The validity and repeatability of the New Aniseikonia Test.
OBJECTIVE
Aniseikonia has been traditionally measured using the New Aniseikonia Test (NAT) based on red/green anaglyphs. This study was designed to establish whether the NAT is a valid and reliable test.


METHODS
The NAT was tested on three groups of subjects: a control group (n = 45) and two groups of participants at risk of experiencing aniseikonia, those with anisometropia greater than or equal to 1.00 D (n = 29) and those with bilateral pseudophakia (n = 26). The validity of the test was established by comparing the measured aniseikonia with that simulated with size lenses in a double-blind study. Repeatability was evaluated by comparing the results obtained at two different time points.


RESULTS
Our results indicate that the NAT underestimates aniseikonia and more so in the horizontal than in the vertical direction. Repeatability was poor, although biases were clinically insignificant. However, the 95% limits of agreement were around +/-2%. The behavior of the test was similar in the three groups of subjects.


CONCLUSIONS
We conclude that the repeatability of the NAT is not very high and recommend that clinicians be cautious when interpreting the results of this test.
Antona
Beatriz
B
Departamento de Optica II (Optometria y Vision), Universidad Complutense, Madrid, Spain. bantona@opt.ucm.es
Barra
Francisco
F
Barrio
Ana
A
Gonzalez
Enrique
E
Sánchez
Isabel
I
D000328:Adult; D000839:Aniseikonia / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D012029:Refraction, Ocular / Q000502:physiology; D015203:Reproducibility of Results; D014787:Vision Tests / Q000592:standards*; D015348:Vision, Binocular / Q000502:physiology