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This Article Full Text Full Text (PDF) All Versions of this Article: iovs.09-4356v1 51/2/723    most recent Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Mandel, Y. Articles by Zadok, D. PubMed PubMed Citation Articles by Mandel, Y. Articles by Zadok, D.

Parameters Associated with the Different Astigmatism Axis Orientations

From the ¹Israel Defense Force Medical Corps Headquarters, Ramat-Gan, Israel; the ²Hebrew University, Center for Bioengineering in the Service of Humanity and Society, Jerusalem, Israel; the ³Department of Ophthalmology, University of Pennsylvania, Scheie Eye Institute, Philadelphia, Pennsylvania; and the ⁴Department of Ophthalmology, Assaf Harofeh Medical Center, Tel Aviv University, Zrifin, Israel.

Corresponding author: Yossi Mandel, The Selim and Rachel Benin School of Computer Science and Engineering, Edmond J. Safra Campus, Givat Ram, Jerusalem 91904, Israel; yossimandel{at}bezeqint.net.

Purpose. To evaluate parameters associated with astigmatism axis orientation.

Methods. A retrospective population-based study was conducted on 67,899 (53% males) Israeli Defense Force conscripts aged 16 to 22 years with 0.25 D of astigmatism, using prerecruitment examination and demographic data that included a validated general intelligence score. Refractive errors were classified by the cylinder axis with the least deviation from emmetropia (LDE), a scheme intended to avoid confounding spherical classification by cylinder power. Perinatal photoperiod was determined from birth date and astronomical tables.

Results. With-the-rule (WTR) axis was associated with higher LDE (P < 0.001), higher cylinder power (P < 0.001), Eastern or Western compared with Israeli origin (P < 0.001), higher body mass index (P < 0.001), lower intelligence scores (P < 0.001), and longer perinatal photoperiod (P < 0.001), using univariate analysis. Multivariate logistic regression confirmed the independent association of these parameters and identified being of the female sex as another WTR axis association. Subjects' cylinder axis also was associated with their siblings' cylinder axis (odds ratio [OR] = 1.58; 95% confidence interval [CI] = 1.31–1.90), using siblings' refractive data for the 3852 available subjects in the regression model. However, the associations of these parameters with WTR, against-the-rule, or oblique astigmatism were neither parallel as a whole nor parallel between any two sets of axis orientations. Further, the directions of the associations of these parameters with astigmatism axis and power did not consistently conform to their previously reported associations for spherical ametropias.

Conclusions. The results suggest both that distinctive mechanisms may account for the different astigmatism axis orientations and that mechanisms influencing astigmatism development are likely to vary from those governing the spherical component of refraction.