Retinopathy of prematurity in middle-income countries

Setting up and improving retinopathy of prematurity programs: interaction of neonatology, nursing, and ophthalmology

Retinopathy of prematurity (ROP) programs require collaboration between neonatologists, ophthalmologists, nurses, and allied health personnel, together with parents. The concept of a ROP program will vary according to the setting. However, in every situation there should be 2 main aspects: primary prevention of ROP through better overall care, and secondary prevention through case detection (often called screening), treatment, and follow-up. ROP programs will have different content and emphasis according to whether the setting is in an economically advanced or developing country.

Retinopathy of prematurity: a nationwide survey to evaluate current practices and preferences of ophthalmologists

PURPOSE

To emphasize the demographic and occupational characteristics of ophthalmologists primarily involved in retinopathy of prematurity (ROP) care and to ascertain their practices and preferences.

METHODS

A questionnaire was sent to all Turkish ophthalmologists known to be primarily involved in ROP. They were asked about personal and occupational characteristics, practices and preferences related to ROP care, and for their proposals related to ROP training.

RESULTS

Seventy questionnaires were sent, of which 63 (90%) were returned. A total of 44 respondents reported performing laser and 13 vitreoretinal surgery. Preferred treatment was transpupillary laser photocoagulation (54.5%), mostly performed in the operating theater (84.1%) under general anesthesia (72.7%). Only 19 (30.2%) reported intravitreal injection of vascular endothelial growth factor inhibitors (anti-VEGF). Ophthalmologists from university hospitals, trained in retina during fellowship, and performing treatment for ROP more commonly performed anti-VEGF injection. Most of them studied ROP after residency and 76.2% think that ROP training during residency is inadequate for clinical practice.

CONCLUSION

This survey reveals considerable variation among Turkish ROP specialists regarding ROP care. The survey data are critical in order to develop quality improvement and help in planning more effective future programs for ROP care in terms of training.

Incidence and risk factors of retinopathy of prematurity in mashhad, northeast iran

BACKGROUND

Retinopathy of prematurity (ROP) is a vascular retinal disease that can cause low vision or blindness and affects premature newborns of very low birth weight.

OBJECTIVES

The purpose of this study was to determine the incidence and risk factors for ROP among very premature infants in Mashhad located northeast of Iran.

MATERIAL AND METHODS

In this cross-sectional study performed between 2006 and 2010, predisposing factors and severity of ROP were evaluated in very premature infants (<32 gestational weeks). Consecutive infants were enrolled at birth and screened for ROP at 4 to 6 weeks of age by indirect ophthalmoscopy. Severe ROP was defined as stage 4 or 5. Chi-square, Student's t-, and Fisher's test were used for statistical analysis.

RESULTS

The incidence of ROP was 26.2%. Significant differences between the ROP and control groups were observed, these include; gestational age, sex, birth weight, Apgar score, durationof parenteral nutrition, oxygen therapy, phototherapy, maximum PaO2 and minimum SpO2 (P < 0.05). Severe ROP was seen in 31.4% (11/32) of ROP cases (5.4% of newborns).

CONCLUSION

The incidence of ROP is relatively high in this region. Risk factors for ROP among very premature infants include hypoxia, severe hyperoxia, relatively low blood SPO2, gestational age, birth weight, and Apgar score.

Neuronal ER stress impedes myeloid-cell-induced vascular regeneration through IRE1α degradation of netrin-1

In stroke and proliferative retinopathy, despite hypoxia driven angiogenesis, delayed revascularization of ischemic tissue aggravates the loss of neuronal function. What hinders vascular regrowth in the ischemic central nervous system remains largely unknown. Using the ischemic retina as a model of neurovascular interaction in the CNS, we provide evidence that the failure of reparative angiogenesis is temporally and spatially associated with endoplasmic reticulum (ER) stress. The canonical ER stress pathways of protein kinase RNA-like ER kinase (PERK) and inositol-requiring enzyme-1α (IRE1α) are activated within hypoxic/ischemic retinal ganglion neurons, initiating a cascade that results in angiostatic signals. Our findings demonstrate that the endoribonuclease IRE1α degrades the classical guidance cue netrin-1. This neuron-derived cue triggers a critical reparative-angiogenic switch in neural macrophage/microglial cells. Degradation of netrin-1, by persistent neuronal ER stress, thereby hinders vascular regeneration. These data identify a neuronal-immune mechanism that directly regulates reparative angiogenesis.

Laser photocoagulation in patients with retinopathy of prematurity undergoing chest physiotherapy

The authors report the correlation between chest physiotherapy and increased risk of vitreous hemorrhage after laser photocoagulation therapy in patients with retinopathy of prematurity (ROP). Two premature neonates, the first born at 26 weeks and the second at 31 weeks gestational age, both underwent chest physiotherapy, the first for congenital cystic fibrosis and bronchopulmonary dysplasia and the second for premature alveolar atelectasis. Both were diagnosed as having ROP that necessitated laser photocoagulation treatment at 34 and 37 weeks, respectively. The first patient developed bilateral vitreous hemorrhage and bilateral cataracts. The second patient developed vitreous hemorrhage in one eye. Chest physiotherapy in neonates with ROP significantly increases the risk of hemorrhage after laser photocoagulation in an otherwise fragile retinal vasculature.

Structural and functional results of indirect diode laser treatment for retinopathy of prematurity from 1999 to 2003 in Kuwait

Purpose

The purpose was to report the structural, visual, and refractive outcomes of infants treated for retinopathy of prematurity (ROP) with laser and to identify the risk factors for unfavorable outcomes.

Materials and methods

The charts of infants with severe ROP treated by diode laser in a tertiary center during the period April 1999 to November 2003 were reviewed. Treated infants were followed up for fundus examination, visual acuity assessment, and cycloplegic refraction. Data regarding ocular risk factors, like zones of ROP and the extent of extraretinal proliferations, and data regarding various systemic risk factors were collected. A minimum follow up of 6 months was needed for inclusion in the study of structural outcome. A minimum follow up of 24 months was needed for the study of visual and refractive outcomes. The outcomes measured were: rate of unfavorable structural outcome, unfavorable visual outcome (visual acuity < 20/40), and high myopia (myopia ≥ 5 diopters). The ocular and systemic risk factors were studied for their significance in the development of unfavorable outcomes.

