Incidence of ROP in two consecutive Swedish population based studies

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.

Retinopathy prematurity: a systematic review and meta-analysis study based on neonatal and maternal risk factors

BACKGROUND

Retinopathy of prematurity is the abnormal development of retinal arteries in preterm neonates less than 32 weeks and weighing 1500 g, and less, which can lead to visual impairment during life and blindness. This study aims to investigate the relationship between some clinical characteristics of neonates and mothers with Retinopathy of prematurity in the world via a systematic review and meta-analysis.

MATERIALS AND METHODS

The present study is a systematic review and meta-analysis on the relationship between maternal and neonatal clinical variables with Retinopathy of prematurity in the world from the beginning of 2000 to the end of 2020. Accordingly, all English articles published on the topic were searched in scientific databases of Web of Science, PubMed, Google Scholar, Science Direct, and Scopus. The articles were searched independently by two researchers. Statistical analysis of data was performed using fixed and random effects model statistical tests in the meta-analysis, Cochran, meta-regression, I² index, Funnel plot, and Begg's by STATA software program, version 14.

RESULT

A total of 191 studies with a sample size of 140,921 persons were including in the meta-analysis. Accordingly, Preterm delivery ≤28 weeks (OR:6.3, 95% CI:4.9-8.1), Birth Weight ≤1000 g (OR:5.8, 95% CI:4.8-6.8), Birth Weight ≤1500 g (OR:4.8, 95% CI:3.8-6.1), PROM (OR:1.2, 95% CI:1.0-1.4), induced fertility (OR:1.9, 95% CI:1.1-3.0) and Chorioamnionitis (OR:1.5, 95% CI:1.0-2.2) There was a statistically significant association with retinopathy.

CONCLUSION

Based on the results of the present meta-analysis, the risk of retinopathy of prematurity in neonates born at 28 weeks and less, LBW (weight 1500 g and less), neonatal hypotension, chorioamnionitis, and induced fertility increases.

Incidence, Long-Term Visual Outcomes, and Mortality in Retinopathy of Prematurity in Korea: A Nationwide Population-Based Study

Purpose

To evaluate the incidence, visual prognosis, and mortality in retinopathy of prematurity (ROP) in Korea.

Methods

We used the National Health Insurance and the Korean Disability Registry database, which covers the entire newborn population in 2006 to 2014 and includes information on all newborns diagnosed with ROP until 2016. Using these databases, we evaluated the incidence, rate of visual impairment (VI), and mortality in patients with ROP according to the birth weight categories and treatment modalities.

Results

The ROP incidence per 1000 newborns was 1.99, which broke down into 317.14 in the very low birth weight (VLBW) less than 1500 g population, 25.45 in the 1500 to 2499 g population, and 0.29 in the 2500 g or greater population. When assessed at age 10, the VI rate was 2.2 per 100 person-years, which was highest at 4.5 per 100 person-years in the VLBW population compared with the population in other birth weight categories. Among treated cases, the proportion of VI in patients undergoing laser photocoagulation or cryotherapy was 1.6% (42/2595), which was lower than the 2.9% (2/68) of patients treated with anti-vascular endothelial growth factor injection, and 32.2% (82/255) of patients undergoing vitrectomy or scleral buckling. The mortality rate was 4.8 per 1000 person-years, which was highest in the VLBW population, but similar across treatment modalities.

Conclusions

The ROP incidence in Korea was approximately 1 in 500 among all newborns, and 1 in 3 in the VLBW population. As the first nationwide population-based study of long-term visual prognosis in ROP, we report the higher VI rate in ROP than previously determined in other studies. Differences in visual outcomes and comparable mortality risks between treatment modalities require further verification.

Prevalence and Risk Factors of Retinopathy of Prematurity in Iran

Purpose

The present study aimed to evaluate the frequency and risk factors of retinopathy of prematurity (ROP) among Iranian infants.

Methods

A retrospective cohort study was conducted on infants who had undergone screening for ROP at Farabi Eye Hospital, between March 2016 and March 2017. Data were analyzed based on the presence of extreme prematurity (gestational age ≤ 28 weeks), extremely low-birth-weight (≤ 1000 g), and multiple-gestation (MG) infants.

Results

The prevalence of ROP was 27.28% (n = 543) among all screened infants, 74.4% for extremely preterm (EP) infants, 77.5% for extremely low birth weight (ELBW) babies, and 27.25% for infants from MG pregnancies. On multivariate analysis, gestational age, birth weight, and history of transfusion (P < 0.0001, P < 0.0001, and P = 0.04, respectively) were found to be significantly associated with ROP. More advanced stages of ROP (P < 0.0001) were observed in EP and ELBW infants. Birth weight (P = 0.088), history of transfusion (P = 0.066), and intubation (P = 0.053) were not associated with increased risk of ROP in EP infants, while gestational age (P = 0.037) and history of transfusion (P = 0.040) were significant risk factors for ROP in ELBW infants. Gestational age (P < 0.001) and birth weight (P = 0.001) were significantly associated with ROP in infants from MG pregnancies in multivariate analysis.

Conclusion

ROP remains a commonly encountered disease, especially in ELBW and EP infants. The history of transfusion may have a role in stratifying the risk for ROP and guiding future screening guidelines.

Norrie disease gene polymorphism in Indonesian infants with retinopathy of prematurity

OBJECTIVE

Retinopathy of prematurity (ROP) is a major cause of blindness in newborn infants, which also occurs in low-income and middle-income countries. Why ROP progresses in some infants while it regresses in others is still presently unknown. Studies suggest that genetic factors might be involved. Mutations in the Norrie disease (ND) gene are suspected to be related to advanced ROP development. Indonesia is a country with relatively high incidence of ROP, yet the role of these genetic factors in the pathogenesis of ROP cases is still unknown. The study aimed to investigate the presence of mutations in ND on the X chromosome in infants with both non-advanced and advanced ROP in Indonesia.

METHODS AND ANALYSIS

This is a case-control study of polymorphisms in six variants within the ND gene in exon 3, C597A, L108P, R121W, A105T, V60E and C110G, in preterm newborn infants in four major hospitals in Greater Jakarta, Indonesia.

