`Types and Side Effects of `EYE` :
1) `Myopia` (Nearsightedness) : if you are myopic, light rays come to a focus before they strike your retina. You are able to see close objects clearly but everything in the distance becomes `blurred`.
2) `Hyperopia` (Farsightedness) : hyperopic people can see distant objects clearly but have difficulty focusing on closer ones, as the rays come to a focus behind the retina.
3) `Astigmatism` : Astigmatism is that condition wherein the refraction varies in different meridians of the eye. It occurs when light entering the eye is "split" into two separate parts instead of focusing on one precise point on the retina. Astigmatism is commonly caused by abnormalities in the curvature of the cornea. If you are astigmatic, you will experience a distortion or blurring of images at all distances, nearby as well as distant.
`Anatomy of an Eye` :
• `Cornea` : The cornea is a curved transparent front surface of the `eye`. Its tough five-layered membrane tat focuses light. It bends light towards the retina to form a visual image helping the eye to see. The cornea’s clear because it has no blood vessels in it. It gets its oxygen supply from air and the aqueous.
• `Aqueous Humor` : It’s a clear watery fluid that bathes the inside of the eye, providing nutrition to the cornea and lens. The aqueous contains glucose, urea, proteins, inorganic salts, ascorbic acid, lactic acid and some dissolved oxygen. The circulation of `Aqueous` humor’s essential for the regulation of intraocular pressure as well as for metabolic activity of intraocular structures.
• `Sclera` : The `Sclera’s` the white of the eye that surrounds the cornea. It’s thick and opaque and is covered by two thin tissues – The Conjunctiva and Episclera which contain tiny blood vessels. The thickness of the sclera varies from place to place and it’s thickest at the posterior pole.
• `Pupil` : The pupil’s an aperture in the middle of the iris that determines amount of light entering an eye. The tiny muscles of the iris control the size of the pupil. Contraction of one muscle in the iris makes the Pupil larger allowing more light into an eye. A separate muscle contracts the actively close down pupil to a smaller opening. It changes according to the lighting conditions to accommodate for the amount of light i.e. available. In dark conditions the pupil dilates (get larger) to allow more light. In bright sunlight constricts (Get smaller) so the retina’s not overexposed to light.
• `Iris` : This Iris’s the pigmented structure that gives our `Eyes` their color. It’s composed of tiny connective tissues. The color of our eyes depends on the amount of pigment in `Iris`!
• `Retina` : The innermost layer of an eyeball is called as Retina. It’s the tissue that transforms light into electrical impulses that are transmitted to the brain to create our sense of vision. This conversion is formed by special light sensitive cells called `Photoreceptor cells`. These are of two types: “Cones and Rods”! The cones are individually connected to nerve fibers and are responsible for the sharpness of our vision and color perception. The rods are primarily responsible for our peripheral vision.
• `Lens` : The lens of the eye’s a transparent, biconvex, a vascular structure. It’s located directly behind the iris and pupil. It’s surrounded by an elastic capsule, which is a semi permeable membrane. The posterior surface of the lens’s more curved than the anterior. The lens consists of about 65% water and 35% proteins, both of which are synthesized by the lens itself. In young people the natural lens can dynamically change it’s shape to allow the eye to focus on objects at all distances. As we grow older this ability of the eye gradually decreases.
• `Macula` : It’s a small area in the centre of retina that has the highest concentration of cones. Thus, it’s the most sensitive part of the retina and has maximal sharpness of vision.
• `Vitreous humour` : Its clear jelly-like fluid that fills the middle of the eye. The Pressure of the vitreous keeps the eyeball round. The structural framework within the vitreous provides it considerable tensile strength and elasticity for maintaining its form. Vitreous degeneration, liquefactions, vitreous detachment and shrinkage may occur with advancement of age.
• `Optic Nerve` : It’s a bundle of nerve fibres that connects the eye to the brain. It’s a part of the visual pathway. The optic nerve carries the impulses formed by the retina to the brain, which interprets them as images.
The various disorders of an `Eye` is measured in `Dioptres`. `Dioptres` represent the amount of correction you need to normalize your vision. The more nearsighted, farsighted, or astigmatic you are, the higher your prescription in dioptres.
