Eye Glasses!

POWER OF GLASSES: DIOPTERS

The number that appears on an eyeglass prescription are written in the form of diopters. A diopter is a unit of measurement based on how much light rays will bend as they pass through the lens. The goal is to create the right amount of bending of the light rays in order for the image to meet on the retina of the eye.

SPHERE OR SPHERICAL NUMBER:
Refers to how near or far sighted you are. A minus(-) in front of the number indicates myopia or short sightedness & plus(+) in front indicates hyperopia or farsightedness.

CYLINDER OR ASTIGMATIC NUMBER:
Refers to amount of astigmatism in your refractive error prescription.

AXIS:This is measured in degrees & only present with cylinder.

ADD: Indicates the power needed for multifocal or bifocal lenses.

LENS MATERIAL:

PLASTIC or polycarbonate: Highly impact resistant, thinner, & lighter. Scratch resistance coatings can be applied on it.

CROWN GLASS: This has been used for longest time. Surface does not scratch.

HIGH INDEX PLASTIC: Thinner than other materials. Thus lighter also.

MULTIFOCAL LENSES:
Most people over forty need reading glasses due to condition called presbyopia, where the eyes ability to focus near objects weakens. Reading glasses is one solution but they can be annoying when you want to see the distance and you have to peer over the top or remove them all together. To avoid this inconvenience bifocals are other alternatives.

BIFOCALS: It has top part for distance & has small segment at bottom for near use. There are different types of bifocals.

1. FLAT TOP OR STRAIGHT TOP

2. KRYPTOC OR ROUND TOP

3. EXECUTIVE; This lens offres widest reading area.

TRIFOCALS:
This lens has three parts top, intermediate & near. Recommended for music players, computer users

PROGRESSIVE:
Designed to satisfy the widest possible range of visual needs without any dividing lines. They are also called invisible or varifocals.In this lens the optic varies gradually from distance to near.The advantage is that the segments are invisible & transition from distance to near is gradual.

COATINGS & TINTS:

Anti reflective coating:
With this special tint lenses appear invisible allowing people to see your eyes very clearly behind the glasses.

TINTS:
Reduces glare and adds to eyewear comfort. Also right selection of tint complements your face & adds more fashionable look.

TINT SELECTION:
yellow, brown & amber helps depth perception.Good for target shooters.Rose or pink tint good for people who work under fluoroscent lighting.

ULTRAVIOLET COATING:
UV is invisible to human eyes.There are two types UV A & UV B.Guarding against both is best.They both can affect & cause long term damage to lens & retina.

PHOTOCHROMATIC LENSES:
This lenses contain millions of light sensitive photochromatic molecules.When exposed to sunlight & uv rays a chemical reaction transforms these molecules into coloured light absorbers.Thus changing the lens from clear indoors to coloured outdoors.

CARING FOR YOUR EYE GLASSES:

1. Keep your lenses clean by washing them daily in warm water or with special lens cleaner. Dry them with a soft cotton towel or special eyeglass cleaning cloth.

2. When not wearing them keep them in protective case.

3. Never rest them face down in a way that the lens touch the surface.

4.Always put on or take off your glasses with both the hands holding the side arms midway on each side & sliding them backwards over your ears.Thid will help them keep the adjustment longer.

5. Dont wipe your lenses while they are dry. Wash or blow off the dust first.

6. Never use paper or silicon products to wipe the glasses as they can be scratched.

7. Avoid spraying aerosol hair sprays & perfumes near the lenses as these can cause the lens coatings to peel.