Question: What were invented by Adolf Fick in 1887 and, while being to all intents and purposes invisible, are used worldwide by an estimated 125 million people?
Answer: Colored contact lenses; Contact lens prescription; Contact lens solutions; Contact Lens; Hioxifilcon d; Thoric lens; Multifocal contact lens; Piggybacked contact lens; Contacts; Contact lenses; Contact lens; RGP contact lenses; Contact lense; Colored contact lens; Disposable contact lens lid; Corneal neutralization; Corneal Neutralization; Monovision; Contact Lenses