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Cocaine 2% solution is effective in treating epithelial ingrowth
Instead of using standard and less reliable methods, a mild cocaine solution has been effective and complete in staving off recurrences of the problem.
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BOSTON — While the use of cocaine solution as an anesthetic and a diagnostic tool is not that unheard of, the use of it as a device for the removal of epithelial ingrowth is a new niche for the product.
In general, the standard treatment of epithelial ingrowth after laser in situ keratomileusis (LASIK) is to use a scraping and washing technique of the stromal bed and flap. However, it is often very traumatic to the eye and not always effective.
Other treatments have included the use of PTK pulses and antiproliferatives, but they can cause some stromal damage. Alcohol also is effective, but can cause drying out and damage if used too often.
Cocaine on the other hand has been successful in removing epithelium for photorefractive keratectomy. One drop of 10% cocaine and rubbing can remove complete corneal epithelium.
With this in mind, Alfredo Castillo, MD, and José L. Hernandez-Matamoros, MD, have been using a diluted version of cocaine solution to handle epithelial ingrowth.
A new art to ingrowths
Dr. Castillo considers this method a new art for treating epithelial ingrowth. He explained that epithelial ingrowths are really not a rare occurrence when you consider they affect anywhere from 1% to 15% of the LASIK population. He said he believes the problem of epithelial ingrowth is usually related to a learning curve on the part of the doctors, as they learn the best methods of irrigation and debridement of the flap and stromal bed.
Isolated epithelial deposits and connected epithelium ingrowths from deposit to flap edge are the two major types of epithelial ingrowth. They come in three grades: grade 1 – non-progressive; grade 2 – slowly progressive; and grade 3 – results in a melting cornea. The isolated epithelium does not create epithelial ingrowth or melting.
“The epithelial ingrowth, most of the time, is mild and clinically insignificant but sometimes can produce photophobia, pain, foreign body sensation and, in very rare cases, loss of best corrected visual acuity (BCVA). Or it will produce irregular astigmatism,” Dr. Castillo said.
The cause of epithelial ingrowth is usually a factor relating to one or all of the following: poor adherence, irregular cuts, perforated corneal flaps, thin flaps and enhancements.
What triggers the epithelial ingrowth is believed to be limbal stem cell activation, the proliferation of epithelial cells and interaction in the epithelial stroma that produced epithelial ingrowth and/or melting. When cytokines on the stroma are activated by the ingrowth, melting usually begins.
The treatment of clinically significant epithelial ingrowth must occur as soon as it is found, and certainly when it is within 2 mm of periphery, when it has caused a loss of BCVA, significant proliferation of ingrowths or melting can be seen.
How the cocaine works
The toxic action of cocaine is a selective disruption of intracellular spaces, which causes reduction of epithelium and the destruction of tonofibrils. According to Dr. Castillo, most importantly, there is the inhibition of cell mitosis immigration. The treatment is effective due to inhibition of cell mitosis and the removal of basement membrane, which diminishes the rate of recurrence.
The safety of the cocaine is important to the treatment. The treatment itself requires 2 minutes of cocaine solution irrigation, followed by scraping of the stromal surface with a blunt blade, and irrigation with balanced salt solution. Later, a contact lens bandage is applied in case there was some lateral epithelial damage.
Dr. Castillo explained that the cocaine solution should be used before scraping because it helps loosen the epithelium deposits.
He also suggested irrigating in the interface to wash out all remaining cocaine solution and to keep nearby endothelial loss to a minimum. A pharmaceutical company prepares the cocaine solution for Dr. Castillo.
For Your Information:
- Alfredo Castillo, MD, and José L. Hernandez-Matamoros, MD, can be reached at Sta. Cruz de Marcenado 33, Madrid, 28015, Spain; (34) 91-538-4271; fax: (34) 91-542-6879; e-mail: acastillo@realvision.com; Web site: www.realvisionweb.com. Dr. Castillo has no direct financial interest in any of the products mentioned in this article, nor is he a paid consultant for any companies mentioned.