Progressive lenses are essentially a spectacle lens that contains your three different prescriptions, in one lens. It’s a progression of power from your distance prescription in the top, progressing down the lens to your intermediate prescription or middle distance just below eye level focusing at arm’s length and then progressing to your near vision prescription towards the bottom of the lens. the lenses are blended and the different zones are seamless, so cosmetically they look just like a single vision lens as your vision changes near tasks and the computer can become a struggle and you may find that wearing a progressive lens design is more comfortable and far more convenient than two or three pairs.
They are a different design to Bi-focal lenses, which as the name implies Bi-focal gives you two foci. Normally your Distance and Reading prescription, but this can be Dispensed specifically to satisfy different criteria. You could have your computer prescription in the top and reading in the bottom or your distance driving prescription in the top and intermediate dashboard prescription in the bottom. The need to have different prescriptions to correct different visual tasks is common from when you are in your forties. We think there is some correlation between the need for this type of visual correction and the number of candles on your birthday cake. But we wouldn’t say that!
The term is called Presbyopia, which means “Old Sight”. Basically, as the Birthday candles on the cake increase the eyes ability to change focus by altering the shape of the lens, reduces this function is called Accommodation and it starts to reduce so you have a reduction in the amplitude of your accommodation and as a result, your function to see clearly at near tasks reduces .