Results

Two hundred seventy eyes of 148 infants were treated for severe ROP, out of which 20 eyes (7.4%) had unfavorable structural outcome. Visual data were available for 149 eyes of 81 infants, of which 70 eyes (47%) had unfavorable visual outcome. Refractive data were available for 131 eyes of 72 infants, and high myopia was present in 23 (17.6%) eyes. Zone I disease was the significant risk factor for unfavorable structural (P < 0.0001), unfavorable visual outcome (P = 0.03), and for high myopia (P < 0.0001). Lower post-conceptional age at treatment was significant for unfavorable structural outcome (P = 0.03) and high myopia (P < 0.0001). Presence of sepsis (P = 0.029) and extraretinal proliferation ≥ 6 hours were significant for unfavorable structural outcome (P = 0.002).

Conclusion

ROP in zone I was the most significant risk factor for all the unfavorable outcomes. Laser-treated ROP infants need long term follow up.

Role of the retinal vascular endothelial cell in ocular disease

Retinal endothelial cells line the arborizing microvasculature that supplies and drains the neural retina. The anatomical and physiological characteristics of these endothelial cells are consistent with nutritional requirements and protection of a tissue critical to vision. On the one hand, the endothelium must ensure the supply of oxygen and other nutrients to the metabolically active retina, and allow access to circulating cells that maintain the vasculature or survey the retina for the presence of potential pathogens. On the other hand, the endothelium contributes to the blood-retinal barrier that protects the retina by excluding circulating molecular toxins, microorganisms, and pro-inflammatory leukocytes. Features required to fulfill these functions may also predispose to disease processes, such as retinal vascular leakage and neovascularization, and trafficking of microbes and inflammatory cells. Thus, the retinal endothelial cell is a key participant in retinal ischemic vasculopathies that include diabetic retinopathy and retinopathy of prematurity, and retinal inflammation or infection, as occurs in posterior uveitis. Using gene expression and proteomic profiling, it has been possible to explore the molecular phenotype of the human retinal endothelial cell and contribute to understanding of the pathogenesis of these diseases. In addition to providing support for the involvement of well-characterized endothelial molecules, profiling has the power to identify new players in retinal pathologies. Findings may have implications for the design of new biological therapies. Additional progress in this field is anticipated as other technologies, including epigenetic profiling methods, whole transcriptome shotgun sequencing, and metabolomics, are used to study the human retinal endothelial cell.

The societal burden of blindness secondary to retinopathy of prematurity in Lima, Peru

PURPOSE

To determine the cost-effectiveness of laser treatment for retinopathy of prematurity (ROP) in Lima, Peru.

DESIGN

A cost-of-illness study (in US dollars) to determine the direct cost of treatment, the indirect lifetime cost of blindness, and the quality-adjusted life years.

METHODS

The direct cost of ROP-related treatment was determined by reviewing data retrospectively from a social security sector hospital. The indirect cost was determined using national economic data of Peru published by the Central Information Agency (CIA), including the per capita gross domestic product, the sex-adjusted income distribution, and years spent in the work force. Indirect costs per child that were avoided by treatment were calculated using the known natural history of ROP vs evidence-based treatment.

RESULTS

For ROP-related neonatal blindness in Peru, we estimate the total indirect cost saving at $197,753 per child and the direct cost of laser treatment at $2496 per child. The societal lifetime cost saving per child is estimated at $195,257. The mean annual income per educated adult in Peru is $8000 and treating 1 child is equivalent to employing 24 educated Peruvians per year. The generational cost savings for society is approximately $516 million, or the equivalent of 64,500 educated Peruvian work years.

CONCLUSIONS

The societal burden of blindness far exceeds the costs of treatment per child. Proper screening and treatment of ROP prevents blindness and leads to substantial cost savings for society. Public health policy in Peru and other middle-income countries should consider financial impact when allocating healthcare resources.

Estrogen and neuroprotection: from clinical observations to molecular mechanisms

We now appreciate that estrogen is a pleiotropic gonadal steroid that exerts profound effects on the plasticity and cell survival of the adult brain. Over the past century, the life span of women has increased, but the age of the menopause remains constant. This means that women may now live over one third of their lives in a hypoestrogenic, postmenopausal state. The impact of prolonged hypoestrogenicity on the brain is now a critical health concern as we realize that these women may suffer an increased risk of cognitive dysfunction and neurodegeneration due to a variety of diseases. Accumulating evidence from both clinical and basic science studies indicates that estrogen exerts critical protective actions against neurodegenerative conditions such as Alzheimer's disease and stroke. Here, we review the discoveries that comprise our current understanding of estrogen action against neurodegeneration. These findings carry far-reaching possibilities for improving the quality of life in our aging population.

A novel, low-cost method of enrolling infants at risk for Retinopathy of Prematurity in centers with no screening program: the REDROP study

PURPOSE

To report the first-year results of the Red Card for Retinopathy of Prematurity (REDROP) study, a low-cost interim strategy to enroll infants into retinopathy of prematurity (ROP) screening where limited expertise exists, piloted at a multi-specialty general hospital.

METHODS

Red "warning" cards were placed alongside green "congratulations" cards above the weighing scale in the neonatal unit. Staff weighing the newborn were instructed to give either one of the cards to each mother depending on the weight of the child (≤ 2000 g, red, and > 2000 g, green). Red cards contained information (tri-lingual) about ROP and the venue of screening. Green cards contained general pediatric eye education and recipients were not called. A portion of the red card with the infant's birth date and mother's contact number was retained and collected weekly by volunteers. Mothers were reminded on the mobile phone to come for ROP screening. Screening and treatment were performed free.

RESULTS

During the study period, 224 of 805 (27.8%) infants were born ≤ 2000 g. Of these, 169 (75.4%) survived and were eligible for the red card; 91 (53.8%) received it. Of these, 43 (47.3%) infants completed ROP screening, 14 (32.6%) had some stage ROP, and three (6.9%) required laser treatment. The main reason for the lower turnout for screening was the inability to contact mothers on their provided phone numbers.

CONCLUSIONS

REDROP demonstrates the feasibility of this low-cost method of enrolling unscreened infants into a ROP program. The cost of enrolling each infant was less than 5 rupees (US$0.10). Suggested strategies to improve use require multi-center validation.

Retinopathy of Prematurity in a rural Neonatal Intensive Care Unit in South India--a prospective study

OBJECTIVE

To report the incidence, spectrum and treatment outcome of Retinopathy of Prematurity (ROP) in a rural neonatal nursery.

