The etiological factors and pathogenesis of retinopathy of prematurity (ROP) are still unclear,which restricted its effective prevention and treatment.The current animal model widely used in ROP investigation is oxygen-induced retinopathy model,which is lack of specificity,and does not mimic the real pathogenesis status of human ROP patients.Thus,we should refresh our concept,seek breakthroughs in multi-disciplines,integrate more risk factors of ROP,utilize the rising technique in transgenic animal,and improve the evaluation system for improving the current models or explore new animal models of ROP.It is important for prevention and treatment of ROP.

Objective:To observe the effects of SARS-CoV-2 infection on the morphology, proliferation, apoptosis, cell cycle, and immune response function of mouse retinal photoreceptor cells (661w cells).Methods:A cell experiment. Logarithmic growth phase 661w cells were cultured in vitro and transfected with angiotensin-converting enzyme 2 (ACE2) overexpressing lentivirus to construct ACE2 overexpressing 661w cells that could be infected with SARS-CoV-2 pseudovirus (hereafter referred to as 'pseudovirus’). The 661w cells were divided into three groups: the normal group (untreated), the siACE2 group (overexpressing ACE2 and not infected with the pseudovirus) and the infected group (overexpressing ACE2 and infected with the pseudovirus), in which the infected group was 5 TU/ml pseudovirus group, 15 TU/ml pseudovirus group, 30 TU/ml pseudovirus group and 50 TU/ml pseudovirus group, and the cells were infected with the pseudovirus for 12, 24, 48 and 72 h, respectively. The infected group was infected with 5 TU/ml pseudovirus group, 15 TU/ml pseudovirus group, 30 TU/ml pseudovirus group and 50 TU/ml pseudovirus group, respectively, for 12, 24, 48 and 72 h. Fluorescence microscopy was used to observe the transfection efficiency of ACE2; protein immunoblotting (Western blot) was used to detect the relative expression level of ACE2 in the cells; light microscope was used to observe the morphology of the cells in the normal and the infected groups; cell proliferation was detected by Cell Counting Kit-8 (CCK8) assay; flow cytometry was used to detect the cell cycle; Western blot and real-time quantitative polymerase chain reaction (qPCR) were used to detect the relative expression of interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α), B lymphocytoma-2 (Bcl-2), Bcl-2-associated X-protein (Bax) proteins and mRNA in the cells of siACE2 group, infected group (30 TU/ml pseudovirus group); qPCR was used to detect the relative expression of nuclear factor ( NF)- κB1 and NF-κB2, as well as NF- kB enhancer ( P65) and precursor protein ( P100) in cells of the siACE2 group and the infected group (30 TU/ml pseudovirus group). One-way ANOVA was used for comparison between multiple groups; t-test was used for comparison between two groups. Results:Compared with the siACE2 group, the cells in the infected group showed different degrees of crumpling, and with the increase of the concentration and time of pseudovirus induction, the crumpling of the cells worsened, and the number of cells decreased. Compared with the normal group, the cells in the infected group showed a gradual decrease in cell viability with the prolongation of pseudovirus induction time, and the difference was no statistically significant ( F=0.840, 0.412, 1.498, 1.138; P>0.05), and the apoptotic index of the cells induced in the 30 and 50 TU/ml pseudovirus group was significantly elevated, and the difference was statistically significant ( F=2.523, 6.716, 3.477, 3.421; P<0.05). At 72 h of pseudovirus induction, compared with the siACE2 group, the G1 phase cells in the 30 TU/ml pseudovirus group were significantly increased, and the difference was statistically significant ( t=3.812, P<0.05); the relative expression of IL-6, TNF-α, Bax protein and mRNA in the cells was up-regulated ( t=7.601, 6.039, 3.088, 5.193, 6.427, 7.667; P<0.05), the relative expression of Bcl-2 protein and mRNA was down-regulated ( t=3.614, 6.777; P<0.05), and the relative expression of NF-κB1, NF-κB2, P65, and P100 mRNA was significantly up-regulated with statistically significant differences ( t=3.550, 3.074, 3.307, 4.218; P<0.05). Conclusion:SARS-CoV-2 infection may inhibit photoreceptor cell proliferation, promote apoptosis and cycle blockade by activating the NF-κB signalling pathway.

AIM: To explore the neuro-ophthalmological characteristics of acute macular neuroretinopathy(AMN)after SARS-CoV-2 infection.METHODS: A total of 8 patients(14 eyes), including 6 females and 2 males, who were diagnosed with AMN in the neuro-ophthalmology department of Xi'an No.1 Hospital(The First Affiliated Hospital of Northwest University)from December 27, 2022 to February 1, 2023 were included in the study. All patients had a history of SARS-CoV-2 infection before the disease, and the results of best corrected visual acuity(BCVA), non-contact indirect intraocular pressure measurement, fundus color photography, near infrared(IR), spectral-domain optical coherence tomography(SD-OCT), OCT angiography(OCTA), fundus fluorescein angiography(FFA), indocyanine green angiography(ICGA), visual field, visual evoked potential(VEP), and electroretinogram(ERG)were collected. Furthermore, the neuro-opthalmology characteristics of the included patients were analyzed and summarized.RESULTS: The included 8 patients aged from 20 to 43, with an average age of(30±6.63)years old. The patients had a history of SARS-CoV-2 infection 3 to 11(mean 5±3.51)d before the disease, and 6 out of 8 patients developed visual symptoms within 5 d of infection with SARS-CoV-2, with manifestated with decreased vision or visual scotoma. The visual acuity varied from 0.08 to 1.0, with visual field defect characterized by central, paracentral or peripheral scotoma. VEP showed prolongation latency of P100 or P2, and ERG revealed impaired function of retinal photoreceptor cell. In the early stage of the disease, the size and shape of early visual acuity, visual field, and extraretinal lesions in patients with AMN associated with SARS-CoV-2 infection may not match, and the lower the visual acuity, the later the VEP peaks.CONCLUSION: The neuro-ophthalmic features of SARS-CoV-2 infection-associated AMN require the attention of clinicians. In addition to multi-mode fundus imaging, clinicians should use a variety of methods to comprehensively evaluate visual function and prognosis of patients.