ME & M@.......FaShioN!!!

As eyeglasses are a must for lots of people I think the information about how to choose the lenses will be very useful. It is not a secret that buying eyeglass lenses requires making decisions about the design of the lenses, the material, and coatings you may want applied to your lenses.



Lens design
If you are careful about your eyes and all concerning that I am sure you have already consulted with your eye doctor about the type of lens design. There are two general options: single-vision lenses or multifocal lenses.

Single-vision lenses are intended for correcting a single vision problem. Such lenses function as all purpose glasses for persons who have normal accommodations.

They can also be worn by those who normally wear bifocals or trifocals for distance or near (reading) lenses.

Single vision lenses can also be used as occupational glasses for certain types of work.

Multifocal lenses work to correct more than one vision problem (for example, nearsightedness and presbyopia). There are different types of multifocal lenses:

• Bifocals: These lenses are divided into two sections. The top part is for distance vision and the bottom part is for close vision. The two segments on the glasses are seen clearly as there is a line dividing the area.
The segment for close-up vision commonly has one of the following shapes at the bottom of the lens:

o A half-moon, also named a flat-top, straight-top, or D segment. This is the most popular type of bifocal.
o A narrow rectangular area, also named a ribbon segment.
o A round segment.
o A full bottom half of a lens, named the Franklin, Executive, or E style.

• Trifocals as well as bifocals come in a variety of designs. Flat top trifocals are the most widely used form. Visible lines divide the lens into 3 sections: the top is for distance, the middle for intermediate vision, and the bottom for close-up vision.

The added segment provides clear vision at arm’s length distance, the area that is usually blurred for bifocal wearers. These can be useful for people who need to work or read at 2 distances.
• Progressive lenses: Progressive lenses have a smooth transition between the sections of the lens with no line dividing the sections. Both bifocals and trifocals can be progressive. However, there is a drawback here - some distortion on the outer edges of the lenses.

But many people prefer progressive lenses for the cosmetic advantage they have - they never reveal the user wears bifocals as there is no line of distinction between the sections of the lens.

Materials

Glass has been the only material possible for many centuries. It has plenty of positive sides but there are disadvantages either.
• Regular glass lenses are not as easy to scratch as plastic lenses. Besides, they are used for many types of prescriptions. But they are heavier than plastic lenses.
• High-index or aspheric glass lenses are made of material that is compressed; as a result less material is used than for regular glass lenses production. High-index lenses are much thinner than normal lenses and can be ideal for people with a strong correction who would ordinarily need very thick glasses.

The purpose of using high-index material and special design techniques is to make the lenses thinner and provide built-in protection against ultraviolet (UV) rays.
Plastic was invented not so long ago but it has become the primary material for many industries including eyeglass lenses production.

• Hard resin lenses are much lighter than glass lenses, almost half the weight. Hard resin lenses are more durable but more easily scratched than glass.

• High-index or aspheric plastic lenses have the same effect as high-index glass lenses. These lenses are manufactured from a compressed material to make lenses thinner and provide built-in protection against ultraviolet (UV) rays.



• Polycarbonate lenses are extremely impact-resistant that makes them popular with athletes, people who need safety glasses for work and kids. Polycarbonate lenses are light and comfortable, and have built-in UV protection.

Coatings

• UV coating provides protection for your eyes from the sun’s harmful ultraviolet rays. A UV coating can be found on both tinted and clear lenses.


If you choose polycarbonate and high-index lenses remember they already have UV protection.
• Scratch-resistant coating is particularly helpful for plastic lenses, because they are more easily scratched than glass.

• Antireflective coating : This coating is particularly effective for reducing eye fatigue for computer operators and anyone driving at night. Besides, antireflective lenses enhance appearance by removing all distracting reflections. However, be extra careful with such glasses as the coating can easily wear away.

• Mirror coating is popular with those who dislike anybody seeing their eyes. They can come in a variety of colors.


This coating protects the eyes of the wearer against glare from surfaces such as water or snow.

• Tinted lenses can be tinted in a range of colors. All lens materials except glass can be tinted in any color desired.

Shades of any color ranges from 1 to 4 with 3 being the most common sunglass shade ordered. Solid and gradient tints are available.

• Photochromatic lenses can be a good option for those who need to go in and out often as the lenses automatically darken when you go outdoors and return to normal when you go back indoors.



• Polarized lenses are perfect for outdoor wear. They tend to cut down on glare and give better clarity and depth perception.