METHODS

This Prospective, observational, non-randomized study was conducted in a level III Neonatal Intensive Care Unit (NICU) at district headquarters in South India. 118 babies with birth weight ≤2000 g and/or period of gestation (POG) ≤34 wk were included in the study. Eligible infants were screened with indirect ophthalmoscopy and wide-field digital imaging (Retcam) until retinal vascularization was complete or disease regressed. Early Treatment Retinopathy of Prematurity (ETROP) guidelines were followed for laser.

RESULTS

The overall incidence of ROP was 41.5% and treatable ROP was 26.4% (24/91) of eyes diagnosed with ROP and 10.2% (24/236) of the overall eyes screened. The mean birth weights and periods of gestation with and without ROP were 1555.9 vs. 1672.5 g (P 0.005) and 32.2 vs. 34.6 wk, respectively (P<0.001). Half of the treated eyes had aggressive posterior ROP in Zone 1. All treated eyes had a favorable outcome. Respiratory distress syndrome, oxygen therapy, neonatal Jaundice and sepsis were higher in the ROP group but was not statistically significant. Of the overall infants screened, 68 (57.6%) were heavier and older than the American screening cut-off. Of these, 36.8% had some stage ROP and 8% required treatment.

CONCLUSIONS

This is the first prospective ROP study from a district NICU in India and compares with previously published urban data. If Western-screening guidelines are used in the rural scenario, we risk a significant proportion of infants being missed who may require treatment.

Meta analysis on the relationship between gene polymorphisms of vascular endothelial growth factor and retinal prognosis risk of prematurity

AIM

To explore the relationship between gene polymorphisms of vascular endothelial growth factor (VEGF) and retinopathy of prematurity (ROP).

METHODS

Literature materials related to gene polymorphisms of VEGF and ROP in PubMed, EMBASE, Cochrane and CBM database were retrieved. These materials were screened according to inclusion and exclusion standards. Patients diagnosed with ROP in clinic were regarded as control group and ROP patients who were in treatment were regarded as observation group. The indexes in two groups were matched except birth weight (BW), gender and gestational weeks. Meta5.1 was used to analyze the relationship between gene polymorphisms of VEGF and ROP.

RESULTS

Four random control tests (RCT) were included in this research, including 2611 patients. Meta analysis results showed that VEGF affected ROP, having statistical significance. The combined ratio was 0.44 (95%CI, 0.07, 0.80), 0.42 (95%CI, 0.09, 0.74) and 0.75 (95%CI, 0.02, 1.49), respectively. Carrying +405 allele might increase the premature infants' risk of having ROP.

CONCLUSION

ROP may be related to its carrying of +405 allele. Large-scale, multi-factor RCT researches are still needed in order to identify the relation between VEGF and ROP.

Development of a mobile phone based ophthalmoscope for telemedicine

Regular retinal examinations can contribute to the management of both hypertensive and diabetic retinopathy. One of the most successful means of evaluating these retinopathies is by means of a fundus camera generating a fundus photograph. Patients in rural clinics unfortunately often lack the financial means to undergo regular examinations. This study produced a handheld ophthalmoscope that combines with a digital camera to capture retinal images. The images are transferred to a mobile phone and then sent to a central website for evaluation. The evaluation report is automatically returned to the mobile phone via SMS. The quality of the images was rated as acceptable for clinical use by medical specialists at the Department of Ophthalmology of the Health Sciences Faculty of Stellenbosch University, South Africa.

Eyeing central neurons in vascular growth and reparative angiogenesis

The generation of blood vessels is a highly synchronized process requiring the coordinated efforts of several vascular and nonvascular cell populations as well as a stringent orchestration by the tissue being vascularized. Stereotyped angiogenesis is vital for both developmental growth and to restore tissue metabolic supply after ischemic events. Central neurons such as those found in the brain, spinal cord, and retina are vast consumers of oxygen and nutrients and therefore require high rates of perfusion by functional vascular networks to ensure proper sensory transmission. During a metabolic mismatch, such as that occurring during a cerebrovascular infarct or in ischemic retinopathies, there is increasing evidence that central neurons have an inherent ability to influence the vascular response to injury. With a focus on the retina and retinal ischemic disorders, this review explores the ever-growing evidence suggesting that central neurons have the propensity to impact tissue vascularization and reparative angiogenesis. Moreover, it addresses the paradoxical ability of severely ischemic neurons to hinder vascular regrowth and thus segregate the most severely injured zones of nervous tissue. The topics covered here are pertinent for future therapeutic strategies because promoting and steering vascular growth may be beneficial for ischemic disorders.

Capacity building of nurses providing neonatal care in Rio de Janeiro, Brazil: methods for the POINTS of care project to enhance nursing education and reduce adverse neonatal outcomes

Background

Increased survival of preterm infants in developing countries has often been accompanied by increased morbidity. A previous study found rates of severe retinopathy of prematurity varied widely between different neonatal units in Rio de Janeiro. Nurses have a key role in the care of high-risk infants but often do not have access to ongoing education programmes. We set out to design a quality improvement project that would provide nurses with the training and tools to decrease neonatal mortality and morbidity. The purpose of this report is to describe the methods and make the teaching package (POINTS of care--six modules addressing Pain control; optimal Oxygenation; Infection control; Nutrition interventions; Temperature control; Supportive care) available to others.

Methods/Design

Six neonatal units, caring for 40% of preterm infants in Rio de Janeiro were invited to participate. In Phase 1 of the study multidisciplinary workshops were held in each neonatal unit to identify the neonatal morbidities of interest and to plan for data collection. In Phase 2 the teaching package was developed and tested. Phase 3 consisted of 12 months data collection utilizing a simple tick-sheet for recording. In Phase 4 (the Intervention) all nurses were asked to complete all six modules of the POINTS of care package, which was supplemented by practical demonstrations. Phase 5 consisted of a further 12 months data collection. In Phase 1 it was agreed to include inborn infants with birthweight ≤ 1500 g or gestational age of ≤ 34 weeks. The primary outcome was death before discharge and secondary outcomes included retinopathy of prematurity and bronchopulmonary dysplasia. Assuming 400-450 infants in both pre- and post-intervention periods the study had 80% power at p = < 0.05 to detect an increase in survival from 68% to 80%; a reduction in need for supplementary oxygen at 36 weeks post menstrual age from 11% to 5.5% and a reduction in retinopathy of prematurity requiring treatment from 7% to 2.5%.

Discussion

The results of the POINTS of Care intervention will be presented in a separate publication.

