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  1. What is the Staining Grid?
  2. Why was the Staining Grid developed?
  3. How do I use the Staining Grid?
  4. What is the exact testing methodology used to create the Staining Grid?
  5. Is the Staining Grid continuously being updated and how will I know when this occurs?
  6. Why do some lens/solution combinations cause more staining than other?
  7. What are private label multipurpose solutions and why were they tested?
  8. What factors should I consider when selecting a multipurpose solution for my patients?
  9. What is the significance of solution-induced corneal staining?
  10. Is the Staining Grid research supported by the contact lens industry?
  11. How are contact lens materials chosen to be tested?
  12. Can the Staining Grid be used with patients?
  13. Explain the color coding system used on the Staining Grid page of this web site.
  14. My Staining Grid is not printing in color or with any shading?


What is the Staining Grid?The Staining Grid is an easy-to-use reference tool allowing the eye care practitioner to evaluate the level of biocompatibility of various contact lens and multipurpose solutions that have been tested. It is presented as a grid with the solutions listed across the top and the lens materials listed down the first column. The percentages which appear in each cell represent the average percentage of the cornea which was stained when observed at 2 hours after lens insertion (refer to testing methodology below). Thirty subjects were evaluated for each cell except where otherwise noted.



Why was the Staining Grid developed?There have been various anecdotal and published reports over the previous decade concerning diffuse corneal staining observed after insertion of contact lenses which had been soaked in various solutions. However, no one had systematically examined the interactions of commonly used lens materials and multipurpose solutions using a consistent testing methodology. Beginning in July 2005, we resolved to undertake this task. The current Staining Grid is the result of this work.



How do I use the Staining Grid?To choose a multipurpose solution that is biocompatible with the patient's lens type simply follow the 2-step procedure:

1) Find the lens material in the first column of the grid.

2) Follow across that row and select a multipurpose solution which results in minimal corneal staining (i.e., green zone).

For easy reference, the Staining Grid is color coded as follows:

Green = less than 10% staining
Yellow = 10-20% staining
Red = greater than 20% staining.



What is the exact testing methodology used to create the Staining Grid?Thirty successful hydrogel contact lens wearers are recruited for each study. Lenses for these subjects are presoaked overnight in the multipurpose solution to be tested. All lens cases have been previously precycled with the test multipurpose solution.

On the day of testing, subjects are required to refrain from any contact lens wear before the testing. Upon beginning each visit the subject is questioned and examined to ensure that he/she does not exhibit any characteristic spelled out in the EXCLUSION criteria for the study. Presoaked lenses are inserted by the co-investigator, not allowing the subject to know which lens or solution is being tested. After 10 minutes of wear, the subject assesses comfort using a 100-point visual analog scale. Lens wear continues for a total of 2 hours at which time the subject again completes the comfort scale. Lenses are then removed by the co-investigator, and placed in a lens case . The investigator then instills sodium fluorescein (FUL-GLO sterile ophthalmic strip 0.6mg Fluorescein Sodium) into each eye. The eyes are examined with a cobalt filter and a Wratten #12 (yellow) filter held in front of the slit lamp to enhance the visibility of micropunctate staining. Corneal staining type (micropunctate, macropunctate, coalesced, and patch) and staining area (in 10% increments) are graded in each of 5 corneal regions (central, superior, inferior, nasal, and temporal). All grading is done by the investigator who is masked as to which lens/solution combination had been used.

Staining area is analyzed by averaging the staining area across the five regions, thus assigning a staining area percentage to each eye. The eye with the maximum staining area for each subject is then averaged with the worst eye of the other subjects to determine an overall average staining area percentage for the lens and solution combination being tested. The 2-hour average staining area is reported on the Staining Grid.



Is the Staining Grid continuously being updated and how will I know when this occurs?Yes, new lenses and multipurpose solutions are continuously being tested. You can register for free under the Contact/Update tab on this site and an e-mail will be sent to you periodically informing you of updates to the Staining Grid. Your contact information will only be used for this purpose and will never be sold or given to a third party.



