Optical Lenses For Glasses

Optical lenses for glasses are manufactured in various shapes, color and materials for many frame types. Appearance is usually foremost to the purchaser . Little thought is given to the physics of the eyeglass lens required for vision improvements. After an optician, optometrist or an ophthalmologist determines your corrective prescription, the selected frame and prescription are sent to an optical laboratory to make corrective lenses specific to you.

Optical lenses in eyeglasses correct one of four common sight problems. The first two, myopia and hyperopia, are sometimes confusing due to their common titles. Myopia, called nearsightedness, is a reflective inability to see distant objects clearly. Eyeball shape change is the most common cause and is correctable with glasses, contacts or surgery.

Hyperopia, called farsightedness, is a vision defect caused by a shortened eyeball, which prevents bending light correctly. Distance vision is clear. The difficulty is seeing near objects. Extreme hyperopia obscures focusing at any distance. Objects moving toward the eye need increased focus power to the retina. Insufficient power of the cornea and lens in hyperopia blurs the image. Mild cases may not need corrected and this is when glasses or contacts are recommended. Severe hyperopia may need surgical lens replacement.

Astigmatism is a refractive issue de to an uneven curvature of the cornea and may be present at birth. Repetitive close work also precipitates astigmia. Presbyopia is the normal changes to eyesight with age. About mid-life the lens thickens and is less flexible. Bifocals for various levels of focus may be needed.

Lenses are made of three material types. Cr-39 is a plastic used for thin lenses. There’s also high index plastic for poor vision cases. As well, some people refer polycarbonate to be used for kids and safety glasses. Glass lenses are still available but not commonly used due to scratching and breakage.