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❤️ Myopia
❤️Hypermetropia
❤️ Presbyopia ​

Answer 1

$\huge\underline\mathfrak\red{Myopia-}$

It is also called near sightedness. In this defect, the person can see nearby objects clearly but can't see distant objects distinctly.In this defect, the far point of a person becomes nearer than infinity.In this defect, the image of object is formed in front of the retina, and not on the retinal yellow spot itself.

Reasons : This defect may arise due to following reasons:

★ Excessive curvature of eye lens.

★ Eye ball elongates.

★ Focal length of eye lens decreases.

Correctness : This defect is corrected by using a concave lens of suitable power. This concave lens brings the image back on the retina and thus defect is corrected.

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$\huge\underline\mathfrak\red{Hypermetropia-}$

It is also called far sightedness.In this defect, a person can see the distant objects clearly but can't see the nearby objects distinctly.In this defect, the image of object is formed away from the retina, hence known the far sightedness.The near point of the eye, recedes away from the normal near point (25cm).

Reasons : This defect may arise due to following reasons:

★ Eye ball becomes too small, in other sense. diameter of eye ball decreases.

★ Curvature of eye lens decreases.

★ Focus length of eye lens increases.

Correctness : This defect can be corrected by using a convex lens of suitable power. This lens provides additional convergence of light rays of objects and bring the image back on the retina.

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$\huge\underline\mathfrak\red{Presbyopia-}$ This defect arises in the old age. The power of accomodation of eye lens decreases.This is due to the loss of flexibility of ciliary muscles.These muscles get relaxed and curvature bof eye lens decreases.So, the focal length increases and person can see only far placed objects.Also the near point of eye recedes away.

Correctness : This defect is corrected by the convex lens of suitable power. Sometimes, a person may suffer from both myopia and hypermetropia. Such people require bi-focal lenses. A common bi-focal lens consists of both concave and convex lenses. Upper portion consists of concave lens of suitable power to see far objects. Lower portion consists of convex lens of suitable power to see nearby points.

Answer 2

$\huge\underline\purple{\sf Myopia :-}$

★Myopia is a condition in which close objects appear but far one object don't★

★Cause★ →Myopia occurs when the eyeball is too long, relative to the focusing power of the cornea and lens of the eye. This causes light rays to focus at a point in front of the retina, rather than directly on its surface.

★Very Common★→In India there are 10 million cases of this per year ←

★Symptons★ → People suffering from this may experience

• Visual : blurred vision or distorted vision
• Eyes: squinting or eye strain

★Chronic★ →It can lasts for years or lifelong

★Treatment★ →Treatment options include glasses, contact lenses and surgery such as LASIK.

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$\huge\underline\purple{\sf HyperMetopia :-}$

★A vision condition in which nearby objects are blurry★

★Cause★ →The main cause for this defect is the insufficiente eye length

★Very Common★ →In India there are more than 10 million cases per year←

★Symptoms★ →People suffering from this may experience

• Visual: blurred vision, vision disorder, or distorted vision
• Eyes: Eye strain or squinting

★Chronic★→ It can lasts for years or lifelong

★Treatment★ →Treatment options include glasses, contact lenses and surgery such as LASIK.

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$\huge\underline\purple{\sf Presbyopia :-}$

★Presbyopia is the gradual loss of your eyes' ability to focus on nearby objects★

★Cause★ → Age-related changes occur within the proteins in the lens, making the lens harder and less elastic over time.With less elasticity, it gets difficult for the eyes to focus on close objects.

★Very Common★ → Worldwide, an estimated 1.3 billion people had presbyopia in 2011 ←

★Symptons★ → Presbyopia can cause headaches, eye strain and visual fatigue that makes reading and other near vision tasks less comfortable and more tiring.

★Chronic★→It can lasts for years or lifelong

★Treatment★ → There are many ways to correct presbyopia with eyeglasses, contact lenses and surgery.

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