Designing a new test for contrast sensitivity function measurement with iPad

PurposeTo introduce a new application (ClinicCSF) to measure Contrast Sensitivity Function (CSF) with tablet devices, and to compare it against the Functional Acuity Contrast Test (FACT).MethodsA total of 42 subjects were arranged in two groups of 21 individuals. Different versions of the ClinicCSF (.v1 and .v2) were used to measure the CSF of each group with the same iPad and the results were compared with those measured with the FACT. The agreements between ClinicCSF and FACT for spatial frequencies of 3, 6, 12 and 18 cycles per degree (cpd) were represented by Bland–Altman plots.ResultsStatistically significant differences in CSF of both groups were found due to the change of the ClinicCSF version (p < 0.05) while no differences were manifested with the use of the same FACT test. The best agreement with the FACT was found with the ClinicCSF.v2 with no significant differences in all the evaluated spatial frequencies. However, the 95% confidence intervals for mean differences between ClinicCSF and FACT were lower for the version which incorporated a staircase psychophysical method (ClinicCSF.v1), mainly for spatial frequencies of 6, 12 and 18 cpd.ConclusionsThe new ClinicCSF application for iPad retina showed no significant differences with FACT test when the same contrast sensitivity steps were used. In addition, it is shown that the accurateness of a vision screening could be improved with the use of an appropriate psychophysical method.

ResumenObjetivoIntroducir una nueva aplicación (ClinicCSF) para medir la Función de Sensibilidad al Contraste (FSC) con dispositivos de tableta, y compararla con el test Functional Acuity Contrast Test (FACT).MétodosSe distribuyeron 42 sujetos en dos grupos de 21 personas. Se utilizaron diferentes versiones del ClinicCSF (.v1 y .v2) para medir la FSC de cada grupo con el mismo iPad, comparándose los resultados obtenidos con los medidos con el test FACT. Se representaron las concordancias entre ClinicCSF y FACT para frecuencias espaciales de 3, 6, 12 y 18 ciclos por grado (cpg) mediante gráficos de Bland–Altman.ResultadosSe hallaron diferencias de FSC estadísticamente significativas en ambos grupos debido al cambio de versión del ClinicCSF (p < 0.05), mientras que no se manifestaron diferencias con el test FACT. La mejor concordancia con el FACT se obtuvo con el ClinicCSF.v2, no hallándose diferencias significativas en todas las frecuencias espaciales evaluadas. Sin embargo, los intervalos de confianza del 95% para las diferencias medias entre ClinicCSF y FACT fueron inferiores para la versión que incorporó un método psicofísico de escalera (ClinicCSF.v1), principalmente para frecuencias espaciales de 6, 12 y 18 cpg.ConclusionesLa nueva aplicación ClinicCSF para el iPad retina no reflejó diferencias significativas con el test FACT al utilizar los mismos pasos de sensibilidad al contraste. Además, la precisión del examen visual puede mejorarse con el uso de un método psicofísico adecuado.