Are you wondering why choosing the correct lenses for eyeglass is important here we will answer

When purchasing eyeglasses, the frame you choose is important for both your appearance and your comfort when wearing glasses, but the eyeglass lenses you choose has 4 factors:

Lens Coating

Lens Functions

Lens Index (refractive index)

Abbe Value

1.Lens Coating

there are various options available for Lens coating some of them you can combine also such as hard coating + Anti-reflection Coating below are the types of coatings:

Hardcoated lens

A hard coating layer is applied on both side of the lens to prevent scratches

Anti-reflection Coated Lens

A series of layers are applied over the hard coated lens to prevent glares from the front and back surface of the lens anti-reflection coating gives your eyeglasses an attractive look it eliminates all glares and your eyes are visible.

Anti-Blue light Coating

Similar to Antireflection coating a series of layers applied on hard-coated that reduces glare and prevent Blue light the is emitted from digital devices this lens is recommended for people using a digital device for more than 4 hours per day these glasses reduces eye strain and headaches that are caused by blue light from digital devices

2.Lens Functions

You can choose lens functions from below three types

Clear Lenses

These lenses always stay clear indoor and outdoor

Transitions / Photochromatic Lenses

These lenses will turn dark in sunlight due to the UV rays in sunlight  and will clears back indoors

Tinted lenses

Tinted lenses always stay dark and can be used in sunlight only to prevent eyes from UV exposures

3.Lens Index (refractive index)

The refractive index of eyeglass lens material is a value that is a relative measure of the extent of refraction of light, which is the ratio of the speed of light in a vacuum divided by the speed of light in the lens material.
For example, the refractive index of an ordinary plastic is 1.498, approximately 1.50, which means that light travels about 50% slower in plastic than it does through a vacuum.

The higher the refractive index of the material, the light moves slower through it, which results in a greater bending (refraction) of the light rays, so the higher the refractive index of the lens material, the less lens material required to refract the light at the same degree as a lens with a lower refractive index.
In other words, to obtain a certain power of view through the lens of the glasses, the lens made of a material with a high refractive index (compressed lens) will be thinner in thickness and weight than a lens made of a material with a lower refractive index.

The refractive index of current eyeglass lens materials ranges from 1.498 (1,50 plastic) to 1.74 (a specific group of high-refractive plastic). So for the same prescription and lens design, the 1.50 regular plastic lens will be the thickest available lens and the 1.74 high refractive plastic lenses will be the thinnest.

4. Abbe number

The Abbe value of the lens material is a measure of the extent to which different colors of light propagate as it passes through the lens, and is a useful measure of optical quality.

Abbe’s low-value lens materials have high dispersion, which may cause noticeable chromatic aberration – visual optical error such as colored halos around illuminating sources especially white lights.
Chromatic aberration is more pronounced when looking at the tips of the eyeglass lenses and less when looking directly through the lens’ central visual area.

Abbe values ​​for eyeglass lens materials range from height 59 (crown glass) to 30 (polycarbonate material). The lower the Abbe number, the more likely the lens material will cause chromatic aberration.

Eyeglass. pk

Eyeglass Pakistan provides their customer the best lenses available in the market according to customer prescription and requirements. All our eyeglasses are prepared with high-quality lenses. we provide the best quality glasses in Pakistan with fast delivery and the lowest prices.