Poorer neurodevelopmental outcomes associated with cystoid macular edema identified in preterm infants in the intensive care nursery

Early Single-Examination Optical Coherence Tomography Biomarkers for Treatment-Requiring Retinopathy of Prematurity

Purpose

Optical coherence tomography (OCT) is an emerging adjunct imaging modality to evaluate retinopathy of prematurity (ROP). From an 11-year research database, we identify early OCT biomarkers that predict treatment-requiring ROP (TR-ROP).

Methods

For preterm infants with acceptable OCT images at 32 ± 1 weeks postmenstrual age (PMA), we extracted the following measures: total retina, inner retinal layer (IRL), and outer retinal layer (ORL) thicknesses at the fovea and the parafovea, inner nuclear layer (INL) and choroidal thickness, parafovea/fovea (P/F) ratio, and presence of macular edema. Using univariable and multivariable logistic regression models, we evaluated the association between retinal and choroidal OCT measurements at 32 ± 1 weeks PMA and development of TR-ROP.

Results

Of 277 eyes (145 infants) with usable OCT images, 67 eyes had TR-ROP. Lower P/F ratio (P < 0.0001), thicker foveal IRL (P = 0.0001), and thinner choroid (P = 0.03) were associated with TR-ROP in univariable analysis, but lost significance of association when adjusted for gestational age and race. Absence of macular edema was associated with TR-ROP when adjusted for gestational age and race (P = 0.01). In 185 eyes without macular edema, P/F ratio was associated with TR-ROP in both univariable analysis (P < 0.0001) and multivariable analysis (P = 0.02) with adjustment for gestational age and race.

Conclusions

Presence of macular edema at 32 ± 1 weeks PMA in infants with lower gestational age may be protective against TR-ROP. In infants without macular edema, P/F ratio may be an early OCT biomarker for development of TR-ROP. Incorporation of early OCT biomarkers may be useful in prediction of TR-ROP.

[Anatomo-functional state of the central retina in premature infants with intraventricular hemorrhage and retinopathy of prematurity]

OBJECTIVE

Assessment of the anatomo-functional state of the central retina in children with intraventricular hemorrhage (IVH) and retinopathy of prematurity (ROP) in the long-term period.

MATERIAL AND METHODS

We examined 51 patients (102 eyes) born 25-34 weeks' of gestation (birth weight 700-2290 g), aged 8.83±3.5 years, and 18 children (36 eyes) born prematurely aged 10.8±3.2 years. The children underwent standard ophthalmologic examination, optical coherence tomography (OCT) and visual evoked potentials (VEP).

RESULTS

Retinal thickness (RT) and retinal volume (RV) in the fovea of premature infants with PH and/or IVH are significantly higher than in healthy full-term infants, which correlates with lower visual acuity (p<0.05). RT and RV in the fovea has an inverse proportional relationship with gestational age (GA), (p<0.05). According to the results of VEP, moderate organic changes in the conduction tract of the visual analyzer are noted in 45% of premature infants (p<0.05).

CONCLUSION

The process of macula formation is affected by many perinatal and postnatal factors, namely: GA, birth weight, ROP, hypoxic-ischemic CNS diseases, and refractive disorders.

A meta-analysis of adverse effects of retinopathy of prematurity on neurodevelopment in preterm infants

BACKGROUND

Retinopathy of prematurity (ROP) increases with the survival of late preterm infants, but its relationship with neurodevelopmental outcomes in preterm infants remains controversial. To investigate the relationship between ROP and its severity and adverse neurodevelopmental outcomes in preterm infants.

METHODS

We conducted a meta-analysis. All relevant literature before November 2022 were retrieved from PubMed, Embase, Cochrane Library Web of Science, CNKI, CBM, Wan fang Data, and VIP Database. According to the inclusion criteria and exclusion criteria, eligible literature were included to conduct clinical trial quality assessment, and the Newcastle-Ottawa scale was used to evaluate the quality of evidence. Meta-analysis was performed using RevMan5.3. Data extraction, quality assessment, and meta-analysis were performed independently by 2 people. Mean difference or standardized mean difference of motor, language and cognitive scores (Bayley III or Bayley II) were used as effect sizes for continuous data analysis, all of which were represented by 95% CI. For heterogeneity (I2 ≥ 50% or P < .10), a random effects model was used, otherwise a fixed effects model was used.

RESULTS

A total of 6 literature were included. The results of the ROP group for motor (comprehensive motor, proportional motor, and fine motor), language and cognitive scores were -5.57 (95%CI, -1.43 to 0.04), -0.95 (95%CI, 1.4-0.50), -1.34 (95% CI, 1.77-0.92), -1.75 (95% CI, 2.26-1.24) and -5.56 (95% CI, 9.56-1.57). Additionally, the results of severe ROP group for motor (comprehensive motor, proportional motor, fine motor), language and cognitive scores were -8.32 (95%CI, -8.91 to 7.74), -1.10 (95%CI, -1.83 to -0.36), -1.08 (95%CI, -1.75 to -0.41), -7.03 (95%CI, -7.71 to 6.35), and -7.96 (95%CI, -8.5 to -7.42).

