More than 4.2 million Americans aged 40 years and older are either legally blind (having best-corrected visual acuity of 6/60 or worse (=20/200) in the better-seeing eye) or are with low vision (having best-corrected visual acuity less than 6/12 (<20/40) in the better-seeing eye, excluding those who were categorized as being blind).
The leading causes of blindness and low vision in the United States are primarily age-related eye diseases such as age-related macular degeneration, cataract, diabetic retinopathy, and glaucoma. Other common eye disorders include amblyopia and strabismus.
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Refractive Errors
Refractive Errors
Refractive errors are the most frequent eye problems in the United States. Refractive errors include myopia (near-sightedness), hyperopia (farsightedness), astigmatism (distorted vision at all distances), and presbyopia that occurs between age 40–50 years (loss of the ability to focus up close, inability to read letters of the phone book, need to hold newspaper farther away to see clearly) can be corrected by eyeglasses, contact lenses, or in some cases surgery. The National Eye Institute states that proper refractive correction could improve vision among 150 million Americans.
At individual level i believe the mechanism of bacteria survival is brought about by the ability of bacteria to survive in extreme conditions such as extreme heat, cold, dehydration, and large amounts of ultraviolet rays. At population level, bacteria can produce quickly and their population grows rapidly.
B. Natural Selection.
It isn’t A because a new species was not formed, the pre-existing species just varied less in color through the generations.
Answer:
False
Explanation:
These embryonic stem cells are pluripotent. This means that they can turn into more than one type of cell.