Plus Disease

Targeting proliferative retinopathy: Arginase 1 limits vitreoretinal neovascularization and promotes angiogenic repair

Current therapies for treatment of proliferative retinopathy focus on retinal neovascularization (RNV) during advanced disease and can trigger adverse side-effects. Here, we have tested a new strategy for limiting neurovascular injury and promoting repair during early-stage disease. We have recently shown that treatment with a stable, pegylated drug form of the ureohydrolase enzyme arginase 1 (A1) provides neuroprotection in acute models of ischemia/reperfusion injury, optic nerve crush, and ischemic stroke. Now, we have determined the effects of this treatment on RNV, vascular repair, and retinal function in the mouse oxygen-induced retinopathy (OIR) model of retinopathy of prematurity (ROP). Our studies in the OIR model show that treatment with pegylated A1 (PEG-A1), inhibits pathological RNV, promotes angiogenic repair, and improves retinal function by a mechanism involving decreased expression of TNF, iNOS, and VEGF and increased expression of FGF2 and A1. We further show that A1 is expressed in myeloid cells and areas of RNV in retinal sections from mice with OIR and human diabetic retinopathy (DR) patients and in blood samples from ROP patients. Moreover, studies using knockout mice with hemizygous deletion of A1 show worsened RNV and retinal injury, supporting the protective role of A1 in limiting the OIR-induced pathology. Collectively, A1 is critically involved in reparative angiogenesis and neuroprotection in OIR. Pegylated A1 may offer a novel therapy for limiting retinal injury and promoting repair during proliferative retinopathy.

Optimal Efficacy and Safety of Humanized Anti-Scg3 Antibody to Alleviate Oxygen-Induced Retinopathy

The retinopathy of prematurity (ROP), a neovascular retinal disorder presenting in premature infants, is the leading causes of blindness in children. Currently, there is no approved drug therapy for ROP in the U.S., highlighting the urgent unmet clinical need for a novel therapeutic to treat the disease. Secretogranin III (Scg3) was recently identified as a disease-selective angiogenic factor, and Scg3-neutralizing monoclonal antibodies were reported to alleviate pathological retinal neovascularization in mouse models. In this study, we characterized the efficacy and safety of a full-length humanized anti-Scg3 antibody (hAb) to ameliorate retinal pathology in oxygen-induced retinopathy (OIR) mice, a surrogate model of ROP, by implementing histological and functional analyses. Our results demonstrate that the anti-Scg3 hAb outperforms the vascular endothelial growth factor inhibitor aflibercept in terms of efficacy and safety to treat OIR mice. Our findings support the development of anti-Scg3 hAb for clinical application.

Ocular Blood Flow in Preterm Neonates: A Preliminary Report

Purpose

Retinopathy of prematurity (ROP) is a vision-threatening complication occurring in pre-term neonates. The standard of care entails regular monitoring by dilated ophthalmoscopy examinations, which entail stress and potential morbidity. In this pilot study, we used plane-wave ultrasound (PWUS) to image, measure, and assess the association of blood-flow velocities in the retrobulbar vessels with ROP stages ranging from stage 0 (immature vessels without ROP) to stage 3.

Methods

Both eyes of 14 preterm neonates at risk for ROP were examined by 18 MHz PWUS. All but two subjects had a follow-up examination. PWUS was acquired for 1.5 seconds at 3000 compound B-scans/sec. Data were postprocessed to form color-flow images and spectrograms depicting flow velocity in the central retinal artery (CRA), central retinal vein (CRV), and the short posterior ciliary arteries (SPCA). Flow parameters derived from spectrograms were compared by ROP stage.

Results

ROP stage was found to correlate with flow velocities. Velocities were significantly elevated with respect to non-ROP eyes in all vessels at stage 3 and in the SPCAs at stage 2.

Conclusions

PWUS measurement of blood flow may provide a quantitative, clinically important, and easily tolerated means for detecting and assessing the risk of ROP in preterm neonates. We speculate that the observed increase in flow velocity results from elevated vascular endothelial growth factor (VEGF) in ROP eyes.

Translational Relevance

PWUS offers a gentle, nonmydriatic method for monitoring neonates at risk for ROP that would complement ophthalmoscopy.

Automated Detection and Tortuosity Characterization of Retinal Vascular Networks

Automated retinal vascular network detection and analysis using digital retinal images continue to play a major role in the field of biomedicine for the diagnosis and management of various forms of human ailments like hypertension, diabetic retinopathy, retinopathy of prematurity, glaucoma and cardiovascular diseases. Although several literature have implemented different automatic approaches of detecting blood vessels in the retinal and also determining their tortuous states, the results obtained show that there are needs for further investigation on more efficient ways to detect and characterize the blood vessel network tortuosity states. This paper implements the use of an adaptive thresholding method based on local spatial relational variance (LSRV) for the detection of the retinal vascular networks. The suitability of a multi-layer perceptron artificial neural network (MLP-ANN) technique for the tortuosity characterization of retinal blood vascular networks is also presented in this paper. Some vessel geometric features of detected vessels are fed into ANN classifier for the automatic classification of the retinal vascular networks as being tortuous vessels or normal vessels. Experimental studies conducted on DRIVE and STARE databases show that the vascular network detection results obtained from the method implemented in this paper detects large and thin vascular networks in the retina. In comparison to preious methods in the literature, the proposed method for vascular network segmentation achieved better performance than several methods in the literature with a mean accuracy value of 95.04% and mean sensitivity value of 75.16% on DRIVE and mean accuracy value of 94.02% and average sensitivity value of 76.55% on STARE with computational processing time of 4.5 seconds and 9.4 seconds on DRIVE and STARE respectively. The MLP-ANN method proposed for the vascular network tortuosity characterization achieves promising accuracy rates of 77.5%, 80%, 83.33%, 85%, 86.67% and 100% for varying training sample sizes.

