Retinopathy of prematurity in a Danish county. Trends over the 12-year period 1982-93

Comparative study of RetCamRetCam II vs. binocular ophthalmoscopy in a screening program for retinopathy of prematurity

OBJECTIVE

To determine the performance of RetCam vs. binocular ophthalmoscopy (BIO) in a screening program for retinopathy of prematurity (ROP).

METHODS

Observational comparative study with prospective data collection. Examinations with RetCam (n=169) were performed on 83 infants included in a screening program for ROP and stored for analysis at a later stage. An experienced ophthalmologist examined the ocular fundus with binocular indirect ophthalmoscopy (BIO). The RetCam images were assessed for the presence of ROP, zone, grade, and presence of plus disease. RetCam and BIO data were compared by visually to estimate sensitivity, specificity, positive (VPP) and negative (VPN) predictive values.

RESULTS

ROP disease was detected in 108 eyes with BIO, and in 74 with RetCam. Out of 306 eyes examined with RetCam, false negative results were found in 34 eyes, with no false positives. Sensitivity of RetCam exam vs. BIO was 0.68, and specificity was 0.99. Positive predictive value was 0.93 and negative predictive value was 0.85. All 34 ROP cases not detected with RetCam were in zone III or outer zone II. They were all mild and regressed spontaneously. No threshold ROP was missed with RetCam.

CONCLUSION

Binocular indirect ophthalmoscopy is the reference method for the diagnosis of ROP. RetCam may be used as an alternative for ROP screening.

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.

Visual impairment in children born prematurely from 1972 through 1989

PURPOSE

To investigate the incidence and causes of visual impairment in children born prematurely in Finland from 1972 through 1989, and to determine what conditions and factors were associated with its occurrence.

DESIGN

Retrospective, cross-sectional study.

SUBJECTS

All visually impaired individuals from 0 to 17 years of age who had been born at fewer than 37 gestational weeks in Finland from 1972 through 1989 for whom records were available in the Finnish Register of Visual Impairment were eligible for this study.

METHODS

Data in the Finnish Register of Visual Impairment relating to 556 children were supplemented with data from hospital records, and from the Register of Births, the Register of Congenital Malformations, the Finnish Care Register, and the Finnish Cancer Register. Data relating to causes associated with visual impairment in particular were collected. Data relating to the children born prematurely were compared with data relating to children born at full term. The chi-square test (Mantel-Haenszel), the Mann-Whitney U test, Fisher exact test, and stepwise logistic regression analysis were used in statistical analysis of the data.

MAIN OUTCOME MEASURES

Visual acuity, ophthalmologic diagnoses, associated systemic disease, multiple handicap, gestational age, birth weight, 5-minute Apgar scores, and prenatal, perinatal, and infantile or juvenile disorders or disease and treatment.

RESULTS

One hundred twenty-five of the 556 visually impaired children (23%; 11/100000 children less than 18 years of age) had been born preterm. Retinopathy of prematurity, optic atrophy, and cerebral amblyopia were the main diagnoses associated with visual impairment (in 46%, 28%, and 12% of cases, respectively). Sixty-six percent of those born prematurely with visual impairment were also affected by other handicaps (mental, motor, auditory), 54% by cerebral palsy and 36% by epilepsy. Eighty-eight of the 125 children (70%) born preterm with visual impairment were blind. Very low birth weight (<1500 g), young gestational age (fewer than 30 weeks), prenatal infection, hyperbilirubinemia, respiratory disorders, asphyxia, and lengthy mechanical ventilation were associated with an increased risk of visual impairment.

CONCLUSIONS

Premature birth was a major risk factor of severe visual impairment and blindness in childhood. The visual impairment often was accompanied by cerebral palsy, epilepsy, and other motor and mental handicaps. Retinopathy of prematurity, optic atrophy, and cerebral amblyopia were the main diagnoses associated with visual impairment. During the 18 years covered by the study, the increasing incidence of survival of infants born weighing fewer than 1500 g was associated with increasing incidence of blindness.

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.

