Estructura y Función de la Córnea

Study Notes

Structure of the Cornea

The cornea is the transparent, front part of the eye, which plays several essential roles in vision:

Sphere Shaping: The cornea's round shape helps focus light entering the eye onto the lens.
Refractive Power: It acts like a natural contact lens, refracting incoming rays of light towards the center by its curved surface.

Let's break down the cornea's structure into three main layers:

1) Epithelium Layer

This layer consists of five layers of cells covering nearly half the thickness of the entire cornea. These layers form a smooth, continuous surface over the corneal stroma.

2) Bowman’s Membrane

Beneath the epithelial layer sits Bowman’s membrane, which anchors the epithelial cells together with collagen fibers. This layer also provides structural support and protection against mechanical injury.

3) Stoma/Stromal Layer

Below Bowman's membrane lies the bulk of the cornea—the stroma. It makes up approximately 90% of the total corneal thickness. This layer is primarily composed of collagen fibers arranged in a lattice pattern and embedded within a matrix of proteoglycans called keratocytes. Intra-stromal fluid pressure keeps the stroma hydrated and plump. Additionally, nerves inside the stroma play a role in sensory perception.

Function of the Cornea

The primary role of the cornea is to focus incoming light accurately onto the crystalline lens, resulting in clear visual acuity. Its power comes from its steep, asymmetrical curve and uniform contour. Despite having fewer nerve endings compared to other parts of the eye, the cornea can still sense pain due to its large quantity of free nerve endings.

Interestingly, the transparency of the cornea is partly maintained through frequent shedding of old corneal epithelial cells and replacement by new ones. A healthy cornea has a balance between cell loss and production, ensuring it remains a highly effective optical component.

Description

Aprende sobre la estructura y función de la córnea, la parte transparente y frontal del ojo crucial para la visión. Descubre las capas que componen la córnea y su papel en enfocar la luz entrante sobre el cristalino para lograr una agudeza visual clara. También explora cómo se mantiene su transparencia y sensibilidad al dolor.