Mechanisms and management of retinopathy of prematurity

A meta-analysis of adverse effects of retinopathy of prematurity on neurodevelopment in preterm infants

BACKGROUND

Retinopathy of prematurity (ROP) increases with the survival of late preterm infants, but its relationship with neurodevelopmental outcomes in preterm infants remains controversial. To investigate the relationship between ROP and its severity and adverse neurodevelopmental outcomes in preterm infants.

METHODS

We conducted a meta-analysis. All relevant literature before November 2022 were retrieved from PubMed, Embase, Cochrane Library Web of Science, CNKI, CBM, Wan fang Data, and VIP Database. According to the inclusion criteria and exclusion criteria, eligible literature were included to conduct clinical trial quality assessment, and the Newcastle-Ottawa scale was used to evaluate the quality of evidence. Meta-analysis was performed using RevMan5.3. Data extraction, quality assessment, and meta-analysis were performed independently by 2 people. Mean difference or standardized mean difference of motor, language and cognitive scores (Bayley III or Bayley II) were used as effect sizes for continuous data analysis, all of which were represented by 95% CI. For heterogeneity (I2 ≥ 50% or P < .10), a random effects model was used, otherwise a fixed effects model was used.

RESULTS

A total of 6 literature were included. The results of the ROP group for motor (comprehensive motor, proportional motor, and fine motor), language and cognitive scores were -5.57 (95%CI, -1.43 to 0.04), -0.95 (95%CI, 1.4-0.50), -1.34 (95% CI, 1.77-0.92), -1.75 (95% CI, 2.26-1.24) and -5.56 (95% CI, 9.56-1.57). Additionally, the results of severe ROP group for motor (comprehensive motor, proportional motor, fine motor), language and cognitive scores were -8.32 (95%CI, -8.91 to 7.74), -1.10 (95%CI, -1.83 to -0.36), -1.08 (95%CI, -1.75 to -0.41), -7.03 (95%CI, -7.71 to 6.35), and -7.96 (95%CI, -8.5 to -7.42).

CONCLUSIONS

The Bayley Scale scores of the ROP group were lower than those of the not ROP group, and the scores of the severe ROP were significantly lower than those of the not severe ROP group. These findings suggest that ROP can indeed delay motor, language and cognitive, especially in severe cases.

Correlation between tear levels of vascular endothelial growth factor and vitamin D at retinopathy of prematurity stages in preterm infants

Deregulation of vascular endothelial growth factor (VEGF) levels leads to retinopathy of prematurity (ROP). Vitamin D (VIT-D) is known to regulate VEGF in an oxygen dependent manner. The purpose of this study was to correlate tear levels of VEGF and VIT-D with different ROP stages in preterm infants. In this prospective cross-sectional study, we enrolled 104 pre-term infants. They were grouped into: Group-1 (Classical ROP) and Group-2 (Aggressive ROP), which were further subdivided into Group-1A (progressing), Group-1B (regressing), Group-2A (pre-treatment), and Group-2B (post-treatment). Tear VEGF and VIT-D levels and their association with different ROP stages were assessed. Stage 1 and stage 2 had higher whereas stage 3 had lower VEGF levels in Group-1B compared to Group-1A. Stage 1 and stage 3 showed higher levels of VIT-D with no difference in stage 2 in Group-1B compared to Group-1A., Group-2B showed higher VEGF and lower VIT-D levels compared to Group-2A. Presence of a positive correlation at an early stage (stage 1) of ROP and a negative correlation at a more advanced stage (stage 3) of ROP with VIT-D and VEGF implies stage-specific distinct signaling crosstalk. These findings suggest that VIT-D supplementation may have the potential to modify the course and outcome of ROP.

Early Empirical Antibiotics and Adverse Clinical Outcomes in Infants Born Very Preterm: A Population-Based Cohort

OBJECTIVE

The objective of this study was to evaluate the association between empirical antibiotic therapy in the first postnatal week in uninfected infants born very preterm and the risk of adverse outcomes until discharge.

STUDY DESIGN

Population-based, nationwide registry study in Norway including all live-born infants with a gestational age <32 weeks surviving first postnatal week without sepsis, intestinal perforation, or necrotizing enterocolitis (NEC) between 2009 and 2018. Primary outcomes were severe NEC, death after the first postnatal week, and/or a composite outcome of severe morbidity (severe NEC, severe bronchopulmonary dysplasia [BPD], severe retinopathy of prematurity, late-onset sepsis, or cystic periventricular leukomalacia). The association between empirical antibiotics and adverse outcomes was assessed using multivariable logistic regression models, adjusting for known confounders.

RESULTS

Of 5296 live-born infants born very preterm, 4932 (93%) were included. Antibiotics were started in first postnatal week in 3790 of 4932 (77%) infants and were associated with higher aOR of death (aOR 9.33; 95% CI: 1.10-79.5, P = .041), severe morbidity (aOR 1.88; 95% CI: 1.16-3.05, P = .01), and severe BPD (aOR 2.17; 95% CI: 1.18-3.98; P = .012), compared with those not exposed. Antibiotics ≥ 5 days were associated with higher odds of severe NEC (aOR 2.27; 95% CI: 1.02-5.06; P = .045). Each additional day of antibiotics was associated with 14% higher aOR of death or severe morbidity and severe BPD.

