Chemistry
Preparations contain carboxymethyl cellulose, hydroxypropyl methylcellulose (a.k.a. HPMC or hypromellose), and hydroxypropyl cellulose. They contain water, salts and polymers but lack the proteins found in natural tears. Patients who use them more frequently than once every three hours should choose a brand without preservatives or one with special non-irritating preservatives.
Read more about this topic: Artificial Tears
Famous quotes containing the word chemistry:
“If thought makes free, so does the moral sentiment. The mixtures of spiritual chemistry refuse to be analyzed.”
—Ralph Waldo Emerson (1803–1882)
“Science with its retorts would have put me to sleep; it was the opportunity to be ignorant that I improved. It suggested to me that there was something to be seen if one had eyes. It made a believer of me more than before. I believed that the woods were not tenantless, but choke-full of honest spirits as good as myself any day,—not an empty chamber, in which chemistry was left to work alone, but an inhabited house,—and for a few moments I enjoyed fellowship with them.”
—Henry David Thoreau (1817–1862)