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Frances Wu, Julie M. Schallhorn, Eugene Lowry; Refractive status during pregnancy in the United States: NHANES 2005-2008. Invest. Ophthalmol. Vis. Sci. 2018;59(9):3369. doi: https://doi.org/.
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Changes in refractive error and corneal curvature have been described during pregnancy. However, these studies are limited by small sample size and convenience-based sampling. We investigate refractive status in pregnancy in a larger sample that broadly reflects U.S. pregnant women.
The National Health and Nutrition Examination Survey (NHANES) is a series of studies on U.S. population health based on interviews and physical examinations of a nationally representative sample. In the 2005-2006 and 2007-2008 NHANES, vision data were obtained including visual acuity (retested with objective refraction if initial acuity was worse than 20/25), lensometry, objective refraction (Nidek Autorefractor Model ARK-760A), and keratometry. Vision examination characteristics of pregnant women aged 20-44 years with available objective refraction data were compared to those of nonpregnant controls matched for age, ethnicity, education, and income. Subjects with best obtainable acuity worse than 20/40 or prior cataract surgery were excluded from the analysis. For subjects with glasses at the time of examination, glasses prescription and objective refraction were compared.
There were 20,497 participants in the 2005-2006 and 2007-2008 NHANES of whom 1,453 met inclusion criteria. Of these, 307 reported pregnancy confirmed with positive urine pregnancy test. They were matched with 307 controls who denied pregnancy and had a negative urine pregnancy test. There was no significant difference in refraction between cases and controls by sphere, cylinder, or mean spherical equivalent (MSE) in right or left eyes (Table 1, all p>0.15). In a subgroup analysis of 61 pregnant women and 61 nonpregnant controls with glasses on presentation, the glasses to objective refraction disparity was similar between groups (Fig. 1, all p>0.17). The vector dioptric distance (VDD) between glasses prescription and objective refraction was not significantly correlated with trimester of pregnancy (p>0.12 for right and left eyes).
Although other studies have suggested changes in refractive status during pregnancy, our analysis did not demonstrate a significant difference in refractive error or keratometry in a cross-sectional survey. Prospective, longitudinal studies are needed to better characterize the effects of pregnancy on refractive status.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
Table 1: Objective refraction
Figure 1: Glasses prescription and objective refraction disparity
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