CONCLUSIONS

Early and prolonged antibiotic exposure within the first postnatal week was associated with severe NEC, severe BPD, and death after the first postnatal week.

LGALS3BP in Microglia Promotes Retinal Angiogenesis Through PI3K/AKT Pathway During Hypoxia

Purpose

Retinal microglia promote angiogenesis and vasculopathy in oxygen-induced retinopathy (OIR); however, its specific molecular mechanism in the formation of retinal angiogenesis remains unclear. The lectin galactoside-binding soluble 3 binding protein (LGALS3BP), a member of the scavenger receptor cysteine-rich (SRCR) domain protein family, is involved in tumor neovascularization, and we therefore hypothesized that LGALS3BP plays an active role in microglia-induced angiogenesis.

Methods

The expression of LGALS3BP in microglia was detected by immunofluorescence, RT-qPCR, and western blotting. Functional assays of human umbilical vein endothelial cells (HUVECs) such as migration, proliferation, and tube formation were measured by Transwell, EdU, and Matrigel assays. Angiogenesis-related factors and PI3K/AKT levels were detected by western blotting. The relationship between LGALS3BP and PI3K or HIF-1α was investigated by immunoprecipitation.

Results

Our results showed that the expression of LGALS3BP was significantly increased in microglia surrounding neovascularization of the OIR mice and was also upregulated in human microglial clone 3 (HMC3) cells after hypoxia. Moreover, HUVECs co-cultured with hypoxic HMC3 cells showed increased migration, proliferation, and tube formation, as well as levels of angiogenesis-related factor. However, the proangiogenic ability and angiogenesis-related factor expression of HMC3 cells was suppressed after silencing LGALS3BP. LGALS3BP induces the upregulation of angiogenesis-related factors through the PI3K/AKT pathway and then promotes angiogenesis in microglia.

Conclusions

Collectively, our findings suggest that LGALS3BP in microglia plays an important role in angiogenesis, suggesting a potential therapeutic target of LGALS3BP for angiogenesis.

A case of anterior persistent hyperplastic primary vitreous associated with morning glory disc anomaly and retinopathy of prematurity like retinopathy in a term-born child

Background

Association of morning glory disc anomaly (MGDA) with persistent hyperplastic primary vitreous (PHPV) has been reported earlier. Retinopathy of prematurity (ROP) like retinopathy in preterm babies with optic disc anomalies has also been published. Our case is unique in terms of presence MGDA, PHPV, unilateral ROP like retinopathy in a term infant with normal birth weight.

Case presentation

A 5-month-old girl, born at term with a birth weight of 3750 g, presented with anterior PHPV, MGDA and ROP like retinopathy. In order to prevent retinal detachment, she received 360 degree barrage laser photocoagulation at the edge of the optic disc excavation of the left eye. In the follow-up a month later, laser scars were found in her left fundus without other complications.

Conclusion

PHPV and MGDA with ROP like retinopathy in term and normal weight baby is rare. The peripheral avascular retinal area, caused by the dragging of the defected optic disc, might have been more vulnerable to the oxygen change after birth which resulted in ROP like retinopathy. High sensitivity to oxygen results in a series of changes such as upregulation of VEGF and IGF-1 may cause ROP-like retinopathy.

Serum VEGF and Ang-2 Levels in Infants Before and After Laser Treatment for Retinopathy of Prematurity

To investigate VEGF and Ang-2 level changes in the systemic circulation after laser photocoagulation in premature infants with ROP. Methods: Eleven infants (4 girls and 7 boys) had serum levels determined for VEGF and Ang-2, collected 1 day prior to and 7 days after ROP laser therapy. Serum levels of VEGF and Ang-2 were quantified by enzyme-linked immunosorbent assay (ELISA). Results: Serum VEGF levels were significantly lower at 7 days after laser therapy compared to that at 1 day prior to laser therapy (p = 0.045). Serum Ang-2 levels increased significantly at 7 days after laser therapy compared with that at 1 day prior to laser therapy (p = 0.046). Conclusions: Serum VEGF levels in patients with ROP were suppressed and Ang-2 levels elevated significantly after laser therapy. The results suggest that changes in VEGF and Ang-2 serum levels may reflect regression and treatment of ROP.

Bilateral Retinoblastoma Presenting in an in vitro Fertilization Infant with Retinopathy of Prematurity

Retinopathy of prematurity (ROP) and retinoblastoma (RB) are well-described entities in premature babies. Although their pathogeneses are different, with ROP representing a disorder of interrupted development and RB a genetic disease, a few co-occurring cases have been reported, raising the possibility that the 2 conditions. Here, we report the sixth such case of co-occurring ROP and RB in an 8-month-old infant conceived by in vitro fertilization (IVF) who developed bilateral retinoblastoma a few months after treatment for advanced-stage ROP. While the ROP was initially adequately managed, bilateral RB necessitated bilateral enucleation. This case raises a number of important questions about whether IVF, ROP, and RB are causally related. Although the associations between IVF, ROP, and RB are likely to be coincidental, this case nevertheless highlights that ROP patients require regular follow-up for early diagnosis and treatment of ocular sequelae including RB.