RESULTS

We included 162 preterm newborn infants. ROP was diagnosed in 83 infants, and 79 infants served as controls. Among those with ROP, 57 infants had type 2, while others had type 1. We did not find any gene polymorphisms in any of the infants with ROP nor in the control group.

CONCLUSION

We conclude that it is very unlikely that the six polymorphisms in exon 3 of the ND gene studied in this paper are involved in the development or progression of ROP in preterm infants in our population sample in Indonesia.

Trends in the incidence of retinopathy of prematurity over a 10-year period

AIM

To describe and evaluate the trends in the incidence of retinopathy of prematurity over a 10-year period in a tertiary hospital in Hong Kong.

METHODS

A retrospective review was performed on all preterm infants screened and/or treated for retinopathy of prematurity from January 2006 to December 2015 at Prince of Wales Hospital, Hong Kong. Preterm infants with incomplete records or transferred-in from other hospitals/region solely for treatment of ROP were excluded. The incidence of any ROP or Type 1 ROP was analysed with gestational age and birth weight over a 10-year period with consecutive 2-year intervals to evaluate the trends.

RESULTS

Of all 754 infants included in the study, 234 (31.0%) patients had any ROP and 34 (4.5%) infants developed Type 1 ROP. The incidence of any ROP demonstrated a statistically significant decreasing trend over the five consecutive 2-year intervals (p = 0.016), but the incidence trend of Type 1 ROP is not statistically significant. No infants weighing more than 1250 g developed Type 1 ROP.

CONCLUSION

We observed a decreasing trend in the incidence of any ROP across the 10-year period in a tertiary hospital in Hong Kong, while the incidence of Type 1 ROP remained stable at 4.5%. The factors leading to the trend were unclear. Improved prenatal care, changing proportion of cases with different birth weight and gestational age, oxygenation level practice in neonatal unit may all contribute to the decreasing trend. Revision of screening criteria may be made according to local experience to maximise cost-effectiveness.

A national telemedicine network for retinopathy of prematurity screening

PURPOSE

To report the results of retinopathy of prematurity (ROP) screening by a telemedicine system in Chile and evaluate its usefulness for referring patients who require treatment.

METHODS

Premature infants at risk of developing ROP from 11 neonatal intensive care units were included. Screening was performed on all infants born at a gestational age of <32 weeks and/or birth weight of <1500 g. A trained nonphysician operator used an imaging system to capture retinal images, which were reviewed by two independent ROP experts. All infants that required treatment were referred for further evaluation.

RESULTS

The study included 2,048 eyes of 1,024 premature infants. Mean gestational age was 28.8 ± 2.2 weeks, and mean birth weight was 1128 ± 279 g. A total of 5,263 telemedicine examinations were performed and reported. The average number of image sets per patient was 2.6 ± 2.5. Of the 5,263 images, 4,903 (93%) were recorded to at least the end of zone II; 5,172 (98%) were graded as having good quality, allowing for staging of ROP disease. Forty-two infants (4%) were referred for treatment. Discharged patients with ROP type 2 that regressed did not present with any complications or adverse effects during 6 months' follow-up.

CONCLUSIONS

Our study demonstrates the utility of telemedicine screening for ROP with ophthalmologist readers in a developing country. Telemedicine screening was able to detect treatment-requiring ROP. Most of the images had good quality and showed the end of zone II, two variables sufficient to discharge patients.

Retinopathy of prematurity in Indonesia: Incidence and risk factors

BACKGROUND

Retinopathy of prematurity (ROP) is a vaso-proliferative disease of the eye, which mainly affects preterm newborn infants with an incompletely vascularized retina. The incidence of ROP has increased in industrialized countries due to the increased survival of extremely low birth weight (ELBW) infants. ROP is also increasing in developing countries like Indonesia, where it is most likely due to the improved survival of ELBW infants.

OBJECTIVE

To ascertain the incidence of ROP and possible risk factors associated with the development of ROP in preterm infants in Indonesia.

METHODS

We reviewed the literature on the incidence and potential risk factors for the development of ROP in Indonesia, obtained data from three referral eye clinics and added data from our institution.

RESULTS

The reported incidence of all stages of ROP in infants with a gestational age of <32 weeks ranged from 18-30%. One study showed that ROP also occurred at older gestational ages. Blindness due to ROP was seen in infants up to 35 weeks and with a birth weight of 2000 g.

CONCLUSION

Retinopathy of prematurity is an important cause of ocular morbidity and blindness in Indonesia. The overall incidence of ROP in infants born below 32 weeks in Indonesia is higher than in developed countries, and it is seen in infants with older gestational ages. This might be due to a less strict monitoring during the use of oxygen in Indonesia compared to industrialized countries.

Retinopathy of Prematurity among Very-Low-Birth-Weight Infants in Korea: Incidence, Treatment, and Risk Factors

This study was conducted to describe the incidence, risk factors, and current treatment status of retinopathy of prematurity (ROP) in very-low-birth-weight (VLBW) infants registered in the Korean Neonatal Network database. Medical records of 2,009 VLBW infants born between January 2013 and June 2014 who underwent examination by an ophthalmologist were reviewed. The total incidence of ROP was 34.1%. Of the patients, 11.6% showed ROP stage ≥ 3 and 11.5% received treatment of VLBW. Among all infants who received treatment of ROP, 63.6% underwent operation only; 16.9%, anti-vascular endothelial growth factor (anti-VEGF) treatment only; and 19.5%, both operation and anti-VEGF treatment. The mean gestational age (GA) and birth weight (BW) were significantly lower and the prevalence rates of respiratory distress syndrome, patent ductus arteriosus (PDA), invasive ventilator duration, and sepsis were significantly higher in the VLBW infants with ROP than in those without ROP. In the multivariable logistic regression analysis, PDA (odd ratio [OR], 2.1; 95% confidence interval [CI], 1.11-3.79) and invasive ventilator duration (OR, 1.0; 95% CI, 1.00-1.02) were significant risk factors of ROP and ROP stage ≥ 3. In conclusion, the high incidence of ROP is associated with low GA and BW, and attempt to reduce the aforementioned risk factors could reduce the incidence of ROP stage ≥ 3 in VLBW infants.

