Validating the vision
(Figure 3) Figure 3: Snellen Light Box Chart Visual acuity measurements were assessed and recorded by two resident medical officers.Patients were instructed to stand 6 metres from both charts.
Methods: Participants were recruited from a tertiary level eye clinic in Western Australia.(Figure 1, Figure 2) Figure 1: Eye Snellen i OS application displayed on an i Pad mini that was mounted to a traditional lightbox with the use of Velcro and a case Figure 2: Screenshot from Apple i Phone 5S with Eye Snellen remote installed The retro illuminated Snellen box chart provided an illumination of 600 lux.The measureable visual acuity intervals provided by the box chart were 6/60, 6/36, 6/24, 6/18, 6/12, 6/9, 6/6, 6/5 and 6/4.Their study collected measurements from 240 eyes and concluded that the Eye Chart Pro app was reliable for visual acuity testing when the Snellen visual acuity was better than a decimal visual acuity of 0.1.The second study, conducted in New Zealand, collected visual acuity measurements on patients without ocular pathology.Visual acuity was assessed using the Snellen Chart function on the Eye Snellen i OS app (ver 1.6) installed on a second generation Apple i Pad mini and using a traditional Snellen light box chart.
The Snellen Chart function was chosen as it is the most commonly used chart for testing acuity of vision in Western Australian ophthalmology clinics.
A spectacle vision occluder was used to first test the right then left eye of patients.
Patients were instructed to read each line until they were no longer able to resolve the optotype.
There have been regular updates with new features and the app is currently version 1.6 (as of December 2013).
There have been over 9500 downloads as of March 2014.
The Eye Snellen app was developed by Dr Stephen Colley ( a Western Australian Ophthalmologist, and released on the i Tunes App store in December 2012.