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C. Koonapareddy, S.P. Epstein, M. Ahdoot, P.A. Asbell; Reliability of Auto–Refraction Compared to Manifest as an Effective Tool for Determination of Refractive Error . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1178.
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Auto refraction needs to be accurate and reliable both for prescribing glasses or evaluating refractive error for refractive surgery. Accurate and reliable refraction would allow auxiliary personnel in developing countries to provide standardized, unbiased, refractive error measurements enabling to create precision spectacles thus preventing avoidable functional blindness, a leading cause of poor vision worldwide. We compared the reliability of a new auto–refractor (NIDEK–OPD Scan) with manifest refraction.
Retrospective analysis of data obtained on 14 patients considering refractive surgery was analyzed. All patients had a complete eye exam that excluded other ocular diseases other than refractive error. Analysis included: sex; manifest; auto–refraction; with sphere, cylinder, and axis. Results obtained from manifest and auto–refraction were compared utilizing paired student t–test. The auto–refractor that was used works on a 3–D Wave technology, the 3–D Wave is based on the dynamic skiascopy principle, which when used to measure the refractive power enables the system to read all the aberrations of the eye, including higher–order aberrations.
On average, autorefraction gave a spherical equivalent (SE) that was slightly more negative than manifest refraction. The mean difference in SE in 5 of the 14 patients was 0.02± 0.05 (SD), in 3 patients it was 0.25± 0.075 (SD), in the remaining 6 patients it was 0.50± 0.025 (SD). Repeatability for all refractive error measurements was < 0.50 diopter (D).
Auto–refraction with OPD scan appears to be an accurate method useful for determining refractive error, as compared to manifest the "gold standard". It can also be used to prescribing spectacles for preventing early onset functional blindness. Such automated systems may also be helpful in large scale screenings and in clinical trials where refractive error is an important endpoint. It can be easily used by non–professionals for prescribing corrective eyewear.
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