Cornea in human eye

The cornea is the transparent, dome-shaped outer layer at the front of the eye [1]. It is a complex tissue composed of five distinct layers, including the epithelium, stroma, and endothelium [3]. Structurally, it is primarily composed of proteins and cells; for instance, the stroma consists of highly oriented collagen fibers (proteins) and keratocytes (cells) [3]. Unlike most tissues, the cornea is avascular, meaning it contains no blood vessels to maintain its transparency for light refraction [1]. It is not a light-sensitive screen; that role belongs to the retina, which contains light-sensitive cells [2]. Furthermore, the iris, not the cornea, is the muscular diaphragm that controls the pupil's size [1]. Therefore, the cornea is best described as being composed of proteins and cells [3].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 10: The Human Eye and the Colourful World > 10.1 THE HUMAN EYE > p. 161
2. [3] https://www.ncbi.nlm.nih.gov/books/NBK470340/
3. [2] Science , class X (NCERT 2025 ed.) > Chapter 10: The Human Eye and the Colourful World > 10.1 THE HUMAN EYE > p. 162