Published on Sep 12, 2023
Visual perception is the ability to interpret the surrounding environment by processing information that is contained in visible light. The resulting perception is also known as eyesight, sight, or vision. Eyes are the organs of vision. They detect light and convert it into electro-chemical impulses in neurons. Eyes can be prone to many diseases and disorders. This project is focused on eye disorders:how it is caused, why it is caused, how to prevent/treat it are inscribed here. In addition, a survey was taken among 50 students, each having an eye disorder. The data and other features areattached to the report as well.
The human eye is a spheroid structure that rests in a bony cavity (socket, or orbit) on the frontal surface of the skull.
The thick wall of the eyeball contains three covering layers: the sclera, the choroid, and the retina.
The sclera is the outermost layer of eye tissue; part of it is visible as the "white" of the eye. In the center of the visible sclera and projecting slightly, in the manner of a crystal raised above the surface of a watch, is the cornea, a transparent membrane that acts as the window of the eye.
A delicate membrane, the conjunctiva, covers the visible portion of the sclera.
Underneath the sclera is the second layer of tissue, the choroid, composed of a dense pigment and blood vessels that nourish the tissues.
Near the center of the visible portion of the eye, the choroid layer forms the ciliary body, which contains the muscles used to change the shape of the lens (that is, to focus).
The ciliary body in turn merges with the iris, a diaphragm that regulates the size of the pupil.
The iris is the area of the eye where the pigmentation of the choroid layer, usually brown or blue, is visible because it is not covered by the sclera.
The pupil is the round opening in the center of the iris; it is dilated and contracted by muscular action of the iris, thus regulating the amount of light that enters the eye.
Behind the iris is the lens, a transparent, elastic, but solid ellipsoid body that focuses the light on the retina, the third and innermost layer of tissue.
The retina is a network of nerve cells, notably the rods and cones, and nerve fibers that fan out over the choroid from the optic nerve as it enters the rear of the eyeball from the brain. Unlike the two outer layers of the eye, the retina does not extend to the front of the eyeball.
Between the cornea and iris and between the iris and lens are small spaces filled with aqueous humor, a thin, watery fluid.
The large spheroid space in back of the lens (the center of the eyeball) is filled with vitreous humor, a jellylike substance.
Nearsighted individuals typically have problems seeing well at a distance and are forced to wear glasses or contact lenses. The nearsighted eye is usually longer than a normal eye, and its cornea may also be steeper. Therefore, when light passes through the cornea and lens, it is focused in front of the retina. This will make distant images appear blurred.
Farsighted individuals typically develop problems reading up close. The farsighted eye is usually slightly shorter than a normal eye and may have a flatter cornea. Thus, the light of distant objects focuses behind the retina unless the natural lens can compensate fully. Near objects require even greater focusing power to be seen clearly and therefore, blur more easily.
Conjunctivitis is a condition in which the tissue that lines the eyelids and covers the cornea becomes inflamed. It is sometimes called "pink eye" or "red eye." It can cause redness, itching, burning, tearing, discharge, or a feeling of something in the eye. Conjunctivitis occurs in people of all ages and can be caused by infection, exposure to chemicals and irritants, or allergies.
Amblyopia is the medical term used when the vision of one eye is reduced because it fails to work properly with the brain. The eye itself looks normal, but for various reasons the brain favors the other eye. This condition is also sometimes called lazy eye. Amblyopia can occur when one eye is more nearsighted, more farsighted, or has more astigmatism
Asthenopiaor eye strainmanifests itself through nonspecific symptoms such as fatigue, pain in or around the eyes, blurred vision, headache and occasional double vision. Symptoms often occur after reading, computer work, or other close activities that involve tedious visual tasks.
Photokeretitis or ultraviolet keratitis is a painful eye condition caused by exposure of insufficiently protected eyes to the ultraviolet (UV) rays from either natural (e.g. intense sunlight at high altitudes) or artificial sources. Photokeratitis is akin to a sunburn of the cornea and conjunctiva, and is not usually noticed until several hours after exposure. Symptoms include increased tears and a feeling of pain, likened to having sand in the eyes.
The survey was taken on Feb, 2015 at Itanagar, Arunachal Pradesh particularly at VKV Itanagar, Chimpu.
Total students were 50 each having an eye disorder. The age range is 6 to 18.
Questions that were asked:
1) Name and age of the person
2) Information on their eye disorder
3) Age when the disorder was diagnosed
No specific tool was used. A friend to assist proved to be helpful.
The pie chart shows relative percentage of people having certain disorders.
• Myopia stands as the most common refractive disorder in children and teens with a big 70%.
• 7 out of 10 people having a disorder are diagnosed with Myopia
• 1 out of 10 people have Hypermetropia.
• 1 out of 10 people have Amblyopia
• 1 out of 25 people have Asthenopia.
• 1 out of 25 people have the problem of eye pain.
If a person is nearsighted, the first number ("sphere") on the eyeglasses prescription or contact lens prescription will be preceded by a minus sign (–). The higher the number, the more nearsighted one is.
Nearsightedness can be corrected with glasses, contact lenses or refractive surgery.
Refractive surgery can reduce or even eliminate the need for glasses or contacts. The most common procedures are performed with an excimerlaser.
1. In PRK the laser removes a layer of corneal tissue, which flattens the cornea and allows light rays to focus more accurately on the retina.
2. In LASIK — the most common refractive procedure — a thin flap is created on the surface of the cornea, a laser removes some corneal tissue, and then the flap is returned to its original position.
If a glasses or contact lens prescription begins with plus numbers, like +2.50, then the person is farsighted.
Farsightedness can be corrected with glasses or contact lenses to change the way light rays bend into the eyes.
Refractive surgery, such as LASIK or CK, is another option for correcting hyperopia. Surgery may reduce or eliminate your need to wear glasses or contact lenses.
The most common treatment for amblyopia is to force the brain to start using the "bad" eye. This is done by putting a patch over the "good" eye. It can take weeks or months for an eye patch to improve vision.
In cases of mild amblyopia, the doctor might recommend using an eye drop called atropine in the "good" eye instead of a patch. Atropine dilates the pupil and blurs the vision in the "good” eye, forcing the "bad" eye to do most of the work.
Most children with amblyopia will also need glasses to help focus.
Amblyopia becomes much more difficult to treat after about 7-9 years of age
Preventative measures, such as taking breaks from activities that cause eye strain are suggested.
The most effective way to ease the pain or discomfort that the affliction causes is to remove all light sources from a room, and allow the eyes to relax in darkness.
Cool compresses also help to some degree, though care should be taken to not use anything cool enough (such as ice) to damage the eyes themselves.
Photokeratitis can be prevented by using sunglasses or eye protection that transmits 5–10% of visible light and absorbs almost all UV rays.
1. Bacterial Conjunctivitis
Antibiotic eyedrop
2. Viral Conjunctivitis
There is no treatment for most cases of viral conjunctivitis. Instead, thevirus needs time to run its course — up to two or three weeks.
3. Allergic Conjunctivitis
different types of eyedrops for different allergies
7 out of 10 people were diagnosed with myopia according to the survey taken.Although Myopia is not a very harmful disorder for the eye and can be treated easily but the numbers are alerting andwe should take preventive measures to avoid it. A complete eye checkup once every one to three years is very beneficial. Many sight-threatening diseases, if detected early, can be cured or treated to prevent, or slow, the progression of any vision loss. Eating green veggies, carrots, fish, etc. are essential for our eyes for functioning well.
Puzari, Prasanta. Biology teacher, VKV ITA
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