A 10-year prospective audit of LASIK outcomes for myopia in 37,932 eyes at a single institution in Asia.

PURPOSE: This study evaluates the efficacy, predictability and safety of LASIK surgery as a treatment for myopia performed as part of a large-scale, prospective clinical audit spanning 10 years in an Asian study population and to evaluate the outcomes and trends. DESIGN: Prospective, nonrandomized, single-center, multisurgeon study. PARTICIPANTS: We included 37,932 eyes of 19,753 patients that underwent myopic LASIK at the Singapore National Eye Centre between 1998 and 2007. METHODS: All eyes underwent LASIK as a treatment for myopia. Pre- and postoperative refractions, uncorrected visual acuity (UCVA), and best-corrected visual acuity (BCVA) were documented. MAIN OUTCOMES MEASURES: Safety, efficacy, refractive predictability, treatment trends, retreatment rates, and complications for mild, moderate, and high myopia according to spherical equivalence (SE) of less than -5.00 diopters (D), -5.00 D or more to less than -10.0 D, and -10.00 D or more, respectively. RESULTS: Patients' median age was 32 years (mean, 33.0+/-7.9 years); there were 6832 males (34.6%) and 12,921 females included. Patients were predominantly ethnic Chinese (90.5%). Mean follow-up time was 68.8 days. The mean spherical error corrected was -5.90+/-2.57 D (median, -5.625 D), and outcomes were categorized into low, moderate, or high myopia. The UCVA achieving > or =20/40 has been consistently above 90% since 2000, with 72.8% achieving > or =20/20. More than 93.0% of eyes achieved within +/-1.00 D target in the last 4 years. An improvement in safety was observed since the start of the study, with the best outcomes observed in 2007; loss of 1 and 2 Snellen line BCVA postoperatively was 2.4% and 0.1%, respectively. The overall retreatment rate was 3.8%; 91% of retreated eyes achieved UCVA of > or =20/30. Between 1998 and 2007, there was a significant improvement in postoperative UCVA and BCVA (P<0.001). CONCLUSIONS: Myopic LASIK performed in Asian eyes within a comprehensive LASIK clinical program with appropriate clinical audit governance can be safe and effective, with high refractive predictability. Improvements in the nomograms to prevent undercorrection and to compensate for myopic regression have led to better efficacy after LASIK, with an increasing percentage of patients achieving 20/15 visual acuity postoperatively.

Efficacy of an aspheric treatment algorithm in decreasing induced spherical aberration after laser in situ keratomileusis.

PURPOSE: To determine the effectiveness of an aspheric laser in situ keratomileusis (LASIK) algorithm for myopia with and without astigmatism in minimizing postoperative induction of spherical aberration. SETTING: Four sites in Asia. METHODS: Patients with -1.00 to -10.00 diopters (D) of spherical myopia with -4.00 D or less of astigmatism were recruited. Patients randomly had bilateral Zyoptix aspheric algorithm (aspheric group) or bilateral conventional Zyoptix Tissue Saving algorithm (control group). A Technolas 217z100 excimer system was used for LASIK ablation. Visual effectiveness, safety, higher-order aberrations, and corneal asphericity (Q value) were evaluated postoperatively. RESULTS: The aspheric group comprised 86 eyes and the control group, 84 eyes. At 3 months, the high-contrast uncorrected distance visual acuity was 20/20 or better in 78% of eyes in the aspheric group and 83% of eyes in the control group. The control treatment induced 0.22 microm of spherical aberration, which was significantly higher than the 0.04 microm induced with the aspheric treatment (6.0 mm pupil) (P<.0001). The aspheric treatment induced significantly less vertical coma and trefoil (P = .02). Eyes in the aspheric group had significantly lower Q values (P<.0001). There was no statistically significant difference in the manifest refraction spherical equivalent between the 2 groups (P >.05). Although high- and low-contrast corrected distance visual acuity (CDVA) was similar between the groups, the aspheric group gained more lines of low-contrast CDVA. CONCLUSION: The aspheric algorithm was more effective than the conventional algorithm in reducing induced spherical aberration and maintaining corneal asphericity after myopic LASIK.

Diffuse lamellar keratitis after laser in situ keratomileusis associated with surgical marker pens.

PURPOSE: To describe a series of cases of diffuse lamellar keratitis (DLK) after laser in situ keratomileusis (LASIK) associated with intraoperative use of a surgical marker pen. SETTING: Singapore National Eye Centre, Singapore, Singapore. METHODS: A review of all 115 patients (125 eyes) who had myopic LASIK from July 23 to July 26, 2007, was performed to determine whether eyes in which the Codman surgical marker pen (Johnson & Johnson Medical) was used intraoperatively developed postoperative DLK. RESULTS: Nine of 12 eyes that had LASIK or flap relifting with a Codman surgical marker pen developed grade 1 to grade 3 DLK on the first postoperative day. The 113 other eyes that had LASIK in the same week with another brand of surgical marker pen (Securline, Precision Dynamics Corp.) did not develop DLK. All eyes with DLK were treated with intensive topical steroid therapy. The DLK resolved in 2 eyes after the steroid treatment; 7 eyes required flap relifting with interface irrigation. One month postoperatively, 6 eyes with DLK had an uncorrected visual acuity of 6/7.5 or better. Two eyes developed central corneal scarring with consecutive hyperopia with a best corrected visual acuity of 6/12 after 1 month. CONCLUSIONS: There was a strong association between the occurrence of DLK after LASIK with the use of the Codman surgical marker pen. One or more constituents of the ink in the Codman pen may have been responsible for this series of cases.

