Significance of isolated neovascular tufts ("popcorn") in retinopathy of prematurity

Isolated retinal neovascularization in retinopathy of prematurity: clinical associations and prognostic implications

OBJECTIVE

Isolated retinal neovascularization (IRNV) is a common finding in patients with stage 2 and 3 retinopathy of prematurity (ROP). This study aims to further classify the clinical course and significance of these lesions (previously described as "popcorn" based on clinical appearance) in patients with ROP as visualized with ultra-widefield optical coherence tomography (UWF-OCT).

DESIGN

Single center, retrospective case series.

PARTICIPANTS

Images were collected from 136 babies in the Oregon Health and Science University neonatal intensive care unit.

METHODS

A prototype UWF-OCT device captured en face scans (>140°), which were reviewed for the presence of IRNV along with standard zone, stage, and plus classification. In a cross-sectional analysis we compared demographics and the clinical course of eyes with and without IRNV. Longitudinally, we compared ROP severity using a clinician-assigned vascular severity score (VSS) and compared the risk of progression among eyes with and without IRNV using multivariable logistic regression (MLR).

MAIN OUTCOME MEASURES

Differences in clinical demographics and disease progression between patients with and without IRNV.

RESULTS

Of the 136 patients, 60 developed stage 2 or worse ROP during their disease course, 22 of whom had IRNV visualized on UWF-OCT (37%). On average, patients with IRNV had lower birth weights (BW) (660.1g vs 916.8g, p = 0.001), gestational age (GA) (24.9 vs 26.1 weeks, p = 0.01), and were more likely to present with ROP in zone I (63.4% vs 15.8%, p < 0.001). They were also more likely to progress to stage 3 (68.2% vs 13.2%, p < 0.001) and receive treatment (54.5% vs 15.8%, p = 0.002). Eyes with IRNV had a higher peak VSS (5.61 vs 3.73, p < 0.001) and averaged a higher VSS throughout their disease course. On MLR, IRNV was independently associated with progression to stage 3 (p = 0.02) and requiring treatment (p = 0.03), controlling for GA, BW, and initial zone 1 disease.

CONCLUSION

In this single center study, we found that IRNV occurs in higher risk babies and was an independent risk factor for ROP progression and treatment. These findings may have implications for OCT-based ROP classifications in the future.

Atypical case of retinopathy of prematurity with candle wax-like preretinal deposits and its surprising response to intravitreal antivascular endothelial growth factor

Presented here is a case of hybrid retinopathy of prematurity (ROP) with features of both aggressive posterior ROP and ridge-like staged ROP with extensive candle wax-like preretinal deposits plastered on the surface of the retina from optic disc to vascular-avascular junction at a postmenstrual age (PMA) of 34 weeks. The baby was too sick for laser photocoagulation and so underwent intravitreal bevacizumab at half adult doses in both eyes. The deposits melted dramatically within 1-2 weeks of antivascular endothelial growth factor injection without any signs of recurrence till the last visit at 58 weeks of PMA.

Secretogranin III stringently regulates pathological but not physiological angiogenesis in oxygen-induced retinopathy

Conventional angiogenic factors, such as vascular endothelial growth factor (VEGF), regulate both pathological and physiological angiogenesis indiscriminately, and their inhibitors may elicit adverse side effects. Secretogranin III (Scg3) was recently reported to be a diabetes-restricted VEGF-independent angiogenic factor, but the disease selectivity of Scg3 in retinopathy of prematurity (ROP), a retinal disease in preterm infants with concurrent pathological and physiological angiogenesis, was not defined. Here, using oxygen-induced retinopathy (OIR) mice, a surrogate model of ROP, we quantified an exclusive binding of Scg3 to diseased versus healthy developing neovessels that contrasted sharply with the ubiquitous binding of VEGF. Functional immunohistochemistry visualized Scg3 binding exclusively to disease-related disorganized retinal neovessels and neovascular tufts, whereas VEGF bound to both disorganized and well-organized neovessels. Homozygous deletion of the Scg3 gene showed undetectable effects on physiological retinal neovascularization but markedly reduced the severity of OIR-induced pathological angiogenesis. Furthermore, anti-Scg3 humanized antibody Fab (hFab) inhibited pathological angiogenesis with similar efficacy to anti-VEGF aflibercept. Aflibercept dose-dependently blocked physiological angiogenesis in neonatal retinas, whereas anti-Scg3 hFab was without adverse effects at any dose and supported a therapeutic window at least 10X wider than that of aflibercept. Therefore, Scg3 stringently regulates pathological but not physiological angiogenesis, and anti-Scg3 hFab satisfies essential criteria for development as a safe and effective disease-targeted anti-angiogenic therapy for ROP.