CONCLUSIONS

The Bayley Scale scores of the ROP group were lower than those of the not ROP group, and the scores of the severe ROP were significantly lower than those of the not severe ROP group. These findings suggest that ROP can indeed delay motor, language and cognitive, especially in severe cases.

Severity of cystoid macular oedema in preterm infants observed using hand-held spectral domain optical coherence tomography improves weekly with postmenstrual age

OBJECTIVE

To investigate the relationship between cystoid macular oedema (CMO) measured in preterm infants using hand-held spectral domain optical coherence tomography (HH SD-OCT), with gestational age at birth (GA), birthweight (BW), diagnosis of retinopathy of prematurity (ROP) and the presence or absence of the external limiting membrane (ELM).

METHODS

We conducted a prospective mixed cross-sectional/longitudinal observational study of 112 participants (23 to 36 weeks GA; n = 25 with, and n = 87 without, CMO). Retinal images were acquired using 344 HH SD-OCT (n = 66 with and n = 278 without, CMO) between 31 to 44 weeks postmenstrual age (PMA). CMO type ('fovea' and 'dome') was measured using thickness, width, area and peak.

RESULTS

CMO was observed in 22.9% of preterm infants, and 19.2% of images. The mean values for  thickness, width, area and peak of 'dome' CMO were 128.47 µm (SD +/- 34.23), 3624.45 µm (SD +/- 1323.03), 0.49 mm2 (SD +/- 0.28) and 279.81 µm (SD +/- 13.57) respectively. The mean values for  thickness, width, area and peak of 'fovea' CMO were 64.37 µm (SD +/- 17.11), 2226.28 µm (SD +/- 1123.82), 0.16 mm2 (SD +/- 0.11) and 95.03 µm (SD +/- 26.99) respectively. Thickness, area width and peak were significantly greater for 'dome CMO compared with 'fovea' CMO (P < 0.0001 for thickness, area and peak; P < 0.01 for width). Area and width significantly decreased with PMA for 'dome' and 'fovea' CMO (p = 0.0028; p < 0.001 respectively). No association was found between the presence of ROP and the detection of CMO or detection of CMO with absence of ELM.

CONCLUSIONS

HH -OCT in preterm infants demonstrates that the severity of CMO appearance improves each week for both fovea and dome CMO.

Preterm infant retinal OCT markers of perinatal health and retinopathy of prematurity

The increasing survival of preterm infants has led to the importance of improving long-term outcomes associated with preterm birth. Antenatal and perinatal insults not only impact mortality, but also long-term disability. While in the intensive care nursery, preterm infants are also exposed to various stressors that lead to long-term cognitive deficits. It is therefore critical to identify early, low-stress, non-invasive biomarkers for preterm infant health. Optical coherence tomography (OCT) is a powerful imaging modality that has recently been adapted to the infant population and provides noninvasive, high-resolution, cross-sectional imaging of the infant eye at the bedside with low stress relative to conventional examination. In this review we delve into discussing the associations between preterm systemic health factors and OCT-based retinal findings and their potential contribution to the development of non-invasive biomarkers for infant health and for retinopathy of prematurity (ROP).

Insights into the developing fovea revealed by imaging

Early development of the fovea has been documented by histological studies over the past few decades. However, structural distortion due to sample processing and the paucity of high-quality post-mortem tissue has limited the effectiveness of this approach. With the continuous progress in high-resolution non-invasive imaging technology, most notably optical coherence tomography (OCT) and OCT angiography (OCT-A), in vivo visualization of the developing retina has become possible. Combining the information from histologic studies with this novel imaging information has provided a more complete and accurate picture of retinal development, and in particular the developing fovea. Advances in neonatal care have increased the survival rate of extremely premature infants. However, with enhanced survival there has been an attendant increase in retinal developmental complications. Several key abnormalities, including a thickening of the inner retina at the foveal center, a shallower foveal pit, a smaller foveal avascular zone, and delayed development of the photoreceptors have been described in preterm infants when compared to full-term infants. Notably these abnormalities, which are consistent with a partial arrest of foveal development, appear to persist into later childhood and adulthood in these eyes of individuals born prematurely. Understanding normal foveal development is vital to interpreting these pathologic findings associated with prematurity. In this review, we first discuss the various advanced imaging technologies that have been adapted for imaging the infant eye. We then review the key events and steps in the development of the normal structure of the fovea and contrast structural features in normal and preterm retina from infancy to childhood. Finally, we discuss the development of the perifoveal retinal microvasculature and highlight future opportunities to expand our understanding of the developing fovea.

Peripheral OCT Assisted by Scleral Depression in Retinopathy of Prematurity

OBJECTIVE

To determine whether handheld widefield optical coherence tomography (OCT) can be used to document retinopathy of prematurity (ROP) stage while using scleral depression to improve peripheral views.