Trial registration

Current Controlled Trials: ISRCTN83110114

Prevailing clinical practices regarding screening for retinopathy of prematurity among pediatricians in India: a pilot survey

AIMS

To evaluate the prevailing practices for proper screening and referral scheme among Indian pediatricians for retinopathy of prematurity (ROP).

MATERIALS AND METHODS

Pediatricians registered with Indian Academy of Pediatrics from six states of India were selected randomly and were telephonically interviewed in accordance with a preformed questionnaire which comprised of questions regarding demographic factors, number of premature children seen per month, awareness and referral scheme to ophthalmologist; responses thus obtained were analyzed.

RESULTS

Hundred percent knowledge about ROP and need for screening in premature babies was observed among the respondents. However, only 135 (58%) pediatricians always referred for ROP screening, 19 (8%) referred only sometimes and 80 (34%) did not refer at all. Consistent referral protocols taking into account all plausible risk factors for ROP were followed by only 25% of those who always referred. Major deterrent in ROP screening was perceived as non-availability of trained ophthalmologists.

CONCLUSIONS

Only 14.5% of total pediatricians contacted were following international recommendations for ROP referral. Screening for ROP remains dismal as observed in this pilot survey as a consequence of non-availability of trained ophthalmologists as well as inconsistent screening guidelines.

Screening for retinopathy of prematurity in a large tertiary neonatal intensive care unit in Turkey: frequency and risk factors

PURPOSE

We aimed to determine applicable guidelines for screening of retinopathy of prematurity (ROP), and evaluate the contribution of risk factors for severe ROP.

METHODS

A prospective cohort study of neonates with a gestational age (GA) < 34 weeks or birth weight < 2000g who were admitted to the Neonatal Intensive Care Unit (NICU) of a tertiary level hospital was conducted. The study group was classified into three groups according to eye examination findings as no ROP, mild ROP and severe ROP.

RESULTS

Of the 700 neonates screened, the frequencies of ROP for any stage and severe ROP were 32.7% and 3.1%, respectively. Laser photocoagulation was needed in 9.6% of neonates with ROP. None of the neonates with a GA ≥ 31 weeks required treatment. Any ROP was detected in 199 (53.6%) of the babies < 32 weeks (n = 371), 22 (5.9%) of whom were treated with laser photocoagulation. Independent risk factors for severe ROP in babies < 32 weeks GA were birth weight, duration of mechanical ventilation and patent ductus arteriosus (PDA).

CONCLUSION

This is the largest prospective cohort study including infants younger than 34 weeks GA from Turkey. Our data which belongs to the last 1-year period shows lower incidence of severe ROP when compared to previous reports from Turkey. According to our data, screening babies smaller than 32 weeks GA or 1500g birth weight seems reasonable. In the presence of long duration of mechanical ventilation and PDA, screening should be intensified.

Analysis of risk factors for retinopathy of prematurity

AIM

To analyze the incidence and risk factors for retinopathy of prematurity (ROP).

METHODS

A retrospective analysis was conducted on 568 premature infants from September 2005 to December 2010 with birth weight(BW) equal to or less than 2 500g or a gestational age(GA) at birth of 34 weeks or less. All of the members were examined by indirect binocular ophthalmoscopy.

RESULTS

ROP occurred with an incidence rate of 10.7% among 568 premature infants, and stages 3 and above ROP occurred with an incidence rate of 2.5%. This study showed the infants were more prone to develop ROP with short geststional age, low BW, long time of oxygen inhalation, and severe infants diseases. Twins had a significantly higher rate of ROP(18.3%) than singleton babies(9.8%), ROP were severer in twins than singleton babies.

CONCLUSION

Short GA, low BW, long time of oxygen inhalation, severe infants diseases, and non-singleton babies were the most significant risk factors associated with ROP.

Causes of blindness and visual impairment in Latin America

We review what is known in each country of the Latin American region with regards to blindness and visual impairment and make some comparisons to Hispanic populations in the United States. Prevalence of blindness varied from 1.1% in Argentina to 4.1% in Guatemala in people 50 years of age and older, with the major cause being cataract. Diabetic retinopathy and glaucoma are starting to make serious inroads, although epidemiological data are limited, and age-related macular degeneration is now a concern in some populations. Infectious diseases such as trachoma and onchocerciasis are quickly diminishing. Although progress has been made, retinopathy of prematurity remains the major cause of childhood blindness. If VISION 2020 is to succeed, many more epidemiological studies will be needed to set priorities, although some can be of the Rapid Assessment of Avoidable Blindness design. Developing the infrastructure for screening and treatment of ophthalmic disease in Latin America continues to be a challenge.

From oxygen to erythropoietin: relevance of hypoxia for retinal development, health and disease

Photoreceptors and other cells of the retina consume large quantities of energy to efficiently convert light information into a neuronal signal understandable by the brain. The necessary energy is mainly provided by the oxygen-dependent generation of ATP in the numerous mitochondria of retinal cells. To secure the availability of sufficient oxygen for this process, the retina requires constant blood flow through the vasculature of the retina and the choroid. Inefficient supply of oxygen and nutrients, as it may occur in conditions of disturbed hemodynamics or vascular defects, results in tissue ischemia or hypoxia. This has profound consequences on retinal function and cell survival, requiring an adaptational response by cells to cope with the reduced oxygen tension. Central to this response are hypoxia inducible factors, transcription factors that accumulate under hypoxic conditions and drive the expression of a large variety of target genes involved in angiogenesis, cell survival and metabolism. Prominent among these factors are vascular endothelial growth factor and erythropoietin, which may contribute to normal angiogenesis during development, but may also cause neovascularization and vascular leakage under pathologically reduced oxygen levels. Since ischemia and hypoxia may have a role in various retinal diseases such as diabetic retinopathy and retinopathy of prematurity, studying the cellular and molecular response to reduced tissue oxygenation is of high relevance. In addition, the concept of preconditioning with ischemia or hypoxia demonstrates the capacity of the retina to activate endogenous survival mechanisms, which may protect cells against a following noxious insult. Part of these mechanisms is the local production of protective factors such as erythropoietin. Due to its plethora of effects in the retina including neuro- and vaso-protective activities, erythropoietin has gained strong interest as potential therapeutic factor for retinal degenerative diseases.

Outcomes of a protocol-based management for zone 1 retinopathy of prematurity: the Indian Twin Cities ROP Screening Program report number 2

PURPOSE

To report the outcomes of zone 1 aggressive posterior retinopathy of prematurity (ROP) treated with aggressive laser photocoagulation by a protocol-based approach over a 10-year period.

