Evaluation of fixation stability using different targets with the MP1 microperimeter

The aim of this study was to evaluate fixation stability using two different fixation targets with the Nidek MP1 microperimeter. Twenty-nine healthy subjects with a mean age of 26.53 ± 7.35 years and visual acuity ≥0.0 logMAR were enrolled in this study. Fifty-eight eyes of 29 patients without ophthalmic and/or systemic disease underwent a fixation test with the MP1 microperimeter. Fixation stability related to a red cross (central) and/or a red circle (pericentral) target was quantified using either Fujii classification or by calculating the bivariate contour ellipse area (BCEA). For statistical analysis, BCEA values were converted into their logarithms (logBCEA) and all data obtained were analyzed using paired Student's t test. The inclination values of the axis of BCEA were analyzed with Chi squared test. The mean values of logBCEA and the mean values of the major and minor axis of the ellipses related to the cross and the circle fixation target were significantly different (68.2 %, p = 0.00; 95.4 %, p = 0.00; 99.6 %, p = 0.00, respectively) for each BCEA standard deviation. Fixation was significantly less stable for the pericentral fixation target in normal subjects, indicating an advantage for central fixation targets. These results are of particular interest when evaluation of changes in fixation is needed.