black metal glasses looking through colorful night cityscape

background black bleach bleaching blind blindness blue blurred brain clear color colorblindness colorful colour colourblindness concept condition correction cure daltonism decoloration decolorization decolouration depression diagnostic different discoloration discolouration disease doctor eye eyeglasses eyesight field frame glass glasses green health healthy hopefulness illusion improve isolated landscape lens lenses look looking medical medicine mental metal monochrome nature optic optical optician optimism outdoor perception perspective red see shape sight summer sunglasses sunlight test therapy view vision visual white world yellow