DESIGN

Prospective, interventional case series.

METHODS

SETTING

Tertiary eye institute and neonatal intensive care units in the twin cities of Hyderabad and Secunderabad in South India.

STUDY POPULATION

Babies screened under the Indian Twin Cities Retinopathy of Prematurity Screening (ITCROPS) program between January 1, 1997 and March 31, 2007.

INTERVENTION

Multiple sessions of laser photocoagulation at any sign of plus disease with abnormal shunt vessels with or without neovascularization in zone 1.

OUTCOME MEASURE

Based on the anatomic status of the retina at the final follow-up, the outcome was classified into good (completely regressed with no vitreoretinal changes), fair (regression with vitreoretinal distortion), or poor (progression into partial or total retinal detachment involving macula). Descriptive statistics (mean and range) were used for gestational age at birth, birth weight, and post-conceptional age at first presentation and at the first intervention. Trends in incidence of zone 1 ROP over 1 decade were analyzed. Outcomes were expressed in terms of proportions and 95% confidence interval (CI).

RESULTS

Of the 3654 babies screened, 227 eyes of 115 babies were detected to have zone 1 aggressive disease, defined as zone 1 retinal vessels having abnormal closed-loop shunts, dilation and tortuosity, flat new vessels, or rapid progression. Laser was performed in 169 eyes. Disease regressed with good outcome in 142 eyes (84%) (95% CI, 77.6-89.2) and progressed to poor outcome in 13 eyes (7.69%) (95% CI, 4.1-12.8), while fair outcome was seen in 6 eyes (3.55%) (95% CI, 1.3-7.5). Thus 148 babies (87.5%) (95% CI, 81.6-92.14) had a favorable outcome. The outcomes in 8 treated eyes (4.7%) lost to follow-up were unknown.

CONCLUSIONS

Zone 1 aggressive ROP has a good outcome if the screening is done early; intervention is prompt and adequate, with frequent follow-up until complete regression is achieved.

Clinical benefits, costs, and cost-effectiveness of neonatal intensive care in Mexico

BACKGROUND

Neonatal intensive care improves survival, but is associated with high costs and disability amongst survivors. Recent health reform in Mexico launched a new subsidized insurance program, necessitating informed choices on the different interventions that might be covered by the program, including neonatal intensive care. The purpose of this study was to estimate the clinical outcomes, costs, and cost-effectiveness of neonatal intensive care in Mexico.

METHODS AND FINDINGS

A cost-effectiveness analysis was conducted using a decision analytic model of health and economic outcomes following preterm birth. Model parameters governing health outcomes were estimated from Mexican vital registration and hospital discharge databases, supplemented with meta-analyses and systematic reviews from the published literature. Costs were estimated on the basis of data provided by the Ministry of Health in Mexico and World Health Organization price lists, supplemented with published studies from other countries as needed. The model estimated changes in clinical outcomes, life expectancy, disability-free life expectancy, lifetime costs, disability-adjusted life years (DALYs), and incremental cost-effectiveness ratios (ICERs) for neonatal intensive care compared to no intensive care. Uncertainty around the results was characterized using one-way sensitivity analyses and a multivariate probabilistic sensitivity analysis. In the base-case analysis, neonatal intensive care for infants born at 24-26, 27-29, and 30-33 weeks gestational age prolonged life expectancy by 28, 43, and 34 years and averted 9, 15, and 12 DALYs, at incremental costs per infant of US$11,400, US$9,500, and US$3,000, respectively, compared to an alternative of no intensive care. The ICERs of neonatal intensive care at 24-26, 27-29, and 30-33 weeks were US$1,200, US$650, and US$240, per DALY averted, respectively. The findings were robust to variation in parameter values over wide ranges in sensitivity analyses.

CONCLUSIONS

Incremental cost-effectiveness ratios for neonatal intensive care imply very high value for money on the basis of conventional benchmarks for cost-effectiveness analysis. Please see later in the article for the Editors' Summary.

Comparison of UK and US screening criteria for detection of retinopathy of prematurity in a developing nation

PURPOSE

To determine the incidence, risk factors, and appropriateness of differing guidelines in developed nations for screening for retinopathy of prematurity (ROP) in a single nursery in a large urban city in southern Turkey.

METHODS

The records of 260 premature infants born ≤34 weeks in a single tertiary unit were retrospectively reviewed for ROP risk factors and diagnosis. Applicability of UK and US criteria were assessed by the use of receiver operating characteristic curves.

RESULTS

ROP of any stage was present in 60 infants (23%); ROP requiring treatment was seen in 30 (11.5%). Univariate analysis showed a significant relationship among the following factors: gestational age, birth weight, total duration of supplemental oxygen, duration of mechanical ventilation, respiratory distress syndrome, anemia, and intraventricular hemorrhage (p < 0.0001). Multiple logistic regression analysis showed gestational age (p = 0.039), birth weight (p = 0.05), respiratory distress syndrome (p = 0.05), and anemia (p = 0.004) as independent predictors of ROP requiring treatment. Area under curve for gestational age alone for diagnosing stage 2 or greater ROP was 0.824 ± 0.03 (p = 0.0001) and for birth weight alone was 0.808 ± 0.03 (p = 0.0001). UK screening criteria detected all stage 2 and greater ROP; US screening criteria missed 2 infants with stage 2 ROP but detected all treatment-requiring disease. Adoption of these screening criteria would have reduced unnecessary examinations by either 21% (UK) or 37% (US).

CONCLUSIONS

UK and US criteria improved the detection accuracy for ROP requiring treatment in Turkey and should be studied for other developing nations.

Association between assisted reproductive technology and advanced retinopathy of prematurity

PURPOSE

To investigate the associations between assisted reproductive technology (ART) and severe retinopathy of prematurity (ROP) requiring treatment.

METHODS

Retrospective analyses of inborn preterm infants screened for severe ROP at the Weill Cornell Medical Center Neonatal Intensive Care Unit at the New York-Presbyterian Hospital by single factor logistic regression and multifactor models.

RESULTS

Of 399 ethnically diverse infants, 253 were conceived naturally and 146 by ART. Eight (3.16%) patients conceived naturally, and 11 (7.53%) with ART required laser treatment. In multifactor analyses, significant risks for severe ROP requiring treatment included both gestational age (odds ratio [OR] 0.34; 95% confidence interval [CI] 0.23-0.52; P < 0.001) and ART ([OR] 4.70; [CI], 1.52-4.57; P = 0.007).

