Birth Weight Is a Significant Predictor of Retinal Nerve Fiber Layer Thickness at 36 Weeks Postmenstrual Age in Preterm Infants

Fetal Growth Restriction Leads to an Enlarged Cup-to-Disc Ratio in Adults Born at Full Term

PURPOSE

This study explores associations between fetal growth restriction or excessive fetal growth, along with perinatal factors on the optic nerve head morphology in adulthood.

DESIGN

Retrospective cohort study.

METHODS

This retrospective cohort study involved a prospective ophthalmological examination of individuals born at full term (with a gestational age of ≥37 weeks) from 1969 to 2002. Each participant underwent nonmydriatic fundus camera photography to capture images of the optic discs, followed by manual measurements. The vertical cup-to-disc ratio (VCDR) and optic disc area were examined and analyzed in relation to the baby's birth weight relative to the gestational age. These categories included those with former moderate (birth weight percentile between the 3rd and <10th), severe SGA (below the third percentile), normal (AGA, 10th-90th percentile), and moderately (birth weight >90th-97th percentile) and severely (birth weight >97th percentile) large for gestational age (LGA) adults within the age range of 18 to 52 years.

RESULTS

Overall, 535 eyes of 280 individuals (age 29.7 ± 9.2 years, 144 females) born at full term were included. Multivariable analysis showed a significant association between a larger VCDR and the severe SGA group (B = 0.05, 95% CI 0.01-0.10; P = .02). In the univariable model, placental insufficiency was associated with VCDR (B = 0.10, 95% CI 0.01-0.19; P = .03). Other perinatal factors did not demonstrate an association with VCDR. Furthermore, there was an indication of an association suggesting a smaller optic disc area in individuals born moderately SGA at full term (B = -0.17, 95% CI -0.33 to -0.001; P = .05).

CONCLUSIONS

This study provides evidence that individuals born at-term with severe SGA have an increased VCDR, suggesting that fetal growth restriction has a lasting impact on optic disc morphology independent of prematurity throughout adulthood.

The long-term influence of perinatal factors on macular morphology and vessel density in preterm children

BACKGROUND

Increased survival rate of extremely preterm children is associated with a higher risk of retinopathy of prematurity (ROP) and long-term sequelae, which implicate retinal changes.

PURPOSE

To assess an influence of perinatal characteristics on morphology and retinal vascularity of the macula in preterm children.

METHODS

A cohort of 123 preterm children at the age of 10.5 years (IQR: 8.12-12.77) was prospectively assessed. Optical coherence tomography angiography (OCTA) was performed using RTVueXR Avanti. Foveal thickness, parafoveal thickness, size of foveal avascular zone (FAZ), superficial and deep vessel density, central choroidal thickness (CCT) were analyzed. The associations between OCTA results and perinatal factors, including the presence of ROP and therapy requirements were assessed in preterm children.

RESULTS

Significantly smaller FAZ, higher foveal thickness and vessel density were noted in children with ROP, Respiratory Distress Syndrome, Bronchopulmonary Dysplasia, required erythropoietin, transfusion or steroids. Foveal thickness was increased in children with ROP (p < 0.001) and following laser treatment (p < 0.05). Thinner CCT was noted in children with a history of sepsis (p < 0.05) and ROP required treatment (p < 0.05). Pregnancy bleeding was associated with higher superficial foveal vessel density (p < 0.05) and smaller FAZ (p < 0.05).

CONCLUSION

Neonatal factors have a huge impact on retinal development, but the role of prenatal factors should not be neglected in preterm children.

Optic atrophy in prematurity: pathophysiology and clinical features

Optic atrophy is an important cause of visual impairment in children, and the aetiological profile has changed over time. Technological advancements led by neuroimaging of the visual pathway and imaging of the optic nerve with optical coherence tomography have accelerated the understanding of this condition. In the new millennium, an increasing prevalence of prematurity as a cause of optic atrophy in children has been highlighted. This new shift has been linked with increasing rates of premature births and improved neonatal survival of preterm infants. The available literature is limited to hospital and registry-based cohorts with modest sample sizes, methodological heterogeneity and selection bias limitations. Larger studies that are better designed are required to better understand the contribution of prematurity to the disease burden. In addition to considering other life-threatening aetiologies, screening for premature birth should be covered as part of a comprehensive history when evaluating a child with paediatric optic atrophy.

