After demonstrating feasibility, we will recruit 300 clinical trial participants during previously scheduled visits at two Kaiser Permanente of Southern California (KPSC) pediatric clinics. We will also send letters and placed phone calls to parents of eligible children who lived in cities proximal to the two clinics. Children will be considered eligible if age is ≥ 2 years old, less than 6 years old; have never visited an ophthalmologist (as this could indicate a pre-existing eye condition and/or introduce biased eye exam results if the physician had seen the patient before), are an active Kaiser Permanente member, and do not have a cognitive and/or developmental disability (ICD-10 codes Z82.79 and F84.0).
Interested participants will either visit an on-site ophthalmology clinic immediately following their pediatric visit or make a future appointment at one of two KPSC ophthalmology clinics. All study activities will be completed during one appointment. Research staff describe the study to parents and obtain informed consent, collected parent-reported demographic data about each participant, screen each participant using the PVS, and documented PVS results, test acquisition time, and participant cooperation. Testing will be performed in a dimly lit room with the child seated on a chair or parents lap. Per manufacturer recommendations, a background calibration measurement is first obtained off of the face with closed eyes. Then the child is asked to open both eyes and fixate on the smiley face target within the device while the binocular retinal polarization scan is performed. PVS results will be interpreted as either "pass" or "refer" based on manufacturer recommendations. Acquisition time is defined as time from when the research staff picked up the PVS to when the result is generated, and cooperation is defined as "excellent" or "fair" based on staff discretion (e.g., a patient who listens to instructions and completes the exam on the first try would be "excellent," whereas a patient who moves his/her head around during testing would be "fair"). A pediatric ophthalmologist masked to the PVS result then performs a gold standard eye examination. Possible gold standard examination results were "normal", "normal with risk factors" (Table Amblyopia Risk Factors - see protocol), "suspected binocular vision deficit," "suspected amblyopia," "amblyopia, "strabismus" and "amblyopia and strabismus." (Diagnostic Categories Rubric - see protocol). Results were mutually exclusive. To compare the PVS results to the gold standard eye examination among the 300 children eligible for analysis, we will perform a validation characteristics analysis with a 95% confidence interval (CI).
