uveal

Uveal is an anatomical term relating to the uvea, the pigmented vascular middle layer of the eye. The uvea comprises three structures: the iris, the ciliary body, and the choroid. It lies between the sclera and retina and is characterized by a rich blood supply and high pigment content.

The anterior uvea includes the iris and the ciliary body, while the posterior uvea refers to the choroid. The iris regulates pupil size and light entry; the ciliary body produces aqueous humor and contains the ciliary muscle for accommodation; the choroid nourishes the outer retina and helps absorb stray light.

Because the uvea is highly vascular and immunologically active, disorders of the uvea are collectively referred to as uveitis when inflamed, and may involve pigmentation changes or tumor formation. Uveal melanoma arises from melanocytes in the uveal tract, most often in the choroid. Other conditions include inflammatory, infectious, and vascular diseases affecting any part of the uveal tract.

Clinical evaluation relies on slit-lamp examination and indirect ophthalmoscopy, with imaging such as ultrasound biomicroscopy, optical coherence tomography, and fluorescein angiography used to assess involvement. Embryology: the uveal tissues are derived largely from neural crest cells.