Understanding Spectacle Specifications : Find the Right Fit

Choosing the correct lens for your eye can be tough. Frames, lenses and the appropriate look all combine to get you the spectacle you require.

Though you may feel confused with the specifications mentioned in your prescription and of course as a layman you wouldn’t even pay heed to the doctor language stating your eye issues. This buying guide will help you cut through the hype about different types of eyeglass lenses and help you choose lenses and coatings that offer the best features and value for your needs.

Choosing The Right Eyeglass Lenses

When buying eyeglasses, the frame you choose is important to both your appearance and your comfort when wearing glasses. But the eyeglass lenses you choose influence four factors: appearance, comfort, vision, and safety. The common mistake people generally incur is not sparing enough time to check out the detailed versions of their lenses, frames, coatings, and materials.

Following are the lenses used as per the disability :-

  • Single vision lenses for nearsightedness, farsightedness, and astigmatism.
  • Progressive lenses / bifocals / multifocal lenses for presbyopia.

Eye lenses in detail

Lenses can be categorized into two genres :-

  • Glass lenses – In early days of vision correction, all lenses were made up of glass. They offer exceptional optics but, they are too heavy, can break easily, potentially causing serious harm to the eyes.
  • Plastic lenses – Armorlite Lens Company in California introduced the first lightweight plastic eyewear. The lenses were made of a plastic named CR-39 (Columbia Resin 39). It is almost half of the weight of glass, low cost and excellent optical qualities.
  • Polycarbonate Lenses – Gentex Corporation in the 1970s introduced Polycarbonate Lenses for safety glasses. They are made up of CR-39 plastic, lightweight and preferred for children.
  • High index plastic lenses – In the past 20 years, in response to the demand for thinner, lighter eyeglasses, a number of lens manufacturers have introduced high-index plastic lenses. These lenses are thinner and lighter than CR-39 plastic lenses because they have a higher index of refraction.

Cylindrical and Spherical

A cylindrical lens focuses light into a line instead of a point. The curved faces of cylindrical lens are defined sections of a cylinder which focus on image passing through it into a line parallel to the intersection of the surface of the lens. While a “spherical lens” is a lens whose surface has the shape of (part of) the surface of a sphere.

Choose the correct lenses for your eyes and stay vision safe!

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