Comparative study of visual dysfunctions in 6-10-year-old very preterm- and full-term-born children

The Effect of High-Dose Erythropoietin Perinatally on Retinal Function in School-Aged Children Born Extremely or Very Preterm

PURPOSE

To investigate the long-term effects of high-dose recombinant human erythropoietin (rhEPO) administered during the perinatal period on retinal and visual function in children born extremely or very preterm.

DESIGN

Randomized, double-blind clinical trial follow-up plus cohort study.

METHODS

 Setting: Department of Ophthalmology, University Hospital Zurich, Zurich, Switzerland.

STUDY POPULATION

Extremely or very preterm-born children aged 7 to 15 years, previously randomized to receive either high-dose rhEPO or placebo in the perinatal period.

INCLUSION CRITERIA

participation in an ongoing neuropediatric study (EpoKids), written informed consent.

EXCLUSION CRITERIA

previous ocular trauma or surgery; retinal or developmental disease unrelated to prematurity. Healthy control (HC) children of comparable age were recruited.

INCLUSION CRITERIA

term birth, informed consent.

EXCLUSION CRITERIA

any ocular/visual abnormality, high refractive error. Intervention status (rhEPO/placebo) was unknown to examiners and subjects at examination, with examiners unblinded only after completion of all analyses.

OBSERVATION PROCEDURES

The electroretinogram (ERG) was performed with the RETeval device (LKC Technologies, Inc). Ophthalmological and orthoptic examinations excluded comorbidity in the prematurely born cohort and ocular diseases in the HC group.

MAIN OUTCOME MEASURES

Scotopic and photopic ERG response amplitudes and peak times (6 amplitudes; 6 peak times). Secondary outcomes were habitual visual acuity and color discrimination performance (for descriptive summary only).

RESULTS

No differences in ERG parameters between EPO (n = 52; 104 eyes) and placebo (n = 35; 70 eyes) subgroups were observed (all corrected P > .05). Two cone system-mediated peak times were slightly slower in the placebo than HC (n = 52; 104 eyes) subgroup (coefficient/95% confidence interval = 0.53/0.21-0.85 and 0.36/0.13-0.60; P = .012 and .022); a predominantly rod system-mediated peak time was slightly faster in the EPO than the HC subgroup (coefficient/95% confidence interval = -4.33/-6.88 to -1.78; P = .011). Secondary outcomes were comparable across subgroups.

CONCLUSIONS

Administration of high-dose rhEPO to infants born extremely or very preterm during the perinatal period has no measurable effects on retinal function in childhood compared to placebo. Premature birth may cause small, likely clinically insignificant effects on retinal function in childhood, which may be partially mitigated by administration of rhEPO during the perinatal period.

Analysis of risk factors associated with the high incidence of amblyopia in preterm infants at the corrected gestational age of 12 months

OBJECTIVE

To investigate the perinatal and in-hospital risk factors associated with the high incidence of amblyopia in preterm infants and to analyze the correlation between the amblyopia and neurodevelopment.

METHODS

Children discharged from the neonatal intensive care unit (NICU) at 12 months of corrected gestational age were retrospectively included in this study. Ocular screening was performed in children. At the risk of amblyopia was determined according to the American Academy of Ophthalmology Guidelines for automated preschool vision screening factors. Differences in perinatal characteristics, complications during hospitalization, and treatment modalities between the two groups of children were analyzed, and multifactorial logistic regression analysis was used to identify the independent risk factors for amblyopia. The results of developmental assessment were collected retrospectively to analyze the correlation between amblyopia and various aspects of neurological development.

