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C Fyffe, J Robichaud, EL Irving, JG Sivak; The Evaluation of Fluid Dynamics in Chick Eyes during Experimental Myopia . Invest. Ophthalmol. Vis. Sci. 2002;43(13):198.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: The dynamics of fluid flow, as well as possible routes of drainage are not well defined for the chick eye. Structures comparable to the human trabeculum or Schlem’s canal have yet to be isolated. An analysis of fluid dynamics in the experimentally induced myopic chick eye was studied in order to gain insight into the nature of the change in fluid flow that occurs during myopia recovery. Methods: Eight newly hatched chicks were unilaterally fitted with -15 D lenses for one week, inducing myopia. Refractive states were measured on days 0 and 7 by retinoscopy. Following measurements on day 7, the chicks’ lenses were removed and each eye injected with 2.5 µl of 25% sodium fluorescein (NaFl). The progression of the dye was then monitored with a slit lamp biomicroscope and recorded in real time with a video camera. Photographs of both the myopic eye and the control eye were taken for all chicks at the time of injection (time 0). Each chick was photographed and then sacrificed at different time intervals post-injection (15 min., 30 min., 1 hr, 2 hr, 4 hr, 6 hr, 12 hr, 24 hr). Results: An average of -17.1 D of myopia was produced with -15 D lens wear. Injection of the NaFl into the posterior portion of the vitreous chamber was observed and documented by slit lamp biomicroscopy. The flow of NaFl into the anterior chamber of both the myopic and control eyes was a continuous process beginning several minutes after injection and reaching a maximum between 2 and 4 hours. Depletion of fluorescein in the anterior chamber was first noted at approximately 6 hours and gradually decreased through to the 24 hr documentation. The flow of NaFl within myopic eyes was qualitatively faster than control eyes in some but not all birds. Conclusion: While the fluid from the posterior segment of the in vivo chick eye was successfully tracked and photo-documented in both the control and myopic eyes, its ultimate destination is still uncertain. The time course for this fluid migration (approximately 24 hrs) is similar to that of maximal thickening of the choroidal lymphatics during myopia recovery and thus the two may be related.
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