Evaluating the effectiveness of the Arclight: A compact solar-powered low-cost direct ophthalmoscope

Abstract: PURPOSE: The purpose of this study is to assess the accuracy and utility of the Arclight device, a frugal direct ophthalmoscope, in evaluating the cup-to-disc ratio (CDR) by a nonophthalmologist examiner in comparison to an expert ophthalmologist using a range of standard diagnostic tools. METHODS: A prospective study was conducted with 108 participants (211 eyes) at ophthalmology clinics associated with the University of California, Irvine. A medical student (naïve nonophthalmologist examiner [NNOE]) performed fundus examinations using the Arclight whereas a pediatric ophthalmologist conducted gold standard evaluations with a combination of direct ophthalmoscopy, indirect ophthalmoscopy, and/or slit-lamp examination. Training for the NNOE included didactic sessions on using the Arclight for fundal “red” reflex testing and fundus assessment including CDR estimation. Data collected included CDR values, ease of use (EOU, rated on a 5-point scale), and examination time. Bland–Altman analysis compared student and ophthalmologist measurements, with stratified analyses exploring performance across demographics, including age, sex, iris color, and dilation status. RESULTS: Examinations with the Arclight were successful in 76.8% (162/211) of cases. Mean CDR values by the student (0.325) aligned closely with those by the ophthalmologist (0.331, P = 0.27), with 95% agreement within ± 0.17. The Arclight performed well across most groups, with highest EOU and shortest examination times in dilated eyes. As expected, challenges were noted in younger children and those with nondilated pupils. CONCLUSION: The Arclight is a reliable, affordable, and user-friendly tool for fundoscopic examinations. Its low cost and portability make it ideal for low- and middle-income countries, supporting global efforts to reduce preventable blindness. Targeted training and technique adjustments could enhance its performance in specific populations.