Early angiographic signs of retinopathy of prematurity requiring treatment

BACKGROUND/OBJECTIVES

Fluorescein angiography (FA) has been a pivotal tool to study the pathophysiology of retinopathy of prematurity (ROP) in vivo. We examined the course of ROP using FA in order to assess the predictive value of angiographic features.

SUBJECTS/METHODS

This is an observational retrospective cohort multi-center study of eyes screened for ROP with binocular indirect ophthalmoscope and with FA. All infants undergoing screening examination for ROP who had retinal vasculature limited to Zone I and posterior Zone II vascularization underwent FA between 31 and 34 weeks postmenstrual age. RetCam fundus imaging and video digital fluorescein angiography were performed in the neonatal intensive care units. Masked grading of the FA images was retrospectively conducted by two ROP expert ophthalmologists. Ten criteria that describe retinovascular and choroidal features on FA were used to assess their predictive value for development of treatment-requiring ROP.

RESULTS

A total of 98 eyes of 56 patients were included for this study. FAs of eyes of premature infants show a wide range of features either at the junction between the vascular and avascular retina and posteriorly to that. Among the angiographic features evaluated, leakage, shunts and hyperfluorescent lesions at the junction between vascular and avascular zone were predictive of the development of treatment-requiring ROP (p < 0.05), but findings in the posterior vascularized retina were not.

CONCLUSIONS

FA can add to our understanding of the evolution of vascular abnormalities in the course of ROP and can help predict which eyes will go on to treatment.

Progression from preplus to plus disease in the Telemedicine Approaches to Evaluating Acute-Phase Retinopathy of Prematurity (e-ROP) Study: incidence, timing, and predictors

PURPOSE

To determine the incidence of and timing and predictors for progression from pre-plus to plus disease, based on evaluation of images.

METHODS

Two trained readers independently evaluated posterior pole images of infants from 13 North American centers for pre-plus/plus disease, stage, and zone of retinopathy of prematurity (ROP). Discrepancies between readers were adjudicated. To be eligible for analysis, eyes had to have at least two imaging sessions, the earlier one with pre-plus disease.

RESULTS

Of 681 eyes of 444 infants with pre-plus first detected at mean postmenstrual age (PMA) of 35.5 ± 2.1 weeks, 54 (7.9%) progressed to plus disease at a mean PMA of 37.6 ± 2.4 weeks with the mean interval for progression of 2.7 weeks (range, 0.4-8.9 weeks). Progression rate was higher for eyes with larger number of quadrants of pre-plus (44% for eyes with four quadrants vs 4% with one quadrant [P < 0.0001]), earlier PMA with pre-plus (18% for 32 weeks' PMA vs 3% for PMA of >37 weeks [P = 0.02]), higher ROP stage (12% for stage 3, 2.5% for no ROP [P < 0.0001]), lower ROP zone (24% for zone I, 6% for zone II or no ROP [P < 0.0001]) at the time of first pre-plus detection.

CONCLUSIONS

Based on image evaluation, 8% of eyes progressed from pre-plus to plus disease at a mean interval of 3 weeks. Pre-plus in multiple quadrants, higher stages of ROP, and lower zones of ROP were associated with higher risk of progression. Image evaluation for pre-plus may help in the identification of high-risk eyes for developing plus disease.

Enhancing vessel visibility in fundus images to aid the diagnosis of retinopathy of prematurity

Retinopathy of prematurity is a disease that can affect premature or in similar conditions babies. For diagnosing of retinopathy of prematurity, the infant is examined as soon as possible. Due to the nature of the examination, the images obtained are poor in quality. This article presents an automated method for processing fundus images to improve the visibility of the vascular network. The method includes several processing tasks whose parameters are predicted using an artificial neural network. A set of 88 clinical images were used in this work. The performance of our proposal is efficient, and the average processing time was 42 ms. The method was assessed using both the contrast improvement index and expert opinions. The contrast improvement index average was 2; this means the processed image successfully improved its contrast. Three pediatric ophthalmologists validated the proposed method and agreed that the visual enhancement can help observe clearly the retinal vessels.

Diagnostic Accuracy of Ophthalmoscopy vs Telemedicine in Examinations for Retinopathy of Prematurity

Importance

Examinations for retinopathy of prematurity (ROP) are typically performed using binocular indirect ophthalmoscopy. Telemedicine studies have traditionally assessed the accuracy of telemedicine compared with ophthalmoscopy as a criterion standard. However, it is not known whether ophthalmoscopy is truly more accurate than telemedicine.

