Validation of a Modified National Eye Institute Grading Scale for Corneal Fluorescein Staining

Abstract

Purpose

Validation of the novel Lexitas modified NEI scale for use in assessment of corneal fluorescein staining.

Patients and Methods

A series of 18 illustrations and 14 clinical photographs depicting varying severity levels of corneal fluorescein staining were assessed by 3 independent examiners. Regions of the cornea were graded for staining severity based on 3 different grading scales: the original NEI staining scale (density-based scoring; 0–3 scale), a structured version of the NEI scale (dot-count scoring; 0–3 scale), and the Lexitas modified NEI staining scale (0–4 scale with half-point increments). Kappa statistics (simple and weighted) were computed to determine intra-examiner image grading repeatability for each examiner over 2 separate assessments. Inter-examiner assessment reliability utilized the scores from the first read of each examiner, and pairs of examiners to compute kappa statistics.

Results

Data was analyzed from the scores provided by the examiners from each gradable corneal region on 32 images (18 illustrations and 14 photographs) for a total of 154 corneal regions across the 3 grading scales for each validation run. The mean intra-examiner simple/weighted kappa values using the NEI density, NEI dot count, and the Lexitas modified NEI staining scales were 0.67/0.72, 0.91/0.94, 0.80/0.92 for the graded illustrations, and 0.83/0.88, 0.76/0.85, 0.77/0.88 for the graded photographs, respectively. The mean inter-examiner simple/weighted kappa values using the NEI density, NEI dot count, and the Lexitas modified NEI staining scales were 0.59/0.65, 0.86/0.90, and 0.78/0.91 for the graded illustrations, and 0.80/0.88, 0.84/0.89, 0.69/0.88 for the graded photographs, respectively.

Conclusion

The expanded scale of the Lexitas modified NEI staining scale demonstrated a high degree of reliability and repeatability of grading assessments within and across individual examiners, comparing favorably with the original NEI staining scale. A future investigation into the in-office utility of the Lexitas modified NEI staining scale is warranted.

Keywords:

• clinical trials
• corneal sodium fluorescein staining
• dry eye disease
• repeatability
• validation

Acknowledgments

The authors would like to thank Drs. Kenneth A Beckman, Carolyn G Begley, and J Daniel Nelson for their expertise and assistance in their role as image examiners. Writing and editorial assistance in preparation of the manuscript was provided by Kurt Brubaker of Bridge Over Brook, Inc., and medical illustrations were prepared by Laura Brubaker of Bridge Over Brook, Inc., with funding provided by Lexitas Pharma Services, Inc.

Disclosure

AD Pucker, RC Zink, and G Magrath are employees of Lexitas Pharma Services, KL Ice is a co-founder and former employee of Lexitas Pharma Services. K Sall and GN Foulks are consultants to Lexitas Pharma Services. AD Pucker has received research or consulting support from Alcon, Art Optical, CopperVision, Euclid Systems, Kala, and Nevakar over the past three years, though this work is unrelated to the current project. K Sall has received consulting support from Allysta, Cloudbreak, Famy, Tarsier, Biorasi, Premark, Betaliq, Lexitas and Glaukos, although this work is unrelated to the current project. GN Foulks has received consulting support from Allysta, Aramis, Bristol Myers Squibb, Hanall, Nicox, Kala, and Tarsus, although this work is unrelated to the current project. AD Pucker reports grants from Alcon, non-financial support from Art Optical, personal fees from CopperVision, Euclid Systems, Kala, and Nevakar, outside the submitted work. The authors report no other conflicts of interest in this work.

Additional information

Funding

This study was funded by Lexitas Pharma Services, Inc. Lexitas Pharma Services, Inc participated in all aspects of this study with the exception of image grading.