The 3 common defects are :- 
# ) Myopia
# ) Hypermetropia
# ) Presbyopia.

Corrections:-

#) Myopia- Concave Lens
#) Hypermetropia - Convex lens
#) Presbyopia - Bifocal lens of corrective focal length.

i hope it's helpful for us...

Common Refractive Defects of Vision:
1. Myopia (Nearsightedness):
Myopia is a common refractive error where distant objects appear blurry while close objects can be seen clearly. This occurs when the eyeball is too long or the cornea is too curved, causing light rays to focus in front of the retina instead of directly on it.
2. Hyperopia (Farsightedness):
Hyperopia is another common refractive error where close objects appear blurry while distant objects can be seen more clearly. This happens when the eyeball is too short or the cornea is too flat, causing light rays to focus behind the retina instead of directly on it.
3. Astigmatism:
Astigmatism is a refractive error caused by an irregularly shaped cornea or lens, resulting in blurred or distorted vision at all distances. It occurs when the cornea or lens is curved more steeply in one direction than the other, causing light rays to focus unevenly on the retina.

Correction Methods:
1. Prescription Eyeglasses:
Eyeglasses are a common and effective way to correct refractive errors. Lenses are prescribed based on the specific refractive error, whether it be myopia, hyperopia, or astigmatism. The lenses help to properly refract light onto the retina, allowing for clearer vision.
2. Contact Lenses:
Contact lenses are another option for correcting refractive errors. They sit directly on the eye and provide a more natural field of vision compared to glasses. Contact lenses are available for various types of refractive errors and can be a convenient alternative for those who prefer not to wear glasses.
3. Laser Eye Surgery:
Laser eye surgery, such as LASIK or PRK, is a surgical procedure that reshapes the cornea to correct refractive errors. It is a more permanent solution to vision problems and can eliminate the need for glasses or contact lenses. However, not everyone is a suitable candidate for laser eye surgery, so it is important to consult with an eye care professional to determine the best corrective option for your specific needs.