People who showed up to Yuga Labs‘ recent three-day event celebrating a collection of Bored Ape Yacht Club NFTs have reported eye and skin irritation, potentially from UV light used at the event.

Yuga Labs’ ApeFest, held Nov. 3-5 in Hong Kong, included a brightly lit party held on Saturday. Several of those who attended wrote on social media that they experienced “eye burn” and other symptoms after the event.

“Yuga Labs is aware that some attendees are reporting eye pain, vision issues, or skin irritation after attending ApeFest,” a company spokesperson said in a statement to Variety. “We are distressed by these reports, as nothing is more important to us than the health and safety of our community, many of whom we spent significant facetime with over the weekend.”

The company is continuing to investigate the reports “alongside our ApeFest vendors and contractors to identify the potential source(s) of these issues,” the rep said. “We will provide updates as we can. Any impacted attendees are encouraged to reach out to us via social media DMs and share information about their experience and symptoms to assist our investigation.”

Yuga Labs told The Verge that it estimated that the “15 people we’ve been in direct communication with so far represent less than 1% of the approximately 2,250 event attendees and staff at our Saturday night event.”

One of the ApeFest attendees, Adrian Zduńczyk, founder and CEO of the blockchain consulting company Birb Nest, posted on X Sunday that he “woke up with severe eye burn” and said he was diagnosed with photokeratitis after visiting a local hospital and eye clinic. Photokeratitis “is like having a sunburned eye,” according to the American Academy of Ophthalmology. “Photokeratitis is caused by damage to the eye from ultraviolet (UV) rays.”

“So far, 30 hours since woke up with severe eye burn, I’ve visited emergency hospital and eye clinic and spent there a total of 6 hours,” Zduńczyk wrote. “Got diagnosed with ‘photokeratitis over both eyes, accident related’ with prescribed steroid eye drops and eye lubricants. My vision was tested as close to perfect with no serious cornea damage, luckily.” He added, “No hate toward the organisers — I doubt it was on purpose and shit like that at times happens almost randomly.”

Another person who said they attended ApeFest, posting on X under the handle “Crypto June,” wrote, “I woke up at 04:00 and couldn’t see anymore. Had so much pain and my whole skin is burned. Needed to go to the hospital. The doctor told me the uv of the lightning of the stage did it. It has the same effect as sunlight.”

Yuga Labs describes itself as “a web3 company shaping the future through storytelling, experiences and community.” The mania for NFTs, which use blockchain technology to verify ownership of digital content, kicked off in earnest in early 2021 — and the Bored Ape Yacht Club NFTs were among the first to catch fire.

In March 2022, Yuga Labs raised a $450 million seed round at a $4 billion valuation. Last month, Yuga Labs CEO Daniel Alegre announced an unspecified number of layoffs at the company. The restructuring “will help us better serve our communities and execute on our vision for the company,” he wrote. “These decisions are not taken lightly as they impact people and roles within the company.”