DESIGN

Prospective observational study.

PARTICIPANTS

Consecutive neonates admitted to the neonatal intensive care unit (NICU) in a single academic medical center who also met criteria for ROP screening and consented for research imaging.

METHODS

Scleral depression was combined with widefield OCT using an investigational 400-kHz, 55-degree field of view handheld OCT during routine ROP screening from October 28, 2020 to March 03, 2021.

MAIN OUTCOME MEASURES

Acquisition of en face and B-scan imaging of the peripheral retina to objectively assess early vitreoretinal pathology, including the demarcation between vascularized and anterior avascular retina, the presence of early ridge formation, and small neovascular tufts.

RESULTS

Various stages of ROP were detected using a rapid acquisition OCT system. In one neonate, serial OCT imaging over a five-week period demonstrated accumulation of neovascular tufts with progression to stage 3 ROP with extraretinal fibrovascular proliferation along the ridge. Videography of this technique is included in this report for instructional purposes.

CONCLUSIONS

Serial examinations using widefield OCT and scleral depression is feasible and may improve detection and documentation of ROP disease progression. Earlier detection of ROP-related proliferation may prevent vitreoretinal traction, retinal detachment, and blindness.

Visuopathy of prematurity: is retinopathy just the tip of the iceberg?

Research on retinopathy of prematurity (ROP) focuses mainly on the abnormal vascularization patterns that are directly visible for ophthalmologists. However, recent findings indicate that children born prematurely also exhibit changes in the retinal cellular architecture and along the dorsal visual stream, such as structural changes between and within cortical areas. Moreover, perinatal sustained systemic inflammation (SSI) is associated with an increased risk for ROP and the visual deficits that follow. In this paper, we propose that ROP might just be the tip of an iceberg we call visuopathy of prematurity (VOP). The VOP paradigm comprises abnormal vascularization of the retina, alterations in retinal cellular architecture, choroidal degeneration, and abnormalities in the visual pathway, including cortical areas. Furthermore, VOP itself might influence the developmental trajectories of cerebral structures and functions deemed responsible for visual processing, thereby explaining visual deficits among children born preterm.

Prostaglandin E2 promotes pathological retinal neovascularisation via EP4R-EGFR-Gab1-AKT signaling pathway

Proliferative retinopathies, such as proliferative diabetic retinopathy (PDR) and retinopathy of prematurity (ROP) are major causes of visual impairment and blindness in industrialized countries. Prostaglandin E2 (PGE2) is implicated in cellular proliferation and migration via E-prostanoid receptor (EP4R). The aim of this study was to investigate the role of PGE2/EP4R signaling in the promotion of retinal neovascularisation. In a streptozotocin (STZ)-induced diabetic model and an oxygen-induced retinopathy (OIR) model, rats received an intravitreal injection of PGE2, cay10598 (an EP4R agonist) or AH23848 (an EP4R antagonist). Optical coherence tomography, retinal histology and biochemical markers were assessed. Treatment with PGE2 or cay10598 accelerated pathological retinal angiogenesis in STZ and OIR-induced rat retina, which was ameliorated in rats pretreated with AH23848. Serum VEGF-A was upregulated in the PGE2-treated diabetic rats vs non-treated diabetic rats and significantly downregulated in AH23848-treated diabetic rats. PGE2 or cay10598 treatment also significantly accelerated endothelial tip-cell formation in new-born rat retina. In addition, AH23848 treatment attenuated PGE2-or cay10598-induced proliferation and migration by repressing the EGF receptor (EGFR)/Growth factor receptor bound protein 2-associated binder protein 1 (Gab1)/Akt/NF-κB/VEGF-A signaling network in human retinal microvascular endothelial cells (hRMECs). PGE2/EP4R signaling network is thus a potential therapeutic target for pathological intraocular angiogenesis.

Retinal imaging in infants

Digital retinal imaging is at the core of a revolution that is continually improving the screening, diagnosis, documentation, monitoring, and treatment of infant retinal diseases. Historically, imaging the retina of infants had been limited and difficult to obtain. Recent advances in photographic instrumentation have significantly improved the ability to obtain high quality multimodal images of the infant retina. These include color fundus photography with different camera angles, ultrasonography, fundus fluorescein angiography, optical coherence tomography, and optical coherence tomography angiography. We provide a summary of the current literature on retinal imaging in infants and highlight areas where further research is required.

Morphological characteristics of early- versus late-onset macular edema in preterm infants

Macular images of infants with early-onset edema (occurring at or before 33 weeks' postmenstrual age [PMA]) and infants with late-onset edema (at or after 36 weeks' PMA) were compared. At first appearance, early-onset edema has a more severe morphology, with foveal bulging and elongated cystoid spaces than late-onset edema, which presents as small cystoid spaces outside the foveal center. Morphological variations may be an indicator of the underlying cause of edema in preterm infants. The presence of mostly parafoveal small cystoid spaces in the late-onset edema group may be suggestive of an association with neurological injury.

