Table 2.

Average Signal-to-Noise Ratio for Swept-Source Optical Coherence Tomography Angiography, Comparing Infant Groups

	Preterm Infants		Full-Term Infants
Characteristic	(n = 154)		(n = 228)		P Valuea
Average SNR, mean (SD), dB
Temporal small quadrant	n = 42	5.16 (1.95)	n = 81	4.97 (1.02)	0.835
Nasal small quadrant	n = 51	4.84 (1.51)	n = 63	4.74 (1.28)	0.696
Temporal large quadrant	n = 20	5.35 (1.16)	n = 49	5.09 (1.01)	0.570
Nasal large quadrant	n = 41	5.16 (1.06)	n = 35	4.78 (1.08)	0.123
All quadrants	n = 154	5.08 (1.52)	n = 228	4.90 (1.12)	0.427
	Preterm Infants with Advanced ROPb		Preterm Infants without Advanced ROPb
	(n = 12)		(n = 142)		P Valuea
Average SNR, mean (SD), dB
Temporal small quadrant	n = 2	11.11 (3.80)	n = 40	4.87 (1.35)	0.020
Nasal small quadrant	n = 6	6.46 (2.56)	n = 45	4.62 (1.22)	0.017
Temporal large quadrant	n = 1	7.19c	n = 19	5.25 (1.14)	0.165
Nasal large quadrant	n = 3	5.21 (0.74)	n = 38	5.16 (1.10)	0.980
All quadrants	n = 12	6.98 (2.92)	n = 142	4.92 (1.23)	0.003

n indicates the number of quadrants after eliminating quadrants of inadequate quality and merging results of superior and inferior quadrants from 8 preterm infants (1 preterm infant with advanced ROP and 7 without advanced ROP) and 12 full-term infants. dB, decibels; the bold and italic values in the table indicate two-side P values less than 0.05.

^a P value obtained from the Wilcoxon rank-sum test using MATLAB 2018a.

^bAdvanced ROP defined as stage 3 and/or pre-plus or worse ROP.

^cThe standard deviation could not be calculated as only one value is in this quadrant.