RESULTS

A total of 128 preterm infants, 30 in the amblyopia risk group and 98 in the non-amblyopia risk group, were included in this study. Univariate analysis showed that the amblyopia risk group had lower birth weights, higher rates of asphyxia, preterm brain white matter injury, bronchopulmonary dysplasia (BPD), intraventricular hemorrhage (IVH), sepsis during hospitalization, and higher rates of treatment with pulmonary surfactant (PS), blood transfusion, invasive ventilator, and levothyroxine. Logistic regression analysis showed that BPD in the neonatal period (odds ratio [OR] 8.355, 95% confidence interval [CI] 1.492, 46.786), brain white matter injury (OR 16.742, 95% CI 0.684, 409.804), treatment with levothyroxine (OR 2.859, 95% CI 0.946, 8.639), and use of an invasive ventilator (OR 2.983, 95% CI 0.942, 9.445) were independent risk factors for amblyopia at 12 months of corrected gestational age, while the administration of glucocorticoids (OR 0.055, 95% CI 0.004, 0.737) was a protective factor. Regarding neurodevelopmental assessment, the number of infants with lagging fine motor development was greater in the amblyopia risk group.

CONCLUSION

The presence of BPD in the neonatal period, brain white matter damage in preterm infants, and use of levothyroxine and invasive ventilator were high risk factors for amblyopia. The use of glucocorticoids therapy was a protective factor. Children with risk of amblyopia had a higher rate of poor fine motor development.

Patterning and Development of Photoreceptors in the Human Retina

Humans rely on visual cues to navigate the world around them. Vision begins with the detection of light by photoreceptor cells in the retina, a light-sensitive tissue located at the back of the eye. Photoreceptor types are defined by morphology, gene expression, light sensitivity, and function. Rod photoreceptors function in low-light vision and motion detection, and cone photoreceptors are responsible for high-acuity daytime and trichromatic color vision. In this review, we discuss the generation, development, and patterning of photoreceptors in the human retina. We describe our current understanding of how photoreceptors are patterned in concentric regions. We conclude with insights into mechanisms of photoreceptor differentiation drawn from studies of model organisms and human retinal organoids.

Retinal ganglion cell complex thickness at school-age, prematurity and neonatal stressors

PURPOSE

To investigate the association between the ganglion cell complex (GCC) thickness at early school-age and prematurity and other neonatal factors.

METHODS

Cross-sectional study. The sample included very preterm children with gestational age (GA) below 32 weeks or birthweight below 1500 g enrolled in a follow-up program (n = 101) and a comparison group of term-born children (n = 49). Ganglion cell complex (GCC) thickness was measured at 4-8 years using high-quality optical coherence tomography (OCT) images. Data on neonatal and postnatal features were extracted from clinical records; analyses included mixed linear models.

RESULTS

Ganglion cell layer (GCL) and retinal nerve fiber layer (mRNFL) were thicker in term than in preterm born children (2.9 μm and 2.4 μm respectively, p < 0.001). Within the preterm group, lower GA was associated with a decrease in total GCL (0.7 μm per week, p < 0.001). Being small for GA was associated with further thinning in both layers (1.4 and 2.8 µm). Postnatal corticosteroids therapy and severe brain lesion were associated with thinning in the total GCL of 6 µm (p < 0.001) and 4.1 µm (p = 0.002), respectively, and shock was associated with thinning in total mRNFL of 6 µm (p < 0.001).

CONCLUSIONS

Lower GA or birthweight are associated with thinning of GCC layers. When performing an OCT examination at school-age and a decrease in GCC thickness is observed, it may be relevant to ask about a history of prematurity, and further enquire about neonatal shock, postnatal corticosteroids therapy or severe brain lesion that are related to additional decrease in GCC thickness.

Cost-effectiveness analysis of tele-retinopathy of prematurity screening in Iran

AIM

To conduct a cost-utility analysis of the tele-retinopathy of prematurity (ROP) screening program against no screening.

METHODS

A decision tree model was developed to identify and treat the infants with threshold ROP through the tele-screening system compared with no screening program from the societal perspective. We used the quality adjusted life years (QALY) index to measure the scenarios' effectiveness, which was discounted for the future years by 0.058. One hundred twenty-six randomly selected newborns with ROP required treatment were investigated to extract the treatment information. We considered the direct medical and non-medical costs in cost calculations analysed by the bottom-up approach. The figures of the model's inputs were calculated using the Monte Carlo simulation that generated 1000 random iteration of the data, and a one-way sensitivity analysis was performed on the model to cope with the potential uncertainties.

