What is the difference between glass lenses and plastic lenses for glasses?

Eye glasses . Glass lenses are heavier and more durable. Plastic lenses are lighter and scratch more easily. Both have good optical characteristics.
Weight and scratches. Glass lenses are: heavier, prone to breakage. They provide slightly superior optics and optimal scratch resistance. Plastic lenses are: lighter, scratch easier. They are shatter resistant and available in more shapes.