Comparative Study of Digital Chart and Print Chart in Measuring of Accommodation Amplitude with Push up Method

Nowadays, appearance of the digital charts and increase of its abilities in comparison with the print charts has resulted in the more usage of these charts in optometric clinics.  But, in measuring of the accommodation amplitude, the print chart has not been replaced by the digital charts yet. Due to the abilities of digital charts, compared with print charts, a question should be investigated whether the print charts can be replaced by the digital charts for measuring the accommodation amplitude.
In the current study, eye accommodation amplitudes of 63 patients in the age of 15-35 years were measured using push up method and five different chart optotypes. For this purpose, for each optotype, first a print chart and then the digital chart installed on the IPhone 7 Plus to measure the accommodation amplitude were used.
To analyze the data, using SPSS (version 24), descriptive statistics like mean, standard deviation, variance, and standard error of measures were calculated. Also, T-test was run.
The results showed that the difference between the mean of the accommodation amplitude measured by digital chart and that of print chart is about 4.7% in 20/20 optotype. This difference increased to 5.5% in 20/50 optotype. The results of the T-test analysis showed that there is a meaningful difference between the accommodation amplitude measured by the two digital and print charts.
According to the results of the study, the accommodation amplitudes measured by digital chart and print chart do not seem to be equal in general, which can be due to the environment light intensity, the chart contrast, the image refreshing speed, and/or other reasons.