Documentation of distribution of normal conjunctival vessels and their changes by mild irritation of photography using automated algorithm

• Published in: Acta ophthalmologica (Oxford, England) Vol. 89; no. s248
• Main Authors: BANAEE, T, POURREZA, HR, KHAJEH DALOUEE, M, DANESHVAR KAKHKI, R, BASIRI, M, ABRISHAMI, M
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-09-2011; Wiley Subscription Services, Inc
• Subjects: Algorithms; Conjunctiva; Irritation; Photography; Radon
• ISSN: 1755-375X; 1755-3768
• DOI: 10.1111/j.1755-3768.2011.4375.x

Purpose To quantify distribution of conjunctival vessels in normal eyes and the changes induced by the irritation of photography.
Methods Digital slit lamp photography of the upper and lower conjunctiva of 728 healthy eyes was done in 4 groups with different orders of succession of the photography in each person. A radon transform based algorithm was used to segment vessels and compute area occupied by vessels (AOV) of different sizes in each image. AOV of small, medium and large vessels were compared in the first photos of cases, and in the successive photos of each person using ANOVA (post hoc: Tukey) and paired sample T tests.
Results AOV of the 3 sizes of vessels had normal distribution in all images. In the first images of photography (un‐irritated eyes); AOV of medium sized vessels was the largest and was less in both fields of the left eye than the upper field of the right eye. Irritation of photography, caused an increase in AOV of the large vessels first, followed by increase in AOV of medium sized vessels accompanied by a decrease in AOV of small vessels, and finally a small increase in AOV of small vessels.
Conclusion Medium sized vessels are the most abundant in un‐irritated eye. During mild irritation, changes in large conjunctival vessels are documented first. Medium and small sized vessels seem to respond later.