Abstract
Purpose :
Corneal neovascularization (CNV) is a vision-threatening condition stemming from a variety of corneal insults affecting 1.4 million people worldwide annually. At present, no standard method exists that represents clinical CNV grading observed in patients. We sought to develop a standardized DELTA grading system representing clinical CNV levels in vivo using a mouse model.
Methods :
Seventy C57BL/6 mice of either sex were used as approved under IACUC protocol. CNV was produced via single topical application of a filter-paper disc (2mm) saturated with 10µl alkali (0.5N sodium hydroxide) on the central cornea for 30 seconds. This initiated sprouting of blood vessels towards cornea on day-14 and peaked on day-35. CNV formation, progression, levels, density, and localization were monitored using slit- and stereomicroscopy at various times. Collected eyes were serially sectioned and subjected to H&E and immunofluorescence. Corneal flat mounts were stained with lectin. The CNV quantification and grading was performed with NIH Image, Adobe Photoshop, and Microsoft Excel by three individuals in a blinded manner.
Results :
DELTA grading was developed by measuring Density of vasculature (D), Enlargement of vasculature (E), Length of vasculature (L), Thickness of vasculature (T), and Area of vasculature (A) in 4 quadrants of each cornea. Topical alkali initiated CNV on day-14 that peaked at day-35. DELTA parameters in each quadrant of the cornea were measured from day 0-35. DELTA score was assigned based on CNV severity and affected area of the cornea:
Grade 0: no CNV with DELTA score 0;
Grade 1: low CNV with DELTA score 1-5 (20-30 % cornea affected);
Grade 2: moderate CNV with DELTA score 5-10 (30-50 % cornea affected);
Grade 3: severe CNV with DELTA score 11-15 (50-70 % cornea affected);
Grade 4: very severe CNV with DELTA score 16-20 (70-90 % cornea affected).
Conclusions :
A newly defined CNV DELTA grading system represents realistic clinical condition as seen in human patients. This novel method is useful for advancing bench-to-bedside translational research and identifying novel therapies for CNV.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.