ABSTRACT
Objective To observe the rate of iris vessels exposure and analyze its relevant factors in normal full-term neonates.Methods A retrospective study.1855 normal full term neonates,including 947 boys and 908 girls,were enrolled.The mean gestational age (GA) was (38.84±1.10) weeks and mean birth weight (BW) was (3 396.52±402.08) g.There were 1235 neonates from normal term vaginal delivery,402 cases of cesarean delivery and 218 cases of forceps delivery.All neonates were examined with hand-held portable slit lamp biomicroscopy within 1 to 3 days after birth by two trained ophthalmologist respectively.Iris vessels exposure was defined as radial red blood vessels along iris fibers.Infants were divided into iris vessels exposure group and iris vessels unexposed group according to the findings of slit lamp biomicroscopy.78 infants with iris vessels exposure were followed up for 42 days after birth till the iris vessels can't be seen under microscope.The differences between the two groups were compared for gender,mode of delivery (MOD),GA,BW and body length (BL).Multiple logistic regressions were used to determine the factors related to iris vessels exposure.Results There were 298 neonates with iris vessels exposure among 1855 neonates and the rate was 16.1％.1557 neonates (83.9％) had unexposed iris vessels.There were no different in gender (x2=0.551) and MOD (x2=3.036) between iris vessels exposure group and unexposed group (P＞0.05),while the differences in GA (x2=47.216),BW (t=4.603) and BL (t=3.936) between the two groups were statistically significant (P=0.000).Multiple logistic regression analysis revealed that only GA (β=-0.291,odds ratio=0.747,95％ confidence interval:0.656-0.85 1,P=0.000) was correlated to iris vessels exposure significantly.The iris vessels couldn't be seen in 77 of 78 infants with iris vessels exposure when followed up to 42 days.Conclusions The iris vessels exposure in normal full-term neonates is frequently observed.There is a significant inverse correlation between GA and iris vessels exposure.