Human eye layer, known as the fibrous tunic, is composed of the cornea and sclera. The middle layer, known as the vascular tunic or uvea, consists of the choroid, ciliary body, pigmented epithelium and iris. The innermost is the retina, which gets its oxygenation from the blood vessels of the choroid (posteriorly) as well as the retinal vessels (anteriorly). The spaces of the eye are filled with the aqueous humour anteriorly, between the cornea and lens, and the vitreous body, a jelly-like substance, behind the lens, filling the entire posterior cavity. The aqueous humour is a clear watery fluid that is contained
Iris cyst a shadow with a tumor but almost never with a cyst. Ultrasound B-scan (USB) uses wavelengths of 10-20MHz to form an image of the eye. USB can be used to identify the extension of the iris cyst in either the anterior or posterior chamber. It can also be used to identify midzonal cysts behind the iris and to determine whether there is ciliary body involvement. The preferred method to determine ciliary body involvement however, is not USB but ultrasound biomicroscopy. Ultrasound biomicroscopy, (UBM) has a higher resolution than USB an di t also using soundwaves with a higher frequency from