However, the tear layer is an extremely complex fluid containing thousands of molecules of various forms and functions from different sources. Nearly 2,000 tear proteins have been reported in humans, and at least 90 small molecule metabolites have been seen in human tears. (8,9)
As discussed, the interface between tears and the air is the single most effective refractive surface the eye possesses. A disrupted tear film will adversely affect your patient’s appreciation of an accurate refraction and your world-class skills and experience employed dispensing spectacles or prescribing contact lenses.