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M. B. Albright, J. Kuo, L. Szczotka-Flynn; An Evaluation of Global Corneal Staining Scales in Soft Contact Lens Wear. Invest. Ophthalmol. Vis. Sci. 2008;49(13):4838.
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Corneal staining has proven to be a significant clinical sign for the development of Corneal Infiltrative Events (CIEs) in soft contact lens (SCL) wear. There is no current standard for grading corneal staining by region or globally. As well, there is no method that is agreed upon to assess global corneal staining in determining clinical significance. This study applied four grading methods to the same photographic database and compared the outcomes in terms of what previous authors have termed clinical significance. A novel method of grading corneal staining is included which utilizes density as one of three grading parameters.
A digital photographic database with adjudicated corneal staining scores from the Longitudinal Analysis of Silicone Hydrogel (LASH) Contact Lens Study was reviewed retrospectively. Each of 5 corneal zones were graded in 45 patients over 95 visits using the CCLRU grading scale for Type and Surface Area of corneal staining. In addition, the Density of corneal staining was graded within each zone. These values were converted to a global staining score based on methods utilized by The Institute for Eye Research (IER), Andrasko, Efron, and a novel LASH grading method. Each cornea was assigned a global positive or negative staining score based on definitions that have been used previously: IER (Toxic or Non-toxic), Andrasko (Danger Zone or Not Danger Zone), Efron (Grade 0 - 4 with 3 and 4 being significant), and LASH (Clinically Significant or Not Clinically Significant).
Data from a total of 174 eyes were reviewed. Positive global corneal staining was present in 29/174 (16.67%) of eyes using the IER scale, 4/174 (2.30%) of eyes using the Andrasko scale, 3/174 (1.72%) of eyes graded as Grade 3 or Grade 4 on the Efron scale, and 18/174 (10.34%) of eyes using the LASH scale. Compared to the LASH grading method, significantly different percentages of positive grading were noted in the Andrasko and Efron adapted scales (p<=0.002), but not the IER scale (p=0.08).
Significant differences exist in methods and outcomes when comparing current corneal staining grading methods and adapted global corneal staining scores during soft contact lens wear. A novel method developed for the LASH Study uses multiple parameters (i.e. type, surface area, and density) to determine clinically significant corneal staining and provides intermediate values compared with other published scales. Differences between the LASH method and other methods demonstrated in this study likely represent the purpose for which the scale and grading method were created.
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