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The outermost layer, known as the fibrous tunic, is composed of the cornea and sclera, which provide shape to the eye and support the deeper structures. The middle layer, known as the vascular tunic or uvea, consists of the choroid, ciliary body, pigmented epithelium and iris.
The retina (from Latin rete 'net'; pl. retinae or retinas) is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs.The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then processes that image within the retina and sends nerve impulses along the optic nerve to the visual cortex to create visual perception.
Layers four and six of the LGN also connect to the opposite eye, but to the P cells (color and edges) of the optic nerve. By contrast, layers two, three and five of the LGN connect to the M cells and P (parvocellular) cells of the optic nerve for the same side of the brain as its respective LGN.
The body of Ophiocoma wendtii, a type of brittle star, is covered with ommatidia, turning its whole skin into a compound eye. The same is true of many chitons . The tube feet of sea urchins contain photoreceptor proteins, which together act as a compound eye; they lack screening pigments, but can detect the directionality of light by the shadow ...
In non-mammalian vertebrates, the homologous structure is known as the optic tectum or optic lobe. [1] [2] [3] The adjective form tectal is commonly used for both structures. In mammals, the superior colliculus forms a major component of the midbrain. It is a paired structure and together with the paired inferior colliculi forms the corpora ...
The vascular tunic, also known as the tunica vasculosa oculi or the "uvea", is the middle vascularized layer which includes the iris, ciliary body, and choroid. [ 4 ] [ 6 ] [ 7 ] The choroid contains blood vessels that supply the retinal cells with necessary oxygen and remove the waste products of respiration .
The macula (/ˈmakjʊlə/) [1] or macula lutea is an oval-shaped pigmented area in the center of the retina of the human eye and in other animals. The macula in humans has a diameter of around 5.5 mm (0.22 in) and is subdivided into the umbo, foveola, foveal avascular zone, fovea, parafovea, and perifovea areas.
Within layer 4 of V1, layer 4cβ receives parvocellular input, and layer 4cα receives magnocellular input. However, the koniocellular layers, intercalated between LGN layers 1–6 send their axons primarily to the cytochrome-oxidase rich blobs of layers 2 and 3 in V1. [14] Axons from layer 6 of visual cortex send information back to the LGN.