Certified Retinal Angiographer (CRA) Practice Exam

The sclera is the opaque, white outer coat that gives the eyeball its shape and protection. Its dense collagen fibers form a tough, protective shell around the globe and provide attachment points for the external eye muscles, helping to maintain structural integrity during movement. It is described as mostly avascular, meaning it has few blood vessels of its own; nutrition reaches deeper tissues by diffusion from surrounding vascular tissues and the underlying layers. The sclera is continuous with the cornea at the limbus, but unlike the cornea, which must stay transparent to allow light to enter, the sclera remains opaque so it can shield and structurally support the eye. The conjunctiva covers only the anterior surface, not the entire white coat, and the retina sits on the inner surface of the eye rather than on the outside.