Evaluation of Plasma Amino Acid Levels in Preterm Infants and Their Potential Correlation with Retinopathy of Prematurity

Aim

The aim of this study is to ascertain whether the level of circulating amino acids (aa) is associated with retinopathy of prematurity (ROP).

Methods

This is a randomized controlled study of 55 infants born at gestational age (GA) ≤32 weeks or birth weight (BW) ≤1500 grams. Serum samples were obtained from two groups: Group A comprised of 26 preterm infants with ROP and Group B comprised of 29 preterm infants without ROP. Plasma aa levels were analyzed using liquid chromatography with tandem mass spectrometry (LC-MS/MS). Correlation test and multivariate regression analysis were used to evaluate the relationship between plasma aa levels and variables.

Results

The mean serum arginine and glutamine levels were significantly higher, but the mean lysine and aspartic acid levels were significantly lower in Group A, compared to Group B (p = 0.04, p = 0.002, p = 0.029, and p = 0.002, respectively). In multivariate analysis, the mean arginine and lysine levels were significantly associated with the stage of the disease (p = 0.03 and p = 0.01, respectively). No significant differences were determined between the groups in terms of alanine, asparagine, valine, leucine, phenylalanine, tyrosine, serine, proline, citrulline, cysteine, ornithine, tryptophan, methionine, threonine, taurine, and isoleucine amino acids (p > 0.05, respectively).

Conclusions

These results indicate a significant association between high arginine and glutamine, with low lysine and aspartic acid serum concentrations with ROP. Due to higher serum concentrations in ROP, extra arginine-glutamine supplementation in hyperoxic conditions may be unfavorable through pathways involving reactive oxygen, particularly in patients with ROP.

Ten-Year Trend of Retinopathy of Prematurity Among Extremely Preterm Infants in One Neonatal Intensive Care Unit in China

Background: Extremely preterm (EP) infants are at the highest risk of retinopathy of prematurity (ROP). With more EP infants survived in China, recent data of ROP is lacking. The aim of the study is to report the trend of incidence of ROP among EP infants in a large neonatal intensive care unit in China over the past 10-year period, in relation with the overall survival rate and the change of oxygen saturation targets. Methods: This retrospective cohort study enrolled all EP infants born before 28 weeks' gestation and admitted to one of the largest tertiary neonatal intensive care units in China from 2010 to 2019. Data were compared between two time periods according to different oxygen saturation targets: 2010-2014 (P1) with low saturation target and 2015-2019 (P2) with higher target. Results: Of 630 EP infants admitted during the 10 years, 447 (71.0%) infants survived to discharge. The survival rate increased significantly from 61.6% in P1 to 75.8% in P2 (P < 0.05). Of the 472 infants who had ROP data, 318 (67.4%) developed ROP of any stage, 67 (14.2%) developed severe ROP, and 44 (9.3%) received treatment. The incidence of any ROP increased significantly from 51.7% in P1 to 74.3% in P2 (P < 0.05). The incidence of severe ROP increased from 11.0% in P1 to 15.6% in P2, and ROP treatment increased from 6.9% in P1 to 10.4% in P2, but neither reached statistical significance (both P > 0.05). Conclusions: We observed an increasing trend in the incidence of ROP across the 10-year period in one of the largest neonatal care units in China. The increased survival rate and the use of high-target oxygen saturation in the later period may partly explain this trend. Further investigations are needed to improve the care practices and to reduce the incidence of severe ROP.

The postnatal presence of human chorionic gonadotropin in preterm infants and its potential inverse association with retinopathy of prematurity

BACKGROUND

Human chorionic gonadotropin (hCG) and luteinizing hormone (LH) are pro-angiogenic gonadotropic hormones, which classically target the reproductive organs. However, hCG, LH, and their shared CG/LH receptor are also present in the human eye. The possibility that a deficiency of these hormones may be involved in the pathogenesis of retinopathy of prematurity (ROP) during its early non-proliferative phase has not been explored.

METHODS

We conducted a cross-sectional study of Michigan-born preterm infants utilizing dried blood spots. We analyzed hCG and LH blood levels at 1 week and 4 weeks of age from 113 study participants (60 without ROP; 53 with non-proliferative ROP). We utilized electrochemiluminescence assays on the Mesoscale Discovery platform.

RESULTS

Similar levels of hCG are found in preterm infants at both 1 week and 4 weeks after birth. Preterm infants with non-proliferative ROP, after adjusting for sex and gestational age, have 2.42 [95% CI: 1.08-5.40] times the odds of having low hCG at fourth week of age.

CONCLUSIONS

We found that hCG is present postnatally in preterm infants and that a deficiency of hCG at 4 weeks of age is potentially associated with non-proliferative ROP. This provides novel evidence to suggest that hCG may participate in human retinal angiogenesis.