CONCLUSIONS

ART is associated with severe ROP requiring treatment in this cohort. This is the first report that demonstrates a statistically significant association between ART and severe ROP requiring treatment in infants in the US.

How to overcome retinal neuropathy: the fight against angiogenesis-related blindness

The retina consists of neuronal cells of high metabolic activity that are supplied by an abundant vasculature. It is a main theme of ophthalmologic research, because retinopathies are common causes of blindness in all age groups: age-related macular degeneration in the elderly, diabetic retinopathy in the middle aged, and retinopathy of prematurity and retinoblastoma in children. Interestingly, angiogenesis underlies the pathogenesis of all these diseases, and breakdown of the blood-retinal barrier is also thought to play an important role before and throughout the process of new vessel formation. However, so far, most treatments have targeted angiogenesis only, especially vascular endothelial growth factor. Consideration of the restoration of the blood-retinal barrier should be required. In this review, we discuss the clinical manifestation, pathogenesis, and current treatment options for angiogenesis-related blindness. In addition, because of the recent introduction of novel strategies, we describe pathogenesis-based treatment options to treat angiogenesis-related blindness.

Incidence of retinopathy of prematurity in a neonatal intensive care unit in Nepal

PURPOSE

To determine the incidence of retinopathy of prematurity (ROP) in low birth weight premature infants admitted to the neonatal intensive care unit of a children's hospital in Kathmandu.

METHODS

A hospital-based prospective study was performed in neonates with a gestational age of less than 36 weeks or birth weight of less than 2,000 g during 1 year. Ophthalmologic examination was performed 2 to 4 weeks after birth and patients were observed until the retinal vascularization was complete. ROP was classified using the revised International Classification of Retinopathy of Prematurity.

RESULTS

A total of 78 infants fulfilled the screening criteria. ROP was detected in 29.5% (n = 23) of neonates. Thirteen infants (16.7%) had stage 1 disease and 5 each (6.4%) were found to have stage 2 and stage 3 ROP. Threshold disease was present in 3.8% (n = 3) of infants with a gestational age of less than 32 weeks and birth weight less than 1,500 g who required laser treatment per Early Treatment of ROP criteria. Low birth weight (P < .01) and low gestational age (P < .01) were significantly associated with the incidence of ROP.

CONCLUSION

Prematurity and low birth weight were found to be major risk factors for ROP. ROP screening should be performed in such infants for early detection because its incidence is likely to increase as more premature infants survive with improved neonatal care.

Retinopathy of prematurity in 7 neonatal units in Rio de Janeiro: screening criteria and workload implications

OBJECTIVES

The goals were to determine optimal screening criteria for retinopathy of prematurity (ROP) in 7 neonatal units in Rio de Janeiro, Brazil, and to explore the workload implications of applying different criteria.

METHODS

Infants with birth weights of < or = 2000 g or gestational age of <37 weeks were examined by 3 ophthalmologists in 7 of the largest units in Rio de Janeiro, during a 34-month period. ROP was classified by using the international classification, and laser treatment was given to infants developing type 1 ROP.

RESULTS

A total of 3437 (87%) of 3953 eligible infants were examined, of whom 124 (3.6% [range: 2.1%-7.8%]) were treated. Eleven infants were treated for aggressive posterior ROP. Appropriate screening criteria for the 2 NICUs with high survival rates (ie, > or =80% among infants with birth weights of <1500 g) would be < or =1500 g or <32 weeks. For NICUs with low survival rates (ie, <80%), appropriate criteria would be < or =1500 g or < or =35 weeks. UK, US, and previous Brazilian criteria would all miss infants needing treatment.

CONCLUSIONS

ROP programs in Brazil should use the wider criteria of < or =1500 g or < or =35 weeks until further evidence-based criteria become available, although this would mean a slight increase in workload across the city, compared with use of the narrower criteria in the better units. Whether survival rates can be used as a proxy to indicate screening criteria requires further investigation.

New-onset maternal gestational hypertension and risk of retinopathy of prematurity

PURPOSE

To evaluate associations between conditions of maternal new-onset gestational hypertension (mHTN) and the features imparting risk of severe retinopathy of prematurity (ROP) in preterm infants.

METHODS

Hospital databases and charts of all preterm inborn infants at the University of North Carolina from 1996 to 2007 were retrospectively reviewed. The presence or absence of mHTN (e.g., pre-eclampsia) and infant factors (birthweight, gestational age, erythropoietin use, and zone and stage of ROP) were analyzed for independence of association.

RESULTS

Of the 5143 infants, 323 had ROP and 76 had mothers with mHTN. Infants with ROP were more likely to have mothers with mHTN and to be younger and smaller at birth. At initial examination, more infants of mothers with mHTN had vascularization into the lower zones than did infants of mothers without mHTN (P < 0.001). However, at the examination in which the most severe ROP was present, there was no association between mHTN and ROP stage (P = 0.2342). Analysis of stage and zone together showed that infants born to mothers with mHTN were more likely to have ROP at initial examination, after adjustment for gestational age, but not for birth weight. The use of erythropoietin was not associated with ROP zone or stage, even after adjustment for maternal condition, infant birth weight, or gestational age.

CONCLUSIONS

Although larger avascular areas or higher severity scores were associated with mHTN after adjustment for gestational age at initial examination, no associations were found between mHTN and ROP severity score at the examination when ROP was most severe. There were no associations between ROP severity and treatment with erythropoietin.

[Screening and treatment for retinopathy of prematurity at the Markusovszky County Hospital, (experience of 20 years: 1989-2009]

The aims of this study was to obtain the frequency and therapy of retinopathy of prematurity (ROP) in Markusovszky Teaching Hospital, Szombathely, Hungary. A population based study on ophthalmological status of preterm infants was performed, between 01.01.1989 and 01.01.2009. During the study period, ophthalmological status was detected in 543 premature infants. Among them, 34 children (6.3%) suffered from retinopathy of prematurity, and all of them were bilateral. ROP occurred in the highest rate (23/78 cases, 29.5%) at the birth weight of lower than 1000 grams, but frequency was only l.2% (2/169 cases) between weight 1250-1500 grams. Spontaneous recovery was observed in 19 eyes of 10 cases. The frequency of spontaneous resolution was 40% and 50% in the group of larger birth weight: between 1251-1500 grams and weight > or = 1500 grams, but on the other hand, complete recovery was only 26% (6/23 cases) below 1000 grams of birth weight. "Threshold retinopathy" (stage 3 plus), that needed therapy was detected in 25 children's 49 eyes. Cryotherapy was performed in both eyes of 16 children (32 eyes), laser photocoagulation was performed in 9 patients (16 eyes). ROP regressed after cryotherapy in 26 eyes, but in 6 eyes symptoms progressed to stage 5. After laser photocoagulation, recovery was observed in 16 eyes; this therapy was not successful in only one case. According to our experiences, stage 5 ROP developed only in two patients' both eyes, and in 1-1 eye of three children, during the 20 years of study. Our ophthalmological screening program proved that providing cryopexia or laser photocoagulation in time, severe visual impairment of retinopathy can be prevented. In spite of the few number of patients, this population based investigation with a long duration (20 years) offers new data in Hungarian ROP epidemiology.

