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Tomohiko Akahori, Takeshi Iwase, Kentaro Yamamoto, Eimei Ra, Hiroko Terasaki; Changes in choroidal blood flow and morphology in response to increase of intraocular pressure. Invest. Ophthalmol. Vis. Sci. 2017;58(8):728.
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© ARVO (1962-2015); The Authors (2016-present)
The choroid has a weak own autoregulation for blood flow, resulting that the status of choroidal blood flow in lasting high intraocular pressure (IOP) would be unclear because of the autoregulation and remains controversial whether blood flow in choroid is decrease in eyes with high IOP, e.g. glaucoma. We investigated choroidal blood flow and the morphology in response to ocular perfusion pressure (OPP) during artificial increase in IOP and whether the choroidal blood flow has some capability to autoregulate.
We included 17 healthy subjects in our study. Choroidal blood flow was assessed by laser speckle flowgraphy (LSFG) using mean blur rate (MBR). Spectral-domain optical coherence tomography was used to image macular regions, to measure the subfoveal choroidal thickness (SFCT), and to calculate the luminal and the stromal areas by the binarisation method before IOP increase, during an artificial IOP increase of 20 or 30 mmHg using an ophthalmodynamometer, and after IOP increase.
The OPP was significantly reduced during 20 (-54.5%, p<0.001) and 30 mmHg (-78.5%, p<0.001) IOP elevation. The macular choroidal MBR and the SFCT were significantly reduced during 20mmHg elevation (ratio -32.5%, p<0.001) (ratio -3.8%, p<0.001) and during 30mmHg elevation (ratio -46.6 %, p<0.001) (ratio -7.7%, p<0.001), but the reduction ratio was smaller than that of the OPP. The luminal area was reduced during 20 mmHg (p<0.001) or 30 mmHg elevation (p<0.001), while the stroma area did not change. There was no correlation between the reduction ratio of OPP and other factors during 20 mmHg elevation, but significant correlation between the percentage reduction of OPP and the choroidal MBR during 30 mmHg elevation.
The present study corroborates previous findings that the choroid shows some ability to regulate its blood flow in response to experimental changes in OPP induced by IOP elevation.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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