Macular OCT Characteristics at 36 Weeks' Postmenstrual Age in Infants Examined for Retinopathy of Prematurity

PURPOSE

To report our ability to capture,-grade reliably, and analyze bedside macular OCT images from preterm infants and relate OCT findings to biological factors and retinopathy of prematurity (ROP) status at a single time window in the Study of Eye Imaging in Preterm Infants (BabySTEPS).

DESIGN

Prospective, observational study.

PARTICIPANTS

Preterm infants eligible for ROP screening with parental consent for research and a 36 ± 1 weeks' postmenstrual age (PMA) visit.

METHODS

We imaged both eyes of preterm infants with an investigational noncontact, handheld swept-source (SS) OCT at the time of clinical ROP examinations. Macular OCT features and layer thicknesses for untreated eyes of infants at 36 ± 1 weeks' PMA were compared with demographic data and clinical ROP examination performed by experts. Statistical analyses accounted for the use of both eyes of infants.

MAIN OUTCOME MEASURES

Macular OCT features and layer thicknesses, gender, race or ethnicity, gestational age, birth weight, ROP stage, and plus disease.

RESULTS

We captured macular OCT from 169 eyes (1 eye excluded because of prior ROP treatment) at 36 ± 1 weeks' PMA. The quality of OCT volumes was excellent in 33 eyes (19%), acceptable in 112 eyes (67%), poor in 24 eyes (14%), and unusable in 0 eyes (0%). Macular edema was present in 60% of eyes and was bilateral in 82% of infants with edema. At the fovea, retinal and inner nuclear layer thickness increased with edema severity: 183 ± 36 μm and 51 ± 27 μm in mild (16% of eyes), 308 ± 57 μm and 163 ± 53 μm in moderate (25%), and 460 ± 76 μm and 280 ± 83 μm in severe edema (12%), respectively. With an increase in ROP stage from 0 to 2, the mean ± standard deviation retinal thickness at the fovea increased from 227± 124 μm to 297 ± 99 μm (P < 0.001). The choroid was thinner, 155 ± 72 μm, with preplus or plus disease versus without, 236 ± 79 μm (P = 0.04), whereas retinal thickness did not vary.

CONCLUSIONS

We demonstrated the reliability of methods and the prevalence of OCT findings in preterm infants enrolled in BabySTEPS at a single time point of 36 ± 1 weeks' PMA. Variations in layer thicknesses in infants at this time point may reflect abnormalities resulting from delay in foveal development that may be impacted by macular edema, ROP, or both.

Regression of Cystoid Macular Edema Three Weeks After Laser for Retinopathy of Prematurity

Cystoid macular edema (CME) has been reported in the neonatal period associated with preterm birth; however, its pathogenesis remains unclear and is likely multifactorial. The authors report the case of a preterm infant imaged using optical coherence tomography (OCT), which revealed severe CME that regressed after laser treatment. Because laser for retinopathy of prematurity aims to reduce vascular endothelial growth factor (VEGF) levels, this case considers the possibility of VEGF-mediated CME pathogenesis. Further, the authors provide additional evidence of the value of OCT for noninvasive visualization of the preterm retina; the modality provides an effective way to evaluate and monitor progression of CME. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:472-475.].

Subclinical Retinal versus Brain Findings in Infants with Hypoxic Ischemic Encephalopathy

PURPOSE

To detect retinal features and abnormalities on optical coherence tomography (OCT) without pupil dilation and relate these to brain injury in infants with a clinical diagnosis of hypoxic ischemic encephalopathy (HIE).

METHODS

Under an institutional review board-approved protocol, we imaged eight infants without pharmacologic mydriasis, using handheld, non-contact spectral-domain (Leica Microsystems, IL) or investigational swept-source OCT at the bedside in an intensive care nursery, after birth (depending on primary clinical care team permission based on health status) and weekly until discharge. The newborn infant with HIE is neurologically unstable; therefore, pharmacologic mydriasis and stimulation with visible light for retinal examination are usually avoided. We analyzed images for retinal pathologies, central foveal thickness, and retinal nerve fiber layer (RNFL) thickness at the papillomacular bundle and compared them to historical controls and published normative data, HIE clinical assessment, and abnormalities on brain magnetic resonance imaging (MRI).

RESULTS

On OCT, three of eight infants had bilateral multiple small macular and perimacular cystoid spaces; two of these three infants also had pronounced retinal ganglion cell layer thinning and severe brain injury on MRI and the third had bilateral paracentral acute middle maculopathy and mild brain injury on MRI. Other findings in HIE infant eyes included abnormally thin fovea and thin RNFL and markers of retinal immaturity such as the absence of sub-foveal photoreceptor development and sub-foveal fluid.

CONCLUSIONS

Bedside handheld OCT imaging within the first 2 weeks of life revealed retinal injury in infants with HIE-related brain injury. Future studies may determine the relationship between acute/subacute retinal abnormalities and brain injury severity and neurodevelopmental outcomes in HIE.

