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 Javal's rule. Conclusions: The results are in agreement with data reported previously for older Native American and non-Native American populations. The modified Javal'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.
Original language | English (US) |
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Pages (from-to) | 855-860 |
Number of pages | 6 |
Journal | Optometry and Vision Science |
Volume | 76 |
Issue number | 12 |
DOIs | |
State | Published - Dec 1999 |
Keywords
- Astigmatism
- Children
- Corneal astigmatism
- Javal's rule
- Native Americans
- Refractive astigmatism
ASJC Scopus subject areas
- Ophthalmology
- Optometry