Comparison of custom ablation and conventional laser in situ keratomileusis for myopia and myopic astigmatism using the Alcon excimer laser.

PURPOSE: To compare the refractive outcomes, higher order aberrations, and contrast sensitivity after laser in situ keratomileusis (LASIK) using wavefront ablation and conventional ablation. SETTING: Private practice in Córdoba, Spain and a free-standing outpatient surgery center. METHODS: This was a prospective, nonrandomized, observational case series comparing outcomes of 239 eyes that underwent LASIK for myopia and myopic astigmatism with either wavefront or conventional ablation using the LADARVISION excimer laser. Manifest refractive sphere ranged from 0.50 D to -8.00 D with astigmatism up to -4.00 D. Eighty-nine eyes underwent conventional LASIK (conventional group), and 150 eyes underwent custom ablation (custom group). Refractive outcomes, ocular higher order root mean square (HOA-RMS), and contrast sensitivity were tested for statistically significant differences between groups. A P-value less than 0.05 was considered statistically significant. Six month postoperative data are reported here. RESULTS: Postoperatively, the mean SE was -0.03 D +/- 0.19 D for the custom group, and -0.14 D +/- 0.35 D for the conventional group (P = 0.003). Ninety-nine percent of the eyes in the custom group, and 92% of the eyes in the conventional group were within 0.50 D of the intended correction (P > 0.05). The HOA-RMS was 0.16 mum lower in the custom group (P < 0.001). Contrast sensitivity was statistically significantly better at 3 cycles per degree (cpd) (P < 0.001) and 6 cpd (P = 0.009) in the custom group. CONCLUSION: There was a statistically significant lower induction of HOA-RMS and better predictability and contrast sensitivity in eyes that underwent custom ablation with the LADARVISION excimer laser.

Description, etiology, and prevention of an outbreak of diffuse lamellar keratitis after LASIK.

PURPOSE: To describe an outbreak of diffuse lamellar keratitis (DLK) and provide a hypothesis about the etiology. METHODS: A retrospective analysis was carried out on 328 eyes of 220 patients who underwent LASIK over 9 months. The occurrence of DLK using two different methods of cleaning and sterilizing surgical instruments and an autoclave reservoir were analyzed. Microbial analyses were carried out by two laboratories on samples obtained from the original autoclave reservoir and tubing. A chi-square test was used to compare qualitative values. The Student t test was used to compare numerical values. RESULTS: Forty-six (24.5%) of 188 cases of DLK were diagnosed. Sphingomona paucimobilis and Burkholderia pickettii were isolated in the reservoir of the steam sterilizer. Electron microscopy revealed gram-negative microbes on the tubing walls. After changing the reservoir of the steam sterilizer and implementing a new cleaning and sterilization protocol based on air-drying the instruments and draining and drying the reservoir of the sterilizer, the occurrence of DLK stopped. No statistically significant correlation was noted between the occurrence of DLK and gender, age, or volume of tissue removed. CONCLUSIONS: Data obtained during this DLK outbreak support the theory that a bacterial endotoxin, which can survive short-cycle steam sterilization, could be responsible for an outbreak of DLK. We recommend cleaning and sterilization protocols based on air-drying surgical instruments and leaving the reservoirs completely dry at the end of each surgical day.

Deep anterior lamellar keratoplasty in post-laser in situ keratomileusis keratectasia.

We describe a technique using deep anterior lamellar keratoplasty (DALK) in 5 eyes that developed keratectasia after LASIK. The technique is based on surgical manipulation that allows visualization of the lamellar dissection depth using a posterior approach to reach the predescemetic space. The mirror effect, indentation effect, and folding effect were used to determine proximity to Descemet's membrane. The same diameter donor and recipient buttons were used to correct myopia. The donor button without Descemet's membrane was placed using 10-0 nylon sutures. No intraoperative or postoperative complications occurred. The mean best spectacle-corrected visual acuity changed from 0.16 diopter (D) +/- 0.05 (SD) (range 0.10 to 0.25 D) before DALK to 0.68 +/- 0.19 D (range 0.5 to 1.0 D) after DALK. Deep anterior lamellar keratoplasty may be a better alternative than penetrating keratoplasty for any pathology with healthy endothelium.