Neurodevelopmental Outcomes Comparing Bevacizumab to Laser for Type 1 ROP

BACKGROUND AND OBJECTIVE

To evaluate neurodevelopmental outcomes among infants treated for retinopathy of prematurity (ROP) at the authors' institution.

PATIENTS AND METHODS

Before-and-after retrospective chart reviews identified 40 infants treated with laser and 46 treated with primary intravitreal bevacizumab (IVB). Primary outcomes were death, hearing loss, bilateral visual impairment (BVI), and cerebral palsy (CP); odds ratios (ORs) were calculated to determine factors associated with CP. Secondary outcomes were mean Bayley Scales of Infant and Toddler Development, Third Edition (BSID-III) scores.

RESULTS

Overall, there were no significant differences in primary outcome measures by treatment group. However, adjusted odds of BVI were significantly higher with laser compared to IVB (OR = 13.1; P = .038). Although IVB was not associated with CP, both hydrocephalus and BVI were strongly correlated with CP. Mean Bayley-III scores were similar when comparing nine laser-treated infants to 13 IVB-treated infants.

CONCLUSIONS

Visual outcomes are an important aspect of neurodevelopment. IVB was not associated with severe developmental disabilities and may protect against vision loss in this analysis. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:337-343.].

Retinopathy of prematurity, visual and neurodevelopmental outcome, and imaging of the central nervous system

Recent findings indicate that retinopathy of prematurity (ROP), presently classified by clinical examinations of retinal vascular tissue, is associated with structural alterations of the central nervous system. Such alterations may be the correlate of the association between ROP and impaired long-term neurocognitive and visual development. The advent of imaging techniques such as structural and diffusion tensor magnetic resonance imaging of the brain, and optical coherence tomography of the retina, will allow the complete visual system to be characterized in greater detail. It has been suggested that ROP may be not only a vascular, but a neurovascular disease, being part of a spectrum that includes pathological development in both the retinal and cerebral neurovascular interphase. We review the present knowledge in the field and point to future directions for research to tackle these questions.

HANDHELD SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY IMAGING THROUGH THE UNDILATED PUPIL IN INFANTS BORN PRETERM OR WITH HYPOXIC INJURY OR HYDROCEPHALUS

PURPOSE

The authors investigated feasibility of undilated handheld spectral domain optical coherence tomography (SDOCT) retinal imaging in preterm infants and children with neurologic abnormalities.

METHODS

Under an institutional review board-approved protocol, the authors attempted handheld SDOCT imaging of the retina, choroid, and optic nerve in infants and young children without pupil dilation. Scans were analyzed for quality and successful capture of foveal, optic nerve, and retinal structural parameters and abnormalities.

RESULTS

The authors obtained images through an undilated pupil of 11 infants/children over 28 eye imaging sessions, 27 at the bedside without sedation, and one under anesthesia. Infants had retinopathy of prematurity (n = 8), hypoxic ischemic encephalopathy (n = 2), or obstructive hydrocephalus (n = 1 child). Pupil sizes ranged from 1.0 mm to 3.5 mm. The authors captured fovea and optic nerve scans in 25/28 eye imaging sessions, with scans of adequate quality to discern prespecified foveal and optic nerve morphology, and of the 25 sessions, the choroidal-scleral junction was visible in all but 6 sessions.

CONCLUSION

Undilated, handheld SDOCT imaging is a potential alternative method to evaluate the retina and optic nerve in patients with relative contraindication to pharmacological pupil dilation. This approach will enable the study of the eye-brain connection and ocular manifestations of neurologic diseases.

Fluorescein Angiographic Characteristics of Macular Edema During Infancy

Importance

Macular edema during infancy, a subclinical feature identified in premature infants by handheld spectral-domain optical coherence tomography (SD-OCT), has been associated with poorer visual acuity and neurodevelopmental outcomes. Features of macular edema on fluorescein angiography (FA) are needed to understand its pathophysiology, but to date have not been reported previously.

Objective

To investigate the FA features of macular edema during infancy.

Design, Setting, and Participants

A retrospective review was conducted of 8 infants at Duke Eye Center who received simultaneous SD-OCT and FA imaging from July 1, 2011, to June 30, 2017. Research and clinical care images were obtained during examination of the infants under anesthesia or at the bedside in the neonatal intensive care unit.

Main Outcomes and Measures

Side-to-side comparison of research handheld SD-OCT images and clinically indicated FA.

Results

Imaging was conducted at a mean (SD) of 42.8 (4.2) weeks' postmenstruation age in the 8 infants (1 [13%] female; 2 [25%] African American; 6 [75%] white). Examination of the FA and SD-OCT images found (1) no macular fluorescein leakage in 3 eyes of 2 infants with retinopathy of prematurity without macular edema and 1 eye with a single cyst, (2) equivocal fluorescein leakage in 2 eyes of 1 infant with mild macular edema, (3) late macular fluorescein leakage in 4 eyes of 2 infants with moderate to severe macular edema, and (4) macular fluorescein leakage from posterior preretinal neovascularization in the macula in 4 eyes of 3 infants with retinopathy of prematurity without macular edema.

