Erythropoietin and retinopathy of prematurity

Amelioration of oxygen-induced retinopathy in neonatal mice with fetal growth restriction

Introduction: With the aim of optimizing the balance of maintaining a safe oxygen saturation and reducing the risk of retinopathy of prematurity in human neonates with fetal growth restriction (FGR), the present study investigated the distinct effects of oxygen supplementation on the retinal neovasculature using a murine premature neonatal oxygen-induced retinopathy (OIR) model with or without fetal growth restriction. Methods: For comparison with normal birth-weight neonates, maternal low-protein diet-induced FGR neonates were subjected to fluctuating oxygen levels to generate oxygen-induced retinopathy. The retinal neovasculature was histologically evaluated, and comprehensive transcriptome analysis was conducted. Results: Compared to OIR neonates with normal birth weight, significant amelioration of the neovasculature, as indicated by decreases in the number of branch junctions, vascular distribution, maximal vascular radius and microaneurysm-like tufts, was observed in OIR mice with FGR. The results of retinal RNA-sequencing revealed downregulation of angiogenic factors that trigger pathological retinal neovascularization, such as the mitogen-activated protein kinase pathway and corresponding upstream signaling pathways in OIR mice with FGR. Conclusion: Our findings demonstrated that FGR neonates have a higher capacity for retinal oxygen stress, and the risk of OIR development is attenuated compared to that in mature neonates with normal birth weight.

Risk factors in the development of retinopathy of prematurity: A 10-year retrospective study

OBJECTIVE

To evaluate Retinopathy of Prematurity (ROP) rate and risk factors in a large cohort of preterm newborns.

METHODS

Single center retrospective study. All preterm inborn hospitalized at the Neonatal Intensive Care Unit of the Policlinico of Catania from January 1, 2009 till December 31, 2018, were included. ROP stage and location, treatments required, maternal and infant risk factors were evaluated.

RESULTS

Medical records of 898 preterms were retrospectively examined (mean gestational age 32.9 ± 2.3 weeks). Of them 149 (16.6 %) developed bilateral ROP (92 stage 1, 44 stage 2 and 13 stage 3); 66 (7.3 %) received bilateral laser treatment. Six eyes of three patients affected by zone I ROP 1, with plus persistence 15 days after an optimal laser treatment, also received intravitreal ranibizumab injection. Risk factors for ROP development were gestational age (GA) (p < 0.001), birthweight (p < 0.001), assisted ventilation duration (p < 0.001), multiple birth (p = 0.003), erythropoietin (EPO) administration (p = 0.005) and persistence of tunica vasculosa lentis. The decision-tree analysis showed gestational age as the most significant predictive factor (P < 0.001); secondary predictive factors were EPO administration (p = 0.001) in newborns 29-31 weeks GA and birthweight lower than 2090 g (p < 0.001) in 32-34 weeks GA; in this latter group patent ductus arteriosus (PDA) was a tertiary predictive factor (p = 0.043).

CONCLUSIONS

In our study ROP incidence was 16,6 %; 7.3 % of the patients required laser treatment. Besides well-known factors, such as GA and birthweight, other factors like duration of assisted ventilation, EPO, multiple births, PDA, tunica vasculosa lentis persistence should be considered to tailor ophthalmic evaluation and follow-up.

Association of umbilical cord insulin-like growth factor 1 levels with severe retinopathy in extremely preterm infants

BACKGROUND

The association between umbilical cord blood insulin-like growth factor 1 (IGF-1) levels and retinopathy of prematurity (ROP) remains unclear. This study aimed to investigate whether umbilical cord blood IGF-1 levels can predict the development of severe ROP in extremely preterm infants.

METHODS

This hospital-based retrospective cohort study included infants born at <37 weeks gestational age (GA) between 2019 and 2021 and then classified them into the two GA groups: extremely preterm, <28 weeks and preterm infants, 28-36 weeks. Extremely preterm infants were further subclassified into two groups according to the laser treatment as follows: the severe ROP (ROP-Tx) and ROP (No ROP-Tx) groups. Median umbilical cord blood IGF-1 values were compared between the groups. Perinatal risk factors were identified by univariate and multivariate analyses. Finally, umbilical cord IGF-1 cut-off values requiring ROP treatment with laser were determined by receiver operating characteristic (ROC) curve analyses.