Treatment of retinopathy of prematurity in Northern Ireland, 2000-2011: a population-based study

PURPOSE

To evaluate the incidence of treatment-requiring retinopathy of prematurity (ROP) over a 12-year-period in Northern Ireland.

METHODS

The medical records of all infants treated for ROP from January 2000 to December 2011 were retrospectively reviewed and cross-referenced with the Neonatal Intensive Care Outcomes Research and Evaluation (NICORE) database.

RESULTS

The Northern Ireland population data showed an increase in the number of live births from 2000 to 2011. The proportion of babies born with a birth weight <1501 g and/or <32 weeks' gestational age remained constant (χ(2) trend = 3.220, P = 0.0727), although the proportion of these babies who died prior to 42 weeks' gestation decreased from 2000 to 2011 (P = 0.0196 using χ(2) for trend = 5.445; P = 0.0354 using χ(2) = 20.809). The prevalence of treatment-requiring ROP in these infants increased from 1.05% in 2000 to 5.78% in 2011 (P < 0.001 using χ(2) trend = 16.309; P < 0.001 using χ(2) = 31.378).

CONCLUSIONS

The present population-based study highlights that the incidence of treatment- requiring ROP is increasing in Northern Ireland. The increasing number of infants requiring treatment will need to be taken into consideration in the commissioning process for ROP services in Northern Ireland.

Intravitreal low-dosage bevacizumab for retinopathy of prematurity

PURPOSE

To report on the therapeutic effect of intravitreal low-dose bevacizumab for treatment for retinopathy of prematurity (ROP).

METHODS

The single-centre retrospective, non-comparative case series study included all infants who consecutively underwent intravitreal injection of 0.375 mg bevacizumab (0.03 ml) under light sedation in topical anaesthesia as therapy of ROP in zone I or zone II.

RESULTS

The clinical charts of 29 patients (57 eyes) with a median birth weight of 630 g (range: 290-1390 g) and median gestational age of 25 + 1 weeks (range: 23 + 1-30 weeks) were reviewed. Six children (12 eyes) were graded as ROP with zone I retinopathy and plus disease. The 23 remaining infants had extraretinal neovascularizations in zone II or partly zone I. The intravitreal bevacizumab injection was injected at a median age of 12 + 1 weeks (range: 7 + 4-21 + 4), the median follow-up was 4.2 months (range: from 3 days to 45.1 months). In all eyes treated, a regression of plus disease occurred within two to six days, retinal neovascularizations regressed within 2-3 weeks and pupillary rigidity improved. None except one child in exceptionally bad general health conditions needed a second intravitreal bevacizumab injection. In none of the infants, any ophthalmologic side-effects of the bevacizumab application were detected during the follow-up period.

CONCLUSIONS

The intravitreal injection of a low dose of 0.375 mg bevacizumab showed a high efficacy as treatment for ROP. The question arises whether the low dosage of bevacizumab as compared to the dosage of 0.625 mg bevacizumab may be preferred.

Incidence of retinopathy of prematurity in southwestern China and analysis of risk factors

Background

The aim of this study was to screen for retinopathy of prematurity (ROP) in southwestern China and understand the prevalence and risk factors of ROP, which may provide evidence useful in the prevention and treatment of ROP.

Material/Methods

1864 preterm infants (gestational age of <37 weeks and birth weight of ≤2500 g) underwent ROP screening from January 2009 to November 2012 in Southwest China. The medical information of infants during perinatal period was reviewed, and risk factors of ROP were determined. A total of 1614 infants were recruited for final analysis.

Results

Incidence of ROP was 12.8%. The first, second, third, and fourth stage of ROP was found in 64.6%, 29.6%, 3.4%, and 0.5% of infants, respectively. No fifth stage of ROP was observed. In addition, 7.7% of infants required surgical intervention. In our Department of Neonatology, the incidence of ROP was 20.0%, which was significantly higher than in non-hospitalized patients (9.9%). The incidence of ROP remained unchanged over the years. Independent risk factors of ROP included low birth weight (p=0.049), low gestational age (p=0.008), days of oxygen supplementation (p=0.008), and myocardial injury after birth (p=0.001).

Conclusions

The prevalence of ROP in preterm infants is relatively high in Southwest China, and low birth weight, low gestational age, days of oxygen supplementation, and myocardial injury after birth are independent risk factors for ROP.

Genetic polymorphisms of vascular endothelial growth factor and risk for retinopathy of prematurity in South of Iran

Retinopathy of prematurity (ROP) is a multifactorial disease, that cause visual impairment in premature children. The exact pathogenesis and etiology of ROP is unknown and genetic susceptibility is considered as risk factor. Vascular endothelial growth factor (VEGF) plays a major role in retinal neovascularization and subsequently retinal detachment. VEGF polymorphism is associated with proliferative ROP in some studies. We examined the possible association of the VEGF gene polymorphisms with ROP in preterm infants in south of Iran. A total of 111 preterm infants were examined by ophthalmologist and after that were genotyped. Genotyping of the VEGF +405 (rs2010963) and VEGF +936 (rs3025039) was done by the polymerase chain reaction and restriction fragment length polymorphism methods. The frequency of VEGF alleles, genotypes and haplotype distribution were compared between groups. The patients were divided in three groups: 66 to the normal group (normal fundoscopy), and 45 to the ROP group; 30 infants were not treated with Lasertherapy (Regressive group) and 15 treated with Lasertherapy. The frequency of VEGF +405 and VEGF +936 G/C genotypes as well as allele frequencies was not different between groups. No significant difference was found between ROP with treatment and ROP without lasertherapy. Our report indicate that there is no association between the carrier states of gene polymorphisms VEGF +405, VEGF +936 and progression or spontaneous regression of ROP in preterm infants in Iranian population. However, it should be considered that angiogenesis is a complex process and genetic factors in addition to environmental factors are contributed in this pathway.

