Objective To design a subjective aniseikonia test using the synoptophore and to evaluate the validity and repeatability of the tests for further use in clinical practice.Methods It was a repeat measurement design.Two graphs were designed based on the ratio of similar triangles.The differences in size,between subjective images for each eye were measured with the synoptophore.The validity of the test was evaluated by comparing the difference between the measured aniseikonia and the theoretical aniseikonia simulated by different power lenses, and the repeatability was evaluated by comparing the results obtained at two different time points with an interval of 24 hours.The data were analyzed by linear regression analysis and analysis of covariance. Results The regression coefficient of the overall regression equation was 0.908 for tbe two different time points,which was lower than the theoretical value (the theoretical value is 1).There was no statistically significant difference between the results of the two different time points.Conclusion The validity and repeatability of this aniseikonia test is relatively high.However,further clinical study should be carried out to test its use in the clinic.