This graduation paper presents the histology of the eyes many segments, which include: conjunctiva, eyelids, lacrimal glands, scelra, cornea, limbus, choroid, ciliary body, iris, lens, vitreous body and the retina. With outlined medical or surgical correlations where appropriate. Featuring a greater emphasis on a particular type of retinal ganglion cell, known as the intrinsically photosensitive retinal ganglion cell. Intrinsically photosensitive retinal ganglion cells are a type of ganglion cell within the mammalian retina which act as a standalone photoreceptor. They are unique in regards to the current dogma of the classical rod and cone photoreceptors. They communicate directly to the brain, their function is not oriented to visual perception, but to physiological responses like the pupillary light response and circadian rhythm synchronization in response to the intensity of environmental illumination. They also seem to have a unique photopigment, the most likely candidate is melanopsin. Five different subtypes of intrinsically photosensitive retinal ganglion cell have been identified and their impact on health and interaction with certain pathological mechanism is under study. The intrinsically photosensitive retinal ganglion cells show great potential for future diagnostic and possible therapeutic options in medicine and may have a greater impact on the overall human environment in regards to environmental illumination.