Table 1.

Risk status by icrop category for the eye with higher risk of poor structural outcome for all 828 infants with prethreshold retinopathy of prematurity in one or both eyes^*

				Risk in prethreshold eye
Icrop category				Low risk	High risk
Zone	Stage	Plus disease	At least one eye prethreshold no. of patients	No. of patients	No.	%
I	3	Yes	29	0	29	100
I	3	No	23	1	22	95.7
I	1 or 2	Yes	19	0	19	100
I	1 or 2	No	117	9	108	92.3
II	3	Yes	271	13	258	95.2
II	3	No	303	295	8	2.6
II	2	Yes	66	11	55	83.3
Total			828	329	499	60.3

ICROP, International Classification of Retinopathy of Prematurity.²⁰

^*Risk of poor structural outcome was based on the RM-ROP2 risk model analysis for each eye (a risk analysis program based on natural history data from the Multicenter Trial of Cryotherapy for Retinopathy of Prematurity Study).⁷ Low risk was less than 0.15; high risk was 0.15 or greater. Plus disease was defined as a degree of dilation and tortuosity of the posterior retinal blood vessels meeting or exceeding that of a standard photograph.²