Why do some lens/solution combinations cause more staining than other?One thought is that the staining noted in the Staining Grid is primarily caused by solution preservatives (chemical keratitis) as they are released on the eye. A recent study has shown that different lens materials absorb and release the various solution preservatives at different rates and in different amounts. In general, the preservatives are released onto the eye in greatest quantities within 2 to 4 hours after lens insertion. For this reason, solution-induced corneal staining is typically more pronounced during the early hours of lens wear. This is why the 2-hour staining percentages are reported on the Staining Grid. Therefore, it is important for the eye care practitioner to evaluate solution induced staining in the lens wearing day (i.e., 2-4 hours after lens insertion).



What are private label multipurpose solutions and why were they tested?Wal-Mart's and Target MPS are both private label brands of multipurpose solution sold by Wal-Mart and Target, respectively. At the time of testing (2006) both solutions were identical to Renu Multiplus solution (Bausch & Lomb). These two private label solutions were chosen for testing since private label brands represent approximately 25-30% of all multipurpose ounces sold in the U.S.



What factors should I consider when selecting a multipurpose solution for my patients?Several factors are important when selecting a multipurpose solution for your patients: Adequate disinfection of all common ocular pathogens (bacteria, virus and fungi) is essential; Patient comfort throughout the entire wearing period is ideal; Biocompatibility of the lens/solution combination with the cornea is important to maintain an intact epithelial barrier. The Staining Grid helps you to identify which multipurpose solutions are biocompatible with each lens material.



What is the significance of solution-induced corneal staining?Corneal staining represents a chronic disruption in the integrity of the corneal epithelial layer. An intact epithelium is the best defense against corneal adverse events. One retrospective record review (Pappas, et. al.) showed that corneas with diffuse solution-induced staining experienced a 3-fold increase in infiltrative events (asymptomatic infiltrates, infiltrative keratitis) compared to corneas without staining. In addition, when moderate to severe staining is observed lens wearing comfort is typically decreased. Finally, recent work by Dr. Paugh has shown a correlation between corneal staining and decreased epithelial barrier function.



Is the Staining Grid research supported by the contact lens industry?Yes, the staining grid research is supported by a grant from Alcon Research, Ltd. In addition, CooperVision has provide support for this project. This website is not funded by industry support.



How are contact lens materials chosen to be tested?Contact lens materials for testing are chosen based upon their current market share percentages and growth rates. If you would like to suggest a material for testing please send an email and we will consider your request.



Can the Staining Grid be used with patients?The use of the staining grid is up to the discretion of the eye care practitioner.



Explain the color coding system used on the Staining Grid page of this web site.The Staining Grid uses a color coding system to identify various staining levels within the individual grid cells as follows:

Green = less than 10% staining area (insignificant staining)
Yellow = 10% to 20% staining area (marginal staining, monitor closely)
Red = greater than 20% staining area (widespread staining, consider solution change).

The boundaries choices for these staining area color codes are based upon clinical experiences and observations of staining within this study. The colors used in the corneal staining grid are intended only to differentiate the identified data groupings and are not meant to suggest that the lens-solution combinations designated red or yellow indicate danger or caution or that such combinations are associated with an increased risk of corneal infection. Eyecare practitioners are encouraged to apply their own criterion in determining which staining amounts are clinically significant within their own practice.



My Staining Grid is not printing in color or with any shading?In Internet Explorer, go to Tools > Internet Options... > Advanced Tab > Printing section > check the 'Print background colors & images' checkbox, then click OK button. Your grid should now print in color or in shades of gray.

In FireFox, go to File > Page Setup... > Format & Options > In the Options section in the lower portion of the screen, check the 'Print Background (colors & images)' checkbox , then click OK button. Your grid should now print in color or in shades of gray.

 
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