In 1958, J. Woodland Hastings and Beatrice M. Sweeney tested the ability of different wavelengths of light - corresponding to different colors -to shift the circadian rhythm in the photosynthetic marine dinoflagellate Gonyaulax polyedra. The greatest power to reset the organism’s daily meter lay in the blues, with a precipitous decline into the greens and a modest boost in the reds.

Bifocals are dual-version glasses, you can see two different fields of vision through one pair of bifocal glasses. Bifocals are designed with two prescirptions on the lenses, so you can see far through the top part of the lenses, and reading book or use computer through the bottom part of the lenses.

Progressives provide a smooth transition from distance through intermediate to near, with all the in-between corrections included as well. You can look up to see anything in the distance, look ahead to view your computer in the intermediate zone, and drop your gaze downward to read and do fine work comfortably in the close zone. That’s to say, progressive lenses are the closest to how natural vision is that you can get in a pair of prescription eyeglasses.

Eyeglasses VS Contact Lenses

What is NV-ADD?

Pupillary distance is measured in millimeters from the center of one pupil to the center of another pupil. This measurement helps to ensure that your prescription is properly centered in the spectacle lens for the clearest and most accurate vision. PD represents the pupillary distance, which is measured from the right pupil to the left pupil. The PD of the adult is between 54-74. The children are between 43-54.