Ortho-K's "reversibility" definition and its source

[jianxin]

One article by Dr. Joseph T. Barr mentioned "reversibility" twice.

My questions are that
1) how to define concept of "reversibility"
2) where "reversibility" came from?  I read FDA approval letter for Paragon CTR in 2002 and package inserts from Paragon, it didn't mention the "reversible" or "reversibility".

Thank you very much in advance!


(A). URL to link the article:
http://www.clspectrum.com/article.aspx?article=&loc=archive\2003\January\0103024.htm
(Contact Lenses 2002: Annual Report
Relive the major contact lens events of 2002, and see what's in store for 2003 and beyond.
By Joseph T. Barr, OD, MS, FAAO
(B) URL to FDA approval and package inserts for two paragon CRT products
http://www.fda.gov/cdrh/pdf/P870024S043.html

[Michael J Kutryb, MD]

I am not a supporter of ortho-k because there are much better ways to correct refractive errors.  It is usually prescribed by optometrists.  When the reverse geometry contact lens is discontinued, the cornea will start to revert back closer to the original curvature.  In other words it is not a permanant procedure.  If you get any useful effect at all, the effect will begin to wear off as soon as you stop the process.  That sounds pretty reversible to me. My question is - can it cause some unhealthy permanant changes in corneal curvature?  I really can't recommend otho-k.  Not trying to knock it - it just seems a little clumsy and perhaps not necessarily any safer than more traditional state of the art treatments.  If you need to go through all that trouble - why not just wear contact lenses at the bare minimum, not to mention LASIK, PRK or IOL procedures.  The ancient Chinese, I was taught, used a method of sleeping with sandbags over their eyes to flatten the corneas and improve myopia (temporarily.)  Sound familiar?


MJK MD

[jianxin]

Dear Michael J Kutryb, MD:

Thank you so much for your reply. I am totally on your side that I do not support Ortho-K especially to the boys/girl with good cornea and with a little myopia (for example less than -5.0).

Some other points are here.

1)"When the reverse geometry contact lens is discontinued, the cornea will start to revert back closer to the original curvature." --- This is one of so-call "reversibility". But where it came from? – This is what I am asking. From the package inserts from paragon has no such word.

Currently based on my understanding, it may be a misinteratation of Paragon package inserts. Because Paragon never says that. The Paragon only says that "...Myopia will reverse to the pretreatment level". “Myopia” not equals to “curvature”.

2) You asked that "can it cause some unhealthy permanent changes in corneal curvature?"
What means "permanent "?  1 year? 2 years? 100 years? 200 years? So, practically, it is no meaning. Also, it is no way to be approved.

3) So, we still try to find a meaningful definition of "Reversibility"