RESULTS

A total of 205 infants were enrolled, with 32 being extremely preterm (ROP-Tx: n = 11; No ROP-Tx: n = 21) and 173 being preterm. IGF-1 levels were significantly lower in extremely preterm (13.5 ng/mL) than preterm infants (36 ng/mL, p < 0.001). In extremely preterm infants, IGF-1 levels were significantly lower in the ROP-Tx group than the No ROP-Tx group (10 vs. 19 ng/mL, respectively, p = 0.024). Only GA, umbilical cord blood IGF-1 levels, birth head circumference, and birth chest circumference were identified as risk factors by univariate analysis (p < 0.05). Multivariate analysis showed that only umbilical cord blood IGF-1 was an independent risk factor (odds ratio: 1.26, p = 0.021). ROC curves revealed an IGF-1 cut-off value of 14 ng/mL.

CONCLUSION

The need of laser treatment for ROP was found to be associated with low umbilical cord blood IGF-1 levels in extremely preterm infants. Umbilical cord blood IGF-1 can be used as a biomarker for the risk of developing severe ROP.

Whether erythropoietin can be a neuroprotective agent against premature brain injury: cellular mechanisms and clinical efficacy

Preterm infants are at high risk of brain injury. With more understanding of the preterm brain injury's pathogenesis, neuroscientists are looking for more effective methods to prevent and treat it, among which erythropoietin (Epo) is considered as a prime candidate. This review tries to clarify the possible mechanisms of Epo in preterm neuroprotection and summarize updated evidence considering Epo as a pharmacological neuroprotective strategy in animal models and clinical trials. To date, various animal models have validated that Epo is an anti-apoptotic, anti-inflammatory, anti-oxidant, anti-excitotoxic, neurogenetic, erythropoietic, angiogenetic, and neurotrophic agent, thus preventing preterm brain injury. However, although the scientific rationale and preclinical data for Epo's neuroprotective effect are promising, when translated to bedside, the results vary in different studies, especially in its long-term efficacy. Based on existing evidence, it is still too early to recommend Epo as the standard treatment for preterm brain injury.

Concurrent Physiological and Pathological Angiogenesis in Retinopathy of Prematurity and Emerging Therapies

Retinopathy of prematurity (ROP) is an ocular vascular disease affecting premature infants, characterized by pathological retinal neovascularization (RNV), dilated and tortuous retinal blood vessels, and retinal or vitreous hemorrhages that may lead to retinal detachment, vision impairment and blindness. Compared with other neovascular diseases, ROP is unique because of ongoing and concurrent physiological and pathological angiogenesis in the developing retina. While the disease is currently treated by laser or cryotherapy, anti-vascular endothelial growth factor (VEGF) agents have been extensively investigated but are not approved in the U.S. because of safety concerns that they negatively interfere with physiological angiogenesis of the developing retina. An ideal therapeutic strategy would selectively inhibit pathological but not physiological angiogenesis. Our group recently described a novel strategy that selectively and safely alleviates pathological RNV in animal models of ROP by targeting secretogranin III (Scg3), a disease-restricted angiogenic factor. The preclinical profile of anti-Scg3 therapy presents a high potential for next-generation disease-targeted anti-angiogenic therapy for the ROP indication. This review focuses on retinal vessel development in neonates, the pathogenesis of ROP and its underlying molecular mechanisms, including different animal models, and provides a summary of current and emerging therapies.