Objective

To directly compare the accuracy and sensitivity of ophthalmoscopy vs telemedicine in diagnosing ROP using a consensus reference standard.

Design, Setting, and Participants

This multicenter prospective study conducted between July 1, 2011, and November 30, 2014, at 7 neonatal intensive care units and academic ophthalmology departments in the United States and Mexico included 281 premature infants who met the screening criteria for ROP.

Exposures

Each examination consisted of 1 eye undergoing binocular indirect ophthalmoscopy by an experienced clinician followed by remote image review of wide-angle fundus photographs by 3 independent telemedicine graders.

Main Outcomes and Measures

Results of both examination methods were combined into a consensus reference standard diagnosis. The agreement of both ophthalmoscopy and telemedicine was compared with this standard, using percentage agreement and weighted κ statistics.

Results

Among the 281 infants in the study (127 girls and 154 boys; mean [SD] gestational age, 27.1 [2.4] weeks), a total of 1553 eye examinations were classified using both ophthalmoscopy and telemedicine. Ophthalmoscopy and telemedicine each had similar sensitivity for zone I disease (78% [95% CI, 71%-84%] vs 78% [95% CI, 73%-83%]; P > .99 [n = 165]), plus disease (74% [95% CI, 61%-87%] vs 79% [95% CI, 72%-86%]; P = .41 [n = 50]), and type 2 ROP (stage 3, zone I, or plus disease: 86% [95% CI, 80%-92%] vs 79% [95% CI, 75%-83%]; P = .10 [n = 251]), but ophthalmoscopy was slightly more sensitive in identifying stage 3 disease (85% [95% CI, 79%-91%] vs 73% [95% CI, 67%-78%]; P = .004 [n = 136]).

Conclusions and Relevance

No difference was found in overall accuracy between ophthalmoscopy and telemedicine for the detection of clinically significant ROP, although, on average, ophthalmoscopy had slightly higher accuracy for the diagnosis of zone III and stage 3 ROP. With the caveat that there was variable accuracy between examiners using both modalities, these results support the use of telemedicine for the diagnosis of clinically significant ROP.

Relating retinal blood flow and vessel morphology in sickle cell retinopathy

Purpose

The purpose of the current study was to determine associations between retinal blood flow and vessel morphology metrics in sickle cell retinopathy (SCR) and healthy normal control (NC) subjects.

Methods

Optical coherence tomography angiography (OCTA) and Doppler OCT imaging were performed in 12 SCR (15 eyes) and 19 NC (26 eyes) subjects. Vessel tortuosity was measured using a dedicated image analysis algorithm applied to OCTA images. Vessel density and spacing between vessels were determined from OCTA images by a fractal dimension analysis method. Retinal blood flow was quantified using a phase-resolved technique applied to en face Doppler OCT images.

Results

There was a significant association between increased retinal blood flow and increased vessel tortuosity (P = 0.03). Furthermore, increased retinal blood flow was associated with increased vessel density (P = 0.03) and decreased spacing between small vessels (P = 0.01). There was no significant association between retinal blood flow and spacing between large vessels (P = 0.11). Vessel tortuosity and blood flow were increased, whereas spacing between small vessels was decreased in SCR compared to NC group (P ≤ 0.03). There were no significant differences in vessel density or spacing between large vessels between the SCR and NC groups (P ≥ 0.31).

Conclusions

Associations between retinal hemodynamics and vessel morphology were reported, providing better understanding of retinal pathophysiology and insight into potential quantitative biomarkers to evaluate SCR.

Imaging in Retinopathy of Prematurity

Retinopathy of prematurity (ROP) is a leading cause of preventable childhood blindness worldwide. Barriers to ROP screening and difficulties with subsequent evaluation and management include poor access to care, lack of physicians trained in ROP, and issues with objective documentation. Digital retinal imaging can help address these barriers and improve our knowledge of the pathophysiology of the disease. Advancements in technology have led to new, non-mydriatic and mydriatic cameras with wider fields of view as well as devices that can simultaneously incorporate fluorescein angiography, optical coherence tomography (OCT), and OCT angiography. Image analysis in ROP is also being employed through smartphones and computer-based software. Telemedicine programs in the United States and worldwide have utilized imaging to extend ROP screening to infants in remote areas and have shown that digital retinal imaging can be reliable, accurate, and cost-effective. In addition, tele-education programs are also using digital retinal images to increase the number of healthcare providers trained in ROP. Although indirect ophthalmoscopy is still an important skill for screening, digital retinal imaging holds promise for more widespread screening and management of ROP.

Antecedents of Screening Positive for Attention Deficit Hyperactivity Disorder in Ten-Year-Old Children Born Extremely Preterm

BACKGROUND

The incidence of attention deficit hyperactivity disorder is higher among children born very preterm than among children who are mature at birth.

METHODS

We studied 583 ten-year-old children who were born before 28 weeks of gestation whose IQ was above 84 and had a parent-completed Child Symptom Inventory-4, which allowed classification of the child as having or not having symptoms of attention deficit hyperactivity disorder. For 422 children, we also had a teacher report, and for 583 children, we also had a parent report of whether or not a physician made an attention deficit hyperactivity disorder diagnosis.

