What is Binocular Harmonization Technology?

Progressive lenses were an amazing step forward in lens technology, however as we continue to innovate, there is more to learn, and more ways we can refine our lens designs. Currently, 7 in 10 presbyopes have different prescriptions between their left and right eyes1, and this leads to a frustrating amount of strain, especially when reading.

Single vision lenses create less strain because the wearer can adjust objects for near vision so they use the central position of the lens, while progressive users need to use different areas of the lens depending on the activity.


Currently, presbyopic patients with different prescriptions in each eye need their brain to work harder to even out the images each eye is processing as their eyewear provides slightly different images when using anything but the central position on their glasses. When using anything but the central position of the lens, the light rays exit the lenses at different locations, creating a difference in image perceived by each eye.


Progressive Distortion



This creates discomfort, and users’ vision is only clear when covering one eye or the other. Our new patented Binocular Harmonization Technology (BHT) corrects for this.


Learn about the 5 primary elements of BHT in our white paper, Binocular Harmonization Technology & Binocular Eye Model.


Download the Free BHT White Paper




BHT takes this difference into account through 5 new measurements in the Binocular Eye Model. These measures consist of:


  • Binocular Clearness Index

  • Convergence Difference between R/L

  • Accommodation Demand Difference between R/L

  • Magnification Difference between R/L

  • Vertical Prismatic Difference between R/L


By taking into account the difference in prescription, we can make adjustments to the progressive lenses to correct for the variation in images perceived by each eye, helping to reduce eye strain because the wearer no longer has to self-correct.



Why is BHT Such a Big Deal for Progressive Lenses

70% of presbyopes have different prescriptions between their right and left eye1, meaning that 7 in 10 of your progressive prescriptions are causing eye strain in your patients. Up until now, this couldn’t be corrected for these patients; there wasn’t the technology to do so. That’s no longer the case.


The eye strain symptoms your patients are feeling present similarly to digital eye strain symptoms, with dry eyes, fatigued eyes, and headaches. This is true for presbyopes whether they are on digital devices or reading a first edition copy of A Tale Between Two Cities.


We’ve found patients commonly don’t realize what’s causing digital eye strain symptoms, or it is misattributed to things other than eyewear. This leaves patients confused and uncomfortable.


There’s a solution to their symptoms, and it’s BHT. Read more.


Download the Free BHT White Paper



BHT Lets You Be the Eye Care Hero for Presbyopes

Whether your patients know they are feeling strain or not, you can offer them this new technology to give them a solution. It’s just in time given that in the year 2030, the last baby boomer will reach the retirement age of 65, meaning there are now more presbyopes needing progressive lenses than ever before.


By providing this new technology, you can help solve their strain issues while providing a more adaptive and reliable lens solution to your patients. Binocular Harmonization Technology is currently available in the following Hoya Vision Products:


  • iD Lifestyle 3

  • iD MyStyle 2

  • Array 2

  • iD Space

  • iD Screen

  • iD Zoom


Learning More About Binocular Harmonization Technology

To learn more about the technology behind BHT and to see the difference it makes for patients — download our comprehensive ebook Binocular Harmonization Technology & Binocular Eye Model.


Download the Free BHT White Paper


1Hoya data in file. European progressive lens orders 2007-2013