LWE: Extract the blue stained area appearing on eyelid images

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LWE (Lid Wiper Ephithelium) is a software product that lets the user automatically extract the blue stained area appearing on eyelid images, and compute automated image-processing derived metrics in a sample comprising subjects with a range of LWE.

For LWE to generate accurate measurements, the upper lid margin needs to be stained with lissamine green (LG) dye using an optimized procedure to detect LWE. To reduce blur and improve depth of field, three images focused on the central, temporal and nasal regions of each upper lid are captured at 12x magnification through a digital camera (Canon EOS 60D) attached to a slit-lamp with constant camera settings maintained during the study. Using LWE, each set of 3 images is automatically registered and processed and metrics characterizing the stained area are computed. To validate the LWE Software, all images that were originally captured were also graded by an investigator using a 0-3 scale (Korb et al. Eye Contact Lens, 2005). Mean difference, correlation, generalized linear model (GLM), and ROC analyses were undertaken using basic statistical analysis.

During software development and validation phases, researchers characterize a number of aspects of LWE using this custom software.
The most useful metrics in the study are staining area, convexity and thickness.
These are strongly associated with the clinical grading using a diverse set of statistical tools. In addition to being more repeatable, objective measurements of LWE offer substantial numerical benefits and seem promising to measure even small changes as compared to manually quantized subjective LWE grades.

Three categories of users are available in LWE: Viewer, Grader and Trainer.

Software capabilities

Viewer mode
  • Display all annotations manually drawn by each grader and the automatic annotations
  • Automatic detection of the blue stained area (before and after registration)
  • Improve the result of the automatic detection using a detection algorithm based on region growing
    The user can then manually edit the segmentation result to add missing areas
  • Compute shape and intensity measurements on the area that has been automatically detected
  • Display measurements in a grid at the bottom of the user interface

Grader mode
  • Manual grading of an image
  • Display of the annotations generated by the current user only
  • Registration of 3 visible 12x images of the same eye lid along with manual annotations of the current user

Trainer mode
  • Automatic processing to generate automatic annotations
  • Manual editing (add, delete, modify automatic annotations)
  • Comparison between automatically detected and edited annotations
  • Compute measurements after manual editing

Technical Specifications

LWE is a stand-alone, software product that can be installed on any personal computer running Windows® XP or higher.
All LWE measurements are calibrated and output in real-world units.
The calibration value is manually entered in the LWE Software as a single value.

Video Tutorials

LWE Grader
LWE Viewer
LWE Trainer