Can Screening for Retinopathy of Prematurity Be Reduced?

Premature infants with gestational age less than 25 weeks require increased ophthalmology resources for retinopathy of prematurity

BACKGROUND

It is unclear how increasing survival of low gestational age (GA) infants affects ophthalmologic screening and treatment rates for retinopathy of prematurity (ROP). This study compared the examination and treatment rates of infants born at GA of <25 weeks and those born at GA of at least 25 weeks.

METHODS

This was a retrospective study of patients who met institutional ROP screening criteria and were admitted to two neonatal intensive care units (NICUs) from January 2017 to June 2020. Variables analyzed were GA, birth weight, number of ophthalmology examinations, worst stage of ROP, presence of type 1 ROP, and comorbidities associated with ROP. The χ², Fisher exact, and two-tailed t tests, as well as univariate and multivariable logistic regression, were used for statistical analysis.

RESULTS

Compared to the GA≥25 group, the GA<25 group had a higher number of total exams (10 vs 4.3 [P < 0.001]), higher average worst stage of ROP (1.4 vs 0.3 [P < 0.001]) and higher rate of type 1 ROP (21% vs 1.4% [P < 0.001]), as well as higher mortality (37% vs 8.11% [P < 0. 001]). Multivariable logistic regression analysis controlling for GA, sepsis, and number of transfusions revealed that only GA was significantly associated with developing type 1 ROP.

CONCLUSIONS

Infants with GA <25 weeks had more severe ROP and required significantly more ophthalmologic examinations than GA ≥25. It is important for ROP services to plan for this increased screening load, especially if the number of such lower-weight infants in their NICUs increases.

Screening and novel therapies for retinopathy of prematurity - A review

With current screening for sight threatening retinopathy of prematurity (ROP) <10% of screened infants need treatment. Prediction models based on birth characteristics, postnatal weight gain and other factors have been developed to reduce examinations in low-risk infants. A model based on advanced statistics using data from >7000 infants registered in the Swedish ROP registry is being developed. Based on birth characteristics only, it appears to predict total risk of ROP-treatment as well as models including weight measurements. Treatment risk peaked at 12 weeks of age. Laser therapy is the method of choice for severe ROP. Anti-VEGF therapies are implemented worldwide despite insufficient knowledge of choice of drug, dosage and long term systemic effects. Prevention of ROP may be achieved through oxygen control and provision of the mother's breastmilk. Other interventions such as supplementation with long chain polyunsaturated fatty acids and preservation of fetal haemoglobin are investigated.

Retinopathy of prematurity: a review of risk factors and their clinical significance

Retinopathy of prematurity (ROP) is a retinal vasoproliferative disease that affects premature infants. Despite improvements in neonatal care and management guidelines, ROP remains a leading cause of childhood blindness worldwide. Current screening guidelines are primarily based on two risk factors: birth weight and gestational age; however, many investigators have suggested other risk factors, including maternal factors, prenatal and perinatal factors, demographics, medical interventions, comorbidities of prematurity, nutrition, and genetic factors. We review the existing literature addressing various possible ROP risk factors. Although there have been contradictory reports, and the risk may vary between different populations, understanding ROP risk factors is essential to develop predictive models, to gain insights into pathophysiology of retinal vascular diseases and diseases of prematurity, and to determine future directions in management of and research in ROP.

Factors associated with retinopathy of prematurity ophthalmology workload

OBJECTIVE

This article reports on retinopathy of prematurity (ROP) workload in the NICU related to severity of disease, gestational age at discharge, and practice variation.

STUDY DESIGN

Data analysis on 1771 patients ≤ 30 weeks of gestation at birth from a de-identified data set of 13 NICUs.

RESULTS

There was a positive relationship between the severity of ROP and (1) the number of exams per patient, (2) the severity of ROP, and (3) postmenstrual age at discharge. The progression between the stages of ROP added to exam workload and postmenstrual age at NICU discharge. The addition of plus disease did not increase the exam burden. There was significant practice variation in the number of exams performed independent of ROP severity.

CONCLUSION

The progression of the severity of ROP independent of plus disease, and practice variations both contribute to ROP workload. Addressing these factors could decrease ROP workload without compromising American Academy of Pediatrics (AAP) guidelines.