THE EVOLUTION OF ISOLATED NEOVASCULAR TUFTS ("POPCORN") IN RETINOPATHY OF PREMATURITY

PURPOSE

To explore the natural evolution of isolated neovascular tufts ("popcorn") in retinopathy of prematurity (ROP) and its significance in the progression of acute ROP.

METHODS

In this retrospective case series, 89 infants (89 eyes) in total having acute ROP were analyzed during serial retinal examinations with a RetCam III wide-angle fundus imaging system, among which 53 eyes were observed to have popcorn and 36 eyes did not. The clinical outcomes of the popcorn (+) group and the popcorn (-) group were compared.

RESULTS

Popcorn was located only in Zone II, Stage 2 ROP, primarily in the temporal field (65%). It appeared at a mean postmenstrual age of (37.6 ± 1.3) weeks, disappeared at (41.0 ± 2.2) weeks, and lasted for (2.8 ± 1.1) weeks. The popcorn (+) group had a significantly higher natural regression incidence than the popcorn (-) group (P < 0.05). The laser-treated eyes in the popcorn (+) group had earlier presentations (36.4 ± 0.7 vs. 38.2 ± 1.3 weeks) and shorter existences (1.5 ± 0.5 vs. 3.2 ± 0.9 weeks) of popcorn than the regressed eyes (P < 0.01, respectively).

CONCLUSION

Popcorn is generally a "benign" indicator of the regression of ROP. The early presentation (<postmenstrual age 37 weeks) and short duration of popcorn require further observation.

Three-dimensional pattern of extraretinal neovascular development in retinopathy of prematurity

BACKGROUND

The application of three-dimensional (3D) visualization techniques to evaluate the earliest visible onset of abnormal retinal vascular development in preterm infants with retinopathy of prematurity (ROP), using bedside non-contact optical coherence tomography (OCT) imaging to characterize morphology and sequential structural changes of abnormal extraretinal neovascularization.

METHODS

Thirty-one preterm infants undergoing routine ROP screening with written informed consent for research imaging were enrolled in this prospective observational study. We imaged the macula and temporal periphery of preterm infants using a handheld OCT system (Envisu 2300 or handheld swept-source research system). The scans obtained were segmented and, using enhanced ray casting, were converted to 3D volumes to which color filter was applied.

RESULTS

Using colorized 3D visualization, we defined extraretinal neovascular structures as buds, bridging networks, and placoid lesions. We could longitudinally follow progression and regression of extraretinal neovascularization in stage 3 ROP after treatment in one infant over 12 weeks and document the appearance of early buds, and formation of florid neovascularization. From stages 2 to 3 ROP, we observed progression from sessile buds to a complex plaque that corresponded to stage 3 ROP on clinical examination. We demonstrated regression of neovascular complexes to small pre-retinal tufts after treatment with anti-VEGF.

CONCLUSIONS

The extension of OCT processing to include surface flattening and colorization that further improved structural analysis rendered better understanding of extraretinal tissue. Our ability to image similar areas in the same infant over multiple visits enabled us to study the evolution of these structural components and follow pathological vascular events longitudinally in development and regression after treatment. These methods can be applied to further study which are likely contribute to our understanding of the pathophysiology of neovascularization in ROP.

Spectral-Domain OCT Findings of Retinal Vascular-Avascular Junction in Infants with Retinopathy of Prematurity

PURPOSE

Bedside examination of premature infants at risk for retinopathy of prematurity (ROP) is predominantly performed with ophthalmoscopic en face viewing of the retina. While postmortem retinal microstructures have been studied at the vascular-avascular junction, a critical location for pathogenesis of ROP, to date this has not been possible in vivo. Here we present bedside, non-sedated in vivo cross-sectional imaging and analysis of retinal microstructures at the vascular-avascular junction in infants with ROP using handheld spectral-domain optical coherence tomography (SDOCT).

DESIGN

Prospective observational study.

PARTICIPANTS

Eleven preterm infants consented for research imaging during ROP screening examinations.

METHODS

We imaged the vascular-avascular junction in the temporal retina using a SDOCT system (Envisu, Bioptigen Inc., NC) in 18 eyes from 11 preterm infants with zone I or II, stage 0 through 4 ROP. B-scan and en face images were analyzed and compared to historical light micrographs.

MAIN OUTCOME MEASURES

SDOCT morphology at the vascular-avascular junction.

