To reduce the influence from retinal reflectance and the intraocular scattering, improvements were made into a multi-eccentric-meridian PR device, the Dynamic Ocular Evaluation System (DOES). In addition, many users point out that the PR systems were affected by the subject’s race 13, 14, 15, 16, which could be from differences in retinal pigmentation, and therefore, the reflectance. Factors that can contribute to the uncertainty of the analysis can include the individual’s retinal reflectance, the level of intraocular scattering, and the pupil size, which may vary with age and environment lighting conditions. PR analysis is based on the double-pass reflex image pattern that is reflected from retina. PR measurement is not sufficiently precise for public screening and is generally considered as means to quickly estimate refraction 1, 10, 11, 12, 13, 14. Although PR has been used successfully for accommodation studies 7, 8, 9, it requires careful individual calibration on the tested animals or humans. PR was introduced in the early 1980s 2, 3, 4 and has since evolved to include different optical systems incorporating infrared video cameras and multiple light sources 5 with improved analytic methods (for review, see Howland, 2009 6). The name photorefraction (PR) refers to the refraction measurement made from PS images.

A less ambiguous means of evaluating a PS device is to determine the accuracy in detecting individual vision abnormalities separately. The result is therefore strongly influenced by the selected cohort and the pass-fail criteria defined for each abnormality. The evaluation of PS devices in vision screening typically uses pass-fail criteria. In addition to the ease of use, PS is capable of simultaneously detecting multiple amblyogenic conditions including strabismus, optical media opacities, and binocular refractive errors. It does not require careful positioning of the eyes or patient cooperation. A PS measurement involves taking photographs of the eyes at a distance, typically one meter. Photoscreening (PS) has been a popular objective method for pediatric vision screening because of its simplicity of use 1. This suggests that enhancements in the PR system and analysis may satisfactorily correct intersubject variability that currently limits the clinical use of PR devices and measurements. Age, race, and pupil size did not appear to significantly affect DOES PR measurement. Inaccuracy increased at high refraction (>4D). In the region between -4 diopter (D) and +4D, the device showed a binocular refraction measurement accuracy of 0.45 D, 0.3 D, and 0.18 D root-mean-square (RMS) error (n=1337) for spherical equivalent and cross cylinders J o and J 45, respectively. The influence of intraocular scattering, retinal reflectance, and pupil size was evaluated by comparing results from different age groups, races, and lighting conditions. The correlation and standard deviation were determined by Bland-Altman analysis. These results were compared to the standard clinical refraction testing performed the same day. We performed DOES measurements in 99 volunteers (198 eyes) under two environmental light conditions and using four fixation targets. The objective of our studies was to clinically evaluate the accuracy of refraction measurements of an improved PR-based device, the Dynamic Ocular Evaluation System (DOES), and to investigate whether the accuracy is affected by the patient’s age, race, and pupil size, which are relevant to individual intraocular scattering and retinal reflectance. While PR is easy to implement, the accuracy of refractive error measurements in humans has been unsatisfactory, largely due to the variations of intraocular scattering, the retinal reflectance, and pupil size. Photorefraction (PR) methods have beenwidely used for pediatric vision screening since the 1980’s.

Pupil measurement