Associations of VEGF/VEGF-receptor and HGF/c-Met promoter polymorphisms with progression/regression of retinopathy of prematurity

PURPOSE

To determine the effect(s) of vascular endothelial growth factor (VEGF), VEGF receptor-2 (VEGFR-2), hepatocyte growth factor (HGF), and HGF receptor (c-Met) polymorphisms on progression/regression of retinopathy of prematurity (ROP) in premature infants.

MATERIALS AND METHODS

This study comprised both a prospective analysis and a clinically relevant laboratory investigation. Enrolled were 123 Turkish preterm infants--gestational age (GA), ≤34 weeks; birth weight (BW), ≤1500 g--from a single tertiary care center. Infants were grouped as those who had undergone laser therapy (Group 1, n = 42), those with spontaneously regressed ROP (Group 2, n = 50), and those with no ROP (controls) (Group 3, n = 31). VEGF (-634) C and VEGF (-460) C polymorphisms were analyzed using the PCR-restriction fragment length polymorphism (RFLP) (PCR-RFLP) technique. VEGFR-2, HGF, and c-Met gene promoter polymorphisms were determined by direct sequencing.

RESULTS

Mean GAs and BWs of infants in Groups 1 and 2 were statistically significantly lower than those of Group 3 (p = 0.001). Frequencies of VEGF (-634) C and VEGF (-460) C polymorphisms were similar for all groups. We found a +32G→A single-nucleotide polymorphism (SNP) in the promoter region of the VEGFR-2 gene. HGF and c-Met gene promoter polymorphisms were not found in any group.

CONCLUSIONS

Our results indicate that there is no association between the carrier states of gene promoter polymorphisms VEGF (-634) C, VEGF (-460) C, and VEGFR-2, and progression or spontaneous regression of ROP in preterm infants. The absence of HGF and c-Met polymorphisms in our study groups suggests that polymorphisms in the minimal promoters of these genes are not involved in the pathogenesis of ROP.

Educational paper: Retinopathy of prematurity

Retinopathy of prematurity (ROP) is a proliferative retinal vascular disease affecting the premature infant with an incompletely vascularized retina. The spectrum of ophthalmological findings in ROP exists from minimal sequelae, which do not affect vision, to bilateral retinal detachment and total blindness. With the increased survival of very small infants, retinopathy of prematurity has become one of the leading causes of childhood blindness. Over the past two decades, major advances have been made in understanding the pathogenesis of ROP, to a large extent as a result of changes in clinical risk factors (oxygen and non-oxygen related) and characteristics observed in ROP cases. This article provides a literature review on the evolution in clinical characteristics, classification and treatment modalities and indications of ROP. Special attention is hereby paid to the neonatal factors influencing the development of ROP and to the necessity for everyone caring for premature babies to have a well-defined screening and treatment protocol for ROP. Such screening protocol needs to be based on a unit-specific ROP risk profile and, consequently, may vary between different European regions.

CONCLUSION

Retinopathy of prematurity is an important cause of ocular morbidity and blindness in children. With better understanding of the pathogenesis, screening and treatment guidelines have changed over time and are unit specific.

Wide-field digital imaging based telemedicine for screening for acute retinopathy of prematurity (ROP). Six-year results of a multicentre field study

Objective

To report on a 6-year experience with wide-field digital imaging based telemedicine (WFDI telemedicine) to reduce the risk for blindness from retinopathy of prematurity (ROP).

Methods

Wide-angle digital fundus cameras (RetCam 120, Massie Lab, Pleasanton, CA, USA) were installed in five neonatal intensive care units (NICUs) in Germany. All prematures at risk were screened with WFDI, and the local ophthalmologists were asked to continue binocular indirect ophthalmoscopy (BIO) according to the German guidelines. Image data were coded and transferred to the Reading Centre in Regensburg. Image evaluation and additional BIO of infants with suspected treatment-requiring ROP (STR-ROP i.e. threshold ROP zone II, prethreshold ROP zone I (type-1 ROP according to ETROP), and ROP possibly requiring treatment but not reliably classifiable from the images) were performed by paediatric ophthalmologists at the Reading Centre. ROP was classified following ICROP, ETROP, and revised ICROP criteria. Outcome measures were incidence of clinically relevant ROP (CR-ROP, i.e. any ROP up to mid-peripheral zone III, ≤ stage 3+), sensitivity to detect STR-ROP, and positive predictive value to detect treatment-requiring ROP (TR-ROP).

Results

In total, 1,222 prematures at risk were screened (mean BW 1395 g, SD ±507 g; mean GA 30 wks, SD ±3 wks). The overall incidence of CR-ROP was 27.6% (71.8% mild = stage 1 to 3 without plus disease, 15.7% prethreshold = type-1 ROP according to ETROP, 12.5% threshold according to ICROP). Zone I disease was present in 3.3%, zone II disease in 76.5%, and zone III disease in 20.2%. According to ETROP, 95 infants were type-1 or type-2 ROP; 67.4% type-1 ROP, and 32.6% type-2 ROP. Of all 1,222 infants, 3.5% received treatment. Following ETROP (not applied in the study), 5.3% would have been treated. The sensitivity for detecting STR-ROP was 100%, and the positive predictive value for TR-ROP 82.4% (28/34) at the time of the first referral (28 infants, ≤ stage 3+ in zone I or II).

Conclusion

All TR-ROP was detected in time, showing the potential of our telemedical screening program. The overall incidence of CR-ROP was comparable to ROP incidences reported in other West European countries.

Early weight gain predicts retinopathy in preterm infants: new, simple, efficient approach to screening

BACKGROUND

The risk for sight-threatening retinopathy of prematurity is predicted by using gestational age and/or weight at birth. All infants below a threshold undergo serial ophthalmologic examinations for identification of those who would benefit from treatment (approximately 10%). We hypothesized that factoring in postnatal weight gain could identify children at risk for sight-threatening retinopathy of prematurity more specifically and earlier.

METHODS

Weekly weights from birth to postmenstrual week 36 were retrospectively entered into a surveillance system that gave an alarm when the rate of weight gain decreased to a certain level. For all children (N = 354) screened and/or treated for retinopathy of prematurity at Sahlgrenska University Hospital in 2004-2007, weekly weights were recorded. One child was excluded because of known nonphysiologic weight gain (hydrocephalus).

