Direct Addition Lens Technology  (DAL)


The Duolux® lenses were designed using the Direct Addition Lens (DAL™) patent, a new methodology where the transition between distance and near visual fields are calculated without an intermediate zone.


The lack of intermediate zone in the Duolux® lenses allows QLDS to produce lens designs that have larger distance and near visual fields, providing wearers a safer, more comfortable, and aesthetically appealing lens.


The eye’s natural path from distance to near is seamless without distortions or image jumps. The eyes effortlessly just zoom in and zoom out between distance and near. 

Using the DAL™ methodology QLDS can develop and optimize new lens designs in a short amount of time giving us the edge in creating customized brands for our business partners.

Best vision correction for Single Vision, Bifocals, and Progressives



No visible line or blend zones

A direct transition between distance and near reducing eye strain

Smooth transitions from distance to near with no image jump

Stable power across both distance and near visual fields