repeated measures. Regular-PTK with epithelial scrape (Group 3) and irregular-PTK with epithelial scrape (Group 4) in the mouse eyes were performed to produce corneal haze. Eyes collected 4 weeks after regular-or irregular-PTK after epithelial scrape showed 22 ± 6.6 (Group 3) or 34 ± 7.9 (Group 4) SMA-positive cells in the anterior cornea. The difference in the SMA-positive cells detected among the groups was statistically significant (p < 0.01). Less than 4 SMA-positive cells were detected in the tissue sections of the mouse eyes collected after 1, 2 or 3 weeks of regular (Group 3) or irregular PTK (Group 4) or controls (Group 1 and 2). The optimized PTK excimer laser conditions developed in this study produces haze selectively in anterior stroma of the mouse cornea immediately beneath the epithelial basement membrane. Irregular PTK performed after epithelial scrape by applying 45 laser pulses was found to be the most effective method to generate myofibroblasts. This PTK technique for inducing haze in mouse cornea in vivo provides a useful model for studying wound healing and myofibroblast biology in transgenic mice.

PURPOSE: To evaluate differences related to ocular aberrations after customized LASIK for myopia using three different microkeratomes. METHODS: Charts of 410 patients who underwent customized LASIK with the Alcon LADARVision4000 excimer laser were reviewed. Patients were stratified according to the device used to create the flap: Moria M 2 mierokeratome, Bausch & Lomb Hansatome microkeratome, or Intra Lase laser. The difference between the wavefront pre- and postoperative value received a positive or a negative sign if the change occurred toward or away from zero, respectively, and it was compared to preoperative minus postoperative manifest refraction spherical equivalent (MRSE). RESULTS: Patients showed increase in the aberration level after LASIK with the three devices used in this study. Intra Lase spherical aberration change tended to be better than mechanical microkeratomes for higher MRSE values (Intra Lase compared to Hansatome, P^. 023 for MRSE values ^4.00 diopters [D]; IntraLase compared to Moria, P^. 015 for MRSE values ^2.00 D). For total aberrations, the improvement values for IntraLase tended to be higher than those for Moria (Intra Lase com pa red to Mo ria, P^. 021 for M RS E va lues 2=3.00 D). For total higher order aberrations, IntraLase values tended to be better than Moria and Hansatome microkeratomes (IntraLase compared to Hansatome, P^.047 for MRSE values between 3.00 and 8.00 D; IntraLase compared with Moria, P^. 002 for MRSE values 2=2.00 D). Change in coma root-mean-square was similar for the three groups. CONCLUSIONS: The findings suggest the femtosecond laser provides a better platform for LASIK than the commonly used microkeratomes analyzed in this study. [J Refract Surg. 2007;23:880-887.]

Interleukin (IL)-1α and β are important modulators of many functions of corneal epithelial and stromal cells that occur following injury to the cornea, including the influx of bone marrow-derived inflammatory cells into the stroma attracted by chemokines released from the stroma and epithelium. In this study, we examined the effect of topical soluble IL-1 receptor antagonist on bone marrowderived cell influx following corneal epithelial scrape injury in a mouse model. C57BL/6 mice underwent corneal epithelial scrape followed by application of IL-1 receptor antagonist (Amgen, Thousand Oaks, CA) at a concentration of 20 mg/ml or vehicle for 24 h prior to immunocytochemical detection of marker CD11b-positive cells into the stroma. In two experiments, topical IL-1 receptor antagonist had a marked effect in blocking cell influx. For example, in experiment 1, topical IL-1 receptor antagonist markedly reduced detectible CD11b-positive cells into the corneal stroma at 24 h after epithelial injury compared with the vehicle control (3.5 ± 0.5 (standard error of the mean) cells/400× field and 13.9 ± 1.2 cells/400× field, respectively, p < 0.01). A second experiment with a different observer performing cell counting had the same result. Thus, the data demonstrate conclusively that topical IL-1 receptor antagonist markedly down-regulates CD-11b-positive monocytic cell appearance in the corneal stroma. Topical IL-1 receptor antagonist could be an effective adjuvant for clinical treatment of corneal conditions in which unwanted inflammation has a role in the pathophysiology of the disorder.

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