The management of retinopathy of prematurity

Retinopathy of prematurity (ROP) is a major problem in both highly developed countries and countries with emerging technology. The incidence of ROP has been stable over the last 2 decades despite improvements in neonatology. Threshold ROP occurs in about 5% of premature infants in the US with birthweights <1.25kg. Despite treatment, a sizable minority will become blind (up to 20 to 30%). The pathophysiology of ROP can be separated into 2 phases. Phase I is hyperoxia-vasocessation. Phase II is hypoxia-vasoproliferation. The former occurs immediately following premature birth. The provision of supplemental oxygen causes retinal hyperoxia, a down regulation of vascular endothelial growth factor (VEGF) and a consequent cessation of normal retinal vascularisation. Systemic factors and increasing retinal metabolic demands cause a shift to phase II when a relative retinal hypoxia develops. This hypoxia stimulates VEGF production, leading to renewed vascularisation. This can be the resumption of normal vascularisation or abnormal neovascularisation, depending on local retinal responses. The management of ROP begins with a reliable evidence-based screening protocol. All interested parties must cooperate in developing and implementing foolproof screening protocols. Hospital officials, nursery personnel, neonatologists and ophthalmologists all have areas of responsibility in ensuring adequate screening. ROP management involves prevention, interdiction and correction. Prevention includes: adequate prenatal care which minimises premature birth, and appropriate systemic intensive care which lessens the tissue hyperoxia/hypoxia swings. Pharmacological vitamin E supplementation has largely been abandoned and ambient light reduction has been shown to be ineffective. The value of inositol supplementation and angiogenesis inhibitors in preventing ROP is presently under investigation. Interdiction concentrates on ablation of the peripheral avascular retina, thus dramatically decreasing VEGF production. Both cryotherapy and laser photocoagulation are effective; however, unfortunately, poor outcomes persist despite treatment. Supplemental oxygen administration has so far proven ineffective in limiting ROP progression. Finally, correction focuses on vitrectomy/retinal detachment repair. While anatomically successful, this procedure is often unsuccessful in terms of restoration of vision (<5% success rate). In conclusion, despite improvements in neonatology, ROP, potentially leading to blindness, continues to be a common problem associated with prematurity. Future management success must concentrate on discovering new modes of treatment, especially prevention.

Reduced incidence of retinopathy of prematurity

AIM

To audit the prevalence of retinopathy of prematurity (ROP) in a level 2 status neonatal unit.

METHODS

Data were collected prospectively over 9 years from September 1989 to September 1998. Preterm infants were examined according to the Royal College of Ophthalmologists' guidelines and retinopathy graded following the International Classification of ROP. ROP 3-5 was analysed using logistic regression in relation to time, and to gestational age and birth weight.

RESULTS

383 babies were examined. Mean gestational age fell over the 9 year period (p=0.051) as did mean birth weight (p<0.001). There was a decrease in the number of infants with ROP grades 3-5 over the 9 years (p=0.045 and, when adjusted for gestational age and birth weight, the decrease in ROP 3-5 was significant (p=0.03).

CONCLUSIONS

This study found a significant reduction in the incidence of ROP during the 9 years of the study period, despite a decrease in mean gestational age of and birth weight. The reduced incidence of ROP is attributed to improvements in ventilation techniques and overall care of the neonate, in particular the use of prenatal steroids and surfactant.

Decreased incidence of retinopathy of prematurity, 1995-1997

PURPOSE

To report a significant decrease in the incidence of retinopathy of prematurity (ROP), both in our neonatal intensive care unit (NICU) and internationally, and review factors in patient care that may be contributory.

METHODS

We retrospectively reviewed the records of all neonates weighing less than 1251 g admitted to our NICU from 1995 to 1997 and evaluated the incidence and stage of ROP. These data on 191 neonates were compared with an international NICU database of 9989 similar neonates, which represents all infants who received an ophthalmologic examination in the Vermont-Oxford Network Database (VOND) in 1997, except those from our institute (the University of Kentucky). In addition to investigating the incidence of ROP, we looked at the use of antenatal corticosteroids given 1 to 7 days prepartum, the use of oxygen at 36 weeks' postconceptional age, and the use of oxygen at home upon discharge.

RESULTS

In our center, we had a 36.1% incidence of ROP compared with an international incidence of 57.2% for the VOND in 1997 (P <.0001). Antenatal corticosteroids were given to 62.6% of infants in our center compared with 48.6% in the VOND (P <.005). In addition, 48.5% of our infants weighing less than 1500 g received oxygen at 36 weeks' postconceptional age versus 29.5% of the VOND infants (P <.001). Upon discharge to home, 37.5% of our infants were on oxygen compared with 15.6% of infants from all VOND centers, excluding the University of Kentucky (P <.001).