Soluble Tei2 fusion protein inhibits retinopathy of prematurity occurrence via regulation of the Ang/Tie2 pathway

The aim of the present study was to investigate the potential mechanism of retinopathy of prematurity (ROP) using an oxygen-induced retinopathy (OIR) mouse model. For experiments, mice were divided into either the OIR group or control group. Fluorescein isothiocyanate-dextran cardiac perfusion and stretched retina preparation were performed. The total retina area, area of instillation, density of microvascular network, area of new blood vessels, vein width and the tortuosity of arteries were measured. Next, mice were randomly assigned into the PBS, soluble TEK receptor tyrosine kinase (sTie2)-fusion protein (Fc), angiopoietin 1 (Ang1), ranibizumab, ranibizumab + sTie2-Fc and ranibizumab + Ang1 treatment groups. Following housing for 5 days, the body weight of each mouse was recorded. Mice in the OIR group presented smaller total retina area and larger area of instillation, larger area of new blood vessels, and higher microvascular network density compared with the control PBS group. Obvious retinal vein dilatation and arterial tortuosity were identified in the OIR group. The amount of endotheliocyte nuclei of new vessels beyond the inner limiting membrane was larger in the OIR group compared with the control group. Furthermore in the next set of experiments, a larger area of instillation, smaller area of new blood vessels and decreased amount of endotheliocyte nuclei of new vessels were observed in the sTie2-Fc group, Ang1 group, ranibizumab group, ranibizumab + sTie2-Fc group and ranibizumab + Ang1 group compared with the PBS group. Specifically, the ranibizumab + sTie2-Fc group and ranibizumab + Ang1 group demonstrated markedly reduced retina instillation area and microvascular network density in the instillation area. Total retina area and body weight following 10 days of the experiment for the ranibizumab group were significantly lower compared with other groups. In conclusion, the combined regulation of the Ang/Tie2 and the vascular endothelial growth factor (VEGF)/VEGF receptor pathways markedly increased the efficacy of treatment with retinal neovascularization (RNV). Regulation of these pathways has a potential for treating RNV, in particular ROP.

Serum Vascular Endothelial Growth Factor Levels before and after Intravitreous Ranibizumab Injection for Retinopathy of Prematurity

Background

Retinopathy of prematurity (ROP) is one of the common complications of prematurity. Intravitreal injection of ranibizumab (IVR), an antivascular endothelial growth factor (VEGF) drug, showed significant benefit for ROP. However, there are concerns about systemic complications of anti-VEGF therapy in preterm infants.

Objectives

To evaluate serum VEGF level in the systemic circulation after IVR and the complications associated with IVR for the premature infants with ROP.

Methods

This prospective investigation assessed the serum concentrations of VEGF in ROP patients before and after IVR therapy. All the infants had binocular retinopathy and received IVR 0.25 mg per eye as the primary treatment. Serum samples were collected 1 day prior to injection and 1 day, 3 days, and 7 days after IVR treatment. Serum VEGF level was measured by the enzyme-linked immunosorbent assay (ELISA).

Results

Fifteen infants (6 girls and 9 boys) were enrolled. The serum concentrations of VEGF 1 day before and 1 day, 3 days, and 7 days after a total of 0.5 mg intravitreal injections of ranibizumab were 226.9 (198.4, 272.4), 12.8 (7.0, 22.4), 16 (12.0, 20.8), and 33.7 (24.0, 48.0) pg/ml, respectively. Serum VEGF levels decreased significantly at 1 day, 3 days, and 7 days after IVR treatment compared with pretreatment concentration (P < 0.05). Compared to days 1 and 3 after IVR, serum VEGF level at 7 days after IVR treatment increased significantly (P < 0.05).

Conclusion

Serum VEGF levels in patients with ROP were suppressed for at least 7 days after IVR treatment. Although the clinical significance of this phenomenon is uncertain, its safety profile requires further investigation.

Duration of Initial Empirical Antibiotic Therapy and Outcomes in Very Low Birth Weight Infants

: media-1vid110.1542/5984244681001PEDS-VA_2018-2286Video Abstract BACKGROUND: Overuse of antibiotics can facilitate antibiotic resistance and is associated with adverse neonatal outcomes. We studied the association between duration of antibiotic therapy and short-term outcomes of very low birth weight (VLBW) (<1500 g) infants without culture-proven sepsis.

METHODS

We included VLBW infants admitted to NICUs in the Canadian Neonatal Network between 2010-2016 who were exposed to antibiotics but did not have culture-proven sepsis in the first week. Antibiotic exposure was calculated as the number of days an infant received antibiotics in the first week of life. Composite primary outcome was defined as mortality or any major morbidity (severe neurologic injury, retinopathy of prematurity, necrotizing enterocolitis, chronic lung disease, or hospital-acquired infection).

