Human Eyeball Structure in 15 min.
Watch our Free video on brief structure of Human Eyeball
Layers of Human Eyeball:
Eye ball has three basic layers:
1. Outermost layer.
2. Middle layer.
3. Innermost layer.
Outermost Layer (Protective layer):
This layer has two parts:
1. Cornea: Anterior 1/6 area of the outermost layer is transparent called Cornea.
2. Sclera: Remaining posterior 5/6 of the outermost layer is made of white collagens called Sclera.
Middle Layer (Vascular layer, Uveal Tract):
-Inner to the sclera, there is a main vascular layer. It extends from posterior surface, i.e. posterior area of eye ball to the anterior surface of the eye ball. It becomes thick as it approaches anteriorly, this thickened part is called Ciliary Body and the remaining vascular layer behind this thickened part is called Choroid. -Anterior most part of this layer is like diaphragm structure with central aperture, i.e. Pupil and this diaphragm like structure is called Iris. – Uveal Tract: This whole vascular layer having Choroid, Ciliary Body and iris is actually called Uveal Tract which is vascular pigmented middle layer of the eyeball.
Innermost Layer (Retina):
Inner most layer is called Retina, it has a lot of rods and cones. It terminates at Ora serrata.
Behind pupil there is a lens. Lens is attached by ligaments to ciliary body and these ligaments are called Zonules or Suspensory ligaments.
Behind the lens, there is vitreous body containing vitreous humor.
Blood Supply to Eyeball:
Blood is mainly supplied to eye ball by ophthalmic artery. This artery has following branches:
1. Central retinal artery: This artery enters through optic nerve and supplies retina.
2. Short posterior ciliary artery: This artery enters into eye ball outside the optic nerve and supplies choroid, as it does not reach upto the anterior part and does not supply blood to ciliary body and iris so it is called Short posterior ciliary artery.
3. Long posterior ciliary artery: This artery supplies blood to ciliary body and iris. The length of this artery is more than that of short posterior ciliary artery.
4. Anterior ciliary artery: This is the muscular branch of opthalamic artery and it enters into the eye ball from anterior part, making anastomosis with long posterior ciliary artery. It supplies blood to ciliary body and iris.
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