letters to the editor
Staining Study Methodologies
I wish to
thank Gary Andrasko, OD, for his letter Staining Study Methodologies
that appeared in the April issue in response to my March article The
New Math of Corneal Staining. There's no denying there are
differences between some of the contact lens/solution combinations.
Other studies have also found this.
was trying to point out were the wide variations in grading methods
and clinical relevance. One fact is that the staining described was
Grade 1 micropunctate. Garofalo's paper states, 90% of the positive
staining scores were grade 1, and generally low grade and readily
reversed. Grade 1 staining is usually clinically insignificant
(Terry RL et al, 1993).
Andrasko correctly quoted me regarding staining and infection: a
break in the epithelium is the first step for bacteria to get a
foothold into the cornea. However, my views have changed since I
wrote the article. Suzanne M. J. Fleiszig, OD, PhD's Glenn A. Fry
award lecture (2006) casts doubt on the role of a micropunctate
break and infection. She says, experiments tell us that disrupted
epithelial barrier function doesn't always make the cornea
susceptible to infection. To paraphrase, many other factors are
involved than just staining.
the transient staining results from preservative release, what
better protection against bacteria than a multipurpose disinfectant?
To date, there's been no connection with patient outcomes.
go on and on with this discussion. The bottom line is the clinical
implications of Grade 1 staining. Personally, I don't like the
overall negative messaging in our industry. Gary, as a researcher, I
do have appreciation for your work. It has brought much interest and
talk back into the specialty we both love: contact lenses.
Hom, OD, FAAO