tests of tear production and function are now emerging. One test measures an iron-binding molecule called lactoferrin. The amount of this molecule appears to be closely related to tear production. Patients with low tear production and dry eyes have low levels of this molecule. This test may be especially valuable for patients with dry eyes since it can point to specific treatment strategies for dry eye. The tears may also be examined for their content of lysozyme, an enzyme normally found in tears. Another test involves fluorescein eye drops, which contain a dye that is placed in the eye. The dye should drain with the tears through the lacrimal duct into the nose within 2 minutes. If patients do not have enough tears to flush the dye into the nose, this time will be longer. A new test is also available to more accurately measure the flow of dye out of the eye. Eye dryness Dry eyes can occur from conditions such as: Aging Arthritis Corneal ulcers and infections Diabetes Eye infections (for example conjunctivitis) Secondary tearing deficiency associated with disorders such as – lymphoma, leukemia, GVHD (graft vs. host disease, after a transplant) Sjögren's syndrome Triple A syndrome Vitamin A deficiency As a temporary or permanent side effect of LASER vision correction surgery such as LASIK or photorefractive keratectomy (PRK) The inability of tears to drain into the nose can occur with: Some eye infections Blockage of the tear duct See also Dry eye syndrome Tear break-up time References External links Photo Diagram Diagnostic ophthalmology Veterinary diagnosis