Question

list the structure and fluids that light passes through from the cornea to the retina?

Answer 1

Cornea covers the front portion of the eye or act as the eyes outermost lens..It is the transparent part of the eye.The cornea consists of thin surface epithelium overlying a layer of substantia propria a dense fibrous connective tissue.The cornea is composed of five layers,the epithelium,stroma,descemets membrane ,bowmans layer and the endothelium.It contain free nerve endings.The main function of the cornea is to refract the light that enters the eyes.Cornea does not contain any blood vessels.Because it may prevent it from refract the light properly.The cornea is composed of proteins and cells.The nutrients are supplied to the cornea is by tears and the watery fluid called acqeous humor .

The first layer epithelium is a layer of cells covering the cornea and it helps in the absoption of nutrients and oxygen from tears.The light enters through thye cornea .After entering in to the cornea light passes through the pupil.The iris inside the pupil conterol the quantity of light that enetrs the eyes.By enlarging or dialating the pupil the iris allows more light into the eye.The action of dialator muscle and the sphincter muscle control the size of the pupil.The lens is situated behind the iris.To focus on nearby objects the lens become thicker by the action of ciliary muscles and become thinner to focus on distant objects.Retina contains the cells that sense photoreceptors.Macula is the most sensitive part of teh retina and has millions of photoreceptors especially the cones.The detailed visual image is due to the presence of high density cones .The images are converted into electrical signals by the photoreceptors in the retina.There are two types of photoreceptors.Cones and rods.Cones are responsible for the central and color vision .Rods are responsible for the peripheral vision.It is seen mainly in the peripheral areas of the retina.

The front part of the eye is filled with a clear fluid called acqeous fluid.Acqueous fluid is made by the ciliary body.Theb fluid flows tthrough out the pupil and is then absorbed into the blood stream through drainage syatem in the eyes.Around the outer edge of the iris there is a mesh of drainage canals .This helps to keep the pressure of eye.This is a continous process helps to keep the eyes healthy.