BACKGROUND: The predictability of LASIK refractive surgery is important both to the patient and the surgeon in obtaining an optimal result and in reducing the need for enhancement surgery. Some instruments, large ablation zones and possibly other variables may increase hyperopic overcorrection. METHODS: A retrospective study was undertaken of 345 myopic LASIK eyes (175 patients) treated with a Nidek EC-5000. The need for additional surgery in the form of an enhancement was determined after the patient had a stable refraction. The variables measured in the study were the patient's refractive correction, corneal curvature using an Alcon EH-290 topographer, the patient's age and Nidek excimer laser ablation optic and transition zone size. The same nomogram was used for all eyes and where possible bilateral surgery was conducted on all patients. The effect of ablation sizes, refractive errors, patient age and corneal curvature on the enhancement surgeries was evaluated using SPSS 6.0. RESULTS: The most significant variable that precipitated a LASIK enhancement was an optic zone of 6.5 mm with a transition zone of 7.5 mm (paired t-test, p < 0.0025). Multivariate analysis indicates that the older the patient and the larger the refractive error, the greater the risk of not achieving a residual refractive error of +/- 0.50 D at three months. The steeper pre-operative corneas have a greater chance of enhancement (mean of sample 44.48 +/- 1.47 D and mean of enhancements 45.30 +/- 1.65 D, p = 0.01, independent sample test). The smaller optic zone was associated with a smaller refractive over-refraction after LASIK surgery (mean for 5.5 mm optic zone, +0.71 +/- 0.29 D; mean, for 6.5 mm optic +1.27 +/- 0.50 D, paired t-test p < 0.0001). CONCLUSIONS: In this study, the 5.5 mm optic zone appears to dampen or reduce the undesirable refractive results. The optic zone size of choice with the Nidek EC-5000 laser should be 5.5 mm if the patient has small pupils and steep corneas. In this sample, the targeted emmetropic refractive state (range plano to +0.50 D sphere and plano to -0.50 D cylinder) was achieved in 93.3 per cent of cases after three months.

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Aim To investigate factors affecting refractive outcome following LASIK for myopia. Method Six hundred and seventy-four consecutive uncomplicated myopic LASIK surgeries, performed by a single surgeon, either using the Technolas 217 planoscan (n ¼ 372) or the NIDEK EC 5000 (n ¼ 302), were evaluated. Stratified random sampling was used to match the groups for refractive error, patient age, and gender. The final analysis included 302 patients from each treatment group. Conditions were identical for both surgeries, and pre-operative refractive errors were between À1.00 and À14.00 DS and oÀ1.50 DC. Refractive success was defined as À0.50 to þ 0.50 DS of the targeted refraction measured 3 months after surgery. A stepwise logistical regression analysis was used to determine variables associated with refractive failure. Results A successful refractive outcome was achieved in 78% (235/302) of surgeries using the Technolas laser and in 88% (266/302) using the NIDEK laser. Predictor variables for not achieving refractive success were pre-operative refractive error of above À5.00 DS, age more than 40 years, and surgery performed with the Technolas laser. Conclusion Both the Technolas 217 and the NIDEK EC-5000 excimer lasers achieve a successful refractive outcome in the majority of cases. However, patient and surgical factors can influence refractive outcome.

Comparisons on 19 demographic variables were made among 81 undergraduates who had made a suicide attempt, 81 “psychiatric” controls, and 81 “normal” controls, all matched for sex and academic status. In addition, a representative sample of 23 suicide attempters was compared with 23 matched “psychiatric” and 23 matched “normal” controls on four psychological and four psychotherapy expectancy scales. Results supported the hypotheses that the suicide attempters would show significantly more depression, somatic complaint, and social isolation than the “normal” students. Analyses failed to yield consistent differences between the suicide attempters and matched “psychiatric” controls. Implications for suicide prevention are discussed.

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