What are the danger signals of eye disease? -Persistent redness of the eye. -Continuing pain and discomfort, especially after an injury. –Disturbance of vision–blurred, loss of side vision, double vision, floating spots.

There are three main types of hearing protection that people can wear to help reduce the impact of noisy environment and risk of developing noise-induced hearing loss. These include earplugs, earmuffs and semi-insert earplugs.

How can people protect themselves from hearing damage? By not putting cotton tipped applicators or other objects into the ear canal. -Wearing ear protectors when constantly exposed to loud noises at work, loud music or loud motors.

Presbyopia is the gradual loss of your eyes’ ability to focus on nearby objects. It’s a natural, often annoying part of aging. A basic eye exam can confirm presbyopia. You can correct the condition with eyeglasses or contact lenses.

Presbyopia is when your eyes gradually lose the ability to see things clearly up close. It is a normal part of aging. In fact, the term “presbyopia” comes from a Greek word which means “old eye.” You may start to notice presbyopia shortly after age 40.

bifocal lens

A person with presbyopia cannot read letters without spectacles. It may also happen that a person suffers from both myopia and hypermetropia. This type of defect can be corrected by using bi-focal lenses. A bifocal lens consists of both convex lens (to correct hypermetropia) and concave lens (to correct myopia).

The increase in near point of eye is called presbyopia. In this eye defect a person suffers from both Myopia and hypermetropia. It can be corrected by bifocal Lens. In which upper porting is concave lens to see the far objects and lower portion is convex lens which is used to see near objects.

Presbyopia and LASIK LASIK (laser-assisted in situ keratomileusis) is a popular eye surgery that can correct farsightedness, nearsightedness and astigmatism. However, the procedure doesn’t prevent presbyopia from occurring. There is a technique used to treat presbyopia using the LASIK procedure called monovision.

Presbyopia is a defect of vision in which image formed on retina is flicks or sway out. This defects occurs with ageing. If a person with ageing, generally the ciliary muscle be weaker which is unable to set sharp image on the retina. Correction: – It is corrected by using bifocal lens.

Presbyopia is that defect of vision due to which an old age person cannot see the nearby objects clearly due to loss of power of accommodation of the eye. In old age , the ciliary muscles becoming weak and the eye lens loses some of its elasticity and the eye loses its power of accommodation.

Presbyopia is an age-related condition that occurs when the lens inside the eye begins to harden and can no longer focus properly. Hyperopia, more commonly known as farsightedness, can be secondary to an abnormality of the lens or cornea.

This defect is usually corrected by using glasses with bifocal power of suitable focal lengths. The upper part of the lens is a concave lens corrects myopia to see the distant objects clearly while the lower part of the lens has a convex lens corrects the hypermetropia to see the nearby objects clearly.

A convex lens (plus lens) is like two prisms placed base to base. Light passing through a convex lens is converged. Convex lenses are used to treat presbyopia, hypermetropia and aphakia. If parallel light is brought to a focus at 1 metre the lens is said to have 1 dioptre of power.

The convex lens is a lens that converges rays of light that convey parallel to its principal axis (i.e. converges the incident rays towards the principal axis) which is relatively thick across the middle and thin at the lower and upper edges. The edges are curved outward rather than inward.

Concave Lenses Are for the Nearsighted, Convex for the Farsighted. Concave lenses are used in eyeglasses that correct nearsightedness. Because the distance between the eye’s lens and retina in nearsighted people is longer than it should be, such people are unable to make out distant objects clearly.

Correcting for long sight Rays from a nearby object need to be converged more, to form the image on the retina. Long sight is corrected using a converging lens which starts to converge light rays from a nearby object before they enter the eye. Converging (convex) lenses are used in reading glasses.

Physics > Short and Long Sight To see clear crisp images, the light from an object must be focussed sharply onto the retina at the back of the eye. Short sight can be corrected by wearing glasses with a suitable concave lens whereas long sight can be corrected by wearing a suitable convex lens.

Shortsightedness is corrected using a concave (curved inwards) lens which is placed in front of a myopic eye, moving the image back to the retina and making it clearer. Longsightedness is corrected using a convex (outward facing) lens.

What are the different types of eyeglass lenses?

• Concave lenses. These are thinnest in the center.
• Convex lenses. These lenses are thickest in the center, like a magnifying glass.
• Cylindrical lenses. These curve more in one direction than in the other.

Spectacles

Eyeglass lenses will almost always be convex on the outer surface, the one farthest from the eye, simply to fit it to the curvature of the face. If the inner surface is concave, and more sharply curved than the outer, then the lens is diverging.