A new application for Apple's iPhone enables users to measure both their near and far pupillary distances (PD) in order to make online purchases of spectacles.
The programme's manufacturer, Sunmore Systems, tells customers that the 'easy to use' application allows them to take their own PD measurements 'with confidence', a service they are advised they will probably be charged for by an optician.
The instructions inform the user being measured to hold a bank card under their nose and take a photo. After the photo is taken, a box locks onto the strip and crosshairs appear, which the user centres in the middle of the pupil for each eye to give the PD. Sunmore claims the software, available from Apple's online iTunes store, is accurate to ±0.5mm, and that the soon-to-be-released iPad version, will be useful for the professional optometrist.
Optician clinical editor Bill Harvey commented: 'Interesting as this feature is, it took longer to take each measurement than using a ruler. Of the measurements I took in the office, every one was lower when measured by the app than with the ruler. Distance PDs were only given as binocular and there is no way yet to take monocular PD so any facial asymmetry could not be adequately catered for. Most of the measurements taken of darker eyes were difficult to do accurately. The small image made it hard to establish the pupil centre or edge. A small error was translated into a several millimetre error in the final measurement. An under-estimate of PD was consistent (3-4mm) in all but a couple of cases.'