Table 5.

Grades of peripheral capillary non-perfusion (CNP)

Lesion	Grading	Definition	Figures
Peripheral CNP	Cannot grade	No gradeable images of any retinal quadrant exist	None
	Absent	One or more gradeable images of one or more peripheral quadrants exist, and no CNP is seen on any of these images	None
	Mild grade 1	Ranges from any CNP in the periphery to multiple areas of CNP that are individually not larger than 1/3 disc area	13, 14
	Grade 2	Multiple areas of CNP that are, individually, between 1/3 and 1 disc area	15, 16
	Grade 3	Includes features of previous grades, plus one or more large bays of peripheral CNP, each >1 disc area	17
	Grade 4	One or more bays of CNP invade the superior, inferior, or temporal borders of zone 1, or zone 2 of the nasal retina	18