Development of a new grading scale for tear ferning

Abstract

28 29Purpose: This paper reports on the development of a new tear ferning (TF) subjective 30 grading scale, and compares it with the Rolando scale. 31Method: TF patterns obtained from tear film samples collected from normal and dry eye 32 subjects in previous studies were collated into a large image library. From this library, 60 33 images were selected, to represent the full range of possible TF patterns, and a further sub-34 set of 15 images was chosen for analysis. Twenty-five optometrists were asked to rank the 35 images in increasing order between extreme anchors on a scale of TF patterns. Interim 36 statistical analysis of this ranking found 7 homogeneous sub-sets, where the image rankings 37 overlapped for a group of images. A representative image (typically the mean) from each 38 group was then adopted as the grade standard. Using this new 7-point grading scale, 25 39 optometrists were asked to grade the entire 60 image library at two sessions: once using the 40 4-point Rolando scale and once using the new 7-point scale, applying 0.25 grade unit 41 interpolation. 42Results: Statistical analysis found that, for the larger image set, the Rolando scale produced 43 3 homogeneous sub-sets, and the 7-point scale produced 5 homogeneous sub-sets. With this 44 refinement, a new 5-point TF scale (Grades 0−4) was obtained. 45 Conclusions:The Rolando grading scale lacks discrimination between its Type I and II 46 grades, reducing its reliability. The new 5-point grading scale is able to differentiate between 47 TF patterns, and may provide additional support for the use of TF for both researcher and 48 clinician. 49 50

A computer-based image analysis for tear ferning featuring

“…The quantities are represented in¯ve characteristics vectors, each vector representing a grade in the recently developed grading scale. 20 The proposed quanti¯cation approach is the¯rst of its kind for TF grading. It constitutes the backbone of computerbased grading method in the new grading scale.…”

“…1) of the new grading scale 20 were used in our experimental study. In order to distinguish between grades, speci¯c observations have been made to the images representing them.…”

“…19 Recently, a new¯ve-point TF grading scale ( Fig. 1) was developed, 20 to overcome some of the limitations associated with Rolando grading scale 13 such as poor di®erentiation between types I and II. The recently developed grading scale is capable of di®erentiating between TF grading patterns and can be used as a support for other dry eye tests.…”

“…The recently developed grading scale is capable of di®erentiating between TF grading patterns and can be used as a support for other dry eye tests. 20 The present study is aimed toward the development of an automatic objective grading of TF G1 G0 G3 G2 G4 Fig. 1.…”

“…The recently developed TF grading scale (grades 0-4). 20 images to assign a grade to a TF image using features extracted from the image itself. The features are grouped into characteristics vector and compared to pre-constructed feature vectors of reference graded images of TF.…”