Changing how eyeglass lenses are made

Most conventional prescription eyeglass lenses start the same way. A liquid monomer is poured between two glass molds and baked for up to 22 h. What comes out is not a finished lens but a thick plastic puck—a blank that is shipped to one of thousands of optical labs around the world. There, a technician clamps it into a grinding machine that carves away up to 90% of the material to create one person’s prescription. The rest ends up in a landfill.

Azul 3D, a start-up spun out of Chad Mirkin’s laboratory at Northwestern University, has developed a way to skip all of it—the casting, the shipping, the grinding, the waste—by 3D printing prescription lenses directly from resins cured by ultraviolet (UV) light. If it works, the technology could reshape both how and where eyeglass lenses are made.

“This is ultimately about completely changing how we think about making, storing, and distributing these types of lenses,” says Mirkin, the company’s chairman and cofounder.

Azul is making an ambitious bet on a market that is enormous and growing. Rising rates of myopia—projected to affect half the world’s people by 2050—and an aging population are keeping demand for corrective lenses climbing.

Azul says its lenses could bring vision correction to regions where the conventional supply chain, with its large inventories, dedicated labs, and long shipping routes, has never made economic sense. People have been grinding lenses to correct vision since the late 13^th century, and the modern plastic-casting workflow has been largely unchanged for nearly 80 years. Whether a new process—no matter how promising—can break into an industry this entrenched remains to be seen.

How lenses are made today

Lens blanks are thermoset resins that lock in place permanently following curing with a chemical initiator. The reaction’s temperature and speed must be carefully controlled because the plastic shrinks as it cures. If the shrinkage happens too fast or unevenly, internal stress gets trapped in the material, warping light passing through the finished lens.

The oldest and most common lens plastic is CR-39, or poly(allyl diglycol carbonate), a thermoset introduced in 1947 with a refractive index of 1.50—a measure of how sharply the material bends light. The higher the index, the thinner and lighter a lens can be for a given prescription.

For higher-index lenses, the dominant material is Mitsui Chemicals’ MR series—a family of urethane polymers that incorporate sulfur atoms into their backbones to bend light more sharply and improve the refractive index of the resulting lens. By threading sulfur throughout the polymer, Mitsui’s chemists pushed the index to 1.60 for MR-8 and as high as 1.74 for MR-174. A 1.74 lens can be as little as 50% the thickness of and significantly lighter than the same prescription in CR-39.

The third major lens material, polycarbonate, is a thermoplastic that is injection molded in minutes rather than cast over hours. Its refractive index of 1.586 and high impact resistance have made it the default high-index lens material in the US for decades.

What comes out of the glass molds is not a finished lens but a puck roughly 65–85 mm across and 8–12 mm thick at the center, deliberately oversized so a lab can cut a lens from it. The front surface, set by the mold, is already optically finished. Everything else is raw material waiting to be removed.

The blanks ship from a handful of casting plants—two major ones being EssilorLuxottica’s facility in Thailand and Carl Zeiss Vision’s operation in Germany—to optical labs on six continents.

A typical lab sits on an inventory of thousands of blanks, covering every combination of material, index, and curvature, according to Karl Citek, a professor of optometry at Pacific University. The blanks are cheap, but expense accumulates in shipping, warehousing, and the labor needed to grind each one to a prescription.

It’s inefficient, but Jeffrey Pyun, a polymer chemist at the University of Arizona who studies optical photopolymers, says the field’s processes are so well oiled that innovation has stalled.

“We make these pucks; we ship them all around the world; we carve 90% of them off and create a bunch of waste,” says David Woodlock, Azul’s chief commercial officer. “It’s a very, very dirty process for something that ends up being the cleanest-looking thing you can imagine.”

3D printing: A different approach

The class of chemistry behind Azul’s process isn’t new. Vat photopolymerization—the family of 3D printing methods that includes stereolithography—works by projecting UV light into a pool of liquid resin and triggering the same kind of free-radical chain reaction that cures a lens blank, but with light instead of heat. The liquid cross-links into a solid in whatever shape the light projects. A platform pulls the hardening object upward, fresh resin flows in, and the process repeats layer by layer.

In conventional stereolithography, the UV light projects upward through a transparent glass window at the bottom of a shallow tray of liquid resin. Each new layer of solidified resin cures directly against the window and must be peeled off before the next one can begin. That peeling step introduces mechanical stress, limits speed, and leaves behind layer lines that can reduce optical quality.

“Every time you do a layer, you make a line,” says James Hedrick, Azul’s cofounder and CEO, “something you might not even perceive with your finger, but when you try to look through the part, you see it.”

Azul’s patented core technology—called HARP, for high-area rapid printing—eliminates that peel step entirely. The process floats the liquid resin on a thin, continuously flowing layer of fluorinated oil. The oil is denser than the resin and immiscible with it, creating a nonstick boundary at the window. Instead of sticking to the window, the solidifying resin slips free continuously. “If you’ve ever been driving and you hydroplaned in the rain, we created that phenomenon on an interface in a 3D printer,” Hedrick says.