CONCLUSION

The incidence of ROP in our center from 1995 to 1997 and in the VOND in 1997 show a significant decrease from the 65.8% incidence from 1986 to 1987 reported by the Multicenter Trial of Cryotherapy for ROP.

The decreasing incidence and severity of retinopathy of prematurity

PURPOSE

We sought to determine whether the incidence of retinopathy of prematurity (ROP) at our institution has changed since the Cryo-ROP recruitment period 10 years ago.

METHODS

We determined the incidences of threshold ROP, prethreshold ROP, less-than-prethreshold ROP, and no disease for each of 3 birth weight classes (<750 g, 750 to 999 g, and 1000 to 1250 g) of infants born between July 1, 1995, and June 30, 1996, and cared for in the Vanderbilt Neonatal Intensive Care Unit. We then compared these with the rates from our institution during the Cryo-ROP study recruitment period (January 1, 1986, to November 30, 1987).

RESULTS

The current incidence and severity of ROP have decreased substantially overall and for each weight group compared with the 1986-87 incidence (P < .001, Cochran-Mantel-Haenszel test). The incidence of "any ROP" decreased by 27% for infants with birth weights less than 750 g, by 51% for infants 750 to 999 g, and by 71% for infants 1000 to 1250 g. The incidence of "prethreshold or greater ROP" decreased by 70% for the 750 to 999 g and 77% for the 1000 to 1250 g weight groups. Although the decrease in "prethreshold or greater ROP" was not as dramatic (25%) for the infants less than 750 g, only 1 infant (10%) progressed to threshold disease in this group, whereas 7 (47%) did in 1986-87. The incidence of threshold ROP decreased by 84% for infants less than 750 g and by 66% for infants 750 to 999 g. No infant with birthweight greater than 999 g progressed to threshold ROP.

CONCLUSIONS

The incidence of all levels of ROP has decreased substantially for all infants with birth weights less than 1251 g at Vanderbilt University Medical Center during the past decade. Putative factors responsible for this decrease may include surfactant use, continuous pulse oximetry, aggressive use of antenatal steroids, and improved neonatal nutritional support.

Central nervous system damage and retinopathy of prematurity--an ophthalmic follow-up of prematures born in 1982-84

Retinopathy of prematurity (ROP) was observed in 28 of 185 pre-term infants born in 1982-84 and under regular ophthalmic surveillance after delivery; their gestational age (GA) range was 25-35 weeks; four became blind. All 28 attended ophthalmic reassessment at age 7-10 years and were compared with 60 pre-term subjects of the same cohort who had not developed ROP. Considering psychomotor development, 45 (51%) of the total 88 had evidence of central nervous system (CNS) damage; minor in 24 and major in 21 (cerebral palsy in particular). With correction for drop-outs, the regional frequency of severe CNS damage was 24% for birth weight below 1500 g and 29.6% for GA less than 32 weeks. Except for the selection due to initial inclusion for ROP surveillance, we have no explanation for the high frequency at the present follow-up. Statistically, the ocular damage of ROP appeared unassociated with CNS impairment. An analysis of perinatal factors based on matched pairs did not indicate any definite association with subsequent development of ROP and/ or CNS damage.

Pre-term delivery and subsequent ocular development. A 7-10 year follow-up of children screened 1982-84 for ROP. 1) Visual function, slit-lamp findings, and fundus appearance

An ophthalmic follow-up comprised 88 children aged 7-10 years who had regular screening for retinopathy of prematurity (ROP) after their pre-term delivery 1982-84. Mean values of birth weight and gestational age in the 88 were 1467 g and 31 weeks. Out of 28 with early evidence of ROP four had progressed to bilateral blindness; the remaining 24 had at least a corrected visual acuity of 0.4 at disposal. The corrected median binocular acuity for all 88 was 0.95; however, the cumulated frequency curve was significantly below a previously stated norm in full-terms. The same conclusion was valid for single eye vision. Within the material, the visual score of the 28 with early ROP was significantly lower than in the remaining 60 subjects. Ophthalmoscopy often showed tortuosity of vessels, but no specific central retinal or optic nerve lesion to explain the slight general depression of visual acuity, and opacities of media contributed in only two subjects. It is concluded, that very preterm delivery generally influences the potential for developing full visual acuity, also in individuals without evidence of early ROP. Evidence of CNS-damage negatively influenced visual acuity score.