Refractive Defects of Vision and their Correction

Vision Defects

• Another name for myopia is nearsightedness.
• In hypermetropia, the vision is affected as the light rays from a closeby object are focused at a point behind the retina.
• Myopia is corrected using a concave lens.
• The exact cause of myopia is not known, but it is thought to be related to a combination of genetic and environmental factors.
• Myopia, or nearsightedness, is a defect that can be corrected by using a concave lens.
• In myopia, the far point is closer than normal.
• Hypermetropia arises when the light rays from a closeby object are focused at a point behind the retina.
• Presbyopia arises due to the gradual weakening of the ciliary muscles and diminishing flexibility of the eye lens.
• In some individuals, bifocal lenses are required for correcting both myopia and hypermetropia.
• Hypermetropia is a defect that arises when the focal length of the eye lens is too long or the eyeball has become too small.
• In hypermetropia, the focal length of the eye lens is too long or the eyeball has become too small.
• A convex lens is used to provide additional focusing power required for forming the image on the retina in individuals with hypermetropia.
• Hypermetropia can be corrected by using a convex lens of appropriate power.
• In individuals requiring correction for both myopia and hypermetropia, bifocal lenses facilitate distant vision.
• Presbyopia arises when the near point of a person gradually recedes away due to the weakening of the power of accommodation with ageing.
• Hypermetropia arises because the eyeball has become too small or the focal length of the eye lens is too long.
• Bifocal lenses can be used to correct both myopia and hypermetropia in some individuals.

Photosynthesis

• Autotrophs fulfill their carbon and energy requirements through the process of photosynthesis.
• Heterotrophs directly or indirectly depend on autotrophs for their survival.
• Autotrophs are organisms that use simple food material obtained from inorganic sources like carbon dioxide and water.
• Enzymes are the bio-catalysts used by organisms to break down complex substances into simpler ones for energy and growth.
• Photosynthesis involves the conversion of substances from the outside into stored forms of energy in autotrophs.
• The primary purpose of storing carbohydrates in the form of starch in plants is to provide energy for growth and development.
• The initial step of photosynthesis involves the absorption of light energy by pigments such as chlorophyll.
• Chlorophyll, essential for photosynthesis, resides in chloroplasts in plant cells.
• Chlorophyll plays a crucial role in the process of photosynthesis by absorbing light energy.
• In C4 plants, the steps of photosynthesis do not occur immediately after each other.