The eye consists of three primary layers, each with distinct histological characteristics:
1. Fibrous Tunic: This outer layer includes the cornea and sclera. The cornea is transparent and avascular, composed of five layers: the epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium. The sclera is dense connective tissue providing structural support.
2. Vascular Tunic (Uvea): This middle layer comprises the choroid, ciliary body, and iris. The choroid is rich in blood vessels and melanocytes, helping to nourish the retina and absorb scattered light. The ciliary body contains the ciliary muscle and processes, crucial for lens accommodation and aqueous humor production. The iris, with its pigment cells, regulates pupil size and light entry.
3. Retina: The innermost layer, sensitive to light, contains photoreceptors (rods and cones), bipolar cells, and ganglion cells. These cells convert light into neural signals, which are transmitted via the optic nerve to the brain.