Alteration of erythrocyte membrane polyunsaturated fatty acids in preterm newborns with retinopathy of prematurity

Extremely preterm infants are at high risk for retinopathy of prematurity (ROP), a potentially blinding disease characterized by abnormalities in retinal vascularization. Whereas animal studies revealed that n-3 polyunsaturated fatty acids (PUFAs) may be of benefit in preventing ROP, human studies conducted on preterm infants during the 1^st weeks of life showed no association between blood n-3 PUFA bioavailability and ROP incidence and/or severity, probably because of the influence of nutrition on the lipid status of infants. In the OmegaROP prospective cohort study, we characterized the erythrocyte concentrations of PUFAs in preterm infants aged less than 29 weeks gestational age (GA) without any nutritional influence. We show that GA is positively associated with the erythrocyte n-6 to n-3 PUFA ratio, and particularly with the ratio of arachidonic acid (AA) to docosahexaenoic acid (DHA), in infants with ROP. A time-dependent accumulation of AA at the expense of DHA seems to occur in utero in erythrocytes of preterm infants who will develop ROP, thus reinforcing previous data on the beneficial properties of DHA on this disease. In addition, preliminary data on maternal erythrocyte membrane lipid concentrations suggest modifications in placental transfer of fatty acids. Documenting the erythrocyte AA to DHA ratio at birth in larger cohorts might be useful to set up new prognostic factors for ROP.

Intravitreal Delivery of VEGF-A165-loaded PLGA Microparticles Reduces Retinal Vaso-Obliteration in an In Vivo Mouse Model of Retinopathy of Prematurity

PURPOSE

Retinopathy of prematurity (ROP) is a condition of abnormal retinal vascularization with reduced levels of vascular endothelial growth factor (VEGF) causing vaso-obliteration (Phase I), followed by abnormal neovascularization from increased VEGF (Phase II). We hypothesized that intravitreal pro-angiogenic VEGF-A in microparticle form would promote earlier retinal revascularization in an oxygen-induced ischemic retinopathy (OIR) mouse model.

MATERIALS AND METHODS

Wildtype mice (39) were exposed to 77% oxygen from postnatal day 7 (P7) to P12. VEGF-A₁₆₅-loaded poly(lactic-co-glycolic acid) (PLGA) (n = 15) or empty PLGA (n = 14) microparticles were fabricated using a water-in-oil-in-water double emulsion method, and injected intravitreally at P13 into mice right eyes (RE). Left eyes (LE) were untreated. At P20, after retinal fluorescein angiography, vascular parameters were quantified. Retinal VEGF levels at P13 and flatmounts at P20 were performed separately.

RESULTS

VEGF-A₁₆₅-loaded microparticles had a mean diameter of 4.2 μm. with a loading level of 8.6 weight.%. Retinal avascular area was reduced in VEGF-treated RE (39.5 ± 9.0%) compared to untreated LE (52.6 ± 6.1%, p < 0.0001) or empty microparticle-treated RE (p < 0.001) and untreated LEs (p = 0.001). Retinal arteries in VEGF-treated RE were less tortuous than untreated LE (1.08 ± 0.05 vs. 1.18 ± 0.08, p < 0.001) or empty-microparticles-treated RE (p = 0.02). Retinal arterial tortuosity was similar in the LE of VEGF and empty microparticle-treated mice (P > 0.05). Retinal vein width was similar in VEGF-treated and empty microparticle-treated RE (P > 0.9), which were each less dilated than their contralateral LE (p < 0.01). VEGF levels were higher in P13 OIR mice than RA mice (p < 0.0001). Retinal flatmounts showed vaso-obliteration and neovascularization.

CONCLUSIONS

Endogenous retinal VEGF is suppressed in OIR mice. Exogenous intravitreal VEGF-A₁₆₅-loaded microparticles in OIR mice reduced retinal vaso-obliteration and accelerated recovery from vein dilation and arterial tortuosity. This may be beneficial in preventing Phase II ROP without systemic effects.

