The cornea is the transparent, dome-shaped outermost layer of the eye that covers the iris, pupil, and anterior chamber. It plays a crucial role in focusing light onto the retina at the back of the eye, helping to create clear vision. The cornea is made up of several layers of cells and proteins, and it is highly sensitive to touch and pain. It also acts as a barrier to protect the eye from dust, debris, and other foreign particles.
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Google Gemini AI
more than 4 weeks ago
Cornea
Definition: The cornea is the transparent, dome-shaped outer layer of the eye that covers the pupil, iris, and anterior chamber. It serves as a protective barrier and contributes to the eye's ability to focus light.
Structure: - Epithelium: The outermost layer, composed of non-keratinized stratified squamous epithelium. - Bowman's Layer: A thin, acellular layer that lies beneath the epithelium and provides structural support. - Stroma: The thickest layer, consisting of highly organized parallel layers of collagen fibers (keratocytes) and ground substance. - Descemet's Membrane: A thin, elastic layer that separates the stroma from the endothelial layer. - Endothelium: The innermost layer, composed of a single layer of hexagonal cells that actively pumps water out of the cornea, maintaining its transparency.
Functions:
- Protection: Shields the inner eye structures from injury and infection. - Refraction: The curved shape and refractive index of the cornea bend light and contribute to the eye's ability to focus an image on the retina. - Transparency: The lack of blood vessels and cellular debris allows light to pass through clearly. - Structural support: Provides a rigid framework for the eye.
Characteristics:
- Non-vascular: The cornea is normally devoid of blood vessels, which prevents inflammation and scarring and maintains its transparency. - Highly innervated: The corneal epithelium is densely innervated by sensory nerves, making it sensitive to touch and pain. - Epithelial regeneration: The corneal epithelium has a high regenerative capacity, enabling it to heal quickly from minor injuries. - Avascular-vascular interface: The junction between the cornea and the vascularized sclera (limbal region) is a critical zone for maintaining corneal health.
Clinical Significance:
- Corneal diseases: Conditions such as corneal ulcers, keratitis, and keratoconus (abnormal curvature) can affect the cornea's structure and function. - Corneal surgery: Procedures like corneal transplant and refractive surgery (e.g., LASIK) involve manipulating the cornea to restore or improve vision. - Contact lenses: Rest on the cornea to correct refractive errors or for therapeutic purposes.