RESULTS

Multiple bedside SDOCT findings at the vascular-avascular junction were comparable to historic light micrographs: thickened inner retinal ridge structure in stage 2 ROP was comparable to thickened vanguard and rear guard cells in micrographs; vascular tufts on the posterior retinal surface in stage 2 ROP, broad arcs of neovascularization above the retina in stage 3 ROP, and splitting of inner retinal layers into clefts on either side of neovascularization mimicked findings of historic light micrographs. A unique findings was thickening of the avascular inner retinal band adjacent to neovascularization. On SDOCT imaging over several weeks, neovascularization and retinal clefts diminished after intravitreal bevacizumab therapy.

CONCLUSIONS

Retinal morphology at the vascular-avascular junction imaged with handheld SDOCT is consistent with known histopathology, and provide the advantage of monitoring change in vivo over time. These unique findings provide new insights into preterm retinal neurovascular development in ROP.

Bioelectric impact of pathological angiogenesis on vascular function

Pathological angiogenesis, as seen in many inflammatory, immune, malignant, and ischemic disorders, remains an immense health burden despite new molecular therapies. It is likely that further therapeutic progress requires a better understanding of neovascular pathophysiology. Surprisingly, even though transmembrane voltage is well known to regulate vascular function, no previous bioelectric analysis of pathological angiogenesis has been reported. Using the perforated-patch technique to measure vascular voltages in human retinal neovascular specimens and rodent models of retinal neovascularization, we discovered that pathological neovessels generate extraordinarily high voltage. Electrophysiological experiments demonstrated that voltage from aberrantly located preretinal neovascular complexes is transmitted into the intraretinal vascular network. With extensive neovascularization, this voltage input is substantial and boosts the membrane potential of intraretinal blood vessels to a suprahyperpolarized level. Coincident with this suprahyperpolarization, the vasomotor response to hypoxia is fundamentally altered. Instead of the compensatory dilation observed in the normal retina, arterioles constrict in response to an oxygen deficiency. This anomalous vasoconstriction, which would potentiate hypoxia, raises the possibility that the bioelectric impact of neovascularization on vascular function is a previously unappreciated pathophysiological mechanism to sustain hypoxia-driven angiogenesis.

Optical coherence tomography in retinopathy of prematurity: looking beyond the vessels

Retinopathy of Prematurity (ROP) is a leading cause of childhood blindness in the United States. Optical Coherence Tomography (OCT) is a relatively new imaging technology capable of imaging ocular structures in cross section at high resolution. We present an age-customized approach to perform Spectral Domain OCT in neonates and infants, and from SDOCT, the in-vivo development of the human fovea during the premature period up through term birth along with retinal changes unique to premature infants with ROP. Finally, we explore how this novel information may affect our understanding of ROP and the possible implications in vision and retinal development.

Insights into advanced retinopathy of prematurity using handheld spectral domain optical coherence tomography imaging

PURPOSE

To elucidate the subclinical anatomy of retinopathy of prematurity (ROP) using spectral domain optical coherence tomography (SD OCT).

DESIGN

Prospective, observational case series.

PARTICIPANTS

Three low-birth-weight, severely premature infants.

METHODS

Clinical examination was performed using a portable slit lamp and indirect ophthalmoscope. Imaging was performed by using a handheld SD OCT device and Retcam (Clarity Medical Systems, Pleasanton, CA) or video-indirect recording. Spectral domain optical coherence tomography imaging was conducted without sedation at the bedside in the neonatal intensive care unit on 1 patient. The other 2 patients had an examination under anesthesia with SD OCT imaging in the operating room.

MAIN OUTCOME MEASURES

In vivo determination of vitreoretinal morphology, anatomy, and pathology by clinical examination, imaging, and SD OCT.

RESULTS

Linear and volumetric imaging was achieved with the handheld system in infant eyes despite tunica vasculosa lentis and vitreous bands. Imaging was not possible in eyes with notable vitreous hemorrhage. Analysis of SD OCT images revealed preretinal structures (ranging from 409 to 2700 microm in width and 212 to 440 microm in height), retinoschisis, and retinal detachment in the posterior pole of patients with advanced ROP. Both the retinoschisis and the preretinal structures were not identified on conventional examination or imaging by expert pediatric ophthalmologists. The preretinal structures varied in location and size, and may represent preretinal fibrovascular proliferation. Some were found in close proximity to blood vessels, whereas others were near the optic nerve.

CONCLUSIONS

Handheld SD OCT imaging can be performed on the sedated or nonsedated neonate and provides valuable subclinical anatomic information. This novel imaging modality can reveal the location and extent of posterior ROP pathology not evident on standard examination. This could affect future clinical decision-making if studies validate a management strategy based on findings from this imaging technique.