RESULTS

The risk profile of screening positive for attention deficit hyperactivity disorder based on a parent's report differed from the risk profile based on the teacher's report, whereas the risk profile according to a physician and according to any two observers closely resembled the parent-reported profile. Among the statistically significant risk factors were young maternal age (parent, physician, and two observers), maternal obesity (parent, physician, and two observers), maternal smoking (parent, physician, and two observers), magnesium given at delivery for seizure prophylaxis (parent and two observers), recovery of Mycoplasma sp. from the placenta (teacher and two observers), low gestational age (parent and two observers), low birth weight (teacher and physician), singleton (parent, physician, and two observers), male (parent, teacher, physician, and two observers), mechanical ventilation on postnatal day seven (physician), receipt of a sedative (parent and two observers), retinopathy of prematurity (parent), necrotizing enterocolitis (physician), antibiotic receipt (physician and two observers), and ventriculomegaly on brain scan (parent and two observers).

CONCLUSIONS

The multiplicity of risk factors identified can be subsumed as components of four broad themes: low socioeconomic state, immaturity or vulnerability, inflammation, and epigenetic phenomena.

Retinopathy of Prematurity-assist: Novel Software for Detecting Plus Disease

Purpose

To design software with a novel algorithm, which analyzes the tortuosity and vascular dilatation in fundal images of retinopathy of prematurity (ROP) patients with an acceptable accuracy for detecting plus disease.

Methods

Eighty-seven well-focused fundal images taken with RetCam were classified to three groups of plus, non-plus, and pre-plus by agreement between three ROP experts. Automated algorithms in this study were designed based on two methods: the curvature measure and distance transform for assessment of tortuosity and vascular dilatation, respectively as two major parameters of plus disease detection.

Results

Thirty-eight plus, 12 pre-plus, and 37 non-plus images, which were classified by three experts, were tested by an automated algorithm and software evaluated the correct grouping of images in comparison to expert voting with three different classifiers, k-nearest neighbor, support vector machine and multilayer perceptron network. The plus, pre-plus, and non-plus images were analyzed with 72.3%, 83.7%, and 84.4% accuracy, respectively.

Conclusions

The new automated algorithm used in this pilot scheme for diagnosis and screening of patients with plus ROP has acceptable accuracy. With more improvements, it may become particularly useful, especially in centers without a skilled person in the ROP field.

Retinal VEGF levels correlate with ocular circulation measured by a laser speckle-micro system in an oxygen-induced retinopathy rat model

PURPOSE

We used a Laser speckle flowgraphy (LSFG)-micro system to examine the relationship between ocular blood flow and retinal vascular endothelial growth factor (VEGF) at retinopathy onset in oxygen-induced ischemic retinopathy (OIR) model rats.

METHODS

Sixteen 50/10 OIR rats were compared with 17 control rats reared in room air. In postnatal day 14 (P14) and P18 rats, we measured and analyzed the left eye's mean blur rate (MBR) by setting a rubber band on the optic nerve head center, using the LSFG-Micro. At P18, the rats were sacrificed and their left-eye retinas were fixed, flat-mounted and stained with adenosine diphosphatase (ADPase). The right-eye retinas were homogenized; the lysate was centrifuged for an enzyme-linked immunosorbent assay (ELISA). The avascular area was measured as the percentage (%AVA) of the total retinal area. Retinal VEGF was measured by an ELISA.

RESULTS

The examination's reproducibility was good. Our multivariate linear mixed model analysis revealed significantly high MBRs in the OIR rats (p = 0.0017). In the P18 OIR rats, significant correlations were seen between the MBR and %AVA (r = 0.80, p = 0.0002) and between the MBR and VEGF (r = 0.76, p = 0.0006).

CONCLUSIONS

The LSFG-Micro provided reproducible blood flow measurements in neonatal rats. Because of the vitreous blood vessels, measurement of only the retinal vessels was not possible. However, the MBR was higher in the OIR rats than in the control rats, and the MBR and %AVA were correlated, as were the MBR and retinal VEGF. The MBR may thus serve as an indicator of OIR severity.

In Vivo Angiography Quantifies Oxygen-Induced Retinopathy Vascular Recovery

Purpose

Retinopathy of prematurity (ROP) is a potentially blinding vasoproliferative disease. There is no standardized way to quantify plus disease (tortuous and dilated retinal vessels) or characterize abnormal recovery during ROP monitoring. This study objectively studies vascular features in live mice during development using noninvasive retinal imaging.

Methods

Using fluorescein angiography (FA), retinal vascular features were quantified in live mice with oxygen induced retinopathy (OIR). A total of 105 wild-type mice were exposed to 77% oxygen from postnatal day 7 (P7) till P12 (OIR mice). Also, 105 age-matched pups were raised in room air (RA mice). In vivo FA was performed at early (P16 to P20), mid (P23 to P27), late (P30 to P34), and mature (P47) phases of retinal vascular development. Retinal vascular area, retinal vein width, and retinal artery tortuosity were quantified.