The oil also circulates through a chiller, pulling heat away from the curing zone and allowing HARP to cure the polymer in seconds rather than the hours needed for traditional lens blanks.

Azul adapts existing lens chemistries to this UV-curable format—acrylates at the low-index end, sulfur-bearing formulations at higher indices—and prints the lenses vertically in pairs, curing a thin crescent-shaped cross-section at a time. Once a pair of lenses comes off the printer, it is hardened with more UV light. From there, the lenses go through polishing, coating, and edging to fit the frame.

“Right now, we polish our lenses, but we are moving toward a solution where there is no postprint polishing required, getting rid of most of today’s manufacturing steps,” Woodlock says.

Azul is not alone in pursuing printed lenses. IOT, a Madrid-based optical firm, debuted a process in January 2026 called Light-Form that cures an entire lens in a single flash of light. Singapore’s NeoVision Technologies is developing an inkjet-based approach that converts prescription data directly into print-ready files, claiming a production cycle of 1–2 days. And Manifest Technologies, a start-up spun out of the University of Colorado Boulder in 2020, projects light from multiple angles simultaneously into a vat of UV-curable resin, solidifying the entire object at once.

All of these firms must achieve their high speeds without sacrificing quality. In conventional casting, 20 h of gradual heating lets the material shrink evenly. In HARP, only a thin slice of resin cures at any given moment, so each section finishes shrinking before the next one solidifies right above it.

“The beauty of 3D printing is the shrinkage happens sequentially during the printing process,” Hedrick says. “This makes the shrinkage predictable and prevents side effects like stress buildup.” He says Azul’s testing under polarized microscopy finds no residual stress.

Timothy Scott, an associate professor of chemical engineering at Monash University who has published on shrinkage stress in photopolymer networks, is not fully convinced. Continuous printing “absolutely” avoids the stress between discrete layers, Scott says, but “it does not inherently eliminate” shrinkage stress in general.

Where 3D printing could matter most

A big part of Azul’s pitch is access. The conventional eyeglass lens supply chain depends on reliable shipping from casting plants in Europe and Asia, large inventories of blanks, and dedicated surfacing labs—infrastructure that makes economic sense only in dense, wealthy markets.

“What if you’re in a low-income country, and you don’t have the luxury of that infrastructure?” Pyun, the polymer chemist, asks. “If you can just do it on the spot, that’s the dream.”

Pacific University’s Citek agrees. Even in a place like Saudi Arabia, “go an hour outside of the city, and you probably don’t have an optical shop.” There’s no money in it for the incumbents, he adds, “and so they’re not going to open the shop.”

Azul sees an early opportunity in the Persian Gulf region because it imports 90-plus percent of its lenses, either as prescription lenses inserted into frames at a local shop or as complete eyeglasses shipped directly, Hedrick says.

Azul has been working with DuPont since 2019 and installed one of its HARP-based printers at Qnity Electronics, an electronic materials company that DuPont spun off in 2025, for use in making components for chip manufacturing.

DuPont led Azul’s $15 million series A funding round in 2023, with the Riyadh-based venture firm Beta Lab among the investors. Separately, Azul has signed a letter of intent with a Saudi Arabian government institution for a production facility in the country, aiming to produce its first lenses in 2028. “We’ve modeled it at approximately a million lenses a year,” Woodlock says, or roughly 20% of the addressable market across the Persian Gulf States the facility would serve.

The production system Azul is building uses 10 small print cells running simultaneously to produce 20 lenses at once. The firm says that it delivers a finished lens every 4.5 min at current speeds and that its roadmap calls for printing in under 2 min.

Azul envisions the Saudi facility as a company-operated plant designed to prove the end-to-end process. From there, its plan is to replicate globally, either by running its own facilities or by partnering with existing optical labs.

“We believe this is the single most efficient way to produce a custom surfaced lens,” Hedrick says. “It requires less material and less energy, enables faster turnaround with more distributed production, and can create a better-performing lens for customers.”

Pyun agrees that a process that cuts the material waste and collapses a supply chain that’s currently spread across the globe would change the manufacturing economics of the industry. “There is nothing that’s higher volume and higher value than plastic optics,” he says.

Robert McLeod, a professor of electrical engineering and materials science at the University of Colorado Boulder and chief scientist at Manifest, says it’s unlikely that Azul will supplant how firms like EssilorLuxottica make lenses. Such firms, he says, are “really, really good at” making lenses the traditional way. But he still sees opportunity in niche areas such as custom optics and lenses for augmented-reality products.

“There might be those niches that may enable exciting new markets that make people billions of dollars,” he says.

David Brzostowicki is a freelance science writer who covers medicine, science, and emerging technologies.