Siriraj Medical Journal (Oct 2004)
Outcome of Manifest Refraction Performed by First Year Residents Evaluating the Schematic Eye
Abstract
Purpose : To evaluate the efficacy of manifest refraction performed by beginners (first year residents) Methods : Prospective study of manifest refraction obtained by first year residents at the Department of Ophthalmology, Faculty of Medicine Siriraj Hospital, Mahidol University was done. The schematic eye (model BC 2174, Bernell Corporation 1995) was present to 7 types of refractive error, including simple hyperopia, simple hyperopic astigmatism, simple myopic astigmatism, compound hyperopic astigmatism, compound myopic astigmatism and mixed astigmatism. Blind manifest refraction was performed by all residents. The results were analyzed. Results : Eight residents with 56 manifest refraction were included. The overall mean error in the spherical equivalent was 0.26 ± 0.99 diopter. The maximum error in the spherical component and spherical equivalent was found in the simple hyperopic astigmatism group (1.32 ± 1.01 diopter and 1.34 ± 0.63 diopter, respectively). The minimum error in the spherical component and spherical equivalent was found in the simple hyperopic group (0.12 ± 0.37 diopter and 0.09 ± 0.02 diopter, respectively). The maximum error in the cylinder was found in the mixed astigmatism group (0.84 ± 0.59 diopter) but no error in the axis was found. The maximum error in the axis of the cylinder was also found in the simple hyperopic astigmatism group (13.75 ± 17.06 degree). Conclusion : Manifest refraction performed by beginners is most likely to have an error in the simple hyperopic astigmatism. The axis cylindrical component is easiest to identity in mixed astigmatism but difficult to quantify in its amount. Refraction of these types of refractive error should be cautionary for the beginners.
