The goal of smart glasses is to keep you connected to the digital world when you need it, while feeling as natural to wear as regular glasses. The big challenge has been finding compelling use cases and designing glasses that are truly all-day wearable. Adoption has accelerated over the past two years, driven by advances in AI and smaller and lighter electronics that fit neatly into glasses form factor. Reportedly Meta alone has sold more than 7 million of its Ray-Ban AI glasses in 2025, up from 2 million sold in total in 2023 and 2024 combined.
Adaptive lenses for older users
While early adopters tend to be people from the younger generation, those 40 and older arguably have as much or more to gain from smart glasses. Most people in this age group already rely on reading glasses (due to presbyopia [i]); there is a clear use case where adaptive lenses could eliminate the need to swap between AI glasses and reading glasses, allowing people to benefit from the AI functionality while instantly adjusting for reading. For older users this could significantly improve their quality of life by removing the need to manage multiple pairs of glasses.
However, the challenge remains: how to provide a reading glasses prescription as part of all-day wearable smart glasses? This becomes especially problematic as smart glasses evolve to integrate display technology.
Tunable liquid crystal lenses for AI and AR glasses
FlexEnable has been developing switchable reading lenses based on our tunable liquid crystal (LC) lens technology which is built on a plastic substrate. FlexEnable lenses are less than 100 microns thick, lightweight, and can be curved and integrated into smart glass lenses. By using FlexEnable tunable lens, a user can switch between a reading glasses power and normal lens with optical prescription (or no prescription).
FlexEnable switchable reading lenses allows for all-day wearable smart glasses without the need to carry around reading glasses, or the need to switch between smart glasses and reading glasses to use a laptop, read a book, or when working on things with your hands. By not needing to switch to reading glasses, the full power of AI smart glasses remains available.
FlexEnable uses a GRIN (gradient index) liquid crystal tunable lens architecture, which works by exploiting the fact that LC molecules are bi-refringent – adjusting the orientation of the liquid crystal results in a change of refractive index (RI) in relation to the incoming light (Figure 1).
FlexEnable lens contains a thin layer of LC material between transparent electrodes. The electrodes are patterned. When voltage is applied, the resulting electric field is carefully designed to vary across the area (aperture) of the lens.
This spatially varying field tilts the LC molecules by different amounts across the aperture, creating a smooth radial gradient RI. That RI profile mimics the shape of a conventional curved lens, bending light to focus while maintaining a flat surface.
Changing the voltage reshapes the field profile, changes the LC tilt angles, which shifts the RI gradient, and changes the focal length continuously – with no moving parts.
Figure 1: FlexEnable’s GRIN architecture utilises patterned electrodes and voltage-controlled liquid crystal alignment to create a programmable radial refractive index. This enables dynamic focal length adjustment across a flat surface with no moving parts.
FlexEnable’s unique technology is able to make LC lenses on plastic through our proprietary materials and designs. The practical upshot for smart glasses is compelling. The ultra-thin and lightweight lens can be tuned across a dioptre range sufficient to address presbyopia across a range, allowing the same glasses to be used for different people, or for an individual who plans to use the same glasses for several years and reading glasses prescription changes.
Integrating FlexEnable tunable liquid crystal lens into smart glasses preserves the aesthetics and form factor of the smart glasses. The plastic liquid crystal component can be thermoformed to the shape of the cell and integrated with a lens, and as seen in Figure 2.
Figure 2: Concept image of glasses with integrated FlexEnable liquid crystal lens (darker grey circle inside full lens).
Contact us at info@flexenable.com for more information.
Notes:
Presbyopia is a condition associated with aging in which the eye’s ability to focus on nearby objects gradually diminishes because the crystalline lens becomes less flexible. This decline in near‑focusing capability usually starts to appear in a person’s early to mid‑40s and continues to worsen until roughly age 60.
As seen in Chart 1, the prevalence of presbyopia (over 1 dioptre of correction needed to read) steadily rises as age increases. Table 1 shows the dioptre adjustment required for reading for those with presbyopia. Dioptre adjustment typically increases with age.
Chart 1: Increasing incidence of presbyopia with age. Chart source: https://blog.hanitalenses.com/fullrange/increasing-prevalence-of-presbyopia-for-ophthalmologists.
| Age | Expected Add Power in |
| 40 to 42 | +0.75 |
| 43 to 45 | +1.00 |
| 46 to 47 | +1.25 |
| 48 to 50 | +1.50 |
| 51 to 52 | +1.75 |
| 53 to 55 | +2.00 |
| 56 to 57 | +2.25 |
| 58 to 60 | +2.50 |
Table 1: Increasing Dioptre Add Power with increase in age
