Background: Uncorrected-refractive-error (URE) is the leading cause of global visionimpairment (VI); 122.5 million people are estimated VI from URE. NETRA is a $30USD clip-on application for smartphones.

Purpose: To validate the NETRA as an alternative to subjective refraction for potential use in resource-poor countries.

Methods: NETRA uses a pinhole mask attached to a smartphone displaying a spatially resolved pattern to the subject. Refractive error is estimated by the patient subjectively aligning patterns by a touchscreen interface on the smartphone. NETRA was compared to subjective refraction in 34 eyes.

Results: The mean Subjective Spherical Equivalent (SSE) was -0.65D (std 2.79, 95%CI ±0.97) Two-sided T-test showed that mean SSE is not statistically significantly different (two sided t-test; t=1.6742 p=0.1036, 95% CI±0.29) from the mean NETRA Spherical Equivalent (NSE) .  Mean difference of Spherical Equivalents (NSE – SSE) was 0.24D (Std 0.84, 95%CI ±0.29). And NETRA produced a mean VA improvement of 0.44LogMAR (Std 0.52, 95%CI±0.18), or four Snellen lines.

Conclusion:In settings where access to a trained refractionist is not possible, NETRA has the potential to estimate refractive error closely enough to render an individual no longer VI from URE. NETRA is potentially a cost-effective tool in meeting the VISION2020 goals to eradicate avoidable blindness and warrants further testing in resource-poor settings.

Background: Eye screening programs have been effective in reducing the burden of eye diseases in the developing world.  Most use paper recording systems which are prone to misplacement and are inefficient for auditing purposes.  Digital data collection via mobile devices may prove more efficient, but reliable strategies information sharing between devices in rural settings remain an issue. This paper examines the speed and range of use of Mobile Tethering technology to synchronize data across devices, and hence the suitability of such devices in the eye screening setting.

Methods: The data synchronization feature of eyePatients software for iPhone and iPad was tested using an Apple iPhone 4 as the central router, with Mobile Tethering activated. Apple iPad 2 devices were connected to the wireless local area networks (WiFi) generated by the iPhone 4. The linear range of data synchronization and the effect of corners and barriers on synchronization were tested.

Results: Synchronization was rapid, taking between 1.0-1.5 seconds to complete when linear distance was within 30 meters.  Beyond 34 meters considerable slowing was noted and no successful connections were able to be established beyond 40 meters. A single corner had no statistically significant effect on the maximum range of a single tether connection, but two corners or a door barrier had a small but statistically significant reduction on range.

Conclusion: Mobile Tethering provides a reliable and fast connection between multiple devices that can be used for the synchronization of large amounts of data required for eye screening purposes.