Conclusions and Relevance

This observation of fluorescein leakage in 4 infant eyes with macular edema provides new insights into the possible mechanisms of this subclinical finding. Macular fluorescein leakage could indicate a breakdown or delayed maturation of the blood-retinal barrier or dysfunction of the retinal pigment epithelium. Furthermore, the cross-sectional OCT view aids in identifying preretinal neovascularization, which can also cause focal macular leakage in these infants. This new perspective may improve our understanding and potentially guide future treatments of premature infants with subnormal vision.

Hot Topics in Retinopathy of Prematurity

Retinopathy of prematurity (ROP) is a condition seen in premature infants that is characterized by abnormal retinal blood vessel growth incited by relative hyperoxia and followed by hypoxia. It can have severe consequences ranging from high myopia to blindness. This article reviews recent "hot" topics related to ROP, specifically the changing incidence of ROP worldwide, the advent of predictive algorithms for screening for ROP, the emerging data behind efficacy of anti-vascular endothelial growth factor treatments for ROP, and advanced retinal imaging in children who were born premature. [Pediatr Ann. 2017;46(11):e415-e422.].

Pathophysiology, screening and treatment of ROP: A multi-disciplinary perspective

The population of infants at risk for retinopathy of prematurity (ROP) varies by world region; in countries with well developed neonatal intensive care services, the highest risk infants are those born at less than 28 weeks gestational age (GA) and less than 1 kg at birth, while, in regions where many aspects of neonatal intensive and ophthalmological care are not routinely available, more mature infants up to 2000 g at birth and 37 weeks GA are also at risk for severe ROP. Treatment options for both groups of patients include standard retinal laser photocoagulation or, more recently, intravitreal anti-VEGF drugs. In addition to detection and treatment of ROP, this review highlights new opportunities created by telemedicine, where screening and diagnosis of ROP in remote locations can be undertaken by non-ophthalmologists using digital fundus cameras. The ophthalmological care of the ROP infant is undertaken in the wider context of neonatal care and general wellbeing of the infant. Because of this context, this review takes a multi-disciplinary perspective with contributions from retinal vascular biologists, pediatric ophthalmologists, an epidemiologist and a neonatologist. This review highlights the latest insights regarding cellular and molecular mechanisms in the formation of the retinal vasculature in the human infant, pathogenesis of ROP, detection and treatment of severe ROP, the risks and benefits of anti-VEGF therapy, the identification of new therapies over the horizon, and the optimal neonatal care regimen for best ROP outcomes, and the benefits and pitfalls of telemedicine in the remote screening and diagnosis of ROP, all of which have the potential to improve ROP outcomes.

Advances in understanding and management of retinopathy of prematurity

The understanding, diagnosis, and treatment of retinopathy of prematurity have changed in the 70 years since the original description of retrolental fibroplasia associated with high oxygenation. It is now recognized that retinopathy of prematurity differs in appearance worldwide and as ever smaller and younger premature infants survive. New methods are being evaluated to image the retina, diagnose severe retinopathy of prematurity, and determine windows of time for treatment to save eyes and improve visual and neural outcomes. New treatments to promote physiologic retinal vascular development, vascular repair, and inhibit vasoproliferation by regulating proteins involved in vascular endothelial growth factor, insulin-like growth factor, or erythropoietin signaling. Reducing excessive oxidative/nitrosative stress and understanding progenitor cells and neurovascular and glial vascular interactions are being studied.

Macular edema in Asian Indian premature infants with retinopathy of prematurity: Impact on visual acuity and refractive status after 1-year

Purpose:

To report the impact of transient, self-resolving, untreated “macular edema” detected on spectral domain optical coherence tomography in Asian Indian premature infants with retinopathy of prematurity (ROP) on visual acuity (VA) and refraction at 1-year of corrected age.

Materials and Methods:

Visual acuity and refraction of 11 infants with bilateral macular edema (Group A) was compared with gestational age-matched 16 infants with ROP without edema (Group B) and 17 preterms infants without ROP and without edema (Group C) at 3, 6, 9 and 12 months of corrected age using Teller Acuity Cards and cycloplegic retinoscopy. Sub-group analysis of the previously described pattern A and B macular edema was performed.

Results:

Visual acuity was lower in infants with macular edema compared with the other two control groups throughout the study period, but statistically significant only at 3 months. Visual improvement in these infants was highest between the 3^rd and 6^th month and plateaued by the end of the 1^st year with acuity comparable to the other two groups. The edema cohort was more hyperopic compared to the other two groups between 3 and 12 months of age. Pattern A edema had worse VA compared to pattern B, although not statistically significant.

Conclusion:

Macular edema, although transient, caused reduced VA as early as 3 months of corrected age in Asian Indian premature infants weighing <2000 g at birth. The higher hyperopia in these infants is possibly due to visual disturbances caused at a critical time of fovealization. We hypothesize a recovery and feedback mechanism based on the principles of active emmetropization to explain our findings.

