Effects of Ranibizumab on ocular biological parameters in the treatment of retinopathy of prematurity / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To investigate the effect of intravitreal ranibizumab injection on ocular parameters in the treatment of retinopathy of prematurity(ROP), and analyze its relationship with birth weight(BW)and postmenstrual age(PMA).METHODS: A total of 98 premature infants who received routine ROP screening at Northwest Women's and Children's Hospital from January 1, 2016 to January 31, 2022 were selected, and they were divided into ROP group(49 cases)and non-ROP group(49 cases)according to the results of Retcam3 fundus screening. All children in ROP group were treated with intravitreal ranibizumab injection, with an average PMA of 38.02±3.03 weeks. The ocular parameters were measured at the PMA of 0 month(40 weeks±14d), 3 months(52 weeks±28d)and 6 months(64 weeks±28d), respectively.RESULTS: There was no difference in axial length(AL), anterior chamber depth(ACD), lens thickness(LT), vitreous length(VL)and central corneal thickness(CCT)between ROP group and non-ROP group at the PMA of 0 month(P>0.05); At the PMA of 3 and 6 months, ACD in ROP group was higher than that in non-ROP group, and LT was lower than that in non-ROP group(P<0.05); at the PMA of 6 months, AL and VL in ROP group were lower than those in non-ROP group(P<0.05). AL, ACD and VL were positively correlated with PMA in ROP group and non-ROP group, while CCT was negatively correlated with PMA; there was a positive correlation between LT and PMA in children without ROP. There was no correlation among LT, BW and PMA in ROP group.CONCLUSION: The ocular development of children with early ROP(PMA 0～6 months)treated by intravitreal ranibizumab injection is slower than that of premature infants without ROP, and BW and PMA are the main influencing factors of ocular parameters of premature infants.

Relationship between body weight and postmenstrual age in a Korean pediatric population

Weight is a covariate representative of body size and is known to influence drug disposition. Recently, with increased use of allometric scaling, this variable has become more significant in accounting for variability in pharmacokinetic parameters. In adults, weight can be considered as a time invariant covariate because physical development is complete. As a result, when weight is missing in data, the typical or median value (say, 70 kg) could be imputed. On the contrary, weight continuously changes with age in the pediatric population. In this case, it is more appropriate to consider different median weight for each age group. We constructed a prediction model for weight using postmenstrual age (PMA) with the data consisting of 83,014 Korean pediatric patients. Weight, PMA, and gender information were collected from electronic medical records. Sigmoid models multiplied by exponential or logistic function were tested for basic model structure. Covariate effects on model parameters were then investigated using selection criteria of p < 0.001. All analyses were performed using NONMEM 7.3.0 and R3.2.0. The sigmoid model multiplied by logistic function best described the data and there was a significant difference between boys and girls in model parameters. It is expected that the results obtained in this work can be used for imputation of missing weights in pediatrics when PMA is available. In addition, the developed model can be used for clinical studies in children under 12 years old whose weight change rapidly with age and for model building in dealing with time varying body weight as a covariate.

Median Motor Nerve Conduction and H-reflex Studies in Premature Infants

Many factors have been identified which to affect the rate of propagation of impulses along motor fibers. These include temperature changes around the nerve, diameter of the axon, degree of myelinization, age of infants, and local environment of the nerve. Motor nerve conduction velocity and Hoffman's reflex latency have been used to assess the degree of myelination and maturation of the nervous system. The conduction velocities in infants of a short gestational age are significantly lower than those of the fullterm infants. The extrauterine myelination and maturation might increase nerve conduction velocity. We measure the median motor nerve conduction velocity, compound muscle action potentials amplitude and H-reflex latency of premature infants to determine the neurological maturation after birth. The premature infants with gestational age above 37 weeks have a significantly higher conduction velocity and a shorter H-reflex latency than those of gestational age below 37 weeks. The premature infants with weight over 2.5 kg have a significantly higher conduction velocity, larger compound muscle action potentials amplitude and a shorter H-reflex latency than those of weight below 2.5 kg. And there is a statistically significant negative correlation of the H-reflex latency with the postmenstrual age. The determination of motor nerve conduction velocities and H-reflex latencies seem to be an additional method in assessing the degree of maturity in infants after birth.

Visual Evoked Potentials in Premature Infants

Visual evoked potentials(VEPs) are the cerebral electrical activities recorded from the occipital scalp following a flash or pattern stimulation and can detect the lesions of sensory visual pathways. Although the VEPs change with the maturation of CNS in children, a few studies have documented the maturational changes in premature infants. Using the light- emitting diode goggles, VEPs were studied in 131 neurologically intact infants of 28~41 weeks gestational age or 34~59 weeks postmenstrual age. The VEPs were analysed by three waveforms; normal, abnormal, and flat, and four patterns; N300, P200-N300, P100-N155-P200-N300, and P100 pattern. Normal waveforms were 63 of 131 VEPs(48.1%). Of the normal waveforms, N300 patterns were 38.1%, P200-N300 36.5%, P100-N155-P200-N300 19.0%, and P100 6.4%. Each pattern correlated with the postmenstrual age. These findings support the hypothesis of VEP pattern changes according to the maturation of the visual system with age.