Retinopathy of prematurity in infants less than 29 weeks' gestation at birth

Global Prevalence and Severity of Retinopathy of Prematurity over the Last Four Decades (1985-2021): A Systematic Review and Meta-Analysis

BACKGROUND

Retinopathy of prematurity (ROP) is a vasoproliferative disease of the retina that occurs in premature infants. The prevalence of ROP reported so far is inconsistent.

AIM

To conduct a systematic review to describe the trend of ROP prevalence between 1985 and 2021, and to determine the influence of countries' economic conditions on ROP prevalence.

METHODS

We searched PubMed, Embase, and Google Scholar for studies published between January 1985 and December 2021 using the following MeSH terms: "retinopathy of prematurity", "ROP", "incidence", and "prevalence". Two independent reviewers examined the articles to select studies that met the selection criteria and performed data extraction and study quality assessment. For the meta-analysis, the pooled prevalence was calculated using a random-effects model and R software.

RESULTS

Of 5,250 titles and abstracts, 139 original studies met the inclusion criteria; a total of 121,618 premature infants were included in these studies. The pooled prevalence of ROP was 31.9% (95% confidence interval [CI] 29.0-34.8) and that of severe ROP was 7.5% (6.5-8.7). In general, no significant differences in prevalence were found over the four decades; however, we found a higher prevalence in premature infants ≤28 weeks of gestational age. In addition, the highest ROP prevalence was found in lower-middle-income countries with high mortality rates. In contrast, the highest severe ROP prevalence was found in high-income countries.

CONCLUSION

ROP remains a common cause of morbidity in premature infants worldwide. Therefore, it seems necessary to maintain early identification strategies for patients at higher risk, particularly in low- and middle-income countries.

Increased use of heated humidified high flow nasal cannula is associated with longer oxygen requirements

AIM

There has been an increased use of heated humidified high flow nasal canula (HFNC) in premature babies (PBs) admitted to our neonatal unit. The aim of this study is to identify clinical characteristics in PBs < 29 weeks gestational age (GA) that distinguish between those who did not or did receive HFNC.

METHODS

This study compared prospectively collected data from 2010 to 2012. Comparisons were undertaken between PBs<29 weeks GA who received continuous positive airway pressure (CPAP: 44/72 (61.1%)) to those who received both CPAP and HFNC (28/72 (38.9%)). Data were analysed using general linear models.

RESULTS

There were no significant differences in baseline characteristics between the groups (GA: 27.6 ± 1.1 vs. 27.5 ± 1.1 (weeks), birth weight: 1066 ± 209 vs. 1057 ± 304 (grams) respectively). When analysing outcome measures with multivariate analysis, we found the corrected GA to cease CPAP and oxygen were significantly longer in the HFNC group (31.2 ± 2.1 vs. 32.7 ± 2.0 weeks, P = 0.01 and 32.8 ± 3.5 vs. 36.5 ± 2.8 weeks, P < 0.0001 respectively).

CONCLUSIONS

Increased use of HFNC has been associated with increased oxygen requirements. These findings highlight the need to review the use of HFNC in small PBs.

Screening Tool for Early Postnatal Prediction of Retinopathy of Prematurity in Preterm Newborns (STEP-ROP)

BACKGROUND

Retinopathy of prematurity (ROP) is a disorder of the preterm newborn characterized by neurovascular disruption in the immature retina that may cause visual impairment and blindness.

OBJECTIVE

To develop a clinical screening tool for early postnatal prediction of ROP in preterm newborns based on risk information available within the first 48 h of postnatal life.

METHODS

Using data submitted to the Vermont Oxford Network (VON) between 1995 and 2015, we created logistic regression models based on infants born <28 completed weeks gestational age. We developed a model with 60% of the data and identified birth weight, gestational age, respiratory distress syndrome, non-Hispanic ethnicity, and multiple gestation as predictors of ROP. We tested the model in the remaining 40%, performed tenfold cross-validation, and tested the score in ELGAN study data.