RESULTS

For 127 (36%) of 353 children, no alarm was given; for 40%, alarm at low risk was given after postmenstrual week 32. None of those children developed retinopathy of prematurity requiring treatment. Of the remaining 24% of children who received alarm at high or low risk before 32 postmenstrual weeks, 41% developed proliferative retinopathy of prematurity and 29% were treated because of sight-threatening disease. The median time from alarm to treatment was 9 weeks.

CONCLUSIONS

The weight, insulin-like growth factor, neonatal retinopathy of prematurity algorithm detected early 100% of infants who developed retinopathy of prematurity requiring treatment and correctly predicted the majority who did not require treatment. With this simple postnatal evaluation, costly stressful eye examinations can be markedly reduced (approximately 75% of infants). In addition, early identification of children at risk may lead to the initiation of interventions and possibly prevent sight-threatening retinopathy of prematurity.

Visual impairment is common in children born before 25 gestational weeks--boys are more vulnerable than girls

INTRODUCTION

Children born extremely preterm have high risk of visual impairment due to retinopathy of prematurity (ROP) and cerebral lesions.

OBJECTIVE

The aim of this study was to investigate the frequency of ROP and visual impairment as defined by the World Health Organization (WHO), with respect to gender in two hospital-based groups of children born at the limit of viability.

PATIENTS AND METHODS

A retrospective chart review was conducted for all children (n = 114), born before 25 gestational weeks and screened for ROP at Karolinska hospital in Stockholm and Sahlgrenska hospital in Gothenburg between 1990 and 2002. Maximal ROP stages, treatment for ROP and visual acuity (VA), with correction when needed at latest available visit, were recorded.

RESULTS

Altogether 97.4% had ROP, 74.6% developed proliferative disease (stage >/= 3) and 63.2% were treated with retinal ablation. Normal VA (>/=0.8) in at least one eye was found in 50.5% of all and in significantly more girls (61.5%) than boys (34.8%) (p = 0.006), while visual impairment (VA < 0.33) was more common in boys (32.6%) than in girls (9.2%) (p = 0.004).

CONCLUSION

A large proportion of children, especially boys, born at the level of viability are visually impaired with low vision or blindness. Development of preventive measures is urgent.

Weight gain measured at 6 weeks after birth as a predictor for severe retinopathy of prematurity: study with 317 very low birth weight preterm babies

BACKGROUND

Recent studies suggest that postnatal weight gain can play an important role in the development of retinopathy of prematurity (ROP).

AIM

To analyze the low weight gain (WG) from birth to 6 weeks of life to predict the development of severe retinopathy of prematurity (ROP) among very low birth weight preterm babies (VLBW).

METHODS

A prospective cohort study included 317 newborns with birth weight (BW) <or=1,500 g and gestational age (GA) <or=32 weeks. The main outcome was the development of severe ROP (defined as threshold ROP and higher stages of ROP). In all patients, the proportion of the WG was defined as the preterm weight measured at 6 weeks of life minus the BW divided by the BW. Seventeen risk factors for ROP were studied by univariate analysis. Chi-square test and Student's t-test were used to compare no-ROP/mild ROP patients and severe ROP patients. Logistic regression and receiver operating characteristic (ROC) curve were used to determine if the WG proportion was independently related to severe ROP development and if it was capable of predicting severe ROP. Ophthalmological examinations started between the fourth and sixth week of life, and were repeated until the 45th week of postmenstrual age. Weight gain proportion was always calculated at completed 6 weeks of life.

RESULTS

Mean GA and mean BW of the whole cohort were 29.6 weeks (+/-1.9) and 1,124 grams (+/-239.5) respectively. After logistic regression, the low WG proportion under 51.2% from the BW, measured at 6 weeks of life, showed OR 3.007 (95%CI: 1.195-7.566; P = 0.019), for severe ROP, when adjusted for BW and for any stage intraventricular hemorrhage. Area under the ROC curve was 0.63 (95%CI: 0.495-0.761; P = 0.037). For the discriminative cutoff of 51.2% of the WG proportion, sensitivity and specificity values were 66.3% and 62.6% respectively. Positive and negative predictive values were 10.2% and 94.7% respectively.

CONCLUSIONS

Low WG by six weeks of life is an important and independent risk factor for severe ROP and is capable to predict the development of severe ROP in most patients that needed treatment.

Abnormal vessel morphology in boys born after intracytoplasmic sperm injection

AIM

Children born after intracytoplasmic sperm injection (ICSI) are at risk of preterm birth, low birth weight and perinatal morbidity which may predispose for diseases of the central nervous and vascular systems. Our aim was to investigate the ocular fundus morphology in children born after ICSI.

METHOD

Children born after ICSI (n = 82) had ocular fundus photographs taken at the age of 5 years and results were compared with those of a control group (n = 203). The ocular fundus morphology with the central retinal vessels was evaluated by digital image analysis.

RESULTS

Children born after ICSI (n = 57) had abnormal retinal vascularization as evidenced by a lower number of vascular branching points compared with the control group (n = 181) (p = 0.0002). A gender difference was found whereby the ICSI boys (n = 35) had significantly fewer retinal branching points (median 24, range 19-29.5) compared with the control boys (median 27.5, range 20-37) (p < 0.0001).

CONCLUSION

Our findings showed that ICSI boys have abnormal vessel morphology as demonstrated by a reduced number of central retinal branching points. The difference still remained after elimination of factors earlier shown to be associated with a low number of vascular branching points, i.e. low birth weight and preterm, suggesting other mechanisms responsible for the low number of vascular branching points.

Human recombinant erythropoietin and the incidence of retinopathy of prematurity: a multiple regression model

BACKGROUND

Recombinant human erythropoietin (rhEPO) is used for the treatment of anemia of prematurity. However, it has also been found to have properties similar to vascular endothelial growth factor (VEGF), the major angiogenic factor implicated in the pathogenesis of retinopathy of prematurity (ROP). We sought to determine whether rhEPO is an independent risk factor for the development of ROP.

