Refraction before and after LASIK

PURPOSE: It is important to know the accurate refractive error of the patients before LASIK because the amount of ablation is determined by that. We analyzed whether there are differences among the preoperative and postoperative results of cycloplegic retinoscopy (CR), module setting value, and autorefraction with and without cycloplegia (ACR, AMR). METHODS: The manifest and cycloplegic refractions of 104 eyes of 104 patients who underwent LASIK from February 2001 to July 2001 were reviewed. The preoperative and postoperative cycloplegic refraction, autorefraction by Canon RK-5, and module setting value were analyzed. RESULTS: In comparison of the preoperative values, AMR showed myopic shift compared to CR, module setting, and ACR (p<.001). ACR showed hyperopic shift compared to CR (p<0.001). The module setting showed myopic shift compared to CR, but it was not statistically significant. Postoperative mean spherical equivalent was 0.04 +/- 0.67D(range: -1.75 ~ +1.5). In comparison of the postoperative results, ACR showed hyperopic shift compared to CR (p<0.001) and AMR showed myopic shift compared to CR (p<0.001). CONCLUSIONS: As there is a difference between autorefraction and cycloplegic refraction, it is inappropriate to decide the amount of ablation only by one method. Hence when LASIK or LASIK retreatment is planned, cycloplegic refraction as well as autorefraction is necessary.

Comparison of computer-photoscreening with non-cycloplegic retinoscopy for amblyopiogenic risk factors in children / 眼科新进展

Objective　To determine the sensitivity and specificity of using the computer-photoscreener and non-cycloplegic retinoscopy in the detection of amblyopiogenic factors in nine to fifty months old infants.Methods　Three hundred children whose ages range from nine to fifty months were screened with the computer-photoscreener and non-cycloplegic retinoscopy. With a masked standardized clinical assessment as the standard, an overall comparison of the results obtained with the two techniques revealed a sensitivity and specificity. Photoscreen images on the computer monitor screen were reviewed and analyzed immediately by two independent observers for indicators of amblyopiogenic risk factors. Simultaneously, the results were compared to the findings of a full ophthalmologic examination.Results　The computer-photoscreener revealed a sensitivity of 94.2% and specificity of 90.1%, and the non-cycloplegic retinocopy revealed a sensitivity of 85.7% and specificity of 81.1% for the detection of amblyopiogenic risk factors, including hyperopia (+2.75 D or more), myopia (-1.50 D or more), astigmatism (2.00 D or more),anisometropia (2.00 D or more), ocular misalignment (5 degrees or more), and media opacity (1.5mm or more). Conclusion　The computer-photoscreener offers an opportunity to identify problems that limit vision, and could provide a feasible and sufficiently reliable screening technique in infants and preschool children who can be screened successfully for amblyopiogenic risk factors.