Retinopathy of prematurity and the peripheral retina

Comparison of different agents and doses of anti-vascular endothelial growth factors (aflibercept, bevacizumab, conbercept, ranibizumab) versus laser for retinopathy of prematurity: A network meta-analysis

Laser photocoagulation (LPC) and/or intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections constitute the current standard treatment for retinopathy of prematurity (ROP). This network meta-analysis focus on whether a ranking of interventions may be established for different dose levels of intravitreal injection of anti-VEGF agents (aflibercept, bevacizumab, conbercept, ranibizumab) as primary treatments for ROP versus laser in terms of retreatment rate as primary outcome, and time to retreatment and refractive error as secondary endpoints, since best anti-VEGF dosage remains under debate. Sixty-eight studies (15 randomized control trials and 53 nonrandomized studies) of 12,356 eyes of 6445 infants were retrieved from databases (2005 Jan. - 2023 June). Studies were evaluated for model fit, risk of bias and confidence of evidence in Network Meta-Analysis (CINeMA). Bayesian NMA showed that anti-VEGF drugs were not inferior to laser in terms of retreatment rate. For intravitreal bevacizumab (IVB), doses half of the conventional infant dose showed a low risk of retreatment rate (risk ratio (RR) of 1.43; 95% credible interval (CrI): 0.508, 4.03). On probability ranking as surface under the cumulative ranking curve (SUCRA) plot, half dose of bevacizumab had a better position than conventional and augmented (1.2-2 times the regular dose) doses. A similar probability trend was observed for half vs. conventional doses of aflibercept and ranibizumab. Conventional infant dose of conbercept showed the lowest risk for retreatment (RR 0.846; 95% CrI: 0.245, 2.91). For secondary endpoints, lower doses of anti-VEGF agents were associated with shorter times to retreatment. The largest changes were noted for the augmented doses of bevacizumab and ranibizumab (0.3 mg) with means of 14.1 weeks (95% CrI: 6.65, 21.6) and 12.8 weeks (95% CrI: 3.19, 20.9), respectively. Finally, NMA demonstrated better refractive profile for anti-VEGF than laser therapy, especially for the conventional infant doses of bevacizumab and ranibizumab which exhibited a significantly better refractive profile than LPC, with mean differences of 1.67 (spherical equivalent - diopters) (95% CrI: 0.705, 2.67) and 2.19 (95% CrI: 0.782, 3.59), respectively. In the SUCRA plots, LPC had a markedly different position with a higher probability for myopia. Further clinical trials comparing different intravitreal doses of anti-VEGF agents are needed, but our findings suggest that low doses of these drugs retain efficacy and may reduce ocular and systemic undesired events.

[Electrophysiological characteristics of the retina in children with cicatrical retinopathy of prematurity]

Visual impairment in children with regressive retinopathy of prematurity (ROP) are diverse and widespread.

PURPOSE

to describe the electrophysiological characteristics of the retina in children with I-V stages of regressive ROP.

MATERIAL AND METHODS

The study included children with stages I-V aged 5 to 17 (in the disease stages of IV and V - with reattachment of the retina after surgical treatment of its detachment). Patients with concomitant diseases of the eye were excluded from the study. The main group included 133 children (163 eyes) aged 5 to 17 (mean age 7.2±0.3). Gestation age was 30.0±0.2 weeks, birth weight - 1368.0±46.6g. The control group consisted of 55 age-matched children. Standard electroretinogram (ERG) was performed in all study subjects. The amplitude-time characteristics of maximum and photopic response a- and b-waves were evaluated, and the b/a-index was calculated.

RESULTS

Visual acuity of 0.6 or higher was observed in 18 eyes (54.5%) of children with stage I-II ROP and significantly less in the disease stages of III and IVa - 29.5% and 15.6% respectively (p<0.01: Φ=2,717-3,663). In patients with IVb-V stages in 94.1% of cases visual acuity was lower than 0.1. Anamnesis showed significant decrease in photopic ERG starting with active period of stage III ROP. The retinal function further progressively decreased with stages. b/a index of maximum ERG increased proportionally to the severity of ROP active period. Core b/a index was significantly reduced in all stages of ROP (p<0.05).

CONCLUSION

Even the early stages of ROP have consequences for the functional status of the retina in premature infants; it is accompanied by significant disturbance of its electrogenesis.

A frequency-tagging electrophysiological method to identify central and peripheral visual field deficits

BACKGROUND

The aim of this study was to develop a fast and efficient electrophysiological protocol to examine the visual field's integrity, which would be useful in pediatric testing.

METHODS

Steady-state visual-evoked potentials (ssVEPs) to field-specific radial checkerboards flickering at two cycle frequencies (7.5 and 6 Hz for central and peripheral stimulations, respectively) recorded at Oz were collected from 22 participants from 5 to 34 years old and from 5 visually impaired adolescents (12-16 years old). Responses from additional leads (POz, O1, O2), and the impact of gaze deviation on the signals, were also investigated in a subgroup of participants.

RESULTS

Steady-state visual-evoked potentials responses were similar at all electrode sites, although the signal from the central stimulation was significantly higher at Oz and was highly sensitive in detecting gaze deviation. No effect of age or sex was found, indicating similar ssVEP responses between adults and healthy children. Visual acuity was related to the central signal when comparing healthy participants with four central visual impaired adolescents. Clinical validation of our electrophysiological protocol was also achieved in a 15-year-old adolescent with a severe peripheral visual deficit, as assessed with Goldmann perimetry.

CONCLUSIONS

A single electrode over Oz is sufficient to gather both central and peripheral visual signals and also to control for gaze deviation. Our method presents several advantages in evaluating visual fields integrity, as it is fast, reliable, and efficient, and applicable in children as young as 5 years old. However, a larger sample of healthy children should be tested to establish clinical norms.

Retinal protective effects of resveratrol via modulation of nitric oxide synthase on oxygen-induced retinopathy

Purpose

Retinopathy of prematurity (ROP) is one of the leading causes of blindness, with retinal detachment occurring due to oxygen toxicity in preterm infants. Recently, advances in neonatal care have led to improved survival rates for preterm infants, and ROP has increased in incidence. In the present study, we aimed to determine whether or not resveratrol exhibits protective effects in an animal model of ROP and in primary retinal cell cultures of neonatal rat via nitric oxide (NO)-modulating actions using western blotting and real-time PCR with inducible nitric oxide synthase (iNOS), endothelial NOS (eNOS) and neuronal NOS (nNOS) antibodies and mRNAs.

Methods

In an in vivo oxygen-induced retinopathy (OIR) model, cyclic hyperoxia was induced with 80% O₂ for one day and 21% O₂ for one day from P1 to P14 in newborn Sprague-Dawley (SD) rats. Resveratrol was injected intravitreally for seven days and rats were sacrificed at P21. In vitro OIR primary retinal cell culture was performed using P0-2 SD rats. Hyperoxia injuries were induced through 100% O₂ exposure for six hours. Western blotting and real-time PCR using iNOS, eNOS, nNOS antibodies and primers were performed in the rat model of ROP and the dispersed retinal cell culture.

Results

In both in vivo and in vitro OIR, the expression of iNOS antibody and mRNA was increased and of eNOS and nNOS were reduced in the resveratrol-treated group.

Conclusions

In conclusion, resveratrol appeared to exert retinal protective effects via modulation of NO-mediated mechanism in in vivo and in vitro OIR models.