RESULTS

Of the 1,052 newborns in the VON database, 627 recorded an ROP status. Forty percent had no ROP, 40% had mild ROP (stages 1 and 2), and 20% had severe ROP (stages 3-5). We created a weighted score to predict any ROP based on the multivariable regression model. A cutoff score of 5 had the best sensitivity (95%, 95% CI 93-97), while maintaining a strong positive predictive value (63%, 95% CI 57-68). When applied to the ELGAN data, sensitivity was lower (72%, 95% CI 69-75), but PPV was higher (80%, 95% CI 77-83).

CONCLUSIONS

STEP-ROP is a promising screening tool. It is easy to calculate, does not rely on extensive postnatal data collection, and can be calculated early after birth. Early ROP screening may help physicians limit patient exposure to additional risk factors, and may be useful for risk stratification in clinical trials aimed at reducing ROP.

Pharmacologic interventions for the prevention and treatment of retinopathy of prematurity

Retinopathy of prematurity (ROP), a significant morbidity in prematurely born infants, is the most common cause of visual impairment and blindness in children and persists till adulthood. Strict control of oxygen therapy and prevention of intermittent hypoxia are the keys in the prevention of ROP, but pharmacologic interventions have decreased risk of ROP. Various drug classes such as methylxanthines (caffeine), VEGF inhibitors, antioxidants, and others have decreased ROP occurrence. The timing of pharmacologic intervention remains unsettled, but early prevention rather than controlling disease progression may be preferred. These drugs act through different mechanisms, and synergistic approaches should be considered to maximize efficacy and safety.

One-year experience in the retinopathy of prematurity: frequency and risk factors, short-term results and follow-up

AIM

As a result of the increase in premature births and the advances in neonatal intensive care, retinopathy of prematurity (ROP) remains one of the most important causes of childhood blindness worldwide. The main factors in the development of ROP are gestational age, birth weight and oxygen therapy. ROP continues to gain importance due to the increasing survival rates of more immature babies.

METHODS

Between January 2007 and October 2008, 203 premature infants treated at the Neonatal Intensive Care Unit (NNICU) were prospectively enrolled and the relationship between known risk factors and the occurance of ROP was studied.

RESULTS

ROP in various stages developed in 86 cases (42.4%). Statistically significant correlations were found between the development of ROP and birth weight (P<0.0001) gestational age (P<0.0001), oxygen treatment and its duration (P<0.0001 and P=0.002), mechanical ventilation (MV) and its duration (P=0,0001 and P=0.0001), apnea (P=0.001), intraventricular hemorrhage (IVH) (P=0.046), sepsis (P=0.0001), use of erythropoietin (EPO) (P=0.003), the number of blood transfusions and frequency (P=0.0001 and P=0.0001), surfactant application (P=0.0001), the presence of patent ductus arteriosus (PDA) (P=0.001) or bronchopulmonary dysplasia (BPD) (P=0.0001). No significant correlations were found between the occurance of ROP and maternal pre-eclampsia (P=0.293), multiple pregnancy (P=0.218), or hyperbilirubinemia (P=0.494). Severity of ROP was related significantly with birth weight (P=0.0001), but no significant correlation between severity of ROP and gestational age was present.

CONCLUSION

Early description and reduction of the risk factors related with the occurance of ROP with the help of routine screening programs may warrant the prevention of visual loss, however early ophthalmic diagnosis and treatment are still mandatory to provide better visual rehabilitation.

Retinopathy of prematurity in very low birth weight infants and the potential protective role of indomethacin

BACKGROUND AND OBJECTIVE

To describe clinical features of very low birth weight (VLBW) infants and examine the effect of indomethacin on the incidence of retinopathy of prematurity (ROP).

PATIENTS AND METHODS

Medical records of all VLBW infants over a 4-year period were reviewed. Data regarding systemic and ophthalmic examinations were analyzed.

RESULTS

Forty-seven infants with ROP were evaluated. Most infants had bilateral stage 1 or 2 disease extending 5 clock hours. Infants with ROP had younger mean gestational age, had lower gestational weight, and demonstrated higher incidence of diseases of prematurity. These infants were exposed to increased doses of surfactant and higher oxygen concentration for a prolonged duration given their immature pulmonary status. Independent predictors of ROP susceptibility also included length of hospitalization and Apgar score at 5 minutes. Patent ductus arteriosus was more common among infants with ROP. Approximately half of the infants who received one or two doses of indomethacin had ROP, but the ROP rate was decreased in infants who received three doses.

