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An ophthalmic lens is a lens for correcting vision in a person with visual impairments where the focal point of the eyes does not hit the retina. Lenses can also be used to address problems like astigmatism. They come in a variety of forms including plastic and glass lenses worn in glasses, contact lenses placed in direct contact with the eye, and lens implants surgically inserted into the eye to correct visual impairments. It is usually necessary to receive a prescription for a specific ophthalmic lens, although some people can correct their vision with over-the-counter lenses.
Basic ophthalmic lenses correct for near- or farsightedness, where the focus point lies in front of or behind the retina. They curve to adjust the focal point and let light hit the retina precisely, allowing people to focus. Other lenses can have additional features. The earliest ophthalmic lens designs were glass. Modern glasses, named for the preferred historic lens material, commonly use plastics for their impact absorption and light weight, although glass lenses are still available.
Contact lenses, including hard and soft designs, are worn on the surface of the eye. Their surfaces curve to bend light and make sure it hits the right point. One advantage of contact lenses is the wide visual range. People who wear glasses can encounter distortions near the edge of the lens, as well as being distracted by the frame of the glasses. It is important to fit glasses properly so they do not impede the patient's vision.
Lens implants are another option. This may be considered for patients with severe damage to their natural lenses. This type of ophthalmic lens is implanted in a sterile surgical procedure by a surgeon after determining the appropriate prescription. Depending on the situation, additional vision correction may be necessary to help the patient see clearly. Implants can be very costly, but have do not have the same maintenance and replacement requirements as glasses and contact lenses.
Specialists in ophthalmic lens design can work in lens manufacturing facilities, grinding lenses and handling complex custom orders. They can also work in lab environments, designing new generations of lenses and improving vision correction options for people with visual impairments. Many patients do not interact directly with the people who make their lenses. Instead, they receive an examination from an ophthalmologist or optometrist, who will determine the appropriate prescription and order necessary lenses from a manufacturer.