1) `Myopia` (Nearsightedness) : if you are myopic, light rays come to a focus before they strike your retina. You are able to see close objects clearly but everything in the distance becomes `blurred`.
2) `Hyperopia` (Farsightedness) : hyperopic people can see distant objects clearly but have difficulty focusing on closer ones, as the rays come to a focus behind the retina.
3) `Astigmatism` : Astigmatism is that condition wherein the refraction varies in different meridians of the eye. It occurs when light entering the eye is "split" into two separate parts instead of focusing on one precise point on the retina. Astigmatism is commonly caused by abnormalities in the curvature of the cornea. If you are astigmatic, you will experience a distortion or blurring of images at all distances, nearby as well as distant.
`Anatomy of an Eye` :
• `Cornea` : The cornea is a curved transparent front surface of the `eye`. Its tough five-layered membrane tat focuses light. It bends light towards the retina to form a visual image helping the eye to see. The cornea’s clear because it has no blood vessels in it. It gets its oxygen supply from air and the aqueous.
• `Aqueous Humor` : It’s a clear watery fluid that bathes the inside of the eye, providing nutrition to the cornea and lens. The aqueous contains glucose, urea, proteins, inorganic salts, ascorbic acid, lactic acid and some dissolved oxygen. The circulation of `Aqueous` humor’s essential for the regulation of intraocular pressure as well as for metabolic activity of intraocular structures.
• `Sclera` : The `Sclera’s` the white of the eye that surrounds the cornea. It’s thick and opaque and is covered by two thin tissues – The Conjunctiva and Episclera which contain tiny blood vessels. The thickness of the sclera varies from place to place and it’s thickest at the posterior pole.
• `Pupil` : The pupil’s an aperture in the middle of the iris that determines amount of light entering an eye. The tiny muscles of the iris control the size of the pupil. Contraction of one muscle in the iris makes the Pupil larger allowing more light into an eye. A separate muscle contracts the actively close down pupil to a smaller opening. It changes according to the lighting conditions to accommodate for the amount of light i.e. available. In dark conditions the pupil dilates (get larger) to allow more light. In bright sunlight constricts (Get smaller) so the retina’s not overexposed to light.
• `Iris` : This Iris’s the pigmented structure that gives our `Eyes` their color. It’s composed of tiny connective tissues. The color of our eyes depends on the amount of pigment in `Iris`!
• `Retina` : The innermost layer of an eyeball is called as Retina. It’s the tissue that transforms light into electrical impulses that are transmitted to the brain to create our sense of vision. This conversion is formed by special light sensitive cells called `Photoreceptor cells`. These are of two types: “Cones and Rods”! The cones are individually connected to nerve fibers and are responsible for the sharpness of our vision and color perception. The rods are primarily responsible for our peripheral vision.
• `Lens` : The lens of the eye’s a transparent, biconvex, a vascular structure. It’s located directly behind the iris and pupil. It’s surrounded by an elastic capsule, which is a semi permeable membrane. The posterior surface of the lens’s more curved than the anterior. The lens consists of about 65% water and 35% proteins, both of which are synthesized by the lens itself. In young people the natural lens can dynamically change it’s shape to allow the eye to focus on objects at all distances. As we grow older this ability of the eye gradually decreases.
• `Macula` : It’s a small area in the centre of retina that has the highest concentration of cones. Thus, it’s the most sensitive part of the retina and has maximal sharpness of vision.
• `Vitreous humour` : Its clear jelly-like fluid that fills the middle of the eye. The Pressure of the vitreous keeps the eyeball round. The structural framework within the vitreous provides it considerable tensile strength and elasticity for maintaining its form. Vitreous degeneration, liquefactions, vitreous detachment and shrinkage may occur with advancement of age.
• `Optic Nerve` : It’s a bundle of nerve fibres that connects the eye to the brain. It’s a part of the visual pathway. The optic nerve carries the impulses formed by the retina to the brain, which interprets them as images.
The various disorders of an `Eye` is measured in `Dioptres`. `Dioptres` represent the amount of correction you need to normalize your vision. The more nearsighted, farsighted, or astigmatic you are, the higher your prescription in dioptres.
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