CONCLUSION

Premature infants with younger gestational age, lower gestational weight, and severe morbidities were found to have an increased prevalence of ROP. Indomethacin treatment for patent ductus arteriosus may have a protective role in the development of severe ROP.

Retinopathy of prematurity: recent advances in our understanding

Retinopathy of prematurity (ROP) has been recognised as an important cause of childhood visual impairment and blindness since the 1940s when improved facilities and treatment increased the survival rate of premature infants. Although its incidence and severity have been decreasing in developed countries over the past two decades, both are increasing in developing nations. ROP is consequently targeted as an important but avoidable disease. This review provides an updated summary and discussion of much of the work that has been produced through population, animal, cell culture, and genetic research. The authors examine the prevalence, risk factors, and possible causes of the disease with a particular focus on genetic studies. They conclude that while significant reductions in the disease have occurred in developed countries, further research is required to fully understand and prevent the disease. In the meantime, development and implementation of appropriate screening and treatment strategies will be critical in reducing blindness in developing countries.

Retinopathy of prematurity: recent advances in our understanding

Retinopathy of prematurity (ROP) has been recognised as an important cause of childhood visual impairment and blindness since the 1940s when improved facilities and treatment increased the survival rate of premature infants. Although its incidence and severity have been decreasing in developed countries over the past two decades, both are increasing in developing nations. ROP is consequently targeted as an important but avoidable disease. This review provides an updated summary and discussion of much of the work that has been produced through population, animal, cell culture, and genetic research. The authors examine the prevalence, risk factors, and possible causes of the disease with a particular focus on genetic studies. They conclude that while significant reductions in the disease have occurred in developed countries, further research is required to fully understand and prevent the disease. In the meantime, development and implementation of appropriate screening and treatment strategies will be critical in reducing blindness in developing countries.

Retinopathy of prematurity in infants < 32 weeks' gestation at birth in New South Wales in 1993 and 1994

OBJECTIVE

To study the incidence and severity of retinopathy of prematurity (ROP) in infants < 32 weeks' gestation.

DESIGN

Review of the records maintained in the New South Wales Neonatal Intensive Care Unit Study (NICUS) database on infants admitted to the neonatal intensive care units (NICU) in NSW from 1 January 1993 to 31 December 1994.

RESULTS

In the more premature infants, 23-26 weeks' gestation, 65% developed ROP (102 of 157 examined for ROP). Forty-four infants (28%) developed severe ROP (Stage ≥ 3 ROP), 19 infants (12.1%) required cryo/laser therapy and one infant (0.6%) in this group had a retinal detachment. One hundred and fifty-seven of 159 surviving infants (98.7%) were examined for ROP. In the infants 27-28 weeks' gestation, 38.3% developed ROP (103 of 269 examined for ROP). Fifteen infants (5.6%) developed severe ROP, seven infants (2.6%) required cryo/laser therapy for threshold ROP and three infants (1.1%) in this group had a retinal detachment. Two hundred and sixty-nine of 299 surviving infants (90%) were examined for ROP. In the infants 29-31 weeks' gestation, 10.8% developed ROP (48 of 443 examined for ROP). Six infants (1.4%) developed severe ROP, one infant (0.2%) required cryo/laser therapy for threshold ROP and no infant in this group had a retinal detachment. However, only 443 of 681 surviving infants (65.1%) in this group were examined for ROP. Of the four infants with detached retinas, one was a 25 week gestation infant weighing 840 g, two were 27 weeks' gestation weighing 960 and 980 g and one infant was a 28 week gestation infant weighing 620 g. No infant developed Stage 5 ROP.

CONCLUSION

In the more mature infants 29-31 weeks' gestation, the rate of ROP is low, although severe ROP still occurs. However, only 65.1% of these infants were examined for ROP and we should be diligent in screening for ROP in the sicker infants in this group. The incidence of severe ROP as well as the rate of cryo/laser therapy in premature infants 23-26 weeks' in NSW has not changed since the increases seen in the early 1990s. Retinal detachment also occurs in the infants 27-28 weeks' gestation and it is important that all these infants are screened for ROP.

