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Hello house, this is my first time using this community and here is what I want us to talk about!! The eye defects.
Eye defects are mostly what deter/inhibit 70% of students in the world from studies or doing their basic duties. It is a defect that are common among us.
Let me begin by making some functions of the eye parts .
A. Eye lashes: They prevent dust and also insects from entering the eyes.
B. Eyelids : Prevent bright light from damaging the eyes. They moisten the conjunctiva.
C. Tear glands: This can also be called lacrimal glands. They produce tears that help to wash away dust and other particles. ( i.e prevent abrasion of the eye's surface). Tears are good because it contains an enzyme called lysozyme that helps to destroy bacteria.
D. Eyebrows: They also prevent bright light and sweat from dropping the eyes.
E. Fats : They are very important because they help to cushion the eyes from shock. In old age, fats are used up showing sunken appearance.
F. Sclerotic layer :The sclerotic layer bugles out in front to form the Cornea, ( cornea is transparent and convex tissue). Helps the lens to bend light rays to form an image on the retina.
G. Choroid layer : It is that small black pigments in the eyes. It is well vascularized (i.e supplies with blood vessels).
H. Iris : It covers the lens except the pupil thus restricting the amount of rays coming inside the eyes. It is also pigmented .
I . Ciliary muscles : They also help to focus light properly from near and far objects.
J. Retina : Last but not the least, is the sensory part of the eye. Where the images are formed. It has two parts ROD (visual purple = rhodopsin) and CONE ( iodopsin)
There are so many eye defects but three of the eye defects are mostly common to students namely ; Astigmatism, Myopia and Hypermetropia .
1.Astigmatism is when the cornea is not able to properly focus an image onto the retina. The result is a blurred image.
There are many astigmatisms like compound astigmatism, regular and irregular astigmatism , lenticular and corneal astigmatism etc.
The main symptom is blurring.
Correction is by wearing Cylindrical glasses or better use Toric contact lenses which are often the best choice for contact lens users with an astigmatism, because they’re specifically designed to address the defect The shape of a toric lens creates different refractive, or focusing, powers that can help correct either a corneal or a lenticular astigmatism etc.
This contact lens has a thicker zone that keeps them from rotating when they’re in your eyes.
- Hypermetropia : This is also called hyperopia or long-sightedness . It is the condition in which the eyeball is too short or the Cornea is not sufficiently curved. A person with this can't see near objects clearly .
It can be corrected by using convex lens eye-glasses
- Myopia : Also called Short-sightedness occurs when the eye ball is too long or the Cornea is too curved. They can't see far objects clearly.
It is corrected by wearing concave lens eye- glasses ( it diverge light rays from distant objects.
Important notes
Accommodation is simply the ability of the eye to focus far and near objects clearly by adjusting its focal length. This helps the light rays fall correctly on the retina enabling vision.
Cornea is the outermost part of the eye. It is a transparent layer that covers the colored part of the eye (iris), pupil, and lens.
It has a dome shape . So when the cornea is not probably shaped, it results in an incorrect focusing of the light that passes through that part of the cornea. There's a condition called Keratoconus which occurs when the cornea thins and becomes cone shaped. It usually occurs around puberty and mostly in women.5tj
In conclusion, I have observed that almost all the students in the world j HH I'm these eye defects . Eye defects are very dangerous defects in the body
Thank you very much for your understanding. Please if you have questions let me know for more clarification. One love ❤️.
References
IDODU UMEH COLLEGE BIOLOGY ISBN : 9768052207
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