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Purpose: The aim of this study was to test the 42 parameters of the ocular response analyzer for distinguishing between the biomechanical properties of emmetropic eyes with normal topography and eyes with moderate-to-high with-the-rule astigmatism (WTA) and against-the-rule astigmatism (ATA) that have symmetric bowtie topography., Methods: This retrospective case series study included 37 patients (37 studied eyes) with WTA astigmatism and 35 patients (35 studied eyes) with ATA astigmatism. The control group consisted of 70 patients with emmetropia (70 studied eyes) with normal topography. We first tested correlations of the parameters that describe the applanation curve during ocular response analyzer measurements with the maximum keratometry values and the corneal thickness in all 3 groups. We then evaluated the significant parameters among them in search of any group differences in the biomechanical properties of the cornea., Results: Fifteen parameters correlated with Kmax reading values or corneal thickness values. The correlation coefficients (r) were low. The best correlated parameters were p1area, p2area, h1, dive1, p2area1, h11, h2, and h21. The ATA group had the highest number of parameters (n = 6) with significant differences compared with the control group. Only p2area was predictive for ATA. In contrast, the WTA group had only 1 parameter (p2area1) that was found to be significantly different compared with the control group., Conclusions: Some of the new waveform parameters can distinguish between patients with ATA and WTA and normal topography patterns and may delineate the differences in biomechanical properties between these groups that may predict the risk of corneal ectasia after laser in situ keratomileusis.

Purpose: To evaluate changes in comeal sensitivity and tear function following myopic LASIK with thin femtosecond flaps., Methods: A retrospective study was performed to compare corneal sensitivity (filament), tear breakup time, and anesthetized Schirmer test preoperatively and at 1 week and 2 and 6 months postoperatively., Results: Seventy-two eyes of 38 consecutive patients (20 women and 18 men) who underwent LASIK for myopia or myopic astigmatism with thin femtosecond flaps (IntraLase femtosecond laser system and Technolas 217 PlanoScan V2.9992 or wavefront-guided Zyoptix 3.1 excimer laser) were evaluated. Preoperative mean corneal sensitivity was 5.3+/-1.5 mm, which decreased to 4.6+/-1.7 mm at 1 week, increased to 5.0+/-1.3 mm at 2 months, and returned to baseline values at 6 months postoperatively. Mean Schirmer score was 13.7+/-5.7 mm preoperatively and 12.1+/-5.1, 13.1+/-4.8, and 13.0+/-5.1 mm at 1 week and 2 and 6 months postoperatively, respectively. Mean tear breakup time was 7.7+/-2.6 seconds preoperatively and 7.8+/-3.5, 9.2+/-4.6, and 8.8+/-4.5 seconds at 1 week and 2 and 6 months postoperatively, respectively. No significant increase in fluorescein staining was observed throughout follow-up., Conclusions: Reductions in corneal sensitivity and tear function tests were minimal after myopic LASIK with thin femtosecond flaps. Despite the relatively narrow hinge, the thin, uniform femtosecond flap does not appear to have an adverse effect on corneal sensitivity and dry eye signs at 6 months postoperatively.

Purpose: To evaluate the clinical outcome of wavefront-guided LASIK in patients with low to high myopia., Methods: The study included 316 eyes of 158 patients; 172 eyes with low to moderate myopia (< or = 6.00 diopters [D]) and 144 eyes with high myopia (> or = 6.25 D). Preoperative wavefront analysis was performed with the Hartmann-Shack aberrometer, and LASIK was done with the Technolas 217z excimer laser. Follow-up was 36 months. Safety, efficacy, predictability, stability, and complications were compared between groups., Results: Mean preoperative spherical equivalent refraction (SE) was -6.50 +/- 7.72 D (range: -1.50 to -16.00 D) in the entire study group, -4.91 +/- 1.38 D in the low to moderate myopia group, and -9.41 +/- 2.51 D in the high myopia group. At 36 months, 222 (70%) eyes showed no change in best spectacle-corrected visual acuity and 67 (21%) eyes gained > or = 1 line. In the low to moderate myopia group, SE of +/- 0.50 D was achieved by 85% of eyes and +/- 1.00 D by 97%, and 65% and 80%, respectively, in the high myopia group. Undercorrection > 0.50 D was observed in 25% (36 eyes) of the high myopia group and 5% (8 eyes) of the low to moderate myopia group. All eyes showed significant reduction in spherical aberration (Z4,0) at 12 months postoperatively with no complications except diffuse lamellar keratitis in 2 eyes (1 eye in each group)., Conclusions: Wavefront-guided LASIK is an efficient refractive surgery technique for patients with low to moderate myopia. Higher degrees of myopia may be subject to under- and overcorrection.