Five degrees-of-freedom mechanical arm with remote center of motion (RCM) device for volumetric optical coherence tomography (OCT) retinal imaging

Handheld optical coherence tomography (HH-OCT) is gaining popularity for diagnosing retinal diseases in neonates (e.g. retinopathy of prematurity). Diagnosis accuracy is degraded by hand tremor and patient motion when using commercially available handheld retinal OCT probes. This work presents a low-cost arm designed to address ergonomic challenges of holding a commercial OCT probe and alleviating hand tremor. Experiments with a phantom eye show enhanced geometric uniformity and volumetric accuracy when obtaining OCT scans with our device compared to handheld imaging approaches. An in-vivo porcine volumetric image was also obtained with the mechanical arm demonstrating clinical deployability.

Biphasic change in retinal nerve fibre layer thickness from 30 to 60 weeks postmenstrual age in preterm infants

BACKGROUND/AIMS

The optic nerve development during the critical postnatal weeks of preterm infants is unclear. We aimed to investigate the change of retinal nerve fibre layer (RNFL) in preterm infants.

METHODS

We used an investigational handheld optical coherence tomography (OCT) system to serially image awake preterm infants between 30 and 60 weeks postmenstrual age (PMA) at the bedside. We assessed RNFL thickness in the papillomacular bundle and nasal macular ganglion cell layer+inner plexiform layer (GCL+IPL) thickness. We applied a segmented mixed model to analyse the change in the thickness of RNFL and GCL+IPL as a function of PMA.

RESULTS

From 631 OCT imaging sessions of 101 infants (201 eyes), RNFL thickness followed a biphasic model between 30 and 60 weeks, with an estimated transition at 37.8 weeks PMA (95% CI: 37.0 to 38.6). RNFL thickness increased at 1.8 μm/week (95% CI: 1.6 to 2.1) before 37.8 weeks and decreased at -0.3 μm/week (95% CI: -0.5 to -0.2) afterwards. GCL+IPL thickness followed a similar biphasic model, in which the thickness increased at 2.9 μm/week (95% CI: 2.5 to 3.2) before 39.5 weeks PMA (95% CI: 38.8 to 40.1) and then decreased at -0.8 μm/week (95% CI: -0.9 to -0.6).

CONCLUSION

We demonstrate the feasibility of monitoring RNFL and GCL+IPL thickness from OCT during the postnatal weeks of preterm infants. Thicknesses follow a biphasic model with a transition age at 37.8 and 39.5 weeks PMA, respectively. These findings may shed light on optic nerve development in preterm infants and assist future study designs.

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).

Associations between systemic health and retinal nerve fibre layer thickness in preterm infants at 36 weeks postmenstrual age

BACKGROUND/AIMS

Neonatal insults from systemic diseases have been implicated in the pathway of impaired neurodevelopment in preterm infants. We aimed to investigate the associations between systemic health factors and retinal nerve fibre layer (RNFL) thickness in preterm infants.

METHODS

We prospectively enrolled infants and imaged both eyes at 36±1 weeks postmenstrual age (PMA) using a hand-held optical coherence tomography system at the bedside in the Duke intensive care nurseries. We evaluated associations between RNFL thickness and 29 systemic health factors using univariable and multivariable regression models.

RESULTS

83 infants with RNFL thickness measures were included in this study. Based on the multivariable model, RNFL thickness was positively associated with infant weight at imaging and was negatively associated with sepsis/necrotising enterocolitis (NEC). RNFL thickness was 10.4 µm (95% CI -15.9 to -4.9) lower in infants with than without sepsis/NEC in the univariable analysis (p<0.001). This difference remained statistically significant after adjustment for confounding variables in various combinations (birth weight, birthweight percentile, gestational age, infant weight at imaging and growth velocity). A 250 g increase in infant weight at imaging was associated with a 3.1 µm (95% CI 2.1 to 4.2) increase in RNFL thickness in the univariable analysis (p<0.001).

CONCLUSIONS

Low infant weight and sepsis/NEC were independently associated with thinner RNFL in preterm infants at 36 weeks PMA. To our knowledge, this study is the first to suggest that sepsis/NEC may affect retinal neurodevelopment. Future longitudinal studies are needed to investigate this relationship further.

