Eye is a sensory organ. Sensory organ is an organ that contains sensory receptors and accessory structures, that contributes to the sensory function of the receptor, included in the sensory organ. In the case of eye, the sensory part is the retina which contains photoreceptors, bipolar, horizontal, amacrine, and ganglionic cells. The other structures of the eye contribute to the function of the eye (vision).
The physiology of the eye, it is an obligatory step to study its structure, because structure- function interrelationship is inseparable .Our approach in studying ocular physiology in this course will be by studying the function of each part of the eye and the function, fulfilled by that structure. The eye ball is composed of three layers (Sclera, cornea, choroid, uvula, and retina) and three transparent media (two chambers of aqueous humour, and vitreous humour). Externally, the eye is protected by eyelids, eye lashes, and eye brows .It is found in the orbit of the skull, and this is an additional protective factor as thus is surrounded by bones.