METHODS

Data were analyzed from 264 infants admitted to the Loma Linda University Children's Hospital neonatal intensive care unit in 1994 and 2002. The data included demographic characteristics, incidence of major morbidities, rhEPO treatment, number of red blood cell transfusions received, and incidence and severity of ROP. A multiple logistic regression model was used to determine the relation of the studied risk factors to the incidence (any stage) and severity (threshold ROP requiring cryotherapy or laser photocoagulation) of ROP.

RESULTS

The risk of developing ROP increased among infants who received >20 doses of rhEPO was higher compared with those who received < or =20 doses (OR, 3.53; 95% CI, 1.59, 7.85). These infants were also more likely to require laser photocoagulation (OR, 4.31; 95% CI, 1.99, 9.33). The age at which rhEPO was started was also a significant risk factor, with those starting rhEPO after 20 days of age having almost fourfold the risk of ROP compared with those starting it on or before 20 days of age (OR, 3.57; 95% CI, 1.59, 8.03).

CONCLUSIONS

rhEPO was found to be a significant independent risk factor for the development of ROP.

An epidemiological analysis of retinopathy of prematurity over 10 years

PURPOSE

To analyze the incidence of retinopathy of prematurity (ROP) in a single neonatal intensive care unit over 10 years to clarify its ROP profile and how it was modified by advances in neonatal care.

METHODS

Epidemiological data related to incidence and severity of ROP were collected over 10 years. Premature infants with a birth weight of less than 1,500 g underwent a screening fundus examination and ROP was defined according to the International Classification of Retinopathy of Prematurity. The survival rates and incidence of ROP were calculated and compared for two consecutive time periods (1995-1999 vs 2000-2004), dividing the study population into subgroups according to their birth weights and gestational age.

RESULTS

Data of 607 preterm infants were collected. Survival rate significantly improved in the later time period (from 76.6% to 88.6%). The incidence of total, severe, and surgical ROP did not differ overall in the two time periods despite changes in survival rate, although some changes occurred in the most immature infants over time.

CONCLUSION

Increased survival of immature infants seemed to correlate with an increased risk for severe ROP and need for retinal ablation therapy, even if the incidence did not reach statistical significance.

Treatment for retinopathy of prematurity in Denmark in a ten-year period (1996 2005): is the incidence increasing?

OBJECTIVE

The objective of this study was to analyze the population incidence of retinopathy of prematurity treatment in Denmark in the 10-year period from 1996 to 2005.

METHODS

Patient charts of infants treated for retinopathy of prematurity and the national birth registry provide information about neonatal parameters. These parameters, along with birth in the latter half of the period (2001-2005), were analyzed as risk factors for retinopathy of prematurity. The national registry for blind and visually impaired children was accessed to obtain information about visual impairment attributable to retinopathy of prematurity in both treated and untreated infants.

RESULTS

The study population consisted of 5467 Danish preterm infants born in 1996 to 2005, with a gestational age of < 32 weeks, who survived for > or = 5 postnatal weeks; 2616 were born in 1996 to 2000, and 2851 were born in 2001 to 2005. The incidence of treated retinopathy of prematurity cases increased significantly from 1.3% in 1996 to 2000 to 3.5% in 2001 to 2005. Significant risk factors for retinopathy of prematurity treatment were low gestational age, small for gestational age, male gender, and multiple birth. Other, yet unknown factors contributed to the increased incidence in the latter half of the period. Of the study population, 0.6% were registered as visually impaired because of retinopathy of prematurity within 2 years after birth (early-detected visual impairment). The incidences were not significantly different between 1996 to 2000 and 2001 to 2005. Of all of the early-detected, visually impaired children, 16% had not been treated for retinopathy of prematurity and were considered screening failures.

CONCLUSIONS

The incidence of retinopathy of prematurity treatment in Denmark has more than doubled during the past half-decade. This increase could not be fully explained by increased survival rates for the infants or by changes in the investigated neonatal risk factors.

Genetic susceptibility to retinopathy of prematurity: the evidence from clinical and experimental animal studies

Despite advances in management and treatment, retinopathy of prematurity remains a major cause of childhood blindness. Evidence for a genetic basis for susceptibility to retinopathy of prematurity is examined, including the influences of sex, ethnicity, and ocular pigmentation. The role of polymorphisms is explored in the genes for vascular endothelial growth factor and insulin-like growth factor-1, and of mutations in the Norrie disease gene. Insights into the genetic basis of retinopathy of prematurity provided by the animal model of oxygen induced retinopathy are examined. Evidence for a genetic component for susceptibility to retinopathy of prematurity is strong, although the molecular identity of the gene or genes involved remains uncertain.

Étude épidémiologique de la rétinopathie du prématuré : les facteurs de risque au CHU de Tours

BACKGROUND

A prospective analysis of the incidence of retinopathy of prematurity (ROP) by documenting clinical perinatal characteristics of affected infants, in an attempt to describe risk factors for ROP.

MATERIALS AND METHODS

Between March 2002 and April 2004, 161 infants, with a gestational age under 31 weeks and/or a birth weight under 1500 g, were screened according to CRYO-ROP guidelines, using direct ophthalmoscopy with a Layden contact lens. Risk factors for ROP were analyzed with the Student and Fischer tests.

RESULTS

ROP developed in 15% of the cases studied, with one out of five at prethreshold or threshold levels of ROP. Gestational age at birth (p<0.0001), low birth weight (p<0.0001), the length of the infant's stay in the neonatal intensive care unit (p<0.0001), the duration of mechanical ventilation (p<0.0001), the duration of oxygen provided (p<0.0001), blood transfusions (p<0.0001), hyaline membrane disease (p=0.0257), and bronchodysplasia (p=0.0012) were significant risk factors for ROP.

CONCLUSION

Despite progress in neonatal intensive care, ROP persists and can be explained by greater and greater prematurity and earlier screening. Effective screening, done between 4 and 6 weeks of life, taking risk factors into account, can improve prognosis.

Can Screening for Retinopathy of Prematurity Be Reduced?