Risk Score for Predicting Treatment-Requiring Retinopathy of Prematurity (ROP) in the Telemedicine Approaches to Evaluating Acute-Phase ROP Study

PURPOSE

To develop a risk score for predicting treatment-requiring retinopathy of prematurity (TR-ROP) in the Telemedicine Approaches to Evaluating Acute-Phase Retinopathy of Prematurity (e-ROP) study.

DESIGN

Second analyses of an observational cohort study.

PARTICIPANTS

Infants with birth weight (BW) <1251 g who had ≥1 imaging session by 34 weeks of postmenstrual age (PMA) and ≥1 subsequent retinopathy of prematurity (ROP) examination for determining TR-ROP by study-certified ophthalmologists.

METHODS

Nonphysician trained readers evaluated wide-field retinal image sets for characteristics of ROP, pre-plus/plus disease, and retinal hemorrhage. Risk score points for predicting TR-ROP were derived from the regression coefficients of significant predictors in a multivariate logistic regression model.

MAIN OUTCOME MEASURES

TR-ROP.

RESULTS

Eighty-five of 771 infants (11.0%) developed TR-ROP. In a multivariate model, significant predictors for TR-ROP were gestational age (GA) (odds ratio [OR], 5.7; 95% confidence interval [CI], 1.7-18.9 for ≤25 vs. ≥28 weeks), need for respiratory support (OR, 7.0; 95% CI, 1.3-37.1 for high-frequency oscillatory ventilation vs. no respiratory support), slow weight gain (OR, 2.4; 95% CI, 1.2-4.6 for weight gain ≤12 g/day vs. >15 g/day), and image findings at the first image session including number of quadrants with pre-plus (OR, 3.8; 95% CI, 1.5-9.7 for 4 pre-plus quadrants vs. no pre-plus), stage and zone of ROP (OR, 4.7; 95% CI, 2.1-11.8 for stage 1-2 zone I, OR, 5.9; 95% CI, 2.1-16.6 for stage 3 zone I vs. no ROP), and presence of blot hemorrhage (OR, 3.1; 95% CI, 1.4-6.7). Image findings predicted TR-ROP better than GA (area under receiver operating characteristic curve [AUC] = 0.82 vs. 0.75, P = 0.03). The risk of TR-ROP steadily increased with higher risk score and predicted TR-ROP well (AUC = 0.88; 95% CI, 0.85-0.92). Risk score ≥3 points for predicting TR-ROP had a sensitivity of 98.8%, specificity of 40.1%, and positive and negative predictive values of 17.0% and 99.6%, respectively.

CONCLUSIONS

Image characteristics at 34 PMA weeks or earlier independently predict TR-ROP. If externally validated in other infants, risk score, calculated from image findings, GA, weight gain, and respiratory support, enables early identification of infants in need of increased surveillance for TR-ROP.

Retinal Oximetry with Scanning Laser Ophthalmoscope in Infants

Purpose

Dual wavelength retinal oximetry has been developed for adults, but is not available for infants. Retinal oximetry may provide insight into the pathophysiology of oxygen-mediated diseases like retinopathy of prematurity. More insight in the oxygen metabolism of the retina in infants may provide valuable clues for better understanding and subsequent prevention or treatment of the disease. The measurements of oxygen saturation are obtained with two fundus images simultaneously captured in two different wavelengths of light. The comparison in light absorption of oxygenated and deoxygenated hemoglobin can be used to estimate the oxygen saturation within the retinal vessels by means of a software algorithm. This study aims to make retinal oximetry available for neonates. The first step towards estimating retinal oxygen saturation is determining the optical density ratio. Therefore, the purpose of this study is to image healthy newborn infants with a scanning laser ophthalmoscope and determine the optical density ratio for retinal oximetry analysis.

Methods

Images of the retina of full-term healthy infants were obtained with an SLO, Optomap 200Tx (Optos), with two laser wavelengths (532nm and 633nm). The infant lay face down on the lower arm of the parent, while the parent supported the chest and chin with one hand, and stabilized the back with the other hand. No mydriatics or eyelid specula were used during this study. The images were analyzed with modified Oxymap Analyzer software for calculation of the Optical Density Ratio (ODR) and vessel width. The ODR is inversely and approximately linearly related to the oxygen saturation. Measurements were included from the superotemporal vessel pair. A paired t-test was used for statistical analysis.

