Clark's parents are visiting Metropolis to celebrate their 30th wedding anniversary here, but in season 4 they celebrate their 35th.
Chen Chow says that he knows Clark because they have the same optometrist. He probably means they get their frames at the same place. This line was a gag based on playing up the resemblance between Yuji Okumoto and Dean Cain, giving Chen and Clark the same dress sense, glasses, hairstyle and wildly patterned tie.