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      Refractive properties of the healthy human eye during acute hyperglycemia

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          Abstract

          Purpose

          To measure the refractive properties of the healthy human eye during acute hyperglycemia by means of Scheimpflug imaging and Hartmann-Shack aberrometry.

          Methods

          Acute hyperglycemia was induced in five healthy subjects (two males, three females, mean age ±SD 24.8 years ± 4.6) by means of an oral glucose tolerance test (OGTT) after subcutaneous somatostatin injection. Before and every 30 minutes after the OGTT, measurements with Scheimpflug imaging and Hartmann-Shack aberrometry were performed. The main outcome measures were the thickness and shape of the lens, and the ocular refractive error and higher order aberrations. The equivalent refractive index of the lens was calculated from these parameters. Measurements at baseline and during hyperglycemia were analyzed by means of Wilcoxon signed rank sum tests.

          Results

          During hyperglycemia (mean blood glucose level at baseline: 4.0 mmol/l; mean maximal blood glucose level: 18.4 mmol/l) no changes could be found in the refractive properties within the group. In one subject, a hyperopic shift (0.4 D) was observed, together with a more convex shape of the anterior lens surface and a decrease in the equivalent refractive index of the lens.

          Conclusions

          This study shows that hyperglycemia generally does not cause changes in the refractive properties of the healthy eye. Nevertheless, in one subject a hyperopic shift accompanied by a change in shape and refractive index of the lens was measured. This finding could provide an explanation for the mechanism underlying the refractive changes that are often observed during hyperglycemia.

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          Most cited references 39

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          The sorbitol pathway and the complications of diabetes.

           K H Gabbay (1973)
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            Refractive status in the Beaver Dam Eye Study.

            To describe the prevalence of refractive errors in a population of adult Americans. From 1988 to 1990, 4926 adults who were 43 to 84 years of age and living in Beaver Dam, Wisconsin at the time of the 1987-1988 census were examined. Refractions were performed according to a modification of the Early Treatment Diabetic Retinopathy Study protocol. Included in this study were 4533 people who had not undergone cataract surgery and who had a best corrected visual acuity better than 20/40 in at least one eye. Myopia was defined as a refractive error less than -0.50 diopters; hyperopia was defined as a refractive error greater than +0.50 diopters. Hyperopia was more frequent than myopia in the study group (age-adjusted of 49.0% and 26.2% in right eyes, respectively, P = 0.0001). The prevalence of hyperopia in the right eye increased with increasing age from 22.1% in those 43 to 54 years of age to 68.5% in those 75 years of age or older. The prevalence of myopia in the right eye decreased from 43.0% in those 43 to 54 years of age to 14.4% in those 75 years of age or older. There was significant relationship between education level and refractive error (age adjusted r = -0.32, P = 0.0001). Neither household income nor occupation was associated with refractive error in our data. These cross-sectional data indicate age-related differences in refractive status in an adult population and suggest that education is associated with myopia independent of age.
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              The shape of the aging human lens: curvature, equivalent refractive index and the lens paradox.

              Scheimpflug slit images of the crystalline lens are distorted due to the refracting properties of the cornea and because they are obliquely viewed. We measured the aspheric curvature of the lens of 102 subjects ranging in age between 16 and 65 years and applied correction for these distortions. The procedure was validated by measuring an artificial eye and pseudophakic patients with intraocular lenses of known dimensions. Compared to previous studies using Scheimpflug photography, the decrease of the radius of the anterior lens surface with age was smaller, and the absolute value for the radius of the anterior and posterior lens surface was significantly smaller. A slight decrease of the posterior lens radius with age could be demonstrated. Generally, front and back surfaces were hyperbolic. Axial length was measured of 42 subjects enabling calculation of the equivalent refractive index of the lens, which showed a small, but highly significant decrease with age. These new findings explain the lens paradox and may serve as a basis for modelling the refractive properties of the lens.
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                Author and article information

                Contributors
                +31-20-4440234 , +31-20-4441015 , ngm.wiemer@vumc.nl
                Journal
                Graefes Arch Clin Exp Ophthalmol
                Graefe's Archive for Clinical and Experimental Ophthalmology
                Springer-Verlag (Berlin/Heidelberg )
                0721-832X
                1435-702X
                4 April 2008
                July 2008
                : 246
                : 7
                : 993-998
                Affiliations
                [1 ]Department of Ophthalmology, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam, The Netherlands
                [2 ]Institute for Research in Extramural Medicine, VU University Medical Center, Amsterdam, the Netherlands
                [3 ]Department of Endocrinology, VU University Medical Center, Amsterdam, the Netherlands
                [4 ]Department of Physics and Medical Technology, VU University Medical Center, Amsterdam, the Netherlands
                Article
                810
                10.1007/s00417-008-0810-y
                2413123
                18389272
                © The Author(s) 2008
                Categories
                Basic Science
                Custom metadata
                © Springer-Verlag 2008

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