SEP 2012

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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September 2012 EWINTERNATIONAL 83 thodical approaches (e.g., incom- plete correction according to age). Therefore, distribution of Keff in its most informative part (about 1.0) should be similar to Gaussian normal distribution, which enables the use of standard methods of mathematical analysis. Deviation of the obtained distri- bution from delta function immedi- ately gives a general idea of the efficiency of a group of the opera- tions performed. In addition, the algorithm's high sensitivity makes possible the analysis and compari- son of specific data sets as applied to different degrees of initial myopia (Figure 4), different installations, and different physicians (Figure 5). It also makes it possible to analyze the results of refractive surgery to reveal and eliminate errors. For example, a shift of the average of distribution from 1.0 may point to the availability of a system- atic error in calculations or measure- ments and high dispersion to low accuracy of measurements or uncer- tainty as a result of the used ablation algorithm. Points widely dropped out of a normal distribution picture are instantly identified and reveal reasons for any shifts. For example, values on the "tail end" on the left from maximum of distribution (provided that this is not the conse- quence of implementation of the method's monovision or blended vision) may characterize incomplete or inaccurate correction or compli- cations that reduce visual acuity. Values that are on the far right from maximum most likely demonstrate improper technique of visual correc- tion before operation. This procedure may be expedi- ently used when comparing the results of various methods of refrac- tive surgical performance or when performing expert evaluations of the quality of work at some medical centers. The described method includes refractive operation results only. However, it may be easily applied to any other measurements that can be compared pre- and post-op. The only requirement is that the meas- urements should be made with proper discreteness and accuracy. This same approach could be used for data on the quality of night and twilight vision, contrast sensitivity, IOP value, and other areas. EW References 1. Dupps WJ, Kohnen T, Mamalis, N, et al. Standardized graphs and terms for refractive surgery results. J Refractive Surg. 2011; 27:7- 9. 2. Myagkikh A.I. Methods of determining the quality of refractive surgery. In Tahchidi JP, ed. Fyodorov reading – 2002: A collection of scientific papers. Moscow, 2002: 246-248. Editors' note: Dr. Myagkikh has no financial interests related to this article. Contact information Myagkikh: ostoptik@mail.ru

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