A Comparison of Distance Visual Acuity Testing using a Standard ETDRS Chart and a Tablet Device

Abstract

Objective: To determine if the portable iPad 3rd generation device with an anti-glare screen protector and installed with the 2020 Duo FLEX visual acuity can be used as an alternative method of distance acuity testing and to compare it with a standard ETDRS visual acuity chart.

Methods: Healthy volunteers with or without spectacle correction were selected and underwent visual acuity testing with an iPad 3 device and a standard ETDRS chart. The iPad 3 was fitted with an anti-glare matte screen protector and installed with the 2020 Duo FLEX visual acuity chart. The subjects read the optotypes in the standard ETDRS chart and the iPad 3 at distances of 4 and 2 meters. Visual acuity results were computed and recorded as logMAR units. Mean differences between the 2 devices were compared using paired t-test.

Results: A total of 46 healthy subjects (92 eyes), mean age of 24 years, had mean logMAR scores at 4 meters of 0.165 and 0.093 for the ETDRS chart and iPad 3 respectively (p<0.001). The mean logMAR scores at 2 meters were -0.049 and -0.089 respectively (p=0.016).

Conclusion: Distance visual acuity testing using the iPad 3 device with high resolution screen equipped with antiglare screen protector was significantly different from the standard ETDRS chart. Before tablet devices can be used to test visual acuity clinically, they should be standardized and tested.