Ciliary zonules are a ring of fibrous structures anchoring the ciliary body with the lens of the eye. These are the structures that help to maintain the position of the lens in the optical path, and anchor muscles that change the shape of the lens to alter focus. When the ciliary muscles contract, the diameter of the ciliary muscle constricts, causing relaxation of the ciliary zonules and allowing the lens to become “thicker” which increases its refractive power allowing people to focus closer.
There is more discussion of ciliary zonules or zonnular fibers on Moran Core. Be sure to check out some of the pathology images from damaged zonules here.
These images were found in an image storage archive here at the Moran Eye Center, and we do not have any information about their origin, or details of their capture. They are however, excellent images and worthy of sharing. My thanks to James Gilman for finding them.
Question: How small can the blood vessels in our retinas get?
Answer: Smaller than the diameter of a red blood cell (~6-8µm wide).
The red blood cells have to fold themselves to get through the tightest of spaces and line up, single file to get through the smallest retinal capillaries.
Image originally posted here.
Bruch’s membrane is a highly specialized and multi-laminar structure in our retinas that forms the basis for mediating interactions between the retinal pigment epithelium and blood flow from the choroid. I’ve not seen many good images online, so figured this image from mouse would be a good addition showing the relationship of the basal surface of the RPE with Bruch’s membrane.
Continue reading “Bruch’s Membrane”