The defect shown in the figure is short sightedness or myopia.
Myopia: (nearsightedness) This is a defect of vision in which far objects appear blurred but near objects are seen clearly. ... Myopia can be corrected by wearing glasses/contacts with concave lenses these help to focus the image on the retina.Myopia or short-sightedness can be corrected by wearing spectacles containing a concave lens. This is because when a concave lens of suitable power is used for the myopic eye then the concave lens first diverges the parallel rays of light coming from a distant object.Vision problems such as myopia and hyperopia can be corrected with lenses that help focus light on the retina. Myopia is corrected with a concave lens, while hyperopia is corrected with a convex lens.
A concave lens is a lens that possesses at least one surface that curves inwards. ... It is a diverging lens, meaning that it spreads out light rays that have been refracted through it. A concave lens is thinner at its centre than at its edges, and is used to correct short-sightedness (myopia).Defects of vision is the loss of power of accommodation of the human eye. They are mainly of three types: Myopia/ near-sightedness: The person can see nearby objects clearly but is unable to see objects beyond some distance. For such a person, far point changes to infinity to some finite distance.
- Cataract. The problem: Light rays from objects in view must pass through your lens to reach your retina's light-sensing cells. ...
- Diabetic retinopathy. The problem: Your retina transforms light into signals your brain can process. ...
- Macular degeneration. ...
- Glaucoma. ...
- Refractive errors.