Results

Fifty-nine infants, (58% female), were included with mean gestational age of 40 ± 1.3 weeks (mean ± SD) and mean post-natal age of 16 ± 4.8 days. A total of 28 images were selected for retinal oximetry analysis. The ODR was 0.256 ± 0.041 for the arterioles and 0.421 ± 0.089 for the venules (n = 28, p < 0.001). The measured vessel-width for the arterioles was 14.1 ± 2.7 pixels and for the venules 19.7 ± 3.7 pixels (n = 28, p < 0.001).

Conclusions

Retinal oximetry can be performed in newborn infants by combining an SLO and a dual-wavelength algorithm software. Sensitivity of the approach is indicated by the fact that the ODR measurements are significantly different between the arterioles and the venules. However, more variability in ODR is seen with the SLO approach in babies than is seen with conventional oximetry in adults. This approach is completely non-invasive, non-contact and even avoids the use of mydriatics or eyelid specula.

Clinical Models and Algorithms for the Prediction of Retinopathy of Prematurity: A Report by the American Academy of Ophthalmology

OBJECTIVE

To assess the accuracy with which available retinopathy of prematurity (ROP) predictive models detect clinically significant ROP and to what extent and at what risk these models allow for the reduction of screening examinations for ROP.

METHODS

A literature search of the PubMed and Cochrane Library databases was conducted last on May 1, 2015, and yielded 305 citations. After screening the abstracts of all 305 citations and reviewing the full text of 30 potentially eligible articles, the panel members determined that 22 met the inclusion criteria. One article included 2 studies, for a total of 23 studies reviewed. The panel extracted information about study design, study population, the screening algorithm tested, interventions, outcomes, and study quality. The methodologist divided the studies into 2 categories-model development and model validation-and assigned a level of evidence rating to each study. One study was rated level I evidence, 3 studies were rated level II evidence, and 19 studies were rated level III evidence.

RESULTS

In some cohorts, some models would have allowed reductions in the number of infants screened for ROP without failing to identify infants requiring treatment. However, the small sample size and limited generalizability of the ROP predictive models included in this review preclude their widespread use to make all-or-none decisions about whether to screen individual infants for ROP. As an alternative, some studies proposed approaches to apply the models to reduce the number of examinations performed in low-risk infants.

CONCLUSIONS

Additional research is needed to optimize ROP predictive model development, validation, and application before such models can be used widely to reduce the burdensome number of ROP screening examinations.

A new risk-based screening criterion for treatment-demanding retinopathy of prematurity in Denmark

OBJECTIVE

The aim of this study was to uncover the most effective and safe criterion to implement for retinopathy of prematurity screening in Denmark.

METHODS

This retrospective national cohort study is based on data from 3 national registers. These registers provided on infants treated for retinopathy of prematurity, infants in need of treatment but missed by the present screening program, and the candidate neonates for advanced retinopathy of prematurity development A nonlinear logistic regression model was fitted to the data, and various screening criteria were evaluated.

RESULTS

During the study period (2002-2006), 116 infants were treated for retinopathy of prematurity, no treatment-demanding retinopathy of prematurity infants were missed by the screening program, and 182 premature infants were candidates for developing treatment-demanding retinopathy of prematurity. Screening criteria combining gestational age at delivery and birth weight limits and new risk-based criteria were compared with regards to their effectiveness. The risk-based criteria were the most effective. Use of the 0.13% risk-based criterion to define the population to be screened resulted in the detection of all treated infants in the study period and 17.4% fewer infants to screen. The model predicted this criterion to result in 1 missed case of treatment-demanding retinopathy of prematurity every 11 years and 1 case of blindness every 18 years in Denmark.

CONCLUSIONS

Screening criteria based on risk estimates of developing treatment-demanding retinopathy of prematurity are the most effective for retinopathy-of-prematurity screening. The risk-based criterion of 0.13% can safely be implemented for future retinopathy-of-prematurity screening in Denmark.

Risk analysis and an alternative protocol for reduction of screening for retinopathy of prematurity

PURPOSE

To determine whether a multivariate risk model can select infants with low-risk eyes for an alternative protocol that reduces retinopathy of prematurity (ROP) screening without loss of effectiveness.

