In today’s 7th U.S. Circuit Court of Appeals case, a patient sued the manufacturer of his contact lenses, claiming they were defective because they caused him pain and problems, but the 7th Circuit explained that the plaintiff needed substantially more than a wisp of circumstantial evidence to prove the product-liability claim.In a diversity action, Steven Kallal sued Ciba Vision Corp. on theories of negligence, strict product liability and breach of implied warranty. He purchased CIBA’s O2 Optix brand contact …