Purpose: To evaluate the safety, efficacy, and visual outcome of wavefront-supported photorefractive keratectomy (PRK) for the correction of myopia and myopic astigmatism in patients with suspected keratoconus., Methods: Forty eyes of 20 patients with myopia -4.0 to -8.0 diopters (D) (mean: -6.25 +/- 1.04 D), cylinder -1.0 to -2.50 D (mean: -1.61 +/- 0.71 D), and corneal thickness 440 to 488 microm were treated with wavefront-supported PRK. Corneal topography evaluation revealed a significantly irregular cylinder (inferior-superior difference > 1.5 D) with possible mild or forme fruste keratoconus. Aberrometry was performed with the Hartmann-Shack aberrometer, and corneal data were evaluated with the Orbscan system. Eyes were treated with the Technolas 217z Bausch & Lomb excimer laser and followed for a minimum of 40 months., Results: Following surgery, mean spherical equivalent refraction was +0.33 +/- 0.8 D. It was within +/- 0.5 D of the intended refraction in 95% of eyes and within +/- 1.0 D in 100% of eyes. Mean uncorrected visual acuity improved from 20/400 preoperatively to 20/25 postoperatively. Mean best spectacle-corrected visual acuity (BSCVA) remained unchanged (20/20) or improved to 20/20 in 92.5% of eyes and to 20/25 in 7.5% of eyes. Individually, BSCVA did not change in 28 (70%) eyes and increased by > or = 2 Snellen lines in 9 (22.5%) eyes; 3 (7.5%) eyes lost 1 Snellen line because of corneal haze. Laser treatment induced a significant flattening of the preoperative inferior corneal steepness in all eyes. Wavefront analysis demonstrated a significant decrease in high order aberrations (total root-mean-square and coma)., Conclusions: Wavefront-supported PRK appears to be effective for the treatment of myopia and astigmatism in patients with suspected keratoconus and thin, irregular corneas. Longer follow-up is needed to prove the safety of the procedure in this patient population.

Objectives: To report central corneal thickness (CCT) measurements on patients requesting refractive surgery and to search for possible associations between CCT and patient's origin, age, sex, and preoperative data., Setting: Department of Ophthalmology, Soroka University Medical Center, and Enaim Refractive Center, Beer-Sheva, Israel., Methods: Subjects were patients undergoing preoperative examination at our refractive centre during 2003. Patient's age, sex, preoperative CCT, refractive status, keratometry, and intraocular pressure (IOP) were obtained together with country of origin of the patients and their parents. Main outcome measures were CCT measurements and relationship between CCT and patient's origin and preoperative data., Results: A total of 204 patients were included in the study. Patients of North African origin had statistically significantly thinner corneas than patients of other origins (518.9+/-31.5 vs. 545.4+/-30.4 microm in the right eye and 518.4+/-32.1 vs. 546.3+/-29.7 microm in the left eye; P<0.00001). Patients of North African origin were significantly older than patients of other origins (P=0.028). No differences were found when comparing for sex, intraocular pressure, refractive status, and keratometry. When multivariate analysis was performed patient's origin was the only independently associated factor associated with CCT., Conclusions: This is the first work in reporting lower CCT in people of North African origin examined in a refractive surgery centre. Studies from similar populations are needed to confirm our results.

A 48-year-old woman had bilateral wavefront-guided laser in situ keratomileusis for myopia with IntraLase corneal flap creation. In the right eye the cavitation bubbles were observed not only in the interface between the flap and the corneal bed but also in the anterior chamber disappearing after 30 minutes. After the procedure, uncorrected visual acuity is 20/25 in both eyes; and specular microscopy shows normal hexagonal cells and density. Although no postoperative complications were observed in our case, further follow-up is needed to examine the long-term effect of this phenomenon of IntraLase.

Purpose: To report a rare case of late bilateral ectasia developing after LASIK for low myopia without preoperative risk factors., Methods: A 21-year-old man underwent bilateral uneventful LASIK for low myopia of -2.75 diopters in both eyes. Preoperative corneal pachymetry was 531 microm in the right eye and 526 microm in the left eye. The total ablation depth was 46.8 microm in the right eye and 42.2 microm in the left eye. Preoperative corneal topography was normal and did not reveal forme fruste keratoconus., Results: Twenty-four months postoperatively, the patient developed bilateral inferior keratectasia of +0.50 -3.00 x 72 degrees in the right eye and +1.00 -2.75 x 99 degrees in the left eye., Conclusions: Late keratectasia may follow LASIK for low myopia despite a thorough preoperative work-up.