Peripapillary Retinal Nerve Fiber Layer Thickness in Adults Born Extremely, Very, and Moderately Preterm With and Without Retinopathy of Prematurity: Results From the Gutenberg Prematurity Eye Study (GPES)

PURPOSE

This study investigated whether prematurity and associated factors or prenatal growth restriction have long-term effects on the peripapillary retinal nerve fiber layer (pRNFL) in adulthood.

DESIGN

Retrospective cohort study.

METHODS

The Gutenberg Prematurity Eye Study (GPES) is a retrospective cohort study with a prospective ophthalmologic examination in Germany. Selected individuals born term and preterm (age 18-52 years) were examined with spectral-domain optical coherence tomography (SD-OCT) in adulthood, and perinatal medical charts were reviewed. The pRNFL thickness was measured using SD-OCT. Univariate and multivariable linear regression analyses were conducted to investigate associations between pRNFL and gestational age (GA; categorical), birth weight percentile (categorical), retinopathy of prematurity (ROP) occurrence, and treatment and other perinatal parameters with adjustment for age, sex, and spherical equivalent.

RESULTS

In total, 766 eyes of 406 preterm and full-term individuals were included (mean age 28.4 ± 8.6 years, 228 females). After adjustment for age, sex, and spherical equivalent, global pRNFL thinning was associated with moderate (GA = 33-36 wk, β = -4.68, P < .001), very (GA = 29-32 wk, β = -5.72, P < .001), and extreme (GA ≤ 28 wk, β = -8.69, P < .001) prematurity but not with low birth weight percentile (<25th percentile, P = .9) and ROP occurrence (P = .9) in multivariable analysis. ROP treatment was associated with increased pRNFL in the temporal sector (P = .002). Maternal smoking during pregnancy showed an association with pRNFL thinning (P = .07).

CONCLUSION

Our data indicate that the more preterm individuals are born the more pRNFL thinning occurs, whereas prenatal growth restriction and postnatal occurrence of ROP show less effects on pRNFL thickness. Furthermore, individuals with severe ROP with treatment but not lower ROP stages without treatment showed an increased temporal pRNFL thickness.

Adults Born Small for Gestational Age at Term Have Thinner Peripapillary Retinal Nerve Fiber Layers Than Controls

PURPOSE

Prenatal growth restriction is associated with impaired neurodevelopment in childhood. This study investigated the effects of being born small for gestational age (SGA) on peripapillary retinal nerve fiber layer (pRNFL) thickness in adults born at term.

METHODS

A retrospective cohort study was conducted with a prospective ophthalmologic examination of participants born at full-term (gestational age ≥37 weeks) between 1969 and 2002. All participants were examined with spectral-domain optical coherence tomography and grouped according to their birth weight in correlation to gestational age as former moderate (birth weight (BW) percentile 3rd to <10th) and severe SGA (<3rd percentile), normal (10th-90th percentile, AGA), and moderately (>90th to 97th percentile) and severely (>97th percentile) large for gestational age (LGA) adults (18 to 52 years).

RESULTS

Overall, 547 eyes of 285 individuals (age 29.9±9.4 years, 151 females) born at term were included. Multivariable regression analyses revealed a strong association between a lower global pRNFL thickness in the severe SGA (B=-8.99 [95%-CI: -12.68; -5.30] µm; p<0.001) and in the moderate SGA groups (B=-6.40 [95%-CI: -10.29; -2.50] µm; p=0.001) compared to the reference AGA group.

CONCLUSION

Our results indicate that restricted fetal growth affects neurologic tissue development of the optic nerve head, particularly in individuals born severely SGA at term. This indicates that fetal growth restriction may exert disturbances in the development of neurologic tissue, which persists in adulthood.

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.

Association Between Retinal Microanatomy in Preterm Infants and 9-Month Visual Acuity

Importance

Preterm infants are at risk for poor visual acuity (VA) outcomes, even without retinal problems on ophthalmoscopy. Infant retinal microanatomy may provide insight as to potential causes.

Objective

To evaluate the association between preterm infant retinal microanatomy and VA at 9 months' corrected age.

Design, Setting, and Participants

This prospective observational study took place from November 2016 and December 2019 at a single academic medical center and included preterm infants enrolled in Study of Eye Imaging in Preterm Infants (BabySTEPS). Infants were eligible for enrollment in BabySTEPS if they met criteria for retinopathy of prematurity (ROP) screening, were 35 weeks' postmenstrual age or older at the time of first OCT imaging, and a parent or guardian provided written informed consent. Of 118 infants enrolled in BabySTEPS, 61 were included in this analysis. Data were analyzed from March to April 2021.