BACKGROUND

As screening for retinopathy of prematurity (ROP) is costly, time-consuming for the ophthalmologist and discomforting for the neonate, the minimum number of infants should be screened for ROP, without missing infants with severe ROP, at risk for threshold ROP.

OBJECTIVES

To develop a diagnostic screening guideline for ROP that would safely reduce the number of ROP screening funduscopies in our department.

METHODS

Data of 275 infants admitted between 1996 and 2000 and screened for ROP according to our Dutch National guideline were studied. Significant risk factors for ROP were calculated, using logistic regression analysis and used to develop a guideline. The discriminative power of the guideline was evaluated using the area under the curve for the receiver operating characteristic curve.

RESULTS

Significant risk factors for ROP were: gestational age, birth weight and number of erythrocyte transfusions within the first 4 weeks of life. The combination of these 3 factors resulted in the highest area under the curve: 0.793. Using these 3 factors, a diagnostic screening guideline for ROP was developed: if birth weight + 2 x (gestational age - 20) - 6 x erythrocyte transfusion value within the first 4 weeks of life >or=34, no screening for ROP is necessary. Using this guideline, 22.2% of the infants of the study group could have been excluded from screening; 3.8% of the infants with ROP stages 1-2 would have been missed.

CONCLUSION

In our department, ROP screening can be safely reduced using our diagnostic screening guideline.

Nordic research in ophthalmology

Nordic ophthalmologists and vision scientists are active in many fields of eye research. This is most evident at the biannual Nordic Congress of Ophthalmology, most recently held in Malmö in June 2004. The authors here review some of the research in vision and ophthalmology presented at this meeting or published recently by Nordic scientists. This paper does not represent a comprehensive review of all Nordic research in the field, but attempts to give an overview of some of the activities underway in eye research in this part of the world.

UK population based study of severe retinopathy of prematurity: screening, treatment, and outcome

BACKGROUND

Retinopathy of prematurity (ROP) is one of the few causes of childhood blindness in which severe vision impairment is largely preventable. Ophthalmic screening for ROP is required to identify disease that requires treatment whereby the development of potentially blinding disease can be minimised.

OBJECTIVES

To make the first UK population based estimate of the incidence of babies with severe ROP (stage 3 or more); to document their clinical characteristics and management and to evaluate the appropriateness of current ROP screening guidelines in the UK.

PATIENTS

Cases were recruited through a national surveillance programme with 1 year ophthalmic follow up and data from clinician completed questionnaires.

RESULTS

Between 1 December 1997 and 31 March 1999, 233 preterm babies with stage 3 ROP were identified. Severity (location, extent, and presence of plus disease) was associated with degree of prematurity, most severe in the most premature babies. Fifty nine percent were treated. The UK screening protocol was followed in two thirds of cases, but in the remainder it was begun too late or was too infrequent. Three quarters of the cases were followed up at 1 year, and 13% had a severe vision deficit as a result of ROP.

CONCLUSIONS

Visual deficit as a result of ROP in premature babies continues to be a severe disability in some of the survivors of neonatal intensive care. Further efforts are needed to organise treatment regionally to improve outcome and standards of practice.

Prise en charge de la rétinopathie du prématuré en service spécialisé

INTRODUCTION

Retinopathy of prematurity is a complication of prematurity whose risk factors are well known. Its prognosis remains fearsome and its treatment is difficult.

PATIENTS AND METHODS

Fifty-four children were managed (108 eyes analyzed) for retinopathy of prematurity in the Ophthalmology Ward of Necker-Enfants-Malades Hospital between 1996 and 2002. A retrospective review of those cases was performed to describe their clinical features, their treatment and their outcome.

RESULTS

Mean gestational age was 26.75 weeks after the mother's last period (24-32.5 weeks) and mean birth weight was 842 g (530-2260 g). Stage zero occurred in ten eyes, stage 1 in two eyes, stage 2 in seven eyes, stage 3 in 42 eyes, stage 4 in ten eyes, stage 5 in 24 eyes, and after-effects stage in 13 eyes. Initial treatment (combined treatments possible) was abstention in 45 eyes, cryotherapy in 16 eyes, laser photocoagulation in 43 eyes, surgical treatment of 13 eyes (scleral buckling or vitrectomy). Cryotherapy was effective in 71.5% of cases, photocoagulation was effective in 77%, and scleral buckling was effective in 25%. Vitrectomy failed in the five eyes treated. Outcome was complicated by legal blindness in 33 eyes.

DISCUSSION AND CONCLUSION

The cases of retinopathy of prematurity that we manage are often severe, stage 3 or above, which explains the outcome of the patients. The 7-year experience reported herein shows how difficult it is to manage this condition, though the need for its detection, diagnosis criteria, and therapeutical indications are well known. Because younger and smaller premature newborns are successfully managed by pediatricians, retinopathy of prematurity is far from having vanished and its morbidity is considerable.

Trends in the incidence of severe retinopathy of prematurity in a geographically defined population over a 10-year period

OBJECTIVE

To examine trends in the incidence of severe (> or =grade 3) retinopathy of prematurity (ROP) in infants with birth weight of < or =1250 g in a geographically defined population over a 10-year period.

METHODS

An observational study was conducted of all infants who had a birth weight < or =1250 g and were born to mothers who were resident in the county of Leicestershire, United Kingdom, during the period January 1, 1990, to December 30, 1999. Cases were identified by the Trent Neonatal Survey. The incidence of severe ROP (> or =grade 3) was compared in 2 successive 5-year periods: 1990-1994 and 1995-1999.

RESULTS

Comparing the first 5-year period (1990-1994) with the second (1995-1999), the total number of live births fell (60 789 vs 56 564). However, there was a significant increase in the number of births with birth weight < or =1250 g (including live and dead; 615 vs 734; live births only: 455 vs 556). Survival to 42 weeks of infants who were born at < or =1250 g was significantly better in the latter time period (203 vs 302; odds ratio [OR] for death: 0.54; 95% confidence interval [CI]: 0.39-0.75). The number of cases of severe ROP was 4 times higher during the second time period compared with the first (9 vs 36). A significantly increased risk for the development of severe ROP was seen during the second time period (OR: 2.92; 95% CI: 1.37-6.20). Even after allowing for the change in gestation induced by the improved survival during the second time period, the increased risk remained (OR: 2.81; 95% CI: 1.27-6.21).

