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Background:

The choroid of the chick swells markedly during recovery from experimentally induced myopia. It has been demonstrated previously that the lymphatic sinusoids of the choroid contribute most to the expansion. This raises important questions about the particular ultrastructural changes occurring in choroidal lymphatics as a means of understanding the role these vessels might play in emmetropization.

Methods:

Thirteen hatchling chicks were monocularly occluded for 2 weeks to induce myopia and then allowed normal visual experiences during recovery for periods of 0 to72 h before sacrifice.

Results:

Electron microscopic analysis detailed the temporal progression of vascular changes and provides qualitative evidence for edema in the extravascular space. Quantitative analysis showed that the frequency of open junctions between lymphatic endothelial cells (an indicator of passive fluid transfer) increased …