Article Date: 5/1/2007

letters to the editor

letters to the editor

Response to 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.

What I 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).

Dr. 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.

And if 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.

We could 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.

Milton M. Hom, OD, FAAO

Azusa, CA

 

Spherical Aberration Correction and Vision

It's important that readers understand the benefits of spherical aberration correction, particularly in low light conditions.

In the general population there's about 0.15� of positive spherical aberration at pupil diameters of about 6mm, and it increases with increased pupil diameter. The negative impact of spherical aberration on visual quality is most apparent in low light conditions or at night, and is typically reported by patients as halos or glare. Aspheric optics can correct for spherical aberration, which is one of the dominant high-order aberrations inherent to the human optical system.

Bausch & Lomb's PureVision aspheric optics are engineered to not only counterbalance the positive spherical aberration of the human ocular system, but they're also designed to minimize contact lens-induced spherical aberration for each lens power.

In a recent patient survey of more than 7,000 patients wearing PureVision:

* 83 percent said, I see objects more clearly at night.

* 80 percent said, I have better vision while driving at night (fewer halos and glare).

* 90 percent said, I have better overall vision with their PureVision lenses.

We believe our aspheric optic lenses successfully demonstrate a visual benefit to patients in the research environment, in the exam lane and in the real world.

Mike Pier, OD

Director, Professional Relations, Bausch & Lomb

 

Nutritional Supplements and Keratoconus

I enjoyed reading the various perspectives on caring for the keratoconic patient from the recent Global Keratoconus Congress. There was no mention of whether nutritional supplements might be of some value in the care of these patients. Do you have any recommendations concerning vitamin supplements for keratoconus?

Charles D. Signorelli, OD

St. Peters, MO

Editor's Response:

I know of no valid evidence of vitamins or diet helping the disease per se.

For dry eye, of course, any of the supplements mentioned (omega fatty acids for example) would be helpful for dry eyed keratoconus patients.

 

For references, please visit www.clspectrum.com/references.asp and click on document #138.

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Contact Lens Spectrum, Issue: May 2007