V Dobson1, J M Miller, E M Harvey. 1. Department of Ophthalmology, University of Arizona, Tucson 85719-3758, USA. vdobson@eyes.arizona.edu
Abstract
PURPOSE: To examine the relation between corneal and refractive astigmatism in a sample of pre-school-age Native American children with a high prevalence of astigmatism. METHODS: Subjects were 250 Tohono O'Odham children, 3 to 5 years of age. Each child had corneal astigmatism measured with the Marco Nidek KM-500 portable autokeratometer without pupil dilation, and with the Nikon Retinomax K-Plus portable autorefractor/autokeratometer without and with pupil dilation. Refractive astigmatism was measured using the Retinomax K-Plus, with cycloplegia, confirmed by retinoscopy. RESULTS: Corneal astigmatism exceeded refractive astigmatism, with a median vector dioptric difference of 0.88 D for the KM-500, 0.76 D for the Retinomax K-Plus without dilation, and 0.75 for the Retinomax K-Plus with dilation. The relation between corneal and refractive astigmatism was adequately described by the modification by Grosvenor et al. of Javal's rule, but not by laval's rule. CONCLUSIONS: The results are in agreement with data reported previously for older Native American and non-Native American populations. The modified laval's rule adequately describes the relation between corneal and refractive astigmatism in a population; however, this rule does not provide accurate prediction of refractive astigmatism in individual children or adults.
PURPOSE: To examine the relation between corneal and refractive astigmatism in a sample of pre-school-age Native American children with a high prevalence of astigmatism. METHODS: Subjects were 250 Tohono O'Odham children, 3 to 5 years of age. Each child had corneal astigmatism measured with the Marco Nidek KM-500 portable autokeratometer without pupil dilation, and with the Nikon Retinomax K-Plus portable autorefractor/autokeratometer without and with pupil dilation. Refractive astigmatism was measured using the Retinomax K-Plus, with cycloplegia, confirmed by retinoscopy. RESULTS:Corneal astigmatism exceeded refractive astigmatism, with a median vector dioptric difference of 0.88 D for the KM-500, 0.76 D for the Retinomax K-Plus without dilation, and 0.75 for the Retinomax K-Plus with dilation. The relation between corneal and refractive astigmatism was adequately described by the modification by Grosvenor et al. of Javal's rule, but not by laval's rule. CONCLUSIONS: The results are in agreement with data reported previously for older Native American and non-Native American populations. The modified laval's rule adequately describes the relation between corneal and refractive astigmatism in a population; however, this rule does not provide accurate prediction of refractive astigmatism in individual children or adults.
Authors: Velma Dobson; Erin M Harvey; Candice E Clifford-Donaldson; Tina K Green; Joseph M Miller Journal: Optom Vis Sci Date: 2010-05 Impact factor: 1.973
Authors: Rachel Knowlton; Jason D Marsack; Norman E Leach; Ralph J Herring; Heather A Anderson Journal: Optom Vis Sci Date: 2015-07 Impact factor: 1.973
Authors: Erin M Harvey; Joseph M Miller; Howard P Apple; Pavan Parashar; J Daniel Twelker; Mabel Crescioni; Amy L Davis; Tina K Leonard-Green; Irene Campus; Duane L Sherrill Journal: Invest Ophthalmol Vis Sci Date: 2014-08-07 Impact factor: 4.799
Authors: Erin M Harvey; Velma Dobson; Joseph M Miller; Candice E Clifford-Donaldson; Tina K Green; Dawn H Messer; Katherine A Garvey Journal: J AAPOS Date: 2009-10 Impact factor: 1.220
Authors: Velma Dobson; Joseph M Miller; Candice E Clifford-Donaldson; Erin M Harvey Journal: Invest Ophthalmol Vis Sci Date: 2008-06-06 Impact factor: 4.799