Hot Topics in Retinopathy of Prematurity

Global Disparities in Retinopathy of Prematurity: A Literature Review

PURPOSE

To provide an overview of the impact of retinopathy of prematurity (ROP), and the challenges in the screening, diagnosis, and treatment of ROP worldwide.

METHODS

A comprehensive search was conducted using the PubMed database from January 2011 to October 2021 using the following keywords: retinopathy of prematurity, laser, and anti-vascular endothelial growth factor (VEGF). Data on patient characteristics, ROP treatment type, and recurrence rates were collected. The countries included in these studies were classified based on 2021-2022 World Bank definitions of high, upper-middle, lower-middle, and low-income groups. Moreover, a search for surgical outcomes for ROP and screening algorithms and artificial intelligence for ROP was conducted.

RESULTS

Thirty-nine studies met the inclusion criteria. ROP treatment and outcomes showed a trend towards intravitreal anti-VEGF injections as the initial treatment for ROP globally and the treatment of recurrent ROP in high-income countries. However, laser remains the treatment of choice for ROP recurrence in middle-income countries. Surgical outcomes for ROP stage 4A, 4B and 5 are similar worldwide. The incidence of ROP and ROP-related visual impairment continue to increase globally. Although telemedicine and artificial intelligence offer potential solutions to ROP screening in resource-limited areas, the current models require further optimization to reflect the global diversity of ROP patients.

CONCLUSION

ROP screening and treatment paradigms vary widely based on country income group due to disparities in resources, limited access to care, and lack of universal guidelines.

Nucleoredoxin Plays a Key Role in the Maintenance of Retinal Pigmented Epithelium Differentiation

Nucleoredoxin (Nrx) belongs to the Thioredoxin protein family and functions in redox-mediated signal transduction. It contains the dithiol active site motif Cys-Pro-Pro-Cys and interacts and regulates different proteins in distinct cellular pathways. Nrx was shown to be catalytically active in the insulin assay and recent findings indicate that Nrx functions, in fact, as oxidase. Here, we have analyzed Nrx in the mammalian retina exposed to (perinatal) hypoxia-ischemia/reoxygenation, combining ex vivo and in vitro models. Our data show that Nrx regulates cell differentiation, which is important to (i) increase the number of glial cells and (ii) replenish neurons that are lost following the hypoxic insult. Nrx is essential to maintain cell morphology. These regulatory changes are related to VEGF but do not seem to be linked to the Wnt/β-catenin pathway, which is not affected by Nrx knock-down. In conclusion, our results strongly suggest that hypoxia-ischemia could lead to alterations in the organization of the retina, related to changes in RPE cell differentiation. Nrx may play an essential role in the maintenance of the RPE cell differentiation state via the regulation of VEGF release.

Thioredoxin 1 Plays a Protective Role in Retinas Exposed to Perinatal Hypoxia-Ischemia

Thioredoxin family proteins are key modulators of cellular redox regulation and have been linked to several physiological functions, including the cellular response to hypoxia-ischemia. During perinatal hypoxia-ischemia (PHI), the central nervous system is subjected to a fast decrease in O₂ and nutrients with a subsequent reoxygenation that ultimately leads to the production of reactive species impairing physiological redox signaling. Particularly, the retina is one of the most affected tissues, due to its high oxygen consumption and exposure to light. One of the main consequences of PHI is retinopathy of prematurity, comprising changes in retinal neural and vascular development, with further compensatory mechanisms that can ultimately lead to retinal detachment and blindness. In this study, we have analyzed long-term changes that occur in the retina using two well established in vivo rat PHI models (perinatal asphyxia and carotid ligation model), as well as the ARPE-19 cell line that was exposed to hypoxia and reoxygenation. We observed significant changes in the protein levels of the cytosolic oxidoreductase thioredoxin 1 (Trx1) in both animal models and a cell model. Knock-down of Trx1 in ARPE-19 cells affected cell morphology, proliferation and the levels of specific differentiation markers. Administration of recombinant Trx1 decreased astrogliosis and improved delayed neurodevelopment in animals exposed to PHI. Taken together, our results suggest therapeutical implications for Trx1 in retinal damage induced by hypoxia-ischemia during birth.

Refractive Outcomes of 4-Year-old Children after Intravitreal Anti-vascular Endothelial Growth Factor versus Laser Photocoagulation for Retinopathy of Prematurity

Purpose

To compare long-term refractive outcomes associated with intravitreal anti-vascular endothelial growth factor (VEGF) versus laser photocoagulation treatment for retinopathy of prematurity (ROP).

Methods

A total of 52 eyes from 27 ROP patients treated at two tertiary referral-based hospitals from August 2006 to December 2013 were reviewed. The primary outcome was refractive error measured at the age of 4 years, accounting for within-patient inter-eye correlation. Secondary outcomes included the recurrence rate and treatment complications.