Purpose: To report 5 eyes of peripheral sterile corneal infiltrates after refractive surgery., Setting: Department of Ophthalmology, Soroka University Medical Center, Beer-Sheva, Israel, and Enaim Ophthalmological Center, Jerusalem, Israel., Methods: Three patients had bilateral refractive procedures for correcting myopia. The procedures included laser epithelial keratectomy in 2 eyes, laser in situ keratomileusis (LASIK) in 2 eyes using a keratome, and LASIK in 1 eye using femtosecond laser., Results: All the patients complained of ocular pain between 1 and 3 days after the procedure. A ring stromal infiltrate peripheral to the flap edge with intact epithelium and an intervening clear zone between the peripheral corneal infiltrates and the limbus was observed in 5 eyes without anterior chamber reaction. All cases improved after several days of topical steroid and antibiotic treatment and systemic steroid. Final visual acuity was 20/25 or better in all cases., Conclusions: The exact mechanism of this complication is still unknown, which can be confused with infectious keratitis. It is important to maintain a high degree of suspicion for infectious keratitis because the management is very different. The potential outcome can be much worse if the keratitis is due to an infectious etiology which can appear after all types of refractive laser procedures.

Purpose: To evaluate the clinical outcome of wavefront-guided laser in situ keratomileusis (LASIK) for the treatment of moderate to high myopia associated with a thin cornea., Setting: Enaim Laser Medical Center, Tel Aviv, Israel., Methods: This retrospective study included 98 eyes of 49 patients with moderate to high myopia (-5.20 to -10.35 diopters [D]) and thin corneas (456 to 498 mum) treated with wavefront-guided LASIK (Zyoptix, Bausch & Lomb) and followed for 36 months. Preoperative wavefront analysis was performed with a Hartmann-Shack aberrometer, and treatment was performed with the Technolas 217 z excimer laser system (Bausch & Lomb). Final refraction data, uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), optic zone size, ablation depth, optical aberrations, and night glare complaints were evaluated., Results: Mean patient age was 28 years +/- 7 (SD), and mean preoperative spherical equivalent refraction was -7.06 D (range -5.20 to -10.35 D). Final UCVA ranged between 6/6 and 6/30. The safety index of the technique was 1.03, and the efficacy index was 0.67. Undercorrection of more than 0.50 D was observed in 41.3% of the high-myopic eyes (-7.00 to -10.35 D, n = 58) compared with 10% in the moderately myopic eyes (-5.00 to -6.75 D, n = 40). A significant reduction in spherical aberration (Z(4)0) was found 12 months postoperatively in all eyes. Night glare was documented in 4 eyes (4%) in the high myopia group. There were no cases of corneal ectasia., Conclusion: Zyoptix was safe in eyes with moderate to high myopia with relatively thin corneas (<498 microm). For myopia between -7.00 D and -10.35 D, a small optical zone (4.3 to 5.6 mm) may be applied as night glare was relatively rare, but significant undercorrection should be expected.

Purpose: To evaluate the safety and efficacy of phototherapeutic keratectomy (PTK) with single application of mitomycin C for patients with severe corneal haze following photorefractive keratectomy (PRK) for high myopia., Methods: Eight eyes of seven patients were treated with PTK and intraoperative topical application of mitomycin C (0.02%) for severe corneal haze (grade 3) following PRK for myopia., Results: All patients' visual performance improved significantly. Mean preoperative visual acuity (20/200 for both UCVA and BSCVA) improved significantly to 20/33 (0.6) and 20/30 (0.7) for UCVA and BSCVA, respectively. Six eyes (85.7%) had improved UCVA to 20/40 or better and gained five or more lines of UCVA. The corneal haze score decreased from grade 3 initially (for all eyes prior to PTK and mitomycin C) to a final mean haze score of 0.3 (range 0 to 0.5). Mean final spherical equivalent refraction achieved was -1.30 +/- 1.60 D (range -3.75 to +1.25 D). One eye gained only three lines of visual acuity due to regression and residual haze. No adverse effects related to the use of mitomycin C were recorded., Conclusion: PTK with a single intraoperative application of mitomycin C was safe and effective in reducing corneal haze and improving visual acuity in patients with severe corneal haze following PRK.