The dome-shaped central portion of the eye lying over the iris is called the
The correct answer and explanation is:
The dome-shaped central portion of the eye lying over the iris is called the cornea.
The cornea is the transparent, dome-shaped tissue that covers the front part of the eye, including the iris, pupil, and anterior chamber. It is crucial for vision because it plays a key role in focusing light entering the eye. It acts as the eye’s outermost lens and helps bend or refract light so that it can be properly focused onto the retina at the back of the eye.
The cornea is made up of five layers. The outermost layer, the epithelium, is a thin layer of cells that acts as a protective barrier against dust, debris, and microorganisms. Beneath this is the Bowman’s membrane, a tough layer that provides strength to the cornea. The stroma, which is the thickest layer, contains collagen fibers and is responsible for the cornea’s transparency. The Descemet’s membrane lies beneath the stroma and is responsible for maintaining corneal health by regulating fluid balance. The innermost layer is the endothelium, which helps pump excess fluid out of the cornea to maintain its clarity.
The cornea is avascular, meaning it does not contain blood vessels. Instead, it gets its nutrients from tears and the aqueous humor, the fluid located behind the cornea. This lack of blood vessels is one of the reasons why the cornea is transparent, as the absence of blood vessels reduces light scattering.
Damage or diseases that affect the cornea, such as infections, injuries, or conditions like keratoconus, can lead to vision impairment. In some cases, a corneal transplant may be required to restore vision. The cornea’s ability to heal itself is one of its remarkable characteristics, but its function is essential for clear vision and overall eye health.