Exposures

Bedside optical coherence tomography (OCT) imaging at a mean (SD) 39.85 (0.79) weeks' postmenstrual age and monocular grating VA measurement at 9 months' corrected age.

Main Outcomes and Measures

Presence and severity of macular edema and presence of ellipsoid zone at the fovea measured by extracting semiautomated thicknesses of inner nuclear layer, inner retina, and total retina at the foveal center; choroid across foveal 1 mm; and retinal nerve fiber layer (RNFL) across the papillomacular bundle (PMB). Pearson correlation coefficients were calculated and 95% CIs were bootstrapped for the association between retinal layer thicknesses and continuous logMAR VA. Associations were analyzed between retinal microanatomy and normal (3.70 cycles/degree or greater) vs subnormal grating VA at 9 months' corrected age using logistic regression and with logMAR VA using linear regression, adjusting for birth weight, gestational age, and ROP severity at the time of OCT imaging and accounting for intereye correlation using generalized estimating equations.

Results

The mean (SD; range) gestational age of included infants was 27.6 (2.8; 23.0-34.6) weeks, and mean (SD; range) birth weight was 958.2 (293.7; 480-1580) g. In 122 eyes of 61 infants, the correlations between retinal layer thicknesses and logMAR VA were as follows: r, 0.01 (95% CI, -0.07 to -0.27) for inner nuclear layer; r, 0.19 (95% CI, 0.01 to 0.35) for inner retina; r, 0.15 (95% CI, -0.02 to 0.31) for total retina; r, -0.22 (95% CI, -0.38 to -0.03) for choroid; and r, -0.27 (95% CI, -0.45 to 0.10) for RNFL across the PMB. In multivariable analysis, thinner RNFL across the PMB (regression coefficient, -0.05 per 10-μm increase in RNFL thickness; 95% CI, -0.10 to -0.01; P = .046) and prior ROP treatment (regression coefficient, 0.33 for ROP treatment; 95% CI, 0.11 to 0.56; P = .003) were independently associated with poorer 9-month logMAR VA.

Conclusions and Relevance

In preterm infants, RNFL thinning across the PMB was associated with poorer 9-month VA, independent of birth weight, gestational age, need for ROP treatment, and macular microanatomy. Evaluation of RNFL thickness using OCT may help identify preterm infants at risk for poor vision outcomes.

Optic Nerve Head Morphology in Adults Born Extreme, Very, and Moderate Preterm With and Without Retinopathy of Prematurity: Results From the Gutenberg Prematurity Eye Study

PURPOSE

This study aimed to investigate associations of prematurity and associated factors with optic disc morphology in adulthood as long-term effects.

DESIGN

Retrospective cohort study.

METHODS

The Gutenberg Prematurity Eye Study (GPES) is a retrospective cohort study with a prospective ophthalmologic examination of adults (age 18-52 years) in Germany. In every participant, photography of optic discs was performed with a nonmydriatic fundus camera, and optic disc measurements were done manually. The vertical cup-to-disc ratio (VCDR), optic disc area, and torted and tilted discs were assessed and exploratively compared between individuals with retinopathy of prematurity (ROP) with treatment, an ROP group without treatment and groups of individuals of different gestational ages (GAs) without ROP (GA ≤ 28 weeks, GA 29-32 weeks, GA 33-36 weeks, and GA ≥ 37 weeks [control group]).

RESULTS

The present analysis included 743 eyes of 393 individuals born preterm and full-term (aged 28.4 ± 8.6 years, 223 females). The VCDR was significantly larger in subjects with a GA ≤28 weeks without ROP compared to the full-term control group (GA ≥37 weeks) (P = .002). Subjects with ROP without treatment also had a larger VCDR (P = .001), whereas those with ROP treatment showed a smaller VCDR than the full-term control group (P = .02). In addition, individuals with ROP treatment were more likely to have a torted disc than the full-term control group (P = .006).

CONCLUSION

The present study provides evidence that individuals born extremely preterm have increased VCDR in adulthood. Furthermore, these results indicate that fetal origins affect optic disc morphology until adulthood, which might predispose the affected individual to degenerative optic nerve head diseases or being incorrectly diagnosed to glaucoma.