IGF-1 in retinopathy of prematurity, a CNS neurovascular disease

The retina is part of the central nervous system and both the retina as well as the brain can suffer from severe damage after very preterm birth. Retinopathy of prematurity is one of the major causes of blindness in these children and brain neuronal impairments including cognitive defects, cerebral palsy and intraventricular hemorrhage (IVH) are also complications of very preterm birth. Insulin-like growth factor 1 (IGF-1) acts to promote proliferation, maturation, growth and survival of neural cells. Low levels of circulating IGF-1 are associated with ROP and defects in the IGF-1 gene are associated with CNS disorders including learning deficits and brain growth restriction. Treatment of preterm infants with recombinant IGF-1 may potentially prevent ROP and CNS disorders. This review compares the role of IGF-1 in ROP and CNS disorders. A recent phase 2 study showed a positive effect of IGF-1 on the severity of IVH but no effect on ROP. A phase 3 trial is planned.

Optical coherence tomography of the preterm eye: from retinopathy of prematurity to brain development

Preterm infants with retinopathy of prematurity are at increased risk of poor neurodevelopmental outcomes. Because the neurosensory retina is an extension of the central nervous system, anatomic abnormalities in the anterior visual pathway often relate to system and central nervous system health. We describe optical coherence tomography as a powerful imaging modality that has recently been adapted to the infant population and provides noninvasive, high-resolution, cross-sectional imaging of the infant eye at the bedside. Optical coherence tomography has increased understanding of normal eye development and has identified several potential biomarkers of brain abnormalities and poorer neurodevelopment.

FUNCTIONAL OUTCOMES OF YOUNG INFANTS WITH AND WITHOUT MACULAR EDEMA

PURPOSE

The authors relate posterior segment microanatomy from perinatal spectral domain optical coherence tomography to visual acuity, brain abnormalities, and neurodevelopment.

METHODS

Thirteen infants (11 preterm and 2 term birth), imaged in the nursery with portable spectral domain optical coherence tomography, had visual acuity and sensorimotor testing at age 9 months to 15 months (grating acuity) or 4 years to 5 years (optotype), and medical records reviewed for brain magnetic resonance imaging reports and Bayley scales testing at age 18 months to 24 months.

RESULTS

Eight children with age-appropriate macular microanatomy without edema on perinatal spectral domain optical coherence tomography had optimal (≥ 20/40) or within normal limits (grating acuity) visual acuity. Five children with perinatal macular edema had suboptimal visual acuity (in 9/10 eyes) and sensorimotor deficits, magnetic resonance imaging abnormalities, or poor neurodevelopment. Macular edema persisted in 1 infant through 9-month corrected age.

CONCLUSION

Maturation of the visual system and evolution of retinal anomalies can be monitored with posterior segment spectral domain optical coherence tomography. Retinal microanatomy observed in infancy might relate to subsequent vision and other central nervous system events, but additional studies are needed to determine the range of normal microanatomy in infants and how this relates to vision and neurodevelopment.

Thinner Retinal Nerve Fiber Layer in Very Preterm Versus Term Infants and Relationship to Brain Anatomy and Neurodevelopment

PURPOSE

To assess retinal nerve fiber layer (RNFL) thickness at term-equivalent age in very preterm (<32 weeks gestational age) vs term-born infant cohorts, and compare very preterm infant RNFL thickness with brain anatomy and neurodevelopment.

DESIGN

Cohort study.

METHODS

RNFL was semi-automatically segmented (1 eye per infant) in 57 very preterm and 50 term infants with adequate images from bedside portable, handheld spectral-domain optical coherence tomography imaging at 37-42 weeks postmenstrual age. Mean RNFL thickness was calculated for the papillomacular bundle (-15 degrees to +15 degrees) and temporal quadrant (-45 degrees to +45 degrees) relative to the fovea-optic nerve axis. Brain magnetic resonance imaging (MRI) scans clinically obtained in 26 very preterm infants were scored for global structural abnormalities by an expert masked to data except for age. Cognitive, language, and motor skills were assessed in 33 of the very preterm infants at 18-24 months corrected age.

RESULTS

RNFL was thinner for very preterm vs term infants at the papillomacular bundle ([mean ± standard deviation] 61 ± 17 vs 72 ± 13 μm, P < .001) and temporal quadrant (72 ± 21 vs 82 ± 16 μm, P = .005). In very preterm infants, thinner papillomacular bundle RNFL correlated with higher global brain MRI lesion burden index (R(2) = 0.35, P = .001) and lower cognitive (R(2) = 0.18, P = .01) and motor (R(2) = 0.17, P = .02) scores. Relationships were similar for temporal quadrant.

CONCLUSIONS

Thinner RNFL in very preterm infants relative to term-born infants may relate to brain structure and neurodevelopment.

