There's at least 6 R&D companies on that list that supply the big name companies. Those companies don't sell to the public either. But they participate because they are part of the vision care and product development business.
When engineers attend the MTT Symposium there are tons of booths with test systems under development, software simulation programs being developed, and there are also booths that peddle crap.
They go because they learn what the other companies are up to. It's an important part of networking within the industry community. It's also exposure to potentially partnering with someone who is interested in your technology and may also be developing similar technology. It's Business 101.
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