Results

Retinal artery tortuosity was higher in OIR than RA mice at early (p < 0.0001), mid (p < 0.0001), late (p < 0.0001), and mature (p < 0.0001) phases. Retinal vascular area in OIR mice increased from early to mid-phase (p < 0.0001), but remained unchanged from mid to late (p = 0.23), and from late to mature phase (p = 0.98). Retinal vein width was larger in OIR mice compared to RA mice during early phase only. Arteries in OIR mice were more tortuous from early to mid-phase (p < 0.0001), but tortuosity remained stable from mid through mature phase. RA mice had an increase in retinal vascular area from early to late phase, but maintained uniform retinal vein width and retinal artery tortuosity in all phases.

Conclusions

In vivo FA distinguished arterial and venous features, similar to plus disease, and revealed aberrant recovery of OIR mice (arterial tortuosity, reduced capillary density, and absent neovascular buds) that persisted into adulthood. Retinal artery tortuosity may be a reliable, objective marker of severity of ROP. Infants with abnormal retinal vascular recovery may need extended monitoring.

Computer-aided diagnosis of retinopathy in retinal fundus images of preterm infants via quantification of vascular tortuosity

Retinopathy of prematurity (ROP), a disorder of the retina occurring in preterm infants, is the leading cause of preventable childhood blindness. An active phase of ROP that requires treatment is associated with the presence of plus disease, which is diagnosed clinically in a qualitative manner by visual assessment of the existence of a certain level of increase in the thickness and tortuosity of retinal vessels. The present study performs computer-aided diagnosis (CAD) of plus disease via quantitative measurement of tortuosity in retinal fundus images of preterm infants. Digital image processing techniques were developed for the detection of retinal vessels and measurement of their tortuosity. The total lengths of abnormally tortuous vessels in each quadrant and the entire image were then computed. A minimum-length diagnostic-decision-making criterion was developed to assess the diagnostic sensitivity and specificity of the values obtained. The area ([Formula: see text]) under the receiver operating characteristic curve was used to assess the overall diagnostic accuracy of the methods. Using a set of 19 retinal fundus images of preterm infants with plus disease and 91 without plus disease, the proposed methods provided an overall diagnostic accuracy of [Formula: see text]. Using the total length of all abnormally tortuous vessel segments in an image, our techniques are capable of CAD of plus disease with high accuracy without the need for manual selection of vessels to analyze. The proposed methods may be used in a clinical or teleophthalmological setting.

Plus Disease in Retinopathy of Prematurity: Improving Diagnosis by Ranking Disease Severity and Using Quantitative Image Analysis

PURPOSE

To determine expert agreement on relative retinopathy of prematurity (ROP) disease severity and whether computer-based image analysis can model relative disease severity, and to propose consideration of a more continuous severity score for ROP.

DESIGN

We developed 2 databases of clinical images of varying disease severity (100 images and 34 images) as part of the Imaging and Informatics in ROP (i-ROP) cohort study and recruited expert physician, nonexpert physician, and nonphysician graders to classify and perform pairwise comparisons on both databases.

PARTICIPANTS

Six participating expert ROP clinician-scientists, each with a minimum of 10 years of clinical ROP experience and 5 ROP publications, and 5 image graders (3 physicians and 2 nonphysician graders) who analyzed images that were obtained during routine ROP screening in neonatal intensive care units.

METHODS

Images in both databases were ranked by average disease classification (classification ranking), by pairwise comparison using the Elo rating method (comparison ranking), and by correlation with the i-ROP computer-based image analysis system.

MAIN OUTCOME MEASURES

Interexpert agreement (weighted κ statistic) compared with the correlation coefficient (CC) between experts on pairwise comparisons and correlation between expert rankings and computer-based image analysis modeling.

RESULTS

There was variable interexpert agreement on diagnostic classification of disease (plus, preplus, or normal) among the 6 experts (mean weighted κ, 0.27; range, 0.06-0.63), but good correlation between experts on comparison ranking of disease severity (mean CC, 0.84; range, 0.74-0.93) on the set of 34 images. Comparison ranking provided a severity ranking that was in good agreement with ranking obtained by classification ranking (CC, 0.92). Comparison ranking on the larger dataset by both expert and nonexpert graders demonstrated good correlation (mean CC, 0.97; range, 0.95-0.98). The i-ROP system was able to model this continuous severity with good correlation (CC, 0.86).

CONCLUSIONS

Experts diagnose plus disease on a continuum, with poor absolute agreement on classification but good relative agreement on disease severity. These results suggest that the use of pairwise rankings and a continuous severity score, such as that provided by the i-ROP system, may improve agreement on disease severity in the future.

A Comparison of 3 Vitamin D Dosing Regimens in Extremely Preterm Infants: A Randomized Controlled Trial

OBJECTIVE

To determine the optimal dose of vitamin D supplementation to achieve biochemical vitamin D sufficiency in extremely low gestational age newborns in a masked randomized controlled trial.

STUDY DESIGN

100 infants 23 0/7-27 6/7 weeks gestation were randomized to vitamin D intakes of placebo (n = 36), 200 IU (n = 34), and 800 IU/d (n = 30) (approximating 200, 400, or 1000 IU/d, respectively, when vitamin D routinely included in parenteral or enteral nutrition is included). The primary outcomes were serum 25-hydroxy vitamin D concentrations on postnatal day 28 and the number of days alive and off respiratory support in the first 28 days.

