JCAT Independent Practice Exam 2026 - Free JCAT Practice Questions and Study Guide

The thickest layer of the cornea is the stroma. This layer constitutes about 90% of the cornea's total thickness and is composed of a network of collagen fibers and other proteins that provide structural support and transparency to the cornea. The stroma's organization is crucial for the cornea's function, as its arrangement of collagen fibers allows light to pass through while maintaining clarity.

In contrast, the epithelium, which is the outermost layer, is thinner and serves mainly as a protective barrier. The endothelium is the innermost layer of the cornea, responsible for maintaining corneal hydration levels and preventing excessive fluid accumulation. The limbus is the border area between the cornea and the sclera, playing a role in the nourishment of the cornea but is not a layer of the cornea itself. Understanding the structure and function of these layers is essential for grasping how the cornea maintains its clarity and overall integrity.