A Comparison of Distance Visual Acuity Testing using a Standard ETDRS Chart and a Tablet Device
Almira A. Manzano, MD and Michael Angelo N. Lagamayo, MD
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 anti-glare 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.
Keywords: visual acuity test, ETDRS chart, tablet device