What is Binocular Harmonization Technology?

Progressive lenses were an amazing step forward in lens technology, but as we continue to innovate, there is more to learn and more ways we can refine our lens designs. Currently, 7 in 10 European presbyopes have different prescriptions between their right and left eye1, which leads to a binocular disharmony resulting in visual disbalance that may cause eye strain while wearing standard progressive lenses, especially during near work activities and reading. 


Single vision lenses create less strain because the wearers use mostly the central part of the lens, while progressive users need to use different areas of the lens depending on working distances to experience a different level of accommodative support.


Currently, presbyopic customers with different prescriptions in each eye need their brain to work to equalize the size, sharpness, and quality of the image that each eye is processing. Looking through different areas of the lens, except the central part, the light rays exit the lenses at different positions, creating different images perceived by each eye. This causes discomfort, and users’ vision is clear only when covering one eye or the other. Our patented Binocular Harmonization Technology (BHT) recalculates and adjusts the progressive power distribution according to the actual used positions on each lens so that both eyes will experience the same accommodation support.


How Binocular Harmonization Technology Works

To perform binocular evaluation, Hoya developed five patented evaluative methods, which are summarized in the Binocular Eye Model:

  • 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


These evaluation methods focus purely on assessing the binocular performance of the different design variations. These new evaluation methods complement existing monocular evaluation methods as well.


Why is BHT Such a Big Deal for Progressive Lenses

More than 70% of European presbyopes have different prescriptions between their right and left eye1, meaning that 7 in 10 of your progressive prescriptions may cause eye strain in your customers. Up until now, this couldn’t be corrected for these consumers as there wasn’t the technology to do so. That’s no longer the case. 


These customers experience digital eye strain symptoms, such as headaches, blur vision, fatigued and dry eyes, and many others. BHT provides a new sense of sight with perfect and effortless focusing, constant stability, and excellent depth vision, which aims to help in reducing digital eye strain problems.


The Vision Council found that 69% of American adults did not know eyewear for digital device use can protect from digital eye strain effects. This knowledge gap leaves customers confused and helpless unless you educate them on potential solutions.


BHT Lets You Be the Eye Care Hero for Presbyopes 

Whether your customers know they are feeling strain or not, you can offer them this technology to give them a better 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 recommending the lenses with BHT to your customers, you provide them a more advanced and reliable lens solution. Binocular Harmonization Technology is currently available in the following Hoya Vision Products: 

  • iD MySelf
  • iD Lifestyle 3
  • iD MyStyle V+2
  • Array 2
  • iD Space
  • iD Screen
  • iD Zoom


Premium progressive lenses, such as the newest Hoyalux iD MySelf lens, provide a more advanced level of personalization for presbyopes, which further improve their visual experience. When discussing BHT with your customers, talk to them about the advantages of personalized progressive lenses.


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

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