1. Introduction When fitting contact lenses, there are multiple measurements that should be taken to ensure the optimum design is being used. The most common measurements are horizontal/diagonal visible iris diameter (HVID/DVID) and corneal curvature, but others, such as pupil size and eccentricity are very important when fitting presbyopic patients. There are various instruments that can be used to take these measurements but they often require subjective assessment which potentially introduces error. The Volk Eye Check Contact Lens (VEC CL) device (Figure 1) eliminates subjectivity by taking objective measurements. The VEC CL device allows for completely objective ocular measurements and produces results very close to the average of major devices (Rosen et al, 2015). Purpose The purpose of this study was to measure the size and positional distribution of pupil eccentricity in a group of unselected patients attending a primary care optometry practice. Methods The Volk Eye Check is a hand-held 14 million pixel medical camera device that captures analyses and displays, in real time, eye measurement data including pupil eccentricity of both eyes. The device algorithm uses colour, shape and surroundings of candidate structures to determine the location of entrance pupil and corneal reflex (CR) by pixel classification. The main landmarks it identifies are the pupil margin and the centre of the first Purkinje image of the camera flashlight The algorithm then measures the distance between the centre of the entrance pupil, the centre of the CR and visible iris margins as ell as other data. (Figure 2). Data were captured from 143 consecutive patients aged between 2 and 91 years. The patients were unselected in terms of any abnormal eye conditions. Results The average horizontal pupil eccentricity was 0.27mm nasally with a standard deviation of 0.13mm. 43 eyes (15%) showed eccentricity of >0.40mm. The largest eccentricity measured was 0.63mm nasally. 4 eyes (1.4%) were temporally displaced with the greatest temporal eccentricity being 0.10mm. The average vertical displacement was 0.11mm superior with a standard deviation of 0.16mm. Only 9 eyes (3%) showed more than 0.40mm vertical displacement with the highest measured being 0.50mm superior. The pupils of 64 eyes (22%) displaced inferiorly, so the pupil centre is lower than the iris centre. The greatest inferior eccentricity was 0.40mm. References Rosen C, Ramdass D, Norman C, Buckingham R. (2015) Visible Iris Diameter with the Volk Eye Check Device, Poster, BCLA conference 2015. Disclosure All the authors are either employed by or have an interest in IRISS Medical Technologies Ltd www.irissmedical.comwww.irissmedical.com Distribution of pupil eccentricity in a group of unelected patients attending a primary care optometry practice Simon Barnard 1,2, Yuval Yashiv 2, Ron Maor 2, Alex Levit 3, Ellis Johnson 2,3 1 PhD, FAAO; Department of Optometry & Visual Science, Hadassah College, Jerusalem, Israel; 2 IRISS Medical Technologies Ltd, London, UK; 3 Optometrist, London Conclusions A literature search suggests that these findings may be novel in terms of reporting eccentricity in a group of patients of this size. Pupil eccentricity is an important datum when fitting multifocal contact lenses. If the optical centre of a concentric multifocal contact lens is not coincident with the pupil poor visual performance would be expected. The Volk Eye Check has the potential to assist contact lens manufacturers and practitioners to design and fit multifocals that are optimised for individuals. Figure 5 (right) An unusual case of extreme superior nasal pupil eccentricity Figure 4 (left) An unusual case of a temporal and superior eccentricity - 0.04mm temporal, 0.4mm superior. Figure 3 A nasally eccentric pupil in a dark eye - eccentricity 0.80mm which is very high. Figure 1 The Volk Eye Check device Figure 2 Comparison of objective data automatically measured between Volk Eye Check EC mode and Volk Eye Check CL mode