METHODS

This was a retrospective, nonrandomized, comparative study. We assigned 712 eyes of 357 premature infants of 401-1,250 g birth weights as high or low risk for prethreshold or threshold ROP using a risk model with variables of birth weight, gestational age, multiple birth, race, and gender. Using simulations, infants with high-risk eyes (p > or = 0.15) were screened conventionally, while those with low-risk eyes were screened with the 35q3 protocol (initial examination at 35 weeks postmenstrual age followed by screening every 3 weeks, with increased or decreased intervals based on ROP severity). The resultant reduction in ROP screening and the delay to detection of severe ROP were calculated.

RESULTS

The 35q3 protocol reduced the mean number of eye examinations per infant in the overall population by 13.4% (p = 0.0051). No eyes had a delay to the detection of threshold or type 1 zone 1 ROP. Of a total of 57 type 1 ROP eyes, 2 eyes with type 1 zone 2 ROP were delayed to detection by 1 week. As our study was done prior to the Early Treatment of ROP study, the 2 eyes were observed and regressed without progression to threshold ROP.

CONCLUSIONS

A risk-based alternative screening protocol increased the efficiency of ROP screening for infants of 401-1,250 g birth weight without an apparent loss of effectiveness. This investigational approach requires further validation by multicenter studies.

Telemedicine screening for retinopathy of prematurity in developing countries using digital retinal images: a feasibility project

PURPOSE

To determine the feasibility in a middle-level human development country of onsite training, image collection, Internet transfer, and remote grading of digital retinal images from babies screened for retinopathy of prematurity (ROP).

METHODS

Two experienced nurses in a neonatal nursery in Lima, Peru, were trained to take posterior pole (30 degrees ) digital retinal images. Nurses obtained posterior pole retinal images from babies undergoing routine ROP screening and selected images for uploading via Internet for remote evaluation by five masked ROP experts. Results of gradings were compared with same-day clinical diagnostic examinations by an experienced ophthalmologist. Success rates for image acquisition and transfer for grading by expert readers were calculated.

RESULTS

Serial image sets from 26 of the 28 babies enrolled in this study were obtained; two babies were too unstable for imaging. Fifty-six of 58 (96.6%) imaging sessions were successful in obtaining retinal images. Three hundred thirty of 336 (98.2%) images obtained were successfully uploaded to an interactive database. Remote graders judged 93.6% to 97.3% of image sets suitable for ROP grading. Preliminary results indicate sensitivities for detection of serious ROP from 45.5% to 95.2% among individual readers, with specificities of 61.7% to 96.2% when images were gradable.

CONCLUSIONS

A telemedicine approach for ROP screening using digital retinal images obtained by nonophthalmologists is feasible in rapidly developing countries that lack ROP-trained ophthalmologists. If remote grading of digital images is validated as an effective method for identifying referral-warranted ROP (RW-ROP), images obtained by nonphysicians may provide a means of identifying babies who require a diagnostic examination by an ophthalmologist.

Cumulative illness severity and progression from moderate to severe retinopathy of prematurity

OBJECTIVE

To test cumulative neonatal illness severity (IS) and IS fluctuation as predictors of progression from moderate to severe retinopathy of prematurity (ROP).

METHODS

Data from research databases and medical record review were collected for infants from four neonatal intensive care unit (NICUs) admitted between 1995 and 2001 and diagnosed with prethreshold ROP. Cumulative neonatal IS measured using daily Scores for Neonatal Acute Physiology (SNAP) for the first 28 days of life, and IS fluctuation as assessed by summing changes between daily SNAP scores, were tested as predictors of progression to threshold ROP using logistic regression.

RESULTS

Infants progressing to threshold (n=79), compared to those not progressing to threshold (n=130), had significantly (P<0.05) lower gestational ages (25.2+/-1.1 versus 25.8+/-1.4 weeks), higher cumulative neonatal SNAP (255+/-77 versus 224+/-63 weeks) and had more severe hospitalizations as indicated by diagnoses and medical management. In regression analysis, gestational age, chronological age and presence of plus disease at first diagnosis of prethreshold were associated with development of threshold. After adjusting for these factors, cumulative neonatal SNAP was significantly associated with progression to threshold. However, addition of cumulative SNAP to the model only increased receiver-operating characteristic curve area from 0.77 to 0.78 (NS). Other factors, including SNAP fluctuation, were not associated with progression to threshold after adjustment using this model.

CONCLUSIONS

Cumulative neonatal IS, as measured by cumulative SNAP, is an independent risk factor for progression from moderate to severe ROP. However, cumulative IS does not enhance assessment of risk for ROP progression after adjusting for simpler clinical factors.