New Freeware for Image Analysis of Lissamine Green Conjunctival Staining.

PURPOSE: Lissamine green (LG) is often used in addition to fluorescein to assess the severity of conjunctival damage in dry eye syndrome, which is graded manually. Our purpose was to describe an algorithm designed for image analysis of LG conjunctival staining. METHODS: Twenty pictures of patients suffering from dry eye with visible LG conjunctival staining were selected. The images were taken by 2 different digital slit lamps with a white light source and a red filter transmitting over the wavelengths absorbed by LG. Conjunctival staining appeared in black on a red background. The red channel was extracted from the original image. Stained areas were then detected using a Laplacian of Gaussian filter and applying a threshold whose value was determined manually on a subset of images. The same algorithm parameters remained constant thereafter. LG-stained areas were also drawn manually by 2 experts as a reference. RESULTS: The delineation obtained by the algorithm closely matched the actual contours of the punctate dots. In 19 cases of 20 (95%), the algorithm found the same Oxford grade as the experts, even for confluent staining that was detected as a multitude of dots by the algorithm but not by the experts, resulting in a high overestimation of the total number of dots (without mismatching the Oxford grade estimated by the experts). The results were similar for the 2 slit-lamp imaging systems. CONCLUSIONS: This efficient new image-analysis algorithm yields results consistent with subjective grading and may offer advantages of automation and scalability in clinical trials.

Dermoscopy for the Diagnosis of Conjunctival Lesions.

This article describes the present literature on dermoscopy of conjunctiva and shows the results of a dermoscopy study of 147 conjunctival tumors. Melanomas were characterized by a heavy pigmentation, irregular dots, and a higher prevalence of gray color compared with nevi. Squamous cell carcinomas had peculiar hairpin and glomerular vessels. Primary acquired melanoses were characterized by regularly distributed light brown dots. A large part of nevi had small cysts.

Micro-instillation of fluorescein with an inoculation loop for ocular surface staining in dry eye syndrome.

PURPOSE: To describe and validate the micro-instillation of fluorescein on the ocular surface by a disposable calibrated inoculation loop to improve corneal and conjunctival staining quality. METHODS: Accuracy and precision of the volume of 0.5% sodium fluorescein collected by a single use 1 µl-calibrated inoculation loop were measured using a precision balance. Twenty patients (40 eyes) suffering from dry eye syndrome were enrolled in a prospective interventional nonrandomized study. Fluorescein was instilled with the loop, and slit-lamp images were taken within 30 seconds using cobalt blue light with and without a yellow barrier filter. For comparison, after a washout period, the same images were retaken after instillation of one drop of fluorescein from a single-dose unit. The main outcome measure was the staining quality assessed by three experts, blind to the instillation method. Patient discomfort (tolerance, by a questionnaire) was also compared. RESULTS: The mean volume collected by the loop was 1.18 ± 0.12 µl, compared with 33.70 ± 6.10 µl using the single-dose unit. The loop avoided excess dye responsible for unpleasant tearing, masking of lesions and rapid diffusion into the stroma. Micro-instillation greatly improved image quality without losing information. The yellow filter further improved image contrast. Tolerance was excellent. CONCLUSION: The 1 µl-calibrated inoculation loop is a safe, convenient, inexpensive, disposable, sterile, well-tolerated tool for reproducible micro-instillation of commercial fluorescein. By greatly improving staining quality, it will help standardize assessment of dry eye severity.