Dexamethasone reduces oxygen induced retinopathy in a mouse model

Dexamethasone is widely used in the postnatal period. Its impact on retinopathy of prematurity (ROP) is extremely controversial; published studies have found a detrimental, protective, or no effect on ROP. The goal of this study was to test the hypothesis that use of dexamethasone during the injury phase (oxygen exposure) reduces the severity of oxygen-induced retinopathy (OIR) in a mouse model. C57BL6 mice pups were exposed to either room air or hyperoxia (75% FiO2) from postnatal d 7 through 12 (PN7-12) with or without dexamethasone (0.5 mg/kg/d s.c.) and killed on PN17-21. Retinopathy was assessed by a scoring system of retinal flat mount preparations and periodic acid-Schiff (PAS) staining of retinal sections. Pups exposed to dexamethasone and oxygen had a lower median retinopathy score of 5 (4, 6) [median (25th, 75th quartile)] compared with animals exposed to oxygen alone with median score of 9 (6, 10) with p < 0.001. PAS staining for extra retinal neovascularization in the dexamethasone and oxygen treated animals showed a significant reduction in number of nuclei extending beyond the inner limiting membrane when compared with oxygen exposed alone (p = 0.04). Animals treated with dexamethasone had decreased weight gain compared with control animals. Dexamethasone did not appear to affect the normal development of retinal vasculature as assessed by the scoring system when compared with control animals. Thus, dexamethasone decreases severity of OIR without having an adverse effect on normal retinal vascular development in the mouse model. We speculate that dexamethasone decreases the injury response that occurs during the hyperoxic phase, thus protecting the developing vasculature and improving the subsequent retinopathy.

Retinopathy of prematurity: lack of association with prenatal care

OBJECTIVES

The overall goal of this study was to prospectively assess risk factors for retinopathy of prematurity (ROP) in infants of birth weight <1250 g in an urban population at Bellevue Hospital Center, New York, New York. The hypothesis tested was that lack of prenatal care increases the incidence of ROP.

METHODS

A consecutive sample of patients admitted to Bellevue Hospital Center's neonatal intensive care unit/special care nursery who weighed <1250 g at birth and survived until their ophthalmology screening examinations were included in the study. The main outcome measures were presence or absence of ROP and prenatal care. Additional relevant clinical information was collected on the patients.

RESULTS

Ninety infants were evaluated. Sixty-one (68%) had ROP; 29 (32%) had no ROP. No differences in incidence or severity of ROP were detected with regard to prenatal care when the 2 groups were compared. In this population <1250 g, there were no differences in birth weight or gestational age with respect to prenatal care or lack of prenatal care.

CONCLUSIONS

Lack of prenatal care was not associated with an increased risk for ROP in infants with birth weight <1250 g in this urban population.

Retinopathy of prematurity in infants less than 29 weeks' gestation: 3 1/2 years pre- and postsurfactant

OBJECTIVE

To determine the effects of surfactant on retinopathy of prematurity (ROP).

DESIGN

We compared infants for 3 1/2 years both before and after the introduction of surfactant in our neonatal intensive care unit (NICU) using prospectively collected data. Exogenous surfactant (Exosurf) was introduced into our NICU on July 1, 1991.

METHODS

We compared the incidence and severity of ROP in two groups of infants born at less than 29 weeks' gestation who required cryo- or laser therapy. Premature infants born during the first 3 1/2 years following the introduction of surfactant were compared with those born during the 3 1/2-year period prior to its introduction. The infants were examined by one ophthalmologist (J.K.) and classified according to the International Classification of ROP.

RESULTS

A total of 124 infants born presurfactant and 152 infants born postsurfactant were examined for the presence of ROP. No significant difference between the two groups regarding any stage of ROP or the necessity for treatment was found. In infants of less than 27 weeks' gestation, a significant reduction in the number requiring cryo- or laser therapy was noted (12 of 48 examined [25.0%] vs 6 of 62 examined [9.7%], respectively; P < 0.05). This decreased need for treatment, however, was found in infants without hyaline membrane disease who did not receive surfactant.

CONCLUSION

Exosurf has had no significant impact on the incidence or severity of ROP. Due to its effect on improved survival rates, the surfactant produces a larger proportion of infants at risk of developing ROP. Other changes in NICU protocol may be causing a reduction in the incidence of severe ROP.