{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,11]],"date-time":"2026-02-11T13:20:25Z","timestamp":1770816025224,"version":"3.50.1"},"reference-count":36,"publisher":"American Physiological Society","issue":"2","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["American Journal of Physiology-Regulatory, Integrative and Comparative Physiology"],"published-print":{"date-parts":[[2011,8]]},"abstract":"<jats:p> Studies using various MRI techniques have shown that a water-protein concentration gradient exists in the ocular lens. Because this concentration is higher in the core relative to the lens periphery, a gradient in refractive index is established in the lens. To investigate how the water-protein concentration profile is maintained, bovine lenses were incubated in different solutions, and changes in water-protein concentration ratio monitored using proton density weighted (PD-weighted) imaging in the absence and presence of heavy water (D<jats:sub>2<\/jats:sub>O). Lenses incubated in artificial aqueous humor (AAH) maintained the steady state water-protein concentration gradient, but incubating lenses in high extracellular potassium (KCl-AAH) or low temperature (Low T-AAH) caused a collapse of the gradient due to a rise in water content in the core of the lens. To visualize water fluxes, lenses were incubated in D<jats:sub>2<\/jats:sub>O, which acts as a contrast agent. Incubation in KCl-AAH and low T-AAH dramatically slowed the movement of D<jats:sub>2<\/jats:sub>O into the core but did not affect the movement of D<jats:sub>2<\/jats:sub>O into the outer cortex. D<jats:sub>2<\/jats:sub>O seemed to preferentially enter the lens cortex at the anterior and posterior poles before moving circumferentially toward the equatorial regions. This directionality of D<jats:sub>2<\/jats:sub>O influx into the lens cortex was abolished by incubating lenses in high KCl-AAH or low T-AAH, and resulted in homogenous influx of D<jats:sub>2<\/jats:sub>O into the outer cortex. Taken together, our results show that the water-protein concentration ratio is actively maintained in the core of the lens and that water fluxes preferentially enter the lens at the poles. <\/jats:p>","DOI":"10.1152\/ajpregu.00173.2011","type":"journal-article","created":{"date-parts":[[2011,5,19]],"date-time":"2011-05-19T00:44:26Z","timestamp":1305765866000},"page":"R335-R342","source":"Crossref","is-referenced-by-count":55,"title":["Visualizing ocular lens fluid dynamics using MRI: manipulation of steady state water content and water fluxes"],"prefix":"10.1152","volume":"301","author":[{"given":"Ehsan","family":"Vaghefi","sequence":"first","affiliation":[{"name":"Department of Optometry and Vision Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand;"},{"name":"Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Beau P.","family":"Pontre","sequence":"additional","affiliation":[{"name":"Centre for Advanced MRI, University of Auckland, Auckland, New Zealand; 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