RESULTS

At birth, 67% of infants had 25-hydroxy vitamin D <20 ng/mL suggesting biochemical vitamin D deficiency. Vitamin D concentrations on day 28 were (median [25th-75th percentiles], ng/mL): placebo: 22 (13-47), 200 IU: 39 (26-57), 800 IU: 84.5 (52-99); P < .001. There were no differences in days alive and off respiratory support (median [25th-75th percentiles], days): placebo: 1 (0-11), 200 IU: 0 (0-8), and 800 IU: 0.5 (0-22); P = .63, or other respiratory outcomes among groups.

CONCLUSIONS

At birth, most extremely preterm infants have biochemical vitamin D deficiency. This biochemical deficiency is reduced on day 28 by supplementation with 200 IU/d and prevented by 800 IU/d. Larger trials are required to determine if resolution of biochemical vitamin D deficiency improves clinical outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01600430.

Computer-Based Image Analysis for Plus Disease Diagnosis in Retinopathy of Prematurity: Performance of the "i-ROP" System and Image Features Associated With Expert Diagnosis

PURPOSE

We developed and evaluated the performance of a novel computer-based image analysis system for grading plus disease in retinopathy of prematurity (ROP), and identified the image features, shapes, and sizes that best correlate with expert diagnosis.

METHODS

A dataset of 77 wide-angle retinal images from infants screened for ROP was collected. A reference standard diagnosis was determined for each image by combining image grading from 3 experts with the clinical diagnosis from ophthalmoscopic examination. Manually segmented images were cropped into a range of shapes and sizes, and a computer algorithm was developed to extract tortuosity and dilation features from arteries and veins. Each feature was fed into our system to identify the set of characteristics that yielded the highest-performing system compared to the reference standard, which we refer to as the "i-ROP" system.

RESULTS

Among the tested crop shapes, sizes, and measured features, point-based measurements of arterial and venous tortuosity (combined), and a large circular cropped image (with radius 6 times the disc diameter), provided the highest diagnostic accuracy. The i-ROP system achieved 95% accuracy for classifying preplus and plus disease compared to the reference standard. This was comparable to the performance of the 3 individual experts (96%, 94%, 92%), and significantly higher than the mean performance of 31 nonexperts (81%).

CONCLUSIONS

This comprehensive analysis of computer-based plus disease suggests that it may be feasible to develop a fully-automated system based on wide-angle retinal images that performs comparably to expert graders at three-level plus disease discrimination.

TRANSLATIONAL RELEVANCE

Computer-based image analysis, using objective and quantitative retinal vascular features, has potential to complement clinical ROP diagnosis by ophthalmologists.

Computer-aided diagnosis of plus disease in retinal fundus images of preterm infants via measurement of vessel tortuosity

An increase in retinal vessel tortuosity can be indicative of the presence of various diseases including retinopathy of prematurity (ROP). Accurate detection and measurement of such changes could help in computer-aided diagnosis of plus disease, which warrants treatment of ROP. We present image processing methods for detection and segmentation of retinal vessels, quantification of vessel tortuosity, and diagnostic-decision-making criteria that incorporate the clinical definition of plus-diagnosis. The obtained results using 110 retinal fundus images of preterm infants (91 without plus and 19 with plus) provide high sensitivity = 0.89 (17/19) and excellent specificity = 0.95 (86/91) in the diagnosis of plus disease.

Predicting the need for laser treatment in retinopathy of prematurity using computer-assisted quantitative vascular analysis

PURPOSE

To investigate whether parameters of retinal vascular dilation and/or tortuosity calculated by ROPtool software can help to predict, prior to diagnosis of plus disease, whether laser will be needed for treatment of retinopathy of prematurity (ROP).

METHODS

Video indirect ophthalmoscopy recordings were obtained during routine ROP examinations. One posterior pole still image of one eye was selected from each examination for each infant. ROPtool was used to calculate vessel dilation, tortuosity, and the sum of adjusted indices (SAI, combining dilation and tortuosity) for each image. The following values were calculated for each vessel characteristic: maximum value from any one vessel across all examinations, largest increase per week in maximum value, highest mean value of all vessels from any one examination, and largest increase per week in mean value. These parameters were compared between infants who eventually received laser and those who did not.

RESULTS

Medians for maximum tortuosity indices were, for the eventual laser group (n = 28), 8.92 tortuosity units and, for the no laser group (n = 56), 6.87 (P < 0.001). Medians for highest mean tortuosity indices were 4.95 tortuosity units for the eventual laser group and 3.66 for the no laser group (P < 0.001). Parameters involving dilation and SAI did not differ significantly between groups. In multivariable analysis, highest mean tortuosity was associated with need for laser (P = 0.003).

CONCLUSIONS

ROPtool analysis of tortuosity parameters from indirect ophthalmoscopy images can help predict need for laser in ROP.

Three-dimensional assessment of vascular and perivascular characteristics in subjects with retinopathy of prematurity

PURPOSE

To study vascular features detected with spectral domain optical coherence tomography (SD-OCT) in subjects undergoing retinopathy of prematurity (ROP) screening.

DESIGN

Cross-sectional study.

PARTICIPANTS AND CONTROLS

Fifty-seven premature neonates, 10 with plus disease in at least 1 eye and 47 without plus disease.