Exogenous erythropoietin aggravates retinal neovascularizationin a murine model of proliferative retinopathy

Background/aim: Erythropoietin (EPO) has been proven recently to be a critical mediator in retinal neovascularization (RNV). Previous studies have indicated that the use of recombinant human EPO (rEPO) is a high risk factor in the development of retinopathy of prematurity. In this study, we aimed to investigate the effect of rEPO administration on RNV and its underlying mechanism in a mouse model of oxygen-induced retinopathy (OIR). Materials and methods: A murine model of OIR was used to generate RNV. After daily intraperitoneal injection of rEPO from postnatal day 12 (P12), mice were euthanized at P17. Whole-mount retina staining was used to indicate the nonperfused area and neovascularization tufts. Preretinal neovascular cells were calculated through hematoxylin and eosin staining. The expression levels of vascular endothelial growth factor (VEGF) and inducible nitric oxide synthase (iNOS) were detected via western blot analysis. Results: We found that injection of rEPO promoted the severity of RNV. The areas of neovascular tufts and preretinal neovascular cells were increased after administration of rEPO. When mice were injected with rEPO, a dose-dependent upregulation in VEGF and iNOS was observed. Conclusion: The study indicates the proangiogenic role of EPO, suggesting that rEPO contributes to the pathogenesis of RNV.

"The effects of family-centered physiotherapy on the cognitive and motor performance in premature infants"

OBJECTIVE

The aim of this study is to investigate the effects of family centered physiotherapy according to the neurodevelopmental treatment (NDT) principles on mental and motor performance in premature infants.

METHODS

A total of 156 infant, ≥24/36 week+6days gestational age included in the study. All the infants were diagnosed by a child neurologist and referred to psychology and physiotherapy department for their neurodevelopmental assessment and treatment. Bayley Scale of Infant II (BSI-II) was used for neurodevelopmental assessment and Alberta Infant Motor Scale (AIMS) was used for assessing their motor performance. Seventy-eight of the infants were in the study group and 76 were recruited as age matched controls according to the classification of their gestational age. Family centered physiotherapy according to the neurodevelopmental treatment principles was used as an intervention and all the mothers are trained accordingly.

RESULTS

Cognitive Development Scores and Motor Development Scores of Bayley II were recorded for the 3., 6., 9., and 12 months respectively. Between the 3. and 12. month of gestational age, within-groups measurements in both Cognitive Development Scores (p<0.001) and Motor Development Scores (p<0.001) were significantly increased. However, the improvements in both Cognitive Development Scores (p=0.059) and Motor Development Scores (p=0.334) between the groups was not different.

CONCLUSION

Family centered physiotherapy with NDT principles may not be enough to improve motor and cognitive performance in preterm infants at the first year of age. For supporting the motor and cognitive development of the preterm infants other intervention modalities also should be considered.

Revisiting the role of erythropoietin for treatment of ocular disorders

Erythropoietin (EPO) is a glycoprotein hormone conventionally thought to be responsible only in producing red blood cells in our body. However, with the discovery of the presence of EPO and EPO receptors in the retinal layers, the EPO seems to have physiological roles in the eye. In this review, we revisit the role of EPO in the eye. We look into the biological role of EPO in the development of the eye and the physiologic roles that it has. Apart from that, we seek to understand the mechanisms and pathways of EPO that contributes to the therapeutic and pathological conditions of the various ocular disorders such as diabetic retinopathy, retinopathy of prematurity, glaucoma, age-related macular degeneration, optic neuritis, and retinal detachment. With these understandings, we discuss the clinical applications of EPO for treatment of ocular disorders, modes of administration, EPO formulations, current clinical trials, and its future directions.

Pharmacologic interventions for the prevention and treatment of retinopathy of prematurity

Retinopathy of prematurity (ROP), a significant morbidity in prematurely born infants, is the most common cause of visual impairment and blindness in children and persists till adulthood. Strict control of oxygen therapy and prevention of intermittent hypoxia are the keys in the prevention of ROP, but pharmacologic interventions have decreased risk of ROP. Various drug classes such as methylxanthines (caffeine), VEGF inhibitors, antioxidants, and others have decreased ROP occurrence. The timing of pharmacologic intervention remains unsettled, but early prevention rather than controlling disease progression may be preferred. These drugs act through different mechanisms, and synergistic approaches should be considered to maximize efficacy and safety.