RESULTS

The total and per capita needed the budget to establish a tele-ROP screening system were estimated at over 1.5 million and 35.13 USD, respectively. The total cost of identifying and treating an ROP case in tele-screening and no screening strategies were obtained as 108.72 and 63.52 USD, respectively, and their lifetime discounted QALY gained were calculated as 15.39 and 15.11, respectively. Therefore, incremental cost-effectiveness ratio (ICER) of tele-screening strategy against the competitive strategy was achieved as 161.43 USD.

CONCLUSION

Tele-ROP screening program is one of the most cost-effective interventions in the Iranian health system and has a high priority to receive a budget for implementation.

Thyroid hormone signaling specifies cone subtypes in human retinal organoids

INTRODUCTION:

Cone photoreceptors in the human retina enable daytime, color, and high-acuity vision. The three subtypes of human cones are defined by the visual pigment that they express: blue-opsin (short wavelength; S), green-opsin (medium wavelength; M), or red-opsin (long wavelength; L). Mutations that affect opsin expression or function cause various forms of color blindness and retinal degeneration.

RATIONALE:

Our current understanding of the vertebrate eye has been derived primarily from the study of model organisms. We studied the human retina to understand the developmental mechanisms that generate the mosaic of mutually exclusive cone subtypes. Specification of human cones occurs in a two-step process. First, a decision occurs between S versus L/M cone fates. If the L/M fate is chosen, a subsequent choice is made between expression of L- or M-opsin. To determine the mechanism that controls the first decision between S and L/M cone fates, we studied human retinal organoids derived from stem cells.

RESULTS:

We found that human organoids and retinas have similar distributions, gene expression profiles, and morphologies of cone subtypes. During development, S cones are specified first, followed by L/M cones. This temporal switch from specification of S cones to generation of L/M cones is controlled by thyroid hormone (TH) signaling. In retinal organoids that lacked thyroid hormone receptor β (Thrβ), all cones developed into the S subtype. Thrβ binds with high affinity to triiodothyronine (T3), the more active form of TH, to regulate gene expression. We observed that addition of T3 early during development induced L/M fate in nearly all cones. Thus, TH signaling through Thrβ is necessary and sufficient to induce L/M cone fate and suppress S fate. TH exists largely in two states: thyroxine (T4), the most abundant circulating form of TH, and T3, which binds TH receptors with high affinity. We hypothesized that the retina itself could modulate TH levels to control subtype fates. We found that deiodinase 3 (DIO3), an enzyme that degrades both T3 and T4, was expressed early in organoid and retina development. Conversely, deiodinase 2 (DIO2), an enzyme that converts T4 to active T3, as well as TH carriers and transporters, were expressed later in development. Temporally dynamic expression of TH-degrading and -activating proteins supports a model in which the retina itself controls TH levels, ensuring low TH signaling early to specify S cones and high TH signaling later in development to produce L/M cones.

CONCLUSION:

Studies of model organisms and human epidemiology often generate hypotheses about human biology that cannot be studied in humans. Organoids provide a system to determine the mechanisms of human development, enabling direct testing of hypotheses in developing human tissue. Our studies identify temporal regulation of TH signaling as a mechanism that controls cone subtype specification in humans. Consistent with our findings, preterm human infants with low T3 and T4 have an increased incidence of color vision defects. Moreover, our identification of a mechanism that generates one cone subtype while suppressing the other, coupled with successful transplantation and incorporation of stem cell-derived photoreceptors in mice, suggests that the promise of therapies to treat human diseases such as color blindness, retinitis pigmentosa, and macular degeneration will be achieved in the near future. ■

The mechanisms underlying specification of neuronal subtypes within the human nervous system are largely unknown. The blue (S), green (M), and red (L) cones of the retina enable high-acuity daytime and color vision. To determine the mechanism that controls S versus L/M fates, we studied the differentiation of human retinal organoids. Organoids and retinas have similar distributions, expression profiles, and morphologies of cone subtypes. S cones are specified first, followed by L/M cones, and thyroid hormone signaling controls this temporal switch. Dynamic expression of thyroid hormone–degrading and –activating proteins within the retina ensures low signaling early to specify S cones and high signaling late to produce L/M cones. This work establishes organoids as a model for determining mechanisms of human development with promising utility for therapeutics and vision repair.