Results

The mean age at refraction was 4.7 ± 0.3 years in the laser group (n = 30) and 4.4 ± 0.3 years in the anti-VEGF group (n = 22). No significant differences were noted in gestational age, birthweight, post-menstrual age at treatment, or ROP stage/zone distribution between groups. Mean spherical equivalent was also not significantly different (−1.0 diopters in the laser group and −0.3 diopters in the injection group, p = 0.603). Clustered regression analysis revealed that only gestational age was significantly correlated with mean spherical equivalent (p < 0.001; 95% confidence interval, −0.007 to −0.002). Recurrence was noted in four eyes (13.3%) in the laser group, but this difference was not significant (p = 0.128). There were no major systemic complications reported in either group.

Conclusions

Treatment type, whether laser or anti-VEGF injection, does not appear to influence long-term refractive outcomes in ROP. Concern regarding refractive outcomes should not be the most important factor when selecting ROP treatment modality.

Intravitreal ranibizumab versus laser photocoagulation for retinopathy of prematurity: efficacy, anatomical outcomes and safety

Background/Aims

To compare the efficacy, anatomical outcomes and complications of intravitreal ranibizumab with those of laser photocoagulation for retinopathy of prematurity (ROP).

Methods

This is a retrospective case series of 314 eyes from 165 infants diagnosed with type I ROP and treated with either laser photocoagulation (161 eyes) or intravitreal ranibizumab (0.25 mg/0.025 mL) injection (153 eyes) between January 2006 and December 2016 in a tertiary referral-based hospital. The main outcome was the rate of recurrence requiring additional treatment. Secondary outcomes included the incidence of major complications and final refractive error.

Results

The mean follow-up was 36.3±31.9 months. Recurrences requiring further intervention were noted in 22 (13.7%) laser-treated and 15 (9.8%) ranibizumab-treated eyes (p=0.196). Retinal detachment (8 vs 1, p=0.037) and macular dragging (7 vs 1, p=0.039) were observed in the laser-treated and injection-treated groups, respectively, but no systemic or neurodevelopmental adverse events were reported. In the ranibizumab group, 95.6% showed fully vascularised retinas. Multivariate analyses revealed that birth weight (OR 0.993, p=0.023) and higher ROP stage (OR 11.222, p=0.008) influenced the incidence of major complications.

Conclusion

Intravitreal ranibizumab for ROP appears to achieve similar therapeutic effects than did laser photocoagulation, but with fewer surgical complications such as retinal detachment or macular dragging.

Anti-vascular Endothelial Growth Factor Treatment of Retinopathy of Prematurity: Efficacy, Safety, and Anatomical Outcomes

PURPOSE

To investigate the efficacy, safety, and anatomical outcomes associated with intravitreal anti-vascular endothelial growth factor (VEGF) treatment of retinopathy of prematurity (ROP).

METHODS

We performed a retrospective review of intravitreal anti-VEGF (bevacizumab or ranibizumab) treatment of 153 eyes (83 infants) diagnosed with ROP at two tertiary hospitals from June 2011 to January 2017. The primary outcome was the rate of recurrence requiring additional treatment; secondary outcomes included incidence of major complications and final refractive error.

RESULTS

A total of 101 eyes were treated with bevacizumab, and 52 with ranibizumab. The bevacizumab and ranibizumab groups were characterized by mean birthweights of 941.8 ± 296.1 and 1,257.7 ± 514.5 g, gestational ages at birth of 26.9 ± 1.9 and 28.1 ± 3.2 weeks, and postmenstrual ages at treatment of 40.4 ± 2.4 and 39.2 ± 2.3 weeks, respectively. The two groups differed significantly in birthweights and gestational ages at birth, but not in postmenstrual ages at treatment. The mean follow-up duration was 30.9 ± 18.4 months for the bevacizumab group, and 13.9 ± 12.5 months for ranibizumab. More cases were classified as zone 1 ROP in the ranibizumab group (44.2% vs. 11.9%, p < 0.001). Major surgical interventions included scleral encircling and vitrectomy (one and two eyes, respectively, both in the bevacizumab group). Retinal detachment was noted in one eye treated with bevacizumab. There was no significant difference in the most recent spherical equivalence for the two groups (+0.10 ± 3.66 and +0.22 ± 3.00 diopters for bevacizumab and ranibizumab, respectively). Univariable analysis revealed that only ROP stage influenced the occurrence of major complications (odds ratio, 9.046; p = 0.012).

CONCLUSIONS

Intravitreal anti-VEGF treatment of ROP with both bevacizumab and ranibizumab achieved stable retinal vascularization with a low rate of complications and recurrence. Ranibizumab achieved similar anatomical outcomes as bevacizumab, without additional risk for major complications.