Genomics in the neonatal nursery: Focus on ROP

Retinopathy of prematurity (ROP) is a complex disease that is influenced by both genetic and environmental factors. Several small studies have found genetic variants in EPAS1, VEGF, SOD, and members of the WNT family in association with ROP. Design in genetic studies is challenging because of changing recommendations for the management of prematurity and ROP, the fact ROP is rare, and that availability of resources for managing premature infants can vary throughout the world. In addition, there is a shortage of ophthalmologists with the ability to diagnose and characterize severe ROP. Careful determination of the degree of prematurity is important when evaluating genetic studies. Controlling for significant epidemiologic factors and multiple comparisons is also important to consider when evaluating genetic studies. One large candidate gene study controlled for degree of prematurity, significant epidemiologic factors, and multiple comparisons and found variants within the intron of BDNF associated with severe ROP. Future studies using unbiased techniques to assess genetic risk are important as are in-depth study of BDNF through deep sequencing and associated mechanistic studies using appropriate experimental models.

Retinal Imaging of Infants on Spectral Domain Optical Coherence Tomography

Spectral domain coherence tomography (SD OCT) has become an important tool in the management of pediatric retinal diseases. It is a noncontact imaging device that provides detailed assessment of the microanatomy and pathology of the infant retina with a short acquisition time allowing office examination without the requirement of anesthesia. Our understanding of the development and maturation of the infant fovea has been enhanced by SD OCT allowing an in vivo assessment that correlates with histopathology. This has helped us understand the critical correlation of foveal development with visual potential in the first year of life and beyond. In this review, we summarize the recent literature on the clinical applications of SD OCT in studying the pathoanatomy of the infant macula, its ability to detect subclinical features, and its correlation with disease and vision. Retinopathy of prematurity and macular edema have been discussed in detail. The review also summarizes the current status of SD OCT in other infant retinal conditions, imaging the optic nerve, the choroid, and the retinal nerve fibre in infants and children, and suggests future areas of research.

Assessment of retinal nerve fiber layer thickness in healthy, full-term neonates

PURPOSE

To measure average retinal nerve fiber layer (RNFL) thicknesses in healthy, full-term neonates.

DESIGN

Descriptive research to develop normative data.

METHODS

Healthy infants born between 37 and 42 weeks postmenstrual age were imaged with hand-held spectral-domain optical coherence tomography. A custom script segmented the RNFL; the fovea and optic nerve center were manually selected. A second script measured the average RNFL thickness along the papillomacular bundle, defined as the arc from -15 degrees to +15 degrees on the axis from the optic nerve to fovea, with radii of 1.1, 1.3, 1.5, and 1.7 mm from the center of the optic disc. Shapiro-Wilk W tests assessed these measurements for normality to determine the age-appropriate radial distance for subsequent analyses. Average RNFL thicknesses for four temporal 45-degree sectors (superior temporal, temporal superior, temporal inferior, and inferior temporal) and the temporal quadrant were calculated and compared to demographic parameters for all infants.

RESULTS

Fifty full-term infants were adequately imaged for RNFL analysis. RNFL thicknesses at 1.5 mm radial distance from the optic nerve were the most normally distributed. While there was a trend toward greater mean superior temporal RNFL thickness for both black and Hispanic vs white infants (128 ± 27 μm, 124 ± 30 μm, and 100 ± 19 μm, respectively, P = .04 for both comparisons), there were no other significant differences noted in RNFL thicknesses by race, sex, gestational age, or birth weight.

CONCLUSIONS

We present RNFL thickness measurements for healthy, full-term infants that may serve as normative data for future analyses.

Delay in retinal photoreceptor development in very preterm compared to term infants

PURPOSE

We compared photoreceptor development from spectral domain optical coherence tomography (SD-OCT) imaging in very preterm infants (VPT, <32 weeks gestational age) with those of term infants.

METHODS

The microanatomy of foveal SD-OCT images obtained at the bedside at 37 to 42 weeks term equivalent postmenstrual age (TEA) was reviewed with qualitative and quantitative analysis of retinal and especially photoreceptor layers in the macula. Measures of maturity included presence of the cone outer segment tips (COST) or the ellipsoid zone (EZ) at foveal center, distance from Bruch's membrane (BM) to the EZ at the foveal center, and radial distance from foveal center to first appearance of the EZ.

RESULTS

The incidence of the EZ developed at the foveal center was lower in VPT infants (9/64, 14%) versus term infants (22/47, 47%, P < 0.001) and lower in VPT infants with macular edema (3/46) versus VPT without edema (6/18, P = 0.01). Mean ± SD distance from the foveal center to the visible EZ was 783 ± 440 μm in VPT, and 492 ± 501 μm in term infants, P = 0.002. The height of the BM-to-EZ at the foveal center did not differ in VPT versus term infants. The COST band was not visible in any infant.

CONCLUSIONS

Photoreceptor inner and outer segment development in VPT infants appears delayed when compared to term infants, and the photoreceptor RPE junction remains immature in all infants at TEA. Delayed maturation of photoreceptors could contribute to differences in visual function in some VPT infants.