Abstract
Purpose:
To describe a new automated method to objectively quantify corneal fluorescein staining (CFS) in clinical slit-lamp photographs.
Methods:
We developed an imaging system that quantifies (i) corneal fluorescein staining as a proportion of the total corneal surface, (ii) the average intensity of fluorescence, and provides a (iii) global index of corneal fluorescein staining using a centesimal scale (0 to 100). The mathematical algorithm objectively quantifies corneal epithelial staining in photographs acquired with different slit lamp-mounted cameras or in different digital formats. The software is based on the widely available platform ImageJ, can be installed on any computer, and does not require training in ophthalmology. Using the National Eye Institute CFS scoring system, we clinically scored the degree of corneal fluorescein staining in a set of clinical photographs (n=50) from patients with dry eye disease. After randomly sorting the images, in a masked fashion, we scored CFS in the same set of photographs using the newly developed computer-assisted system. Finally, we analyzed the correlation between the CFS scores generated by the software and those obtained by an experienced clinician.
Results:
We analyzed a total of 50 corneal images with various degrees of corneal epitheliopathy. There was a statistically significant correlation between the CFS scores obtained with the clinical assessment and the automated analysis. The scores obtained with the automated analysis, which measured the compromised area, were strongly correlated with the scores from the clinical evaluation (R=0.80, P<0.001). Similarly, there was a strong correlation between the computer-generated scores that measured fluorescence intensity and the scores from the clinical evaluation (R=0.85, P<0.001).
Conclusions:
The CCFI provides with a reliable, continuous and objective score for evaluating corneal fluorescein staining in patients with punctate keratitis. This system may be used for assessing corneal epitheliopathy in a variety of clinical conditions and in clinical trials.
Keywords: 486 cornea: tears/tear film/dry eye •
482 cornea: epithelium •
465 clinical (human) or epidemiologic studies: systems/equipment/techniques