RESULTS

Of the 14 207 included infants, 21% (n = 2950), 38% (n = 5401), and 41% (n = 5856) received 0, 1 to 3, and 4 to 7 days of antibiotics, respectively. Antibiotic exposure for 4 to 7 days was associated with higher odds of the composite outcome (adjusted odds ratio 1.24; 95% confidence interval [CI] 1.09-1.41). Each additional day of antibiotic use was associated with 4.7% (95% CI 2.6%-6.8%) increased odds of composite outcome and 7.3% (95% CI 3.3%-11.4%) increased odds in VLBW infants at low risk of early-onset sepsis (born via cesarean delivery, without labor and without chorioamnionitis).

CONCLUSIONS

Prolonged empirical antibiotic exposure within the first week after birth in VLBW infants is associated with increased odds of the composite outcome. This practice is a potential target for antimicrobial stewardship.

The potential effect of human chorionic gonadotropin on vasoproliferative disorders of the immature retina

Human chorionic gonadotropin (hCG) is known to be a powerful vascular endothelial growth factor (VEGF)-regulating hormone. It stimulates vascularization of the gravid uterus by upregulating VEGF expression. In the body, hCG activates the same receptor as luteinizing hormone (LH). Like hCG, LH is also strongly proangiogenic. Recently, it has been shown that LH/hCG receptors are present in the retina and that both LH and hCG are found in the eye. In fact, the human eye can synthesize its own hCG. We have previously shown that LH and VEGF are significantly correlated in mammalian eyes, potentially implicating LH-receptor/hCG-receptor activation in intraocular VEGF regulation. Given that elevated VEGF is associated with progression of two vasoproliferative pediatric retinal disorders, retinopathy of prematurity and retinoblastoma, our objective was to determine whether hCG may potentially affect VEGF production and pathologic retinal vascularization in vasoproliferative disorders affecting the immature retina. In this study, we used (a) oxygen-induced retinopathy mouse model (standard model for retinopathy of prematurity) and (b) Y79 retinoblastoma cells (a human cell line derived from immature retinal cells). In the oxygen-induced retinopathy model, number of preretinal nuclei (representing pathologic retinal neovascularization) significantly increases by 57% (P<0.05) in hCG-treated mice. In Y79 cells, VEGF production significantly increases by 37% (P<0.05) in hCG-treated cells. These findings suggest that hCG is potentially able to influence retinal vascularization and VEGF production and thus, the hCG receptor may potentially represent a therapeutic target for vasoproliferative retinal disorders affecting the young eye.

Demographic profile and ocular characteristics of stage 5 retinopathy of prematurity at a referral center in Northwest China: implications for implementation

Background

Severe retinopathy of prematurity (ROP) with extremely unfavorable prognosis among infants can do great damage to individuals and bring tremendous social-economic burden. The purpose of this study is to describe the demographic and ocular characteristics of infants who presented with stage 5 ROP in order to identify reasons why they have become blind, and to identify contributing factors in order to focus great attention on the current ROP program and to inspire more effort in ROP screening in middle income countries.

Methods

A retrospective review of consecutive infants with stage 5 ROP from December 2010 to December 2016 in Department of Ophthalmology, Xijing Hospital. Various parameters retrieved included birthweight, gestational age, age at initial examination, postmenstrual age, screening details, check-up details and reasons for consultation. Ocular findings were recorded and also detected by ultrasonography.

Results

A retrospective review of 20 consecutive infants with stage 5 ROP are included. Mean birthweight was1712.3 ± 512.97 g and mean gestational age at birth was 32.1 ± 2.21 weeks. Median age at first consultancy was 9.7 month. Median postmenstrual age first consultancy was 52 weeks. All infants were never screened for ROP before they came to the referral center. Of twenty stage 5 ROP infants, 13 cases presented with bilateral stage 5 features. Of the 40 eyes of 20 infants, 33 eyes were diagnosed as stage 5. Leukocoric pupil, closed funnel configuration of retinal detachment (RD), posterior synechia, extraretinal fibrovascular proliferation and retinal folds were the most significant indicators of bad prognosis. Ten eyes appeared no fixation to light, while 30 eyes exhibited following to light or following to toys.

Conclusions

Our study shows that in relatively less-developed regions of China, more needs to be done to spread awareness about the disease among pediatricians, neonatologists and ophthalmologists as well as parents of premature infants. Thus, a comprehensive control system which is a whole network of propaganda, screening, treatment and follow-up are encouraged especially in less developed areas in China as well as worldwide.

The treatment and risk factors of retinopathy of prematurity in neonatal intensive care units

Background

Retinopathy of prematurity (ROP) is a vascular proliferative disorder of the developing retina and a significant cause of childhood blindness around the world. The incidence of ROP is affected by many factors, and the incidence rate varies from country to country. The purpose of this study is to report the incidence and risk factors of ROP in neonatal intensive care unit (NICU) of Guangzhou First People’s Hospital in China.

Methods

A retrospective review was performed on 436 premature infants who were consecutive ROP screened in the NICU of Guangzhou First People’s Hospital from March 2013 to October 2017. The single-factor analysis and the logistic multivariate regression analysis were used to detect risk factors of ROP.

