lens /lenz/
(noun) a curved piece of glass or plastic that makes things look larger, smaller or clearer when you look through it
Example: I have two pairs of glasses with different coloured lenses.

bifocals /ˌbaɪˈfəʊklz/
(noun) a pair of glasses with each lens made in two parts. The upper part is for looking at things at a distance, and the lower part is for looking at things that are close to you.
Example: The doctor looked at me again over his bifocals as he wrote something in his book.

corrective lens
corrective lens /kəˈrɛktɪv lɛnz/
(noun) is a lens (i.e. a transmissive optical device) that is typically worn in front of the eye to improve daily vision
Example: The doctor said I needed to wear corrective lens.

adjustable focus
adjustable focus /əˈdʒʌstəbl ˈfəʊkəs/
(noun) are eyeglasses with an adjustable focal length.
Example: Adjustable focus eyeglasses are eyeglasses with an adjustable focal length.

safety glasses
safety glasses /ˈseɪfti ɡlɑːsɪz/
(noun) special pieces of strong glass or plastic in a frame that fits tightly to a person's face to protect their eyes from dangerous chemicals or machines
Example: Goggles or safety glasses are forms of protective eyewear.

sunglasses /ˈsʌnɡlæsɪz/
(noun) a pair of glasses with dark glass in them that you wear to protect your eyes from bright light from the sun
Example: Should everyone have to wear sunglasses?

3D glasses
3D glasses /θriː diː ɡlɑːsɪz/
(noun) is a technique for creating or enhancing the illusion of depth in an image by means of stereopsis for binocular vision.
Example: We use 3D glasses to watch this movie.

bioptics /bʌɪˈɒptɪks/
(noun) head-mounted eyeglasses of extreme magnification
Example: Bioptics are a combination two-lens optical system with a telescope attached to a pair of glasses.

contact lens
contact lens /ˈkɑːntækt lenz/
(noun) a small round piece of thin plastic that you put on your eye to help you see better
Example: All contact lens users must remove and clean their lenses as instructed.