The influence of gestational age on the dynamic behavior of other risk factors associated with retinopathy of prematurity (ROP)

Background

Improved survival of preterm neonates has increased the incidence of retinopathy of prematurity (ROP) in many middle-income countries.

Aim

This study aimed to verify the main risk factors for the development of ROP according to different gestational age (GA) groups.

Methods

A prospective cohort study including infants weighing ≤1,500 g or GA ≤32 weeks at birth was conducted. The main clinical outcomes were the occurrence of any stage of ROP and severe ROP. The perinatal variables considered for the study were: birth weight; GA; gender; to be small for GA (SGA); weight gain from birth to the sixth week of life; use of oxygen in mechanical ventilation or nasal CPAP; multiple gestations; therapeutic use of surfactant, indomethacin, and erythropoietin; occurrence of sepsis, meningitis, intraventricular hemorrhage, and patent ductus arteriosus; need for and volume of blood transfusion; and 10-min Apgar score. The patients were divided into three groups according to GA: (group 1) infants of GA ≤28 weeks at birth (n = 100); (group 2) infants of GA = 29–31 weeks at birth (n = 215); and (group 3) infants of GA ≥32 weeks at birth (n = 152).

Results

A total of 467 newborn infants were included. Mean BW and GA in the total cohort were 1,216.5 g (±278.3) and 30.3 weeks (±2.2), respectively. Gestational age groups were not matched for BW and SGA. Any stage of ROP occurred in 111 patients (23.8%) and 24 (5.1%) patients developed severe ROP. Only BW and volume of blood transfusion were significant factors for the occurrence of any stage of ROP in all groups. In group 1, GA, the twin situation, and use of erythropoietin were statistically significant factors. In group 2, only GA and need for blood transfusion were significant. In group 3, use of oxygen in mechanical ventilation, sepsis, and need for blood transfusion were significant for ROP onset. The logistic regression determined that patients in groups 2 and 3 were less likely to develop ROP than patients in group 1.

Conclusions

Patients in groups 1 and 2 developed ROP due to general immaturity, whereas bigger babies, of GA ≥32 weeks, developed ROP because they were “sicker” babies with more comorbidities.

Telemedicine for retinopathy of prematurity diagnosis: evaluation and challenges

Retinopathy of prematurity (ROP) is a vasoproliferative disorder affecting low birth weight infants. Although timely diagnosis and treatment can significantly reduce the risk of severe complications, ROP remains a leading cause of childhood blindness worldwide. Limitations of current disease management strategies include extensive travel and logistical coordination requirements for ophthalmologists and neonatologists, decreasing availability of adequately trained ophthalmologists at the point of care, variability in how retinal findings are diagnosed and documented, and a growing need for ROP care worldwide. Store-and-forward telemedicine is an emerging technology by which medical data are captured for subsequent interpretation by a remote expert. This has potential to improve accessibility, quality, and cost of ROP management. In this article, we summarize the current evaluation data on applications of telemedicine for ROP, particularly involving the diagnostic accuracy and reliability of remote image interpretation by experts. We also address challenges such as the cost-effectiveness of telemedicine, and highlight potential barriers to implementation of these systems. Understanding these principles is essential to determine future directions in research and development of telemedicine systems for ROP, as well as for other ophthalmic diseases.

Proliferative retinopathies: angiogenesis that blinds

Proliferative ischemic retinopathies such as proliferative diabetic retinopathy (PDR), retinopathy of prematurity (ROP) and those stemming from retinal vein occlusion are the leading causes of blindness in the working age and pediatric populations of industrialized countries. They present major financial burdens for health care systems and account for significant loss of productivity. These pathologies are characterized by excessive pre-retinal blood vessel growth that can ultimately lead to a fibrous scar formation and culminate in retinal detachment. This abnormal and disproportionate hyper-vascularization is a compensatory mechanism to overcome an earlier phase of microvessel degeneration and reinstate metabolic equilibrium to the hypoxic retina. To date, the treatment modalities to counter these diseases largely rely on invasive and moderately efficient surgical interventions. In this review, we discuss the current views on retinal vaso-obliteration, neovascularization and available treatments and present future strategies to tackle these diseases.

Image analysis for retinopathy of prematurity diagnosis

PURPOSE

To review findings from the authors' published studies involving telemedicine and image analysis for retinopathy of prematurity (ROP) diagnosis.

METHODS

Twenty-two ROP experts interpreted a set of 34 wide-angle retinal images for presence of plus disease. For each image, a reference standard diagnosis was defined from expert consensus. A computer-based system was used to measure individual and linear combinations of image parameters for arteries and veins: integrated curvature (IC), diameter, and tortuosity index (TI). Sensitivity, specificity, and receiver operating characteristic areas under the curve (AUC) for plus disease diagnosis were determined for each expert. Sensitivity and specificity curves were calculated for the computer-based system by varying the diagnostic cutoffs for arterial IC and venous diameter. Individual vessels from the original 34 images were identified with particular diagnostic cutoffs, and combined into composite wide-angle images using graphics editing software.

RESULTS

For plus disease diagnosis, expert sensitivity ranged from 0.308-1.000, specificity from 0.571-1.000, and AUC from 0.784 to 1.000. Among computer system parameters, one linear combination had AUC 0.967, which was greater than that of 18 of 22 (81.8%) experts. Composite computer-generated images were produced using the arterial IC and venous diameter values associated with 75% under-diagnosis of plus disease (ie, 25% sensitivity cutoff), 50% under-diagnosis of plus disease (ie, 50% sensitivity cutoff), and 25% under-diagnosis of plus disease (ie, 75% sensitivity cutoff).

