Progressive Lenses and Their Measurement Factors

Progressive lenses are a sophisticated alternative for those with varying focus needs at multiple distances. They require measurements of very intricate details in order to design the best lenses for a patient's vision.

Inter-Pupillary Distance is the most basic measurement we must obtain for your eyewear. It tells us the position of the eyes, and in particular their distance apart. When we know this measurement, we can put the very best part of your progressive lenses right in front of your eyes.  We also use this measurement to make a more accurate measure of your near point inset and down gaze angle. “What are those?” you might ask.

Near Point Inset measures the distance your eyes will turn in order to see an object that is close. If you follow a pencil moving closer and closer, your eyes will move inward towards each other so you see one single pen, not two. Knowing how far your eyes turn in when you look at close things allows us to place the best reading prescription exactly in front of your eyes when you read and when you look at your hand-held devices or the computer.   

Down Gaze Angle has to do with how far your eyes turn down when you look at something close, or up when you look at something far. Typically, we use distance vision when we look up — at a distant TV, traffic lights, movie, or presentation. The opposite is also true for near vision; we look down for nearby objects. How much is as unique as any individual patient. Petite patients will turn their eyes down less than a tall patient, and petite patients will almost always hold things closer because they have shorter arms.

There really is a lot that goes into crafting the perfect lens for you, and we pride ourselves on being a place where many Calgarians will make the switch from bifocals to progressive lenses. If you have any questions about making the switch yourself, an appointment is a great place to start. To make one now, call 403-333-3353.

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