Protecting Stem Cells
August 15, 2009DrHovanesian No Comments »Be Kind to Your Stem Cells
The unsung heroes of the ocular surface–the limbal stem cells–are under assault nearly every day with so many of our patients who take chronic medications, artificial tears, and use other preserved products on and in their eyes. Preservatives like benzalkonium chloride (BAK) (and even worse thimerosal) are extremely effective killers of fungal and bacterial contaminants of eyedrops, but their long term administration is not without side effects.
Take, for example, a patient who was recently referred to me for management of “dry eye”. She is 72 years old and has been taking topical antiglaucoma drops for over 30 years. Her tear production was in the normal range (no aqueous deficiency), and her meibomian glands produced clear, liquid lipid (no MGD), but her cornea had a circumferential superficial vascular pannus extending 3 mm from the limbus. Worse yet, the whole of her corneal epithelium was irregular. She had virtually no functional limbal stem cells
Patients like this are very difficult to treat because their eyes lack a fundamental need: a source of new, healthy cells to replace sloughed corneal epithelial cells. While limbal transplantation from the contralateral eye can help some patients with limbal stem cell disease, this isn’t an option in someone who takes medications in both eyes.
It’s a great relief to see the pharmaceutical industry embracing topical meds with new generation preservatives or no preservatives at all. Making these new offerings affordable will be their next challenge.
“Patients report complaints about the financial impact of dry eye frequently, saying the cost of these drops are abusive to their pocketbooks,” said John A. Hovanesian, MD.
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