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Choroidal thickness changes after dynamic exercise as measured by spectral-domain optical coherence tomography

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      Abstract

      Purpose:

      To measure the choroidal thickness (CT) after dynamic exercise by using enhanced depth imaging optical coherence tomography (EDI-OCT).

      Materials and Methods:

      A total of 19 healthy participants performed 10 min of low-impact, moderate-intensity exercise (i.e., riding a bicycle ergometer) and were examined with EDI-OCT. Each participant was scanned before exercise and afterward at 5 min and 15 min. CT measurement was taken at the fovea and 1000 μ away from the fovea in the nasal, temporal, superior, and inferior regions. Retinal thickness, intraocular pressure, ocular perfusion pressure (OPP), heart rate, and mean blood pressure (mBP) were also measured.

      Results:

      A significant increase occurred in OPP and mBP at 5 min and 15 min following exercise ( P ˂ 0.05). The mean subfoveal CT at baseline was 344.00 ± 64.71 μm compared to 370.63 ± 66.87 μm at 5 min and 345.31 ± 63.58 μm at 15 min after exercise. CT measurements at all locations significantly increased at 5 min following exercise compared to the baseline ( P ˂ 0.001), while measurements at 15 min following exercise did not significant differ compared to the baseline ( P ˃ 0.05). There was no significant difference in retinal thickness at any location before and at 5 min and 15 min following exercise ( P ˃ 0.05).

      Conclusion:

      Findings revealed that dynamic exercise causes a significant increase in CT for at least 5 min following exercise.

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      Most cited references 46

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      Enhanced depth imaging spectral-domain optical coherence tomography.

      To describe a method to obtain images of the choroid using conventional spectral-domain (SD) optical coherence tomography (OCT) and to evaluate choroidal thickness measurements using these images. Observational case series. The images were obtained by positioning the SD OCT device close enough to the eye to obtain an inverted representation of the fundus in healthy volunteers who did not have pupillary dilation. Seven sections, each comprised of 100 averaged scans, were obtained within a 5- x 15-degree rectangle centered on the fovea. The choroidal thickness under the fovea in each image was measured by independent observers. The choroidal thickness could be evaluated in every subject's choroidal image. The mean choroidal thickness under the fovea was 318 microm in the right eye and 335 microm in the left eye. The choroidal thickness showed a high correlation in both eyes (r = 0.82; P < .001). The correlation between the measurements performed by the independent observers was highly significant (right eye, r = 0.93; left eye, r = 0.97; P < .001 for both). This method provides detailed, measurable images from the choroid, a structure that heretofore has been difficult to image in clinical practice.
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        Age-predicted maximal heart rate revisited.

        We sought to determine a generalized equation for predicting maximal heart rate (HRmax) in healthy adults. The age-predicted HRmax equation (i.e., 220 - age) is commonly used as a basis for prescribing exercise programs, as a criterion for achieving maximal exertion and as a clinical guide during diagnostic exercise testing. Despite its importance and widespread use, the validity of the HRmax equation has never been established in a sample that included a sufficient number of older adults. First, a meta-analytic approach was used to collect group mean HRmax values from 351 studies involving 492 groups and 18,712 subjects. Subsequently, the new equation was cross-validated in a well-controlled, laboratory-based study in which HRmax was measured in 514 healthy subjects. In the meta-analysis, HRmax was strongly related to age (r = -0.90), using the equation of 208 - 0.7 x age. The regression equation obtained in the laboratory-based study (209 - 0.7 x age) was virtually identical to that obtained from the meta-analysis. The regression line was not different between men and women, nor was it influenced by wide variations in habitual physical activity levels. 1) A regression equation to predict HRmax is 208 - 0.7 x age in healthy adults. 2) HRmax is predicted, to a large extent, by age alone and is independent of gender and habitual physical activity status. Our findings suggest that the currently used equation underestimates HRmax in older adults. This would have the effect of underestimating the true level of physical stress imposed during exercise testing and the appropriate intensity of prescribed exercise programs.
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          The multifunctional choroid.

          The choroid of the eye is primarily a vascular structure supplying the outer retina. It has several unusual features: It contains large membrane-lined lacunae, which, at least in birds, function as part of the lymphatic drainage of the eye and which can change their volume dramatically, thereby changing the thickness of the choroid as much as four-fold over a few days (much less in primates). It contains non-vascular smooth muscle cells, especially behind the fovea, the contraction of which may thin the choroid, thereby opposing the thickening caused by expansion of the lacunae. It has intrinsic choroidal neurons, also mostly behind the central retina, which may control these muscles and may modulate choroidal blood flow as well. These neurons receive sympathetic, parasympathetic and nitrergic innervation. The choroid has several functions: Its vasculature is the major supply for the outer retina; impairment of the flow of oxygen from choroid to retina may cause Age-Related Macular Degeneration. The choroidal blood flow, which is as great as in any other organ, may also cool and warm the retina. In addition to its vascular functions, the choroid contains secretory cells, probably involved in modulation of vascularization and in growth of the sclera. Finally, the dramatic changes in choroidal thickness move the retina forward and back, bringing the photoreceptors into the plane of focus, a function demonstrated by the thinning of the choroid that occurs when the focal plane is moved back by the wearing of negative lenses, and, conversely, by the thickening that occurs when positive lenses are worn. In addition to focusing the eye, more slowly than accommodation and more quickly than emmetropization, we argue that the choroidal thickness changes also are correlated with changes in the growth of the sclera, and hence of the eye. Because transient increases in choroidal thickness are followed by a prolonged decrease in synthesis of extracellular matrix molecules and a slowing of ocular elongation, and attempts to decouple the choroidal and scleral changes have largely failed, it seems that the thickening of the choroid may be mechanistically linked to the scleral synthesis of macromolecules, and thus may play an important role in the homeostatic control of eye growth, and, consequently, in the etiology of myopia and hyperopia. Copyright 2009 Elsevier Ltd. All rights reserved.
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            Author and article information

            Affiliations
            Department of Ophthalmology, Kanuni Sultan Suleyman Education and Research Hospital, Istanbul, Turkey
            [1 ]Department of Ophthalmology, Gaziantep University, Gaziantep, Turkey
            [2 ]Department of Ophthalmology, Pamukkale University, Denizli, Turkey
            [3 ]Department of Ophthalmology, Ataturk Training and Research Hospital, Ankara, Turkey
            Author notes
            Correspondence to: Dr. Nihat Sayin, Atakent Mahallesi, 4. Cadde, C 2-7 Blok, Kat: 3 Daire: 13, Kücükcekmece, Istanbul, Turkey. E-mail: nihatsayin@ 123456yahoo.com
            Journal
            Indian J Ophthalmol
            Indian J Ophthalmol
            IJO
            Indian Journal of Ophthalmology
            Medknow Publications & Media Pvt Ltd (India )
            0301-4738
            1998-3689
            May 2015
            : 63
            : 5
            : 445-450
            26139808 4501143 IJO-63-445 10.4103/0301-4738.159884
            Copyright: © Indian Journal of Ophthalmology

            This is an open-access article distributed under the terms of the Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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