CONCLUSIONS

Computer-based image analysis has the potential to diagnose severe ROP with comparable or better accuracy than experts, and could provide added value to telemedicine systems. Future quantitative definitions of plus disease might improve diagnostic objectivity.

A systematic analysis of the off-label use of bevacizumab for severe retinopathy of prematurity

PURPOSE

To examine the quality of evidence and the variability in the off-label use of bevacizumab (Avastin; Genentech Inc, South San Francisco, California, USA) in the treatment of retinopathy of prematurity (ROP) and to discuss the implications for the design of future randomized controlled trials.

DESIGN

Systematic literature review.

METHODS

A systematic review of the literature indexed by Ovid MEDLINE, EMBASE, and the Cochrane database was performed with a broad and inclusive search strategy. All case reports and retrospective and prospective trials in peer-reviewed journals reporting the use of bevacizumab in ROP were included.

RESULTS

Nine articles, including 6 case reports, 2 retrospective studies, and 1 prospective case series representing 77 eyes of 48 infants, were selected for the review. The doses used ranged from 0.4 to 1.25 mg, with 0.75 mg being the most common, used in 3 of the 9 studies. A total of 8 of the 11 eyes in the case received bevacizumab as a first-line therapy and two articles noted worsening of an already present retinal detachment. One retrospective study and the prospective case series used bevacizumab alone, whereas the other retrospective study used bevacizumab before and with retinal surgery.

CONCLUSIONS

Considerable variability exists in how bevacizumab is used for the treatment of ROP in the literature to date. Further randomized control trials are warranted and should aim to assess statistically the optimal timing, frequency, and dose of the drug. Careful attention should be given to the potential for systemic complications and long-term effects of intravitreal bevacizumab in infants.

Incidence of retinopathy of prematurity in the United States: 1997 through 2005

PURPOSE

To determine the incidence of retinopathy of prematurity (ROP) based on a national database and to identify baseline characteristics, demographic information, comorbidities, and surgical interventions.

DESIGN

Retrospective study based on the National Inpatient Sample from 1997 through 2005.

METHODS

The National Inpatient Sample was queried for all newborn infants with and without ROP. Multivariate logistic regression was used to predict risk factors for ROP.

RESULTS

Thirty-four million live births were recorded during the study period. The total ROP incidence was 0.17% overall and 15.58% for premature infants with length of stay of more than 28 days. Our results conclusively demonstrated the importance of low birth weight as a risk for ROP development in infants with length of stay of more than 28 days, as well as association with respiratory conditions, fetal hemorrhage, intraventricular hemorrhage, and blood transfer. An interesting finding was the protective effect conferred by hypoxia, necrotizing enterocolitis, and hemolytic disease of the newborn. Infants with ROP had a higher incidence of undergoing laser photocoagulation therapy, pars plana vitrectomy, and scleral buckle surgery.

CONCLUSIONS

The current study represents a large, retrospective analysis of newborns with ROP. The multivariate analysis emphasizes the role of birth weight in extended-stay infants, as well as respiratory conditions, fetal hemorrhage, intraventricular hemorrhage, and blood transfer.

Retinopathy of prematurity

This article briefly reviews the history of ROP followed by a discussion of the pathogenesis of this complex disorder. We describe the International Classification System for ROP and identify risk factors and screening recommendations. Finally, we discuss some of the measures that have been used in an attempt to both prevent and treat ROP.

Severe retinopathy of prematurity in big babies in India: history repeating itself?

OBJECTIVE

To describe the characteristics of babies with severe retinopathy of prematurity (ROP) attending a tertiary referral eye hospital in South India.

METHODS

Data on consecutive preterm infants with severe ROP presenting between July 2002 and October 2007 were retrieved from medical records. Severe ROP was defined as high risk prethreshold disease or worse.

RESULTS

144 babies with severe ROP were divided into two groups: group 1 had high risk prethreshold or threshold ROP while group 2 had stages 4 or 5 ROP. The overall mean gestational age was 30.7 weeks (range 25-35 weeks) and the mean birth weight was 1410 g (range 650-2310 g). Most babies had received unmonitored supplemental oxygen (ascertained through discussion with the treating pediatricians).

CONCLUSION

More bigger and mature babies are developing severe ROP in South India than in industrialized countries. The characteristics of babies affected are similar to those seen during the first epidemic of ROP which occurred during the 1950s in Europe and North America. Guidelines on oxygenation and screening policies should be jointly developed by pediatricians and ophthalmologists to end this epidemic of avoidable blindness in India.

The Relationship of Retinal VEGF and Retinal IGF-1 mRNA with Neovascularization in an Acidosis-Induced Model of Retinopathy of Prematurity

PURPOSE

Acidosis-induced retinopathy (AIR) in the neonatal rat provides an alternative model for retinopathy of prematurity (ROP). We studied the relationship of vascular endothelial growth factor (VEGF) retinal mRNA and insulin-like growth factor-1 (IGF-1) retinal mRNA expression with the emergence of neovascularization (NV) in AIR.

METHODS

Two hundred seventy-five newborn Sprague-Dawley rats were raised in 11 expanded litters of 25. Using our established AIR model, acidosis was induced by twice-daily gavage with NH4Cl from day 2 to day 8 of life (n=175). Rats were sacrificed at days 5, 8, and 10. Nongavaged rats were used as age-matched controls (n=100). Retinae from left eyes were dissected, flatmounts were ADPase-stained, and the presence and severity of NV was scored in a masked manner. Individual right retinae were processed for analysis of retinal VEGF and IGF-1 mRNA using quantitative real-time reverse-transcriptase PCR (qRT-PCR).

RESULTS

Retinal VEGF mRNA was increased 1.4-fold at day 10 in AIR, when compared with age-matched controls (p=0.03). This correlated with maximal NV at day 10 in AIR. Retinal IGF-1 mRNA was decreased to 82% of its normal expression on day 8 (p=0.006), prior to maximal NV, before returning to normal expression at day 10, when compared with nonacidotic controls.

CONCLUSIONS

In AIR, preretinal neovascularization is associated with decreased retinal IGF-1 mRNA prior to maximal NV and increased retinal VEGF mRNA at the time of maximal NV. These growth factor changes in AIR are similar to those seen with hypercarbic oxygen-induced retinopathy. The retinal IGF-1 pathway may provide an alternative target for therapeutic intervention in abnormal retinal angiogenesis.