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DO Mutti, LA Jones, GL Mitchell, ML Moeschberger, K Zadnik; Excess Accommodative Lag Accompanies But Does Not Precede The Onset Of Myopia . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1512.
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Purpose: Hyperopic defocus from accommodative lag is a putative risk factor for myopia onset and progression. We investigated the importance of lag in the etiology of myopia by testing whether increased amounts of lag preceded the onset of myopia and whether myopic children had different amounts of lag compared to other refractive error groups. Methods: We measured the accommodative response to a letter target at 0 D and 4 D in a total of 903 children in grades 1 through 8 participating in the Orinda Longitudinal Study of Myopia between 1997-2000. Accommodative response was measured monocularly in the right eye using a Canon R-1 autorefractor while subjects wore their habitual refractive correction. Responses were corrected for lens effectivity. Results: Greater accommodative lag did not increase the risk of the onset of myopia. Age and refractive error adjusted odds ratios (with 95% confidence intervals) associated with a 0.50 D unit increase in accommodative lag were not significant one year prior to the onset of myopia (1.02; 0.69, 1.51), two years prior to myopia onset (1.08; 0.79, 1.49), or three years prior to myopia onset (1.30; 0.95, 1.78). Statistical power was 0.96 to detect a difference in lag of 0.25 D between emmetropic children who later became myopic compared to those who remained emmetropic. Once children developed myopia, there was a significant association between refractive error and accommodative lag. Age adjusted least-square mean values for lag were significantly greater for prevalent myopes compared to emmetropes in three out of four study years by an average of 0.24 D (1997 P<0.0001; 1999 P=0.0074; 2000 P=0.038; 1998 P=0.11). Conclusion: Accommodative lag was not a significant predictor of the onset of myopia. Increased accommodative lag was associated with prevalent, but not incident, cases of myopia. Increased accommodative lag may be more a symptom, or an effect, of juvenile myopia than a cause.
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