Convex and Concave Lenses in the Ophthalmic Industry

With 75 percent of Americans using some type of corrective lens, the ophthalmic industry plays an important role in our world today. This percentage translates to roughly 225 million people with 64 percent of this group wearing glasses and 11 percent using contact lenses.

Historically, these glasses lenses were made using glass and grinding it into various shapes. Plastics became a more popular material for lenses in the 20th century. Instead of grinding the plastic, the material is molded to the desired shape. This method can be done in mass quantities and for much less money than its glass counterpart. Though plastic is much lighter to wear in a pair of glasses, it also scratches more easily. So, protective coatings have been introduced to reduce possible damage.

Regardless of if it is plastic or glass, the theory remains the same on how a lens helps improve a person’s vision. Refraction is what makes a lens work. As rays pass through the lens, the light rays bend and change direction. This gives the illusion that the rays come from a point closer or farther from actuality, and, therefore, making objects seen through the lens seem smaller or larger than they are in reality.

To achieve either of these results, there are two basic lens types—convex and concave. Convex lenses can also be referred to as positive lenses or converging. With a surface curving outward in the center, the lens bends parallel light rays to meet, or converge, at a point just past the lens, which is the focal point. Farsighted people use glasses with convex lenses, and you’ll also find this type in telescopes and binoculars.

Concave, or diverging, lenses have the exact opposite effect. The outer surface curves inward, making parallel light rays diverge. Nearsighted people wear glasses with concave lenses. TV projectors also spread light rays using this type of lens.

With medical and scientific advancements, it is also possible to have a combination of these two lenses in a pair of glasses. Named the compound lens, it offers a more complex design for multiple purposes. For example, some people require a lens to see small words in a book, as well as far away street signs, which means part of the lens is concave and part is convex.

More products use lens technology than the glasses we see used every day. Many medical fields require the use of microscopes for research and tools using lenses to check and correct a patient’s’ vision imperfections or eye disorders. United Lens Company has supported the ophthalmic industry for 100 years using a special molding process for a wide range of glasses types.

Our experience helps us easily work on custom projects and continue to innovate for only the best products. We know how important it can be to see properly, as it’s how most of us obtain and share information with one another. That’s why our standards are at their strictest in safety, quality and accuracy before products leave our facility. For more information on lenses or the ophthalmic industry, contact our team.