Vision deficiencies caused by refractive errors, such as astigmatism, hyperopia, presbyopia, and myopia, can be dealt with by corrective lenses. Corrective lenses can be inserted in a frame and worn on the face as eye glasses, or worn on the surface of the eye, as in contact lenses. Surgically implanted intraocular lenses replace the natural lens and are used to remove cataracts, and more recently to correct refractive errors.
Corrective lenses work by changing the distance the light has to travel from the lens to the retina. A person with myopia, or short-sightedness, has an elongated eyeball and the image falls in front of the retina instead of on the retina. A concave lens increases the distance the light travels so that the image lands directly on the retina. Convex lenses work in the reverse for hyperopia, or far-sightedness. Presbyopia is a condition that myopic people develop as they age and is caused by a decrease in the elasticity of the lens. Presbyopia can be corrected by bi- or multi-focal eye glasses or contact lenses. Various types of astigmatism are caused by irregularities in the curvature of the cornea that results in the same image landing at different points. The corrective lens for astigmatism typically carries a different adjustment for each plane, though suppliers of all kinds of lenses are contactable using productpilot.com.
Refractive errors are “conditions” rather than diseases of the eye and are widespread in all populations. There are a several factors, including the changes in demographic, that will increase the amount of corrective lenses that the manufacturer and wholesale dealers will be obliged to supply. All-in-all, manufacturers and wholesaler dealers of optical lenses can anticipate a steady market and can benefit from networking services such as productpilot.com.
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