CONCLUSIONS

There is strong evidence that the incidence of severe ROP among infants with birth weight < or =1250 g increased in the latter half of the last decade. The increased risk seems to be independent of the increase in survival.

Ophthalmic impairment at 7 years of age in children born very preterm

AIMS

To determine the prevalence of ophthalmic impairments in very preterm compared with term infants, the relation between impairments and cerebral ultrasound appearances and retinopathy, and the correlation with visual perception and motor and cognitive measures.

SUBJECTS

279 children at 7 years of age born before 32 weeks gestation within Liverpool during 1991-92 and attending mainstream schools, and 210 term controls.

METHODS

Visual acuity was assessed by Snellen chart, and strabismus by the cover test. Stereopsis was determined using the TNO random dot test, and contrast sensitivity using the Cambridge low contrast gratings. Visual and motor abilities were assessed using the Developmental test of motor integration (VMI) and the Movement ABC. Intelligence was measured with the Wechsler intelligence scale for children UK. Perinatal cranial ultrasound and retinopathy data were extracted from clinical records.

RESULTS

Children born preterm were significantly more likely to wear glasses, to have poor visual acuity, reduced stereopsis, and strabismus than term controls, but they showed no significant decrease in contrast sensitivity. Ophthalmic impairments were significantly related to poorer scores on the VMI, Movement ABC, and Wechsler IQ tests, but were not significantly related to neonatal cranial ultrasound appearances. Stage 3 retinopathy was related to poorer subsequent acuity.

CONCLUSIONS

Children born very preterm and without major neurodevelopmental sequelae have an increased prevalence of ophthalmic impairments at primary school age which are associated with visual perceptional, motor, and cognitive defects. The cause may be a generalised abnormality of cortical development rather than perinatally acquired focal lesions of the brain.

Threshold retinopathy at threshold of viability: the EpiBel study

AIM

To describe incidence, co-morbidity characteristics, and risk factors associated with threshold retinopathy of prematurity (ROP) in survivors with a gestational age (GA) of < or =26 weeks at birth.

METHODS

Retrospective analysis of perinatal data of all inborn survivors in all perinatal centres of Belgium in the period 1999-2000 (EpiBel cohort) believed to be between 22 and 26 weeks GA at time of delivery. Data on survivors who did and survivors who did not develop threshold ROP were compared (chi(2), Mann-Whitney U) and logistic regression was performed.

RESULTS

Of 303 admitted infants 175 (58%) were discharged alive. Incidence of major retinopathy (> or =stage 3) and of threshold ROP was 25.5% and 19.8% in survivors. Associated central nervous abnormalities were documented in six (17%) and associated chronic lung disease in 19 (54%) threshold ROP infants. Threshold ROP without additional morbidity characteristics at discharge was documented in 14 (40%) infants. Besides often reported risk factors, renal insufficiency (creatinaemia>1.5 mg/dl) was a risk factor to develop threshold ROP (p<0.0015) (chi(2)). Days of respiratory support (OR 1.02; 95% CI 1.002 to 1.039), number of transfusions (OR 1.118; 95% CI 1.030 to 1.214), and renal insufficiency (OR 3.31; 95% CI 1.344 to 8.196) remained independent risk factors to develop threshold ROP in this cohort in a stepwise logistic regression model (MedCalc).

CONCLUSIONS

Incidence of threshold ROP is high at the limits of viability. Renal insufficiency is a risk factor to develop threshold ROP in this cohort.

Nordic research in ophthalmology

PURPOSE

To provide an overview of some of the current activities in eye research in the Nordic countries.

METHODS

The presentations at the biannual Nordic Congress of Ophthalmology, held in Tampere, Finland in 2002, were reviewed and the contributions found most noteworthy are included in this article along with a limited discussion of each research field. However, space requirements prevented the inclusion of many interesting scientific contributions.

RESULTS

Important contributions in various subfields of eye research and ophthalmology are reviewed. These include cornea, cataract, paediatric ophthalmology, glaucoma, diabetic eye disease, age-related macular degeneration, physiology and pharmacology and oncology.

CONCLUSIONS

Eye research is very active in the Nordic countries and significant contributions are being made to ophthalmology in several fields on a world scale. We hope to continue to review Nordic contributions to eye research after each Nordic Congress of Ophthalmology and plan to make the reviews more systematic and comprehensive in the future.

Screening for retinopathy of prematurity: evaluation and modification of guidelines

AIMS

To evaluate current screening guidelines for ROP (retinopathy of prematurity) and to determine whether they can be modified.

METHODS

In accordance with the authors' present criterion, infants born in Stockholm County, Sweden, from 1 August 1998 to 31 July 2000, with a gestational age of < or =32 weeks, were screened for ROP. The effectiveness of screening was studied.

RESULTS

The incidence of ROP was 25.5% in this study. A dropout group comprising almost 20% of the population studied (< or =32 weeks), was never referred, were lost to follow up, or died before screening was completed. No infant with a gestational age of >31 weeks at birth developed severe ROP (stages 3-5) and no infant with a gestational age of >29 weeks was treated for ROP.

CONCLUSION

80% of infants in this population with a gestational age at birth of < or =32 weeks, the current screening criterion, were effectively screened for ROP. The authors recommend that the screening criterion be lowered to Collapse

Key Words

• retinopathy of prematurity
• screening
• guidelines

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MESH Headings

• Birth Weight
• Female
• Gestational Age
• Humans
• Incidence
• Infant, Newborn
• Infant, Premature
• Logistic Models
• Male
• Practice Guidelines as Topic
• Predictive Value of Tests
• Prospective Studies
• Regression Analysis
• Retinopathy of Prematurity/diagnosis
• Retinopathy of Prematurity/epidemiology
• Sweden/epidemiology
• Vision Screening/methods

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Affiliation(s)

E Larsson Department of Ophthalmology, University Hospital, Uppsala, Sweden
G Holmström

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