Evaluation of higher order ocular aberrations in patients with keratoconus.

PURPOSE: To describe higher order ocular aberrations in eyes with keratoconus. METHODS: Prospective, observational, case-control study comparing higher order ocular aberrations in patients with keratoconus with control subjects with myopia. RESULTS: One hundred sixteen patients with keratoconus were recruited. Data were analyzed in 35 keratoconus eyes, 38 keratoconus suspect eyes, and 166 right eyes with myopia. Mean total higher order root-mean-square (RMS) values (3rd to 5th order) were 1.73 +/- 0.71 microm in eyes with keratoconus, 0.94 +/- 0.66 microm in eyes with keratoconus suspect, and 0.49 +/- 0.16 microm in control eyes. Keratoconus eyes had greater total higher order RMS, 3rd to 5th order RMS, and RMS for all Zernike terms than those in the control group (P < .001). CONCLUSIONS: Keratoconus and keratoconus suspect eyes had significantly larger higher order aberrations in total higher order RMS and 3rd order RMS than control eyes.

Evaluation of keratoconus in Asians: role of Orbscan II and Tomey TMS-2 corneal topography.

PURPOSE: To evaluate the corneal topographic patterns of Asian patients with keratoconus (KC). DESIGN: Prospective observational case-control study. SETTING: Institutional. STUDY POPULATION: A total of 116 patients (both eyes included) with KC were recruited. The control group consisted of 70 laser in-situ keratomileusis (LASIK) candidates with myopia. Patients with previous ocular surgery and trauma were excluded. OBSERVATION PROCEDURE: Corneal topography was performed using the Tomey KC screening system (Topographic Modeling System, software version 2.4.2J, Tomey Corp, Nagoya, Japan) and Orbscan II corneal topography system (Bausch & Lomb Surgical, Orbtek Inc, Salt Lake City, Utah, USA). MAIN OUTCOME MEASURES: Videokeratographic variables were analyzed and the eyes were grouped into KC, KC suspect, and control groups. RESULTS: The corneal topographic patterns of 196 eyes were analyzed. The topographic patterns displayed by Tomey (TMS-2N) and Orbscan II were similar. The majority of eyes with KC (71.2%) and KC suspect (70%) had asymmetric bowtie patterns. Thirteen indices of TMS-2N were analyzed and the means of the indices were found to be significantly higher in eyes in the KC group than the KC suspect group (P < .001). Fourteen indices of Orbscan II were analyzed. Eyes in the KC suspect group had higher mean posterior elevation (46 +/- 17 microm), 3 mm irregularity (2.44 +/- 1.36 diopters [D]), 5 mm irregularity (2.61 +/- 1.19 D) and had thinner corneas (mean 504.4 +/- 40.4 microm) than normal eyes (26 +/- 8 microm, 1.05 +/- 0.37 D, 1.38 +/- 0.39 D, and 554.0 +/- 25.0 microm, respectively). CONCLUSION: Corneal topography pattern recognition combined with quantitative diagnostic indices is useful for the screening and classification of KC with the Orbscan II being more sensitive in screening for KC than TMS-2N.

Higher order ocular aberrations in eyes with myopia in a Chinese population.

PURPOSE: To describe the characteristics of higher order ocular aberrations of adult Chinese eyes with myopia. METHODS: Higher order aberrations in consecutive right eyes of 166 Chinese patients with myopia who enrolled for preoperative assessment for LASIK were retrospectively reviewed. Wavefront aberrations were measured with the Bausch & Lomb Zywave over a 6-mm dilated pupil. The correlations between higher order aberrations and myopia, astigmatism, and age, respectively, were analyzed. RESULTS: Mean patient age was 32.1 +/- 6.2 years, the mean refractive error was sphere -5.23 +/- 1.79 diopters (D) and cylinder -1.29 +/- 0.98 D. The mean of the total higher order root-mean-square (RMS) (third to fifth order) was 0.49 +/- 0.16 microm. Third-order RMS was largest (mean 0.37 +/- 0.16 microm), followed by fourth-order RMS (mean 0.29 +/- 0.11 microm). For individual higher order Zernike coefficients, spherical aberration (C4(0)) predominated with a mean of 0.23 +/- 0.14 microm. No correlation was found between total higher order RMS and myopia or between total higher order RMS and age. Small but statistically significant relationships were found in the following groups: age and vertical primary coma (C3(-1))(r=-0.206, P=.008); age and spherical aberration (C4(0)) (r=0.196, P=.012); and myopia and horizontal trefoil (C3(3)) (r=-0.158, P=.042). CONCLUSIONS: Higher order aberrations varied among individuals with myopia. Third-order RMS was the predominant higher order aberration. Spherical aberration and vertical primary coma increased slightly with age. Our study helps establish ocular aberration standards for Chinese refractive surgery candidates.

