[Are there predictors for proliferative retinopathy of prematurity and is supplemental oxygen a useful conservative treatment option?]

Global Prevalence and Severity of Retinopathy of Prematurity over the Last Four Decades (1985-2021): A Systematic Review and Meta-Analysis

BACKGROUND

Retinopathy of prematurity (ROP) is a vasoproliferative disease of the retina that occurs in premature infants. The prevalence of ROP reported so far is inconsistent.

AIM

To conduct a systematic review to describe the trend of ROP prevalence between 1985 and 2021, and to determine the influence of countries' economic conditions on ROP prevalence.

METHODS

We searched PubMed, Embase, and Google Scholar for studies published between January 1985 and December 2021 using the following MeSH terms: "retinopathy of prematurity", "ROP", "incidence", and "prevalence". Two independent reviewers examined the articles to select studies that met the selection criteria and performed data extraction and study quality assessment. For the meta-analysis, the pooled prevalence was calculated using a random-effects model and R software.

RESULTS

Of 5,250 titles and abstracts, 139 original studies met the inclusion criteria; a total of 121,618 premature infants were included in these studies. The pooled prevalence of ROP was 31.9% (95% confidence interval [CI] 29.0-34.8) and that of severe ROP was 7.5% (6.5-8.7). In general, no significant differences in prevalence were found over the four decades; however, we found a higher prevalence in premature infants ≤28 weeks of gestational age. In addition, the highest ROP prevalence was found in lower-middle-income countries with high mortality rates. In contrast, the highest severe ROP prevalence was found in high-income countries.

CONCLUSION

ROP remains a common cause of morbidity in premature infants worldwide. Therefore, it seems necessary to maintain early identification strategies for patients at higher risk, particularly in low- and middle-income countries.

Gamma-Secretase Inhibitor, DAPT, Prevents the Development of Retinopathy of Prematurity in a Rat Model by Regulating the Delta-Like Ligand 4/Notch Homolog-1 (DLL4/Notch-1) Pathway

Background

Retinopathy of prematurity (ROP), or retrolental fibroplasia, affects premature infants who have undergone intensive care with oxygen therapy. This study aimed to investigate the inhibitory effect of the gamma-secretase inhibitor, DAPT, on neovascularization and its mechanism in a rat model of ROP.

Material/Methods

Sixty neonatal Sprague-Dawley (SD) rats included the control group (n=20), the model group (n=20), and the DAPT-treated group (n=20). The rat model of ROP was established using repeat cycles of oxygen inhalation. Enzyme-linked immunosorbent assay (ELISA) measured serum levels of vascular endothelial growth factor (VEGF), VEGF receptor-1 (VEGFR-1), and VEGFR-2. Histology of the retinal tissue included immunohistochemistry for the expression of Notch homolog-1 (Notch-1) and delta-like ligand 4 (DLL4). Retinal mRNA levels of DLL4, Notch-1, VEGF, VEGFR-1, and VEGFR-2 were evaluated with quantitative real-time polymerase chain reaction (qRT-PCR).

Results

The rat model of ROP showed increased serum levels of VEGF, VEGFR-1, and VEGFR-2 compared with the control group, which were decreased in the DAPT group. Histology of the retinal tissue in the model group showed degeneration of the retinal ganglion cells, and immunohistochemistry showed increased expression of Notch-1 and DLL4 compared with the control group and DAPT group. Retinal tissue in the model group had increased mRNA levels of DLL4, Notch-1, VEGF, VEGFR-1, and VEGFR-2 compared with the control group, and the DAPT group.

Conclusions

In a rat model, treatment with DAPT reduced the retinal changes associated with ROP with a mechanism that involved VEGF and its receptors through the DLL4/Notch-1 pathway.