Rimless and semi-rimless glasses are common variations that differ from regular glasses in that their frames do not completely encircle the lenses. Three-piece rimless glasses have no frame around the lenses, and the bridge and temples are mounted directly onto the lenses. Semi-rimless (half-rimless) glasses have a frame that only partially encircles the lenses. Most rimless glasses feature the lenses held inside of the frame by high strength nylon wire. However, a rare variation is rimless and frameless glasses attached to a piercing at the bridge called a pince-nez.
Prescription Glasses:
Magnifying lenses or generic spectacles that are used to treat mild presbyopia and hyperopia can be purchased from our site. Although such glasses are generally considered safe, an individual prescription, as determined by an ophthalmologist or optometrist and made by a qualified optician, usually results in better visual correction. Moreover, visiting an ophthalmologist or optometrist can provide the opportunity to be screened for asymptomatic eye diseases such as glaucoma.
Corrective lenses are used to correct refractive errors of the eye by modifying the effective focal length of the lens in order to alleviate the effects of conditions such as; nearsightedness (myopia), farsightedness (hyperopia) or astigmatism. Another common condition in older eye patients is called presbyopia which is a result of the eye’s crystalline lens losing elasticity, progressively reducing the ability of the lens to accommodate (to focus on objects close to the eye).
The power of a lens is generally measured in diopters. Over-the-counter reading glasses are typically rated at +1.00 to +3.25 diopters. Glasses correcting for myopia will have negative diopter strengths. Prescription lenses, made to conform to the prescription of an ophthalmologist or optometrist, are used to make prescription glasses, which are then verified correct using a professional lensmeter.
Prescription Sunglasses:
Prescription Sunglasses may be made with either prescription or non-prescription lenses that are darkened to provide protection against bright visible light and, possibly, ultraviolet (UV) light. Photosensitive lenses called photochromic lenses darken when struck by UV light.
Light polarization is an additional advantage which can be applied to sunglass lenses. Polarization filters can remove horizontally arranged polarized rays of light, which can cause glare. Wearers of Polarized sunglasses are able to see into water when normally glare or reflected light would be seen.
Colored Lenses:
Yellow lenses increase color contrast and improve depth perception. Brown lenses are common among golfers, but cause color distortion. Blue, purple, and green lenses offer no real benefits to vision enhancement, and are mainly cosmetic. Some sunglasses with interchangeable lenses have optional clear lenses to protect the eyes during low light or night time activities and a colored lens with UV protection for times where sun protection is needed.
Our Glasses:
Many of our eyeglass lenses are made from plastic called CR-39 and polycarbonate. These materials reduce the danger of breakage and weigh less than glass lenses. Some of our plastics also have more advantageous optical properties than glass, such as greater transmission of visible light as well as greater absorption of ultraviolet light. 39 plastic lenses have a greater index of refraction than most types of glass; this is useful in the making of corrective lenses shaped to correct various vision abnormalities like myopia thereby allowing thinner lenses for a given prescription. Newer plastic lenses, called izon, can also correct for the higher order aberrations that naturally occur in the surface of our eye. These lenses create sharper vision for the people who have problems with sight and help with the halos, starbursts, and comet-tails often associated with night time driving glare.
Scratch-resistant coatings can be applied to most plastic lenses giving them similar scratch resistance to glass. Hydrophobic coatings designed to ease cleaning are also available, as are anti-reflective coatings intended to reduce glare, improve night vision and make the wearer’s eyes more visible.
CR-39 lenses are the most common plastic lenses due to their low weight, high scratch resistance, and low transparency for ultra violet and infrared radiation. Polycarbonate and Trivex lenses are the lightest and most shatter-resistant, making them the best for impact protection.
