EVALUATION OF THE HAND-HELD AUTOREFRACTOR NIKON RETINOMAX ON ADULTS AND CHILDREN

Background A measurement of ametropia with a table-top mounted autoref ractor can be difficult or impossible on children - especially when th e children are very young or handicapped. A hand-held autorefractor, h owever, may be successfully applied in some of these problematic cases . Methods Results of comparative measurements are presented concerning the accuracy and applicability of the handheld autorefractor. The dat a were obtained on healthy young adults (100 eyes) and children (age 2 -10 years, 50 eyes). In the group of adults,the autorefractor readings (obtained with a Retinomax K-plus) were compared with the results of subjective refractions. The effectiveness of the technique to relax ac commodation was also evaluated. All children were measured with a Reti nomax in cycloplegia. Here, retinoscopy and a conventional autorefract or sewed as reference methods. The accuracy of measurement was analyse d by using the following criteria: ''Difference of the spherical equiv alents'' (Delta SA), ''difference of the cylinder powers'' (Delta C), ''axis difference'' (Delta A), and ''difference of the cylindrical cor rections'' (Delta CK). Results a) Adults: On average, the spherical eq uivalent of the autorefractor was +0.28 D larger than the subjectively obtained value. In 88% of all cases, the difference of the spherical equivalents fell into the interval [-0.25 D, +0.75 D]. Delta C and Del ta A were less than or equal to +/-0.5 D in 95% and 87% respectively. b) Children: When compared with retinoscopy, Delta SA fell into the in tervall [-0.25 D, +0.75 D] in 72% of all cases. Delta C and Delta A we re less than or equal to +/-0.5 D in 86% and 87% respectively. Conclus ions The accuracy of measurement of the handheld autorefractor is comp arable to conventional table-top autorefractors. As it is also applica ble in some problematic cases, such as small children, on whom objecti ve refraction data can not be obtained with ordinary autorefractors, i t seems to be a valuable addition to the existing set of ophthalmic re fraction devices.