Abstract
Purpose :
Trachoma is the most common infectious cause of blindness. In vivo confocal microscopy (IVCM) provides high-resolution images of the ocular surface. We reported a validated grading system for the quantitative assessment of IVCM in trachomatous scarring (TS) showing clinical scarring had a characteristic appearance on IVCM and was also strongly associated with the presence of dendritiform cells (DCs). The present study looked at the use of this grading system in a cohort of individuals with TS to identify IVCM parameters associated with scarring progression.
Methods :
Cohort study involving 800 participants in Tanzania with TS who underwent clinical examination, photography and IVCM at 0 and 24 months. Masked grading of IVCM images using a validated grading system was performed. Two independent observers identified scarring progression by comparing photographs taken at 0 and 24 months.
Results :
Clinical and IVCM assessment of 800 participants were performed at baseline; 617 of these were re-examined at 24 months. Of these, 438 had gradable IVCM images taken at both time points; 342 could be confidently graded as having either progressed or not by comparing photographs. Clinical progression was found to occur in 79 (23.1%). Multivariable logistic regression modelling showed that scarring progression was strongly associated with a high IVCM scarring grade at both baseline (OR 1.84 for each increase in scarring category; p=0.002) and 24-months (OR 1.60 for each increase in scarring category; p=0.021), adjusting for age and sex. DCs at baseline were associated with future scarring progression, but this lost significance after adjusting for age and sex. DCs present at 24 months remained strongly associated with scarring progression adjusting for age and sex (OR 2.62; p=0.025).
Conclusions :
Numerous diseases cause conjunctival scarring; progression of scarring can lead to blindness. Clinical assessment and stratifying risk of blindness is challenging. Quantitative IVCM parameters, including connective tissue grade and the presence of DCs, are associated with disease progression and may be useful markers in trachoma and other conjunctival fibrotic diseases. DCs are thought to represent dendritic cells, which have a central role in mediating the immune response and potentially in the pathogenesis of TS. Further investigation of DCs is needed, potentially as a novel antifibrotic therapeutic target.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.