The primary aim of spectacles is to help enhance a person’s vision and aid the correction of visual impairments, if any, though the recent times have seen a swelling list of its functions. To this end, corrective lenses are used. These lenses come with different specifications corresponding to individuals requirements.

Lens is dubbed as the all inclusive medicine for optical sickness. It varies for different optical requirements. Lenses can be clear (in-door) or dark (out door) or photochromatic lenses that darken when exposed to sun. The lenses can be embodied in different materials like glasses, plastics and poly carbonate materials.

Lenses can be classified based on material used for making it, Shape of the lens or vision provided by the lens

Based on Materials

Glass Lens : Are known for their scratch resistance and hardness, but are easily breakable and guarantees very little protection from Ultra Violet rays. The glasses are also too heavy for comfort.

Poly Carbonate Lens : The Poly Carbonate, a synthetic plastic material, is known for its high impact resistance. The impact quality makes this lens highly preferred for sports wear and safety wear. Weighing only 35 percent of plastic lens, it is one of the lightest ophthalmic materials. The in built protection properties offer considerable ultra violet blocking.

Plastic Lens : The plastic lens, on the other hand, is lighter, shatter resistant and ensures greater protection from UV rays though at the cost of inherent softness and scratch proneness.

Based on shape of Lens

Spherical Lens : This is the old and conventional shape of lens. There are inherent disadvantages in this form of lens. These type of lens tend to bulge out of the frame and also magnify or reduce the appearance of the eyes depending on the correction.

Aspheric Lens : Aspheric lenses have arrived and they are here to stay. These models have emerged as a credible alternative to the traditional spherical lenses. With its advent, optical distortions are a thing of the past. Since aspheric lenses do not bulge out of the frame as much as regular lenses, they are much more appealing to eyes. The fact that they lessen the magnification or minification of eyes, a problem for patients requiring strong correction, draw customers to this variety. Most lens designs can now be ordered in aspheric form.

Based on Vision

Progressive Lenses : Progressive lenses offer greater visual correction than ordinary reading glasses and bifocals. These lenses have taken optical assistance closer to natural vision than ever before. They pull off an amazing feat by allowing good vision near, far without annoying or distracting lines. This is why they are sometimes called no-line bifocals. Progressives provide a smooth transition from distance through intermediate to near with all the in-between corrections included as well.

Single Vision : Lenses are intended to correct one of the two common types of refractive errors, nearsightedness (myopia) or farsightedness (hyperopia) and may also correct astigmatism. For example, patients with myopia have difficulty seeing objects in the distance, so the lens is made to improve distance vision.

Multi Focal : Lenses correct more than one refractive error. The most common multi focal lens is the BIFOCAL lens, where the upper portion of the lens is corrected for distance viewing and the lower portion of the lens is corrected for near viewing. TRIFOCALS add a third segment, typically just above the near segment, to allow for intermediate viewing. With traditional bifocals and trifocals, the near and intermediate segments are distinct, so they are often referred to as LINED BIFOCALS or LINED TRIFOCALS.

Lens Options

Once you select a lens material, you can also select whether to add the following options to your lenses.

Scratch-Resistant Coating can be applied to plastic lenses; they generally are a standard feature on progressive, high-index, photo chromatic and polycarbonate lenses. The coating provides a harder finish to the lens, making the lens more scratch resistant.

Anti-Reflective Coating is a multi-layered coating that helps reduce lens surface reflection and improves vision by allowing more light to pass through the lens. Without anti-reflective coating, glass lenses have a tendency to produce glare, reflections and halos around lights. Anti-reflective coating reduces these distortions and the lens reflections that other people see on your glasses when they look at you. Early versions of anti-reflective coating wore off easily, but current coatings such as Crizal and Zeiss Advantage eliminated these problems. A one-year no-cost warranty is also available for these premium anti-reflective coatings.

Tinted Lenses are an option for patients who are particularly sensitive to bright lights and sunlight. While tinting is an affordable option, it often reduces vision in dimly lit environments. Many patients now find more success with photochromatic lenses, prescription sunglasses or regular glasses fitted with a removable sunglass clip.