Marco M3/Nidek TonorefII Autorefractor Intermethod Reliability Study

Background: Autorefractors are commonly used as a starting point for subjective refraction and accordingly the repeatability and accuracy ofthese devices are of great importance to efficiently and effectively assessing refractive error. This study analyzes the repeatability and accuracy of three different autorefractors which are the same manufacturer model. Methods: The instruments used in this study were three Marco M3/Nidek Tonorefll. Each
participant was autorefracted using each of these three devices by the same trained operator. Participants were free of ocular media opacities and without ocular or systemic disease. Data was then analyzed for inter-method reliability/test-retest reliability.
Results: Raw data was collected with the traditional sphere, cylinder, and axis components. This data was then translated into components amenable to statistical analysis: M, JO, J45, and P. Bland-Altman analysis for these components of the three instruments is reported. Repeated measures multivariate analysis is also presented.
Discussion: Bland-Altman analysis shows the measurements obtained on each of the three instruments are similar. Repeated measures multivariate analysis shows that there isn't a statistically significant difference between the measurements obtained on each of the three instruments.
Conclusion: Since Bland-Altman analysis shows the instruments produce similar measurements and repeated measures multivariate analysis shows the measurements differ by a statistically insignificant amount, the Marco M3/Nidek Tonorefll shows reliability between instruments