METHODS

Bedside noncontact SD-OCT imaging was performed after obtaining parental consent on 97 consecutive infants between January 2009 and September 2012. Fifty-seven subjects (31-49 weeks' post-menstrual age) who had an SD-OCT scan in at least 1 eye showing the edge of the optic nerve and at least 1 major retinal vascular arcade were included. One eye per subject was randomly selected for analysis. Two masked graders evaluated scans for (1) retinal vessel elevation, (2) scalloped retinal layers, (3) hyporeflective vessels, and (4) retinal spaces. To coalesce the weight of these features, a Vascular Abnormality Score by OCT (VASO) was created. For quantitative assessment of vessel elevation, retinal surface maps were created.

MAIN OUTCOME MEASURES

Prevalence of SD-OCT vascular abnormalities, the VASO, intergrader agreement, and presence of elevation on surface maps.

RESULTS

From among 67 SD-OCT characteristics that were recorded, the most common characteristics found were vessel elevation (44%), hyporeflective vessels (40%), scalloped layers (22%), and retinal spaces (11%). Features significantly associated with plus disease were vessel elevation (P = 0.01), hyporeflective vessels (P = 0.04), and scalloped retinal layers (P = 0.006). Intragrader agreement was between 74% and 90% for all features. The VASO was significantly higher in subjects with plus disease (P = 0.0013). On 3-dimensional SD-OCT volumes, eyes with plus disease had greater retinal surface elevation that more often matched en face retinal vascular patterns.

CONCLUSIONS

We present a novel 3-dimensional analysis of vascular and perivascular abnormalities identified in SD-OCT images of eyes with ROP. The SD-OCT characteristics that are more common in eyes with plus disease provide the first in vivo demonstration of the effects of vascular dilation and tortuosity on perivascular tissue. The VASO and surface maps also delineate the severity of vascular pathology in plus disease. Further studies evaluating these findings in eyes with pre-plus versus normal posterior pole vessels may determine the usefulness of SD-OCT in the early detection of vascular abnormalities in ROP.

Quantification of vascular tortuosity as an early outcome measure in oxygen induced retinopathy (OIR)

Oxygen-induced retinopathy (OIR) in mice is a popular model system to study pathological angiogenesis in the retinal vasculature. The system is based on vessel depletion by exposure to hyperoxia, which results in acute retinal hypoxia upon return to room air. This hypoxia then triggers neovascularization in the remaining vessels after 5 days. Here we aimed to establish an additional and earlier experimental readout of the vascular response to hypoxia by quantifying the tortuosity of retinal arteries after 2 days. Mouse pups from three different mouse strains were exposed to hyperoxia from postnatal day (P) 7 to P12 and retinas were analysed at P12, P14 and P17. Hypoxia was assessed by staining with the hypoxia marker EF5 and by measuring Vegf mRNA by qPCR. The retinal vasculature was stained in whole mount retinas and tortuosity of radial arterioles was quantified. C57BL/6J mice were used because the vascular response at P17 is well characterised in this strain. We also used C3H/HeJ mice, which contain the retinal degeneration 1 (Rd1) mutation (Pde6b(Rd1)) and have abnormally thin retinas. These thinner, C3H/HeJ retinas do not become ischemic during the OIR model and do not develop neovascularization. They can therefore be used as a control. In addition, we included C3H/HeJ mice that lack the Rd1 mutation (C3H/He(Rd1-)), with normal thickness retinas, to control for strain differences between C57BL/6J and C3H/HeJ. Quantification of vessel tortuosity at P14 showed tortuous arteries in normal thickness retinas (C57BL/6J and C3H/He(Rd1-)) and straight arteries in the thin C3H/HeJ retinas. This correlated with hypoxia, which was severe in normal thickness retinas and mild in the thin C3H/HeJ retinas. Furthermore, at P17 the normal thickness retinas showed strong neovascularisation whereas in the thin C3H/HeJ retinas the retinal vasculature regenerated normally. In conclusion we have demonstrated that arterial tortuosity can act as an early readout for hypoxia in the OIR model before neovascularisation develops.

Assessment of vessel tortuosity in retinal images of preterm infants

Diagnosis of plus disease is crucial for timely treatment and management of retinopathy of prematurity. An indicator of the presence of plus disease is an increase in the tortuosity of blood vessels in the retina. In this work, we propose a new angle-variation-based measure for quantification of tortuosity in retinal fundus images of preterm infants. The methods include the use of Gabor filters to detect vessels as well as to obtain their orientation at each pixel. Morphological image processing methods are used to obtain a skeleton image of the vessels for measurement of tortuosity. Out of 11 vessel segments, marked by an expert ophthalmologist as showing high levels of tortuosity due to plus disease, all were correctly identified using the proposed methods.

A murine model for retinopathy of prematurity identifies endothelial cell proliferation as a potential mechanism for plus disease

PURPOSE

To characterize the features and possible mechanism of plus disease in the mouse oxygen-induced retinopathy (OIR) model for retinopathy of prematurity.

