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The continuation of: A comparison of monocular and binocular refractive results in preprespyopes

1 May 1997


It has been reported that binocular refraction methods yield different results than tradition refraction methods m slightly less than 10% of subjects. Binocular refraction is said to provide better balance between the eyes, and more accurate astigmatism measurements. The purpose of this study was to identify individuals whose binocular and traditional prescriptions differed, and to have subjects wear and rate spectacle lenses determined by each method. One hundred thirty prepresbyopic subjects were refracted twice in succession using both refraction methods in counterbalanced order. The AO Vectographic Slide was used for the binocular refractions. Autorefraction results were utilized as a common starting point for both methods. Refractions were judged different if there was: >0.25D difference in either spherical power, cylindrical power, equivalent sphere power, anisometropia (based on equivalent sphere), and vertical prism. They were also considered different if there was an induced cylindrical power due to axis shift of 0.25D or greater. It was found that 69%, or 90 subjects, had significant differences in one or more of these parameters. Thirty-eight subjects elected to participate in the doubly masked, randomized, crossover second phase of the study alternately wearing the results of each refraction method in identical frames. Following a three week wearing schedule, subjects completed a questionnaire. Based upon all subjects, mean sphere significantly differed by 0.22D, mean cyl differed by 0.04D, and mean equivalent sphere by 0.24D. Binocular refraction means were more minus for all three values. In the clinical trial, 47% of the 38 subjects preferred the binocular prescription, 42% preferred the traditional prescription, and 11% liked both prescriptions equally. In conclusion, a high percentage of subjects in this study yielded statistically more minus spectacle lens prescriptions when refracted binocularly compared to the traditional method. In the clinical lens wear trial, neither refraction method yielded lens prescriptions that were preferred by a majority of the subjects in lens wear trials.


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