Abstract
Purpose :
Superior limbic keratoconjunctivitis (SLK) is a chronic and recurrent condition of unknown etiology. SLK is described as an inflammatory disease of the superior bulbar conjunctiva, limbus and cornea. Current medical and surgical treatments are aimed at reducing symptoms. However, relief is variable among patients and even after surgical removal, discomfort can recur. Previous studies suggest that SLK has a rich vascular density compared to normal conjunctiva. The purpose of this study is to determine if vascular endothelial growth factor (VEGF) expression is increased in SLK compared to patients without conjunctival disease.
Methods :
In total, 12 surgically removed SLK samples from 9 patients were identified; 6 non SLK eyes were used as controls. FFPE specimens were stained using an anti-VEGF monoclonal antibody and automated immunohistochemistry was performed. The slides were digitalized and VEGF expression in the epithelium and conjunctival substantia propria was scored using a customized pixel count algorithm. Results were compared to VEGF expression in normal conjunctival samples. Vascular density for SLK was also scored (normal, high, clusters) by an experienced ocular pathologist.
Results :
The histopathological findings observed in all cases (12/12) included acanthosis, hyperkeratosis and a decrease in the number of goblet cells, as classically described in SLK. Increased vascularization was observed in 75% (9/12) of SLK cases and three samples presented with vessel clusters. VEGF expression in epithelial cells was noted to be significantly elevated for all cases of SLK compared to controls (P=0.009). Similarly, VEGF expression in the substantia propria was higher in SLK samples compared to normal conjunctiva (P=0.027), regardless of vascular density.
Conclusions :
VEGF levels are significantly elevated in the epithelium and substantia propria of the conjunctiva in SLK patients. The high expression of VEGF in both the substantia propria and epithelium indicates that this phenomenon may be independent of vascular density. Our data indicate that anti-angiogenic therapies may be beneficial for the treatment of SLK to improve patient symptoms and minimize recurrences due to the ubiquitous expression of VEGF.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.