An assessment of the iPad as a testing platform for distance visual acuity in adults

Abstract

ObjectivesVisual acuity is a common measurement in general practice, and the advent of new technology such as tablet computers offers a change in the way in which these tests are delivered. The aim of this study was to assess whether measurements of distance visual acuity using LogMAR letter charts displayed on an iPad tablet computer were in agreement with standard clinical tests of visual acuity in adults with normal vision.DesignBlinded, diagnostic test study.SettingSingle centre (University) in Auckland, New Zealand.ParticipantsUniversity staff and students (n=85). Participants were required to have visual acuity better than 6/60 and wear habitual refractive correction during testing. Participants were excluded if there was any history of ocular pathology.Primary and secondary outcome measuresVisual acuity measured under a number of conditions.ResultsThe iPad tablet with its glossy screen was highly susceptible to glare resulting in acuity measurements that were significantly poorer (approximately 2 LogMAR lines) than those made using an ETDRS chart and a standard computerised testing system (n=56). However, fitting the iPad with an antiglare screen and positioning the device away from sources creating reflected (veiling) glare resulted in acuity measurements that were equivalent those made using gold standard charts (n=29).ConclusionsTablet computers are an attractive option for visual acuity measurement due to portability, the ability to randomise letters, automated scoring of acuity and the ability to select from a range of charts. However, these devices are only suitable for use in situations where sources of glare can be eliminated.

The Effect of Fractal Contact Lenses on Peripheral Refraction in Myopic Model Eyes

“…Unlike a previous work carried out with another VA test for iPad, 26 we did not have glare problems. Given that our study was conducted in a room without any kind of reflections over the screen, there is a possibility that dissimilar results would have arisen if the VA had been measured in a high light environment with reflections over the screen.…”

“…24 Visual acuity and contrast sensitivity with iPad 4 Ever since tablets appeared, new applications (apps) have been proposed in the field of visual science. 25,26,27 The big advantage of using these portable devices is the potential standardization of results since there are many common models which share characteristics such as screen chromaticity. Therefore, it can be hypothesized that if a developer takes into account the technical data of the tablets in the design of an app, any operator who uses the same device in any part of the world will approximately measure the visual function in the same conditions.…”

Measurement of Retinal Sensitivity on Tablet Devices in Age-Related Macular Degeneration

“…Advances in technology have led to the development of portable tablet devices where the resolution and luminance range of the touch-screens could allow visual function measures to be performed. 11,12 Previous studies have reported that visual acuity 13,14 and contrast sensitivity 15,16 measurements can, indeed, be performed reliably on such devices. Recently, an open-source platform that allows visual psychophysics experiments to be performed on an iPad tablet device (Apple, Inc., Cupertino, CA) called PsyPad also was introduced by Turpin et al 17 to allow customized tests to be created, and, thus provide an avenue to develop and evaluate visual function measures with ease.…”

Visual acuity and contrast sensitivity screening with a new iPad application

“…Ever since computer tablets appeared, new applications (apps) have been proposed in the field of visual science [18][19][20][21]. The great advantage of using these portable devices is the potential standardization of measurements.…”

“…The assessment of the VA and CS with an iPad has recently been proposed under different approaches: Black et al [19] implemented a platform for testing distance VA. To evaluate CS, Kollbaum et al [20] developed an elementary test consisting of two letters on each page of an iBook, having 0.1 log units of difference between pages. This test was compared with the Pelli-Robson and Freiburg VA tests and gave significantly lower values with the first one and good agreement with the second one.…”