By Sarah Guy, medwireNews Reporter
Visual impairment that is not explained by refractive error is increasing, as is the prevalence of diabetes - particularly diabetes lasting 10 years or longer, show US study results.
The findings indicate a significant association between nonrefractive visual impairment and diabetes that patients with long-term diabetes are more at risk, in particular, than their counterparts who have had the condition for less time.
"These results have important implications for resource allocation," remark the researchers, who contend that if the trend persists, it could result in increasing rates of disability in the US population. "Including greater numbers of patients with end-organ diabetic damage who would require ophthalmic care," they write, in the JAMA.
David Friedman (Johns Hopkins University School of Medicine, Baltimore, Maryland) and colleagues compared the prevalence of nonrefractive visual impairment, its risk factors, and changes in prevalence using National Health and Nutrition Examination Survey results from 1999 to 2000 (n=8790) and 2005 to 2008 (n=9762), in patients who completed a visual acuity examination.
Nonrefractive visual impairment prevalence was significantly different between these time points, increasing from 1.4% to 1.7%. The presence of diagnosed diabetes also increased, from 6.5% to 8.2%, as did the figures for diabetes of 10 years duration or more, from 2.8% to 3.6%.
Furthermore, multivariate analysis revealed that a 10-year or longer diabetes diagnosis increased the risk for nonrefractive visual impairment in both time periods, increasing the odds 1.93-fold in 1999 to 2000 and 2.67-fold in 2005 to 2008.
Poverty, defined as having a poverty income ratio of 1.0 or less, also significantly increased the odds for nonrefractive visual impairment, by 2.18 times in the earlier time period and 2.23 in the later.
The early time period also indicated an association between nonrefractive visual impairment and a lack of health insurance, as well as non-Hispanic black ethnicity, although this was not apparent in the later time period. Conversely, in 2005 to 2008 only, there was an increased risk for nonrefractive visual impairment among those educated to less than high school level.
While overall prevalence of these factors decreased or remained stable between the two time periods, diabetes prevalence increased. Thus, after stratifying data according to diabetes status, the estimated prevalence of nonrefractive visual impairment was significantly higher among those with any diagnosis compared with those who were diabetes-free.
The highest estimated prevalence was among individuals with a diabetes diagnosis of 10 years or more, at 6.1% and 8.1% in the two time periods, respectively.
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