METHODS

Wild-type and Adam (A Disintegrin And Metalloproteinase) knockout mice were exposed to 75% oxygen from postnatal day 7 to 12 (P7 to P12) (hyperoxia), then returned to normal air (relative hypoxia). Live fundus imaging and fluorescein angiography at P17 were compared to immunofluorescence analysis of flat-mounted retinas. Two hallmarks of plus disease, arterial tortuosity and venous dilation, were analyzed on fixed retinas (P12-P17). The length of tortuous vessels was compared to a straight line between two points; the diameter of retinal vessels was determined using ImageJ software, and bromo-deoxyuridine (BrdU) labeling was used to visualize proliferation of retinal vascular cells.

RESULTS

Mice developed retinal arterial tortuosity and venous dilation after exposure to OIR, which was visible in live fundus images and fixed whole-mounted retinas. Vein dilation, arterial tortuosity, and BrdU incorporation gradually increased over time. Moreover, Adam8(-/-) and Adam9(-/-) mice and mice lacking Adam10 in endothelial cells were partially protected from plus disease compared to controls.

CONCLUSIONS

The mouse OIR model can be used to study the pathogenesis of plus disease and identify potential therapeutic targets. The severity of plus disease increases over time following OIR and correlates with increased proliferation of endothelial cells, suggesting that proliferation of vascular cells may be a mechanism underlying the development of plus disease. Moreover, our findings suggest that ADAMs 8, 9, and 10 could be targets for treatment of plus disease.

Telemedicine detection of type 1 ROP in a distant neonatal intensive care unit

PURPOSE

To demonstrate the feasibility of telemedicine screening for retinopathy of prematurity (ROP) by summarizing the results of our experience screening premature infants at a distant hospital in a rural location.

METHODS

Records of all premature infants remotely screened for ROP at a neonatal intensive care unit in Great Falls, Montana, from January 1, 2007 to June 30, 2011, were retrospectively reviewed. The RetCam II imaging system was used to capture retinal images, which were posted on a secure server for evaluation by one of two pediatric ophthalmologists. Infants suspected of having ROP approaching the criteria for laser treatment were transferred to a hospital, where a diagnostic examination was performed and treatment administered when indicated. All other infants received an outpatient diagnostic examination within 2 weeks of discharge.

RESULTS

A total of 582 telemedicine examinations were performed on 137 infants during the study period. Of 13 infants transferred for referral-warranted ROP, 9 ultimately required laser treatment. Good outcomes were noted in all cases, with none progressing to stage 4 or 5 ROP.

CONCLUSIONS

Telemedicine ROP screening detected patients at a remote site in need of laser treatment, allowing prompt transfer with no poor outcomes over a 4.5-year period. Our experience demonstrates the utility of remote screening for ROP.

Plus Disease: Why is it Important in Retinopathy of Prematurity?

Retinopathy of prematurity (ROP) is one of the leading causes of preventable blindness in childhood. Early posterior pole vascular signs of severe ROP have been studied since the first description of the disease. The progressive changes that take place in the posterior pole vessels of an extremely premature baby occur in a predictable fashion soon after birth. These vascular changes are described as plus disease and are defined as abnormal dilation and tortousity of the blood vessels during ROP that may go on to total retinal detachment. The ophthalmological community now has a better understanding of the pathology and cascade of events taking place in the posterior pole of an eye with active ROP. Despite many years of scientific work on plus disease, there continue to be many challenges in defining the severity and quantification of the vascular changes. It is believed that understanding of the vascular phenomenons in patients with ROP will help in designing new treatment strategies that will help in salvaging many of the eyes with severe ROP.

Predictive value of pre-plus disease in retinopathy of prematurity

OBJECTIVES

To investigate prospectively whether the presence of pre-plus disease predicts progression to severe retinopathy of prematurity (ROP) requiring laser treatment.

METHODS

Posterior retinal video recordings were obtained during 710 indirect ophthalmoscopy examinations of 214 premature infants over a period of 5 years. Two masked experts reviewed short video recordings and determined whether there was plus disease, pre-plus disease, or neither. The primary analysis included results of one examination of the right eye at 33 to 34 weeks' postmenstrual age. The primary outcome was a comparison of the proportion of eyes subsequently requiring laser treatment between the group graded as having pre-plus disease vs the group graded as having neither plus disease nor pre-plus disease.

RESULTS

Of 10 eyes with pre-plus disease at 33 to 34 weeks' postmenstrual age, 7 (70%) subsequently required laser treatment; of 154 eyes without pre-plus disease or plus disease at 33 to 34 weeks' postmenstrual age, 14 (9%) subsequently required laser treatment (risk ratio, 7.7; 95% confidence interval, 4.1-14.8; P < .001). The mean time between the examination diagnosing pre-plus disease and laser treatment was 1.6 weeks (range, 1.0-2.4 weeks). When adjusting for birth weight, gestational age, ROP location (zone), and ROP severity (stage), the presence of pre-plus disease at 33 to 34 weeks' postmenstrual age independently predicted the need for laser treatment (adjusted odds ratio, 7.6; 95% confidence interval, 1.4-42.3; P = .02).

CONCLUSIONS

Pre-plus disease observed early during the course of ROP is strongly associated with the development of severe ROP requiring laser treatment. The diagnosis of pre-plus disease has prognostic value beyond that already provided by birth weight, gestational age, ROP zone, and ROP stage. Eyes with pre-plus disease should be closely observed to allow optimal timing of intervention.