Evaluation of Orbscan II corneal topography in individuals with myopia.

PURPOSE: To evaluate Orbscan II (Bausch & Lomb, Orbtek Inc., Salt Lake City, UT) corneal topography in individuals with myopia. DESIGN: Retrospective, observational, consecutive, clinical case series. PARTICIPANTS: One hundred forty eyes of 70 persons with myopia. METHODS: Manifest refraction results and the Orbscan II corneal topographic maps were reviewed retrospectively. MAIN OUTCOME MEASURES: Refractive powers and the following test indices produced by Orbscan II were analyzed: anterior elevation best-fit sphere (BFS), posterior elevation BFS, maximum posterior elevation (Max PE), radius of Max PE, maximum keratometry, minimum keratometry, astigmatism, 3-mm irregularity, 3-mm mean power, 3-mm astigmatism, 5-mm irregularity, 5-mm mean power, 5-mm astigmatism, corneal diameter, pupil diameter, thinnest pachymetry, and anterior chamber depth. The correlations between right eyes and left eyes and between indices were explored. RESULTS: Of the 140 eyes, the mean manifest refraction was -5.27+/-2.19 diopters (D; range, -10.50 to 0.00 D), the mean Max PE was 28+/-7 mum, and the mean maximum keratometry was 44.5+/-1.5 D. Correlation coefficient analyses of Orbscan II quantitative indices combined with pattern recognition showed that there were high degrees of correlations between the right and left eyes of each individual patient. Maximum posterior elevation, corneal irregularity, and thinnest pachymetry did not vary with the degree of maximum keratometry. CONCLUSIONS: This article provides a detailed description and analysis of Orbscan II corneal topography of a normal population with myopia. This helps in establishing normal standards in Orbscan II corneal topography that will aid in preoperative assessment in refractive surgery.

Performance of the Hansatome microsuction ring for laser in situ keratomileusis in eyes with narrow palpebral apertures.

PURPOSE: To evaluate the performance of a new microsuction ring during laser in situ keratomileusis (LASIK) in eyes with narrow palpebral apertures. SETTING: Singapore National Eye Centre, Singapore, Republic of Singapore. METHODS: Laser in situ keratomileusis was performed sequentially in both eyes of 33 Chinese patients. A randomization table was used to determine the control and test eyes. A standard suction ring (20.3 mm diameter) was used in control eyes, and a microsuction ring (19.0 mm diameter) was used in test eyes. Corneal flaps were created using the Hansatome microkeratome (Baush & Lomb). The following ring performance parameters were evaluated: flap diameter deviation (actual minus nominal flap diameter), ease of suction ring application, adequacy of suction, and overall microkeratome performance. Parameters 2 to 4 were rated by the surgeons using a subjective 1 to 100 scale. RESULTS: The mean flap diameter deviation was 0.45 mm in the control eyes and 0.22 mm in the study eyes; the mean difference was 0.23 mm (95% confidence interval, 0.39-0.07) (P<.001). For ease of application, the mean score of the microsuction ring was 100 and of the standard suction ring, 89.9. For adequacy of suction, the mean score of the microsuction ring was 99.7 and of the standard suction ring score, 98.2 (P = .13). The mean overall microkeratome performance score using the microsuction ring was 99.4 and using the standard suction ring, 94.6 (P = .011). CONCLUSION: The Hansatome microsuction ring was easy to apply during LASIK in eyes with narrow palpebral apertures, and there appeared to be no compromise of ring performance and safety.

Visual function and outcomes after cataract surgery in a Singapore population.

PURPOSE: To identify the predictors of visual outcomes (visual acuity and visual function) in cataract surgery patients in Singapore and compare the visual outcomes of phacoemulsification and extracapsular cataract extraction (ECCE). SETTING: Singapore National Eye Center, Singapore, Republic of Singapore. METHODS: The visual function was measured by the VF-14 and visual acuity in the operated and the better eye in 460 systematically sampled cataract surgery patients preoperatively and 3 months after surgery. Several patient- and surgery-related predictive factors were recorded. RESULTS: After cataract surgery, 85.1% of patients reported improved visual acuity in the operated eye and 77.6% reported improved visual function. Patients with poorer visual acuity and visual function at baseline reported greater improvements in visual acuity and visual function. Patients who had phacoemulsification had better final visual function (P =.006) and better final visual acuity (P <.001) scores. In multiple linear regression models, final visual function was better in patients without preexisting eye disease and with better baseline visual function, and final visual acuity in the operated eye was better in patients who were younger, were better educated, had no preexisting conditions or postoperative complications, and had a better baseline visual acuity. CONCLUSIONS: Patients with poorer baseline visual acuity or who had no preexisting eye disease reported more improvement in visual acuity in the operated eye. Several factors including no preexisting eye disease were associated with better final visual acuity and visual function scores.