Results

Total 436 premature infants were consecutive ROP screened, 138 (31.65%) were found ROP, and 61(13.99%) were treated. The single-factor analysis revealed that the incidence of ROP was associated with multiple births, gestational age, birth weight, mechanical ventilation, intravascular hemolysis, the number of operations and blood culture results. The logistic multivariate regression analysis revealed that gestational age; birth weight, mechanical ventilation, minimum SaO2 and daily weight gain were independent risk factors for ROP onset. Forty-nine patients underwent retinal laser photocoagulation with recurrence 20 patients. Twelve patients underwent anti-VEGF drug (Ranibizumab) via intraocular injection with 5 patients of recurrence.

Conclusions

The incidence of ROP in NICU of Guangzhou China will match those in middle-income countries, but higher than high-income countries. Anti-VEGF drugs could be preferred as a good treatment method for zone 1 ROP and aggressive posterior ROP.

Invasive Fungal Infections in Neonates in Canada: Epidemiology and Outcomes

BACKGROUND

Neonatal fungemia is associated with adverse neonatal outcomes and higher overall healthcare expenditure. Our objective is to review the epidemiology of invasive fungal infections (IFIs) in neonates in Canada.

METHODS

A retrospective cohort study using data collected by the Canadian Neonatal Network (CNN) was conducted. Using a nested matched cohort study design, risk factors and outcomes of neonates born <33 weeks gestation (n = 39,305) during 2003-2013 were compared between neonates diagnosed with an IFI during their stay to infection-free controls.

RESULTS

Overall incidence of IFI among all admitted neonates was 0.22% (n = 286), while the incidence of IFI in the group of neonates born <33 weeks gestation was 0.64%. Of the isolates, 170 (59%) had Candida albicans and 59 (21%) had Candida parapsilosis. Risk factors for IFI were lower gestation, male sex, Apgar score <7 at 5 minutes, higher severity of illness score, maternal diabetes and vaginal birth. Neonates with IFI had higher odds of mortality [adjusted odds ratio (aOR): 1.60; 95% confidence interval (CI): 1.06-2.43], necrotizing enterocolitis (aOR: 2.97; 95% CI: 1.76-5.01) and severe retinopathy of prematurity (aOR: 2.15; 95% CI: 1.26-3.67).

CONCLUSIONS

The overall incidence of IFI in neonates was low in Canada in comparison to other large population cohort studies; however, the mortality and morbidity remained high.

Elimination of Signaling by the Luteinizing Hormone Receptor Reduces Ocular VEGF and Retinal Vascularization during Mouse Eye Development

Purpose/Aim: Vascular endothelial growth factor (VEGF) dysregulation is implicated in the pathogenesis of retinopathy of prematurity (ROP). Identifying the factors that contribute to VEGF regulation during normal retinal vascularization is the key to ROP prevention. Currently, physiologic hypoxia is thought to be responsible for retinal VEGF regulation in utero. However, a potential hormonal contribution to VEGF regulation during eye development has not been fully investigated. The placental hormone, human chorionic gonadotropin and the pituitary hormone, and luteinizing hormone (LH) induce VEGF expression in several tissue types. Both of these gonadotropins activate the same LH receptor (LHR) in the human body; LHRs are expressed in the retina. In this study, we aimed to show that LHR signaling participates in VEGF regulation in the developing eye.

METHODS

When offspring from breeding pairs of LHR knockout mice (lhrkos) reached 21 days old, eyes and serum were extracted from homozygote lhrkos and wildtype (WT) siblings. VEGF levels were measured using Mouse VEGF Quantikine immunoassay kit. Retinas were incubated with isolectin for endothelial cell staining, flat mounted and imaged by confocal microscopy. Retinal vascular density was quantified using Imaris software. Some eyes were sectioned and stained for histopathologic review.

RESULTS

Ocular VEGF and retinal vascular volumes were significantly reduced by ~ 15% in lhrko eyes. Serum VEGF was not changed. The lhrko retinas did not display any anomalies.

CONCLUSIONS

We provide evidence that LHR signaling plays a role in VEGF regulation and vascularization in the developing eye. Given that human preterm infants may have altered LHR-activity, the effect of gonadotropins on eye development should be further studied to identify novel strategies for ROP prevention.

Association of admission temperature and death or adverse neurodevelopmental outcomes in extremely low-gestational age neonates

OBJECTIVE

Preterm infants are at higher risk of developing hypothermia and complications from cold stress, resulting in high mortality and short-term morbidity. Our objective is to evaluate the association between admission temperatures of extremely low-gestational age neonates (ELGAN) (<29 weeks') and adverse short-term neurodevelopmental outcomes.

STUDY DESIGN

In this retrospective study, we included ELGAN admitted to NICUs across Canada between April 2009 and September 2011, who underwent neurodevelopmental assessment at 18-21 months' corrected age.

RESULTS

Of 2739 infants with a complete data set identified during the study period, 968 (35.3%) had admission temperatures ≤36.4 °C (hypothermia group), 1489 (54.5%) had temperature of 36.5-37.2 °C (normothermia group), and 282 (10.3%) had hyperthermia (≥37.3 °C). Their mean birth weight was 823 ± 230 g, 944 ± 227 g and 927 ± 223 g, respectively (p < 0.01). More than 50% of infants born at 23-24 weeks were in the hypothermic group compared to 28.5-36.1% at higher gestational ages. We found 39.5% of infants in the hypothermic group had primary composite outcome of death or severe neurodevelopmental impairment (sNDI). Multivariate logistic regression revealed an increased adjusted odd of primary composite outcome (OR = 1.32; 95% CI = [1.05, 1.66]) in the hypothermic group, compared to infants with normothermia on admission.

