pros and cons of wearing spectacles
TRANSCRIPT
Pros and Cons of Wearing Spectacles
Prepared By
Mostafizur Rahman
Spectacles are the most widely used visual instrument in the world
Spectacles, also known as Glasses, are frame bearing lenses worn in front of the eyes.
They are normally used for vision correction or eye protection.
Spectacles In Brief
Spectacle Users
Approximately 207 million people wear glasses.
About 64% adults wear eyeglasses. Nearly 3 million children under 4 years
wear spectacles.
History of Spectacles
Chinese used special type of spectacles to protect their eyes in hazardous situation.
Egiptians first invented the method of magnification of a particle eith the help of polished rock crystal.
Eyeglasses first appeared in Pisa, Italy, around the year 1286.
The first known artistic representation of eyeglasses was designed about 50 years latter.
Types of Spectacles
Spectacles are mainly of two types: Convex Lens Concave Lens
Some other types of Spectacles:
Photochromic Lenses
Bifocals
Trifocals
Varifocal
Spectacles MaterialsSpectacle frame consist of:
Metal Frame Pure Titanium frame Non-Allergenic Nickel coated frame Stainless steal frame Titanium alloy Frame
Plastics Frame
Spectacles Materials
Lens Materials:
Glass Lenses
Plastic Lenses (CR39)
Hi-Index Lenses
Polycarbonate Lenses
Aspheric Lenses
How To Take CareKeeping glasses in a hard case
Cleaning with warm soapy water
Taking off before sleeping
Keeping the Screws of the spectacles Tight
To avoid touching the lens while removing from
eyes
Choosing Proper Spectacles
Light WeightLeast ThicknessComfortable FramePhotochromic EyeglassesAnti-Reflective CoatingAnti Scratch Coating
Any Questions
?
Thanks For Listening