Comparison of the handheld Retinomax K-Plus2 and on-table autokeratometers in children with and without cycloplegia

Purpose: To compare the keratometry measurements in children by the handheld Nikon Retinomax K-Plus2 (Rmax) and the on-table Topcon KR8100 autokeratometers and evaluate the degree of agreement in the 2 instruments between children with and without cycloplegia. Setting: Department of Ophthalmology, Kaohsiung Municipal United Hospital, and Chang-Gung Memorial Hospital, Kaohsiung, Taiwan. Methods: The first cohort comprised 61 children who were consecutively collected in the pediatric ophthalmology clinic. The keratometry was measured under cycloplegia. The second cohort included 156 school children who received routine vision screening without cycloplegia. The horizontal and vertical keratometry data were measured by both instruments. The mean bias and agreement between the 2 types of measurements were evaluated. Results: Both horizontal and vertical keratometry data from the Rmax were systemically and mildly lower than the data from the Topcon. The mean keratometric difference in the 2 types of instruments was minimal and clinically acceptable: 72% to 85% was within ±0.5 diopter. The agreement of measured data in the children without cycloplegia was higher than that in the children with cycloplegia. Conclusions: The handheld Retinomax provided comparable data to that of the conventional on-table Topcon. It is useful in the clinic to measure keratometry in children and therefore may offer a convenient tool for assessing corneal curvature for fitting contact lenses or for implanting intraocular lenses in young children.