CONCLUSIONS

In our cohort of ELGAN, hypothermia on admission was associated with increased risk of death or sNDI.

Microglial density determines the appearance of pathological neovascular tufts in oxygen-induced retinopathy

The oxygen-induced retinopathy (OIR) animal model established in C57 mice and SD rats has been widely used in retinal neovascular disease studies, while Balb/c mice have not been used because Balb/c OIR mice lack neovascular tufts. One study found a substantial difference in the density of retinal microglia between C57 and Balb/c mice; however, no direct evidence could clarify whether the density of retinal microglia in Balb/c mice led to this difference. In our study, intraperitoneal injection of minocycline was used to inhibit the activation of microglia and intravitreal injection of clodronate liposomes was used to decrease the density of microglia in Balb/c OIR model mice. We found that with the decline in microglia induced by the two drugs, the avascular area in treated Balb/c OIR mice was higher than that in untreated Balb/c OIR mice; moreover, a small area of neovascular tufts appeared at P17. After checking the expression of Iba1, a microglial marker and GFAP, an astrocyte and Müller cell marker, we found that minocycline and clodronate could inhibit the activation of microglia or decrease the density of microglia, while they had no significant effect on astrocytes and Müller cells. Therefore, these data suggest that the density of microglia in the retina may determine the result of vasculopathy in OIR mice to some extent. In future studies, predicting the development of retinal neovascular diseases by detecting the density of microglia in living animals or human beings with newly developed instruments and methods may be useful.

Impact of minocycline on vascularization and visual function in an immature mouse model of ischemic retinopathy

The role of microglia in the pathophysiology of ischemic retinal diseases has been extensively studied. Retinal microglial activation may be correlated with retinal neovascularization in oxygen-induced retinopathy (OIR), an animal model that has been widely used in retinopathy of prematurity (ROP) research. Minocycline is an antibiotic that decreases microglial activation following hyperoxic and hypoxic-ischemic phases in neonatal rodents. Here, we investigated the effects of minocycline on vascularization and visual function. In our results, we found that after the administration of minocycline, microglial reactivity was reduced in the retina, which was accompanied by an increase in the avascular area at P12, P14 and P17. Although microglial reactivity was reduced at P17, minocycline treatment did not attenuate retinal neovascularization. A changing trend in microglial number was observed, and the apoptosis and proliferation states on different days partly contributed to this change. Further study also revealed that although minocycline downregulated the levels of proinflammatory factors, visual function appeared to be significantly worsened. Collectively, we demonstrated that minocycline disturbed the physiological vascularization of the avascular area and exacerbated visual dysfunction, indicating that minocycline may not be an effective drug and may even be detrimental for the treatment of ischemic retinopathy in immature mammals.

RORα modulates semaphorin 3E transcription and neurovascular interaction in pathological retinal angiogenesis

Pathological proliferation of retinal blood vessels commonly causes vision impairment in proliferative retinopathies, including retinopathy of prematurity. Dysregulated crosstalk between the vasculature and retinal neurons is increasingly recognized as a major factor contributing to the pathogenesis of vascular diseases. Class 3 semaphorins (SEMA3s), a group of neuron-secreted axonal and vascular guidance factors, suppress pathological vascular growth in retinopathy. However, the upstream transcriptional regulators that mediate the function of SEMA3s in vascular growth are poorly understood. Here we showed that retinoic acid receptor-related orphan receptor α (RORα), a nuclear receptor and transcription factor, is a novel transcriptional regulator of SEMA3E-mediated neurovascular coupling in a mouse model of oxygen-induced proliferative retinopathy. We found that genetic deficiency of RORα substantially induced Sema3e expression in retinopathy. Both RORα and SEMA3E were expressed in retinal ganglion cells. RORα directly bound to a specific ROR response element on the promoter of Sema3e and negatively regulated Sema3e promoter-driven luciferase expression. Suppression of Sema3e using adeno-associated virus 2 carrying short hairpin RNA targeting Sema3e promoted disoriented pathological neovascularization and partially abolished the inhibitory vascular effects of RORα deficiency in retinopathy. Our findings suggest that RORα is a novel transcriptional regulator of SEMA3E-mediated neurovascular coupling in pathological retinal angiogenesis.-Sun, Y., Liu, C.-H., Wang, Z., Meng, S. S., Burnim, S. B., SanGiovanni, J. P., Kamenecka, T. M., Solt, L. A., Chen, J. RORα modulates semaphorin 3E transcription and neurovascular interaction in pathological retinal angiogenesis.

Evaluation of Visunex Medical's PanoCam(TM) LT and PanoCam(TM) Pro wide-field imaging systems for the screening of ROP in newborn infants

INTRODUCTION

Retinopathy of Prematurity (ROP) is a leading cause of childhood blindness. The incidence of ROP is rising, placing greater demands on the healthcare providers that serve these patients and their families. Telemedicine remote digital fundus imaging (TM-RDFI) plays a pivotal role in ROP management, and has allowed for the expansion of ROP care into previously underserved areas.

AREAS COVERED

A broad literature review through the pubmed index was undertaken with the goal of summarizing the current state of ROP and guidelines for its screening . Furthermore, all currently used telemedicine remote digital fundus imaging devices were analyzed both via the literature and the companies' websites/brochures. Finally, the PanoCam LT™ and PanoCam™ Pro created by Visunex Medical were analyzed via the company website/brochures. Expert commentary: The PanoCam LT™ and PanoCam™ Pro have recently been approved for use within the USA and CE marked for international commercialization in European Union and other countries requiring CE mark. These wide-field imaging systems have the intended use of ophthalmic imaging of all newborn babies and meet the requirements for ROP screening, thereby serving as competition within the ROP screening market previously dominated by one camera imaging system.

Retinal oxygen: from animals to humans

This article discusses retinal oxygenation and retinal metabolism by focusing on measurements made with two of the principal methods used to study O₂ in the retina: measurements of PO₂ with oxygen-sensitive microelectrodes in vivo in animals with a retinal circulation similar to that of humans, and oximetry, which can be used non-invasively in both animals and humans to measure O₂ concentration in retinal vessels. Microelectrodes uniquely have high spatial resolution, allowing the mapping of PO₂ in detail, and when combined with mathematical models of diffusion and consumption, they provide information about retinal metabolism. Mathematical models, grounded in experiments, can also be used to simulate situations that are not amenable to experimental study. New methods of oximetry, particularly photoacoustic ophthalmoscopy and visible light optical coherence tomography, provide depth-resolved methods that can separate signals from blood vessels and surrounding tissues, and can be combined with blood flow measures to determine metabolic rate. We discuss the effects on retinal oxygenation of illumination, hypoxia and hyperoxia, and describe retinal oxygenation in diabetes, retinal detachment, arterial occlusion, and macular degeneration. We explain how the metabolic measurements obtained from microelectrodes and imaging are different, and how they need to be brought together in the future. Finally, we argue for revisiting the clinical use of hyperoxia in ophthalmology, particularly in retinal arterial occlusions and retinal detachment, based on animal research and diffusion theory.

Smouldering retinopathy of prematurity: a case treated by multiple antivascular endothelial growth factor therapy

A 13 months old female baby born at 24 weeks of gestational age (GA) presented with stage 4A retinopathy of prematurity (ROP) with plus disease in the right eye and stage 3 with plus disease in the left eye. The baby was diagnosed with stage 3 zone 2 ROP in both eyes with plus disease at 32 weeks of GA and received intravitreal bevacizumab in both eyes. The baby received intravitreal bevacizumab and ranibizumab injections at 39 and 57 weeks of postmenstrual age (PMA), respectively for recurrence. Laser treatment to peripheral avascular retina was carried out at 67 weeks of PMA. The right eye progressed to stage 4A and left eye developed pre-retinal haemorrhages. This case reports late recurrence treated with initial multiple antivascular endothelial growth factor (VEGF) injections alone. One should be cautious in using anti-VEGF agents as a monotherapy in cases of ROP that appear different from the current understanding of the natural course of the disease.

Proteomic profiling of the retinas in a neonatal rat model of oxygen-induced retinopathy with a reproducible ion-current-based MS1 approach

Investigation of the retina proteome during hypoxia-induced retinal neovascularization is valuable for understanding pathogenesis of retinopathy of prematurity (ROP). Here we employed a reproducible ion-current-based MS1 quantification approach (ICB) to explore the retinal proteomic changes in early stage of ROP in a rat model of oxygen-induced retinopathy (OIR). Retina proteins, which are rich in membrane proteins, were efficiently extracted by a detergent-cocktail and subjected to precipitation/on-pellet-digestion, followed by nano-LC-MS analysis on a 75-cm column with a 7-h gradient. The high reproducibility of sample preparation and chromatography separation enabled excellent peak alignment and contributed to the superior performance of ICB over parallel label-free approaches. In this study, sum-of-intensity with rejection was incorporated to determine the protein ratios. In total, 1325 unique protein groups were quantified from rat retinas (n = 4/group) with at least two distinct peptides at a protein FDR of 1%. Thirty-two significantly altered proteins were observed with confidence, and the elevated glial fibrillary acidic protein and decreased crystalline proteins in OIR retinas agree well with previous studies. Selected key alterations were further validated by Western blot analysis. Interestingly, Rab21/RhoA/ROCK2/moesin signaling pathway was found to be involved in retinal neovascularization of OIR. Moreover, highly elevated annexin A3, a potential angiogenic mediator, was observed in OIR retinas and may serve as a potential therapeutic target. In conclusion, reproducible ICB profiling enabled reliable discovery of many altered mediators and pathways in OIR retinas, thereby providing new insights into molecular mechanisms involved in pathogenesis of ROP.