How accurate is the I-test?
An Initial Sample Inspection Report (ISIR) was carried out by Carclo to verify the performance of the I-test vision screener. Typically, the optical tolerance on the lens power in a conventional lens test kit is +/- 0.09 dioptres. The measurements demonstrated that the optical power differences obtained with Carclo moulded lens parts were almost a factor of 2 better at +/- 0.05 dioptres.The design of the I-test allows the user to adjust for the distance between the pupils of each eye (45-78mm) while the shape and edge contours ensure a ‘snug’ positioning of the I-test across the bridge of the nose to minimise accommodation effects.The lenses are ranged in 0.5 dioptre steps for confident diagnosis while the test range gives 92% coverage: Monocular 0 to +/- 8 and Binocular 0 to +/- 4.The shutter feature means that each eye can be screened separately and then together.