Erythropoietin promotes retinal angiogenesis in a mouse model

This study aimed to investigate the effect and potential mechanisms of exogenous administration of recombinant human erythropoietin (rhEPO) on retinal angiogenesis in a mouse model of oxygen-induced retinopathy (OIR). Postnatal day 7 (P7) mice (n=132) were randomly assigned to one of six groups: Control group (n=22), OIR group (n=22), OIR + vehicle control group (n=22), OIR + rhEPO 10 IU group (n=22), OIR + rhEPO 50 IU group (n=22), and OIR + rhEPO 100 IU group (n=22). OIR was induced by exposing mice to 75±2% O2 for five days, followed by exposure to room air for a further five days. Animals in groups 3-6 (the OIR + vehicle control group and OIR + rhEPO 10 IU, 50 IU, and 100 IU groups) received an intraperitoneal injection of saline, or rhEPO 10 IU, 50 IU and 100 IU, respectively, which were administered daily from P7-P12. Immunofluorescent and hematoxylin-eosin staining were used to detect retinal neovascularization (RNV) in retinal whole mounts. Quantitative polymerase chain reaction and western blot analysis were used to detect the expression levels of vascular endothelial growth factor (VEGF), endothelial nitric oxide synthase (eNOS), and neuronal nitric oxide synthase (nNOS). RNV occurred in the OIR groups and was accompanied by dilated, twisted and occluded blood vessels. rhEPO treatment resulted in an increase in the number of newly formed and severely dilated vessels. rhEPO increased RNV in a dose-dependent manner, which was accompanied by an increase in the messenger RNA and protein expression of VEGF, eNOS and nNOS. Thus, exogenous use of rhEPO promotes the RNV in a mouse model of OIR and is accompanied by increased expression levels of VEGF, eNOS and nNOS.

Use of erythropoietin is associated with threshold retinopathy of prematurity (ROP) in preterm ELBW neonates: a retrospective, cohort study from two large tertiary NICUs in Italy

BACKGROUND

Retinopathy of prematurity (ROP) is a multifactorial disease with evidence of many associated risk factors. Erythropoietin has been reported to be associated with this disorder in a murine model, as well as in humans in some single-center reports. We reviewed the data from two large tertiary NICUs in Italy to test the hypothesis that the use of erythropoietin may be associated with the development of the most severe stages of ROP in extremely low birth weight (ELBW) neonates.

DESIGN/METHODS

Retrospective study by review of patient charts and eye examination index cards on infants with birth weight <1000g admitted to two large tertiary NICUs in Northern Italy (Sant'Anna Hospital NICU in Torino, and Ca' Foncello Hospital Neonatology in Treviso) in the years 2005 to 2007. Standard protocol of administration of EPO in the two NICUs consisted of 250 UI/kg three times a week for 6-week courses (4-week in 1001-1500g infants). Univariate analysis was performed to assess whether the use of EPO was associated with severe (threshold) ROP. A control, multivariate statistical analysis was performed by entering into a logistic regression model a number of neonatal and perinatal variables that - in univariate analysis - had been associated with threshold ROP.

RESULTS

During the study period, 211 ELBW infants were born at the two facilities and survived till discharge. Complete data were obtained for 197 of them. Threshold retinopathy of prematurity occurred in 26.9% (29 of 108) of ELBW infants who received erythropoietin therapy, as compared with 13.5% (12 of 89) of those who did not receive erythropoietin (OR 2.35; 95% CI 1.121-4.949; p=0.02 in univariate analysis, and p=0.04 at multivariate logistic regression after controlling for the following variables: birth weight, gestational age, days on supplemental oxygen, systemic fungal infection, vaginal delivery). Use of erythropoietin was not significantly associated with other major sequelae of prematurity (intraventricular hemorrhage, bronchopulmonary dysplasia, necrotizing enterocolitis). © 2014 Elsevier Ireland Ltd. All rights reserved.

CONCLUSIONS

Use of erythropoietin is an additional, independent predictor of threshold ROP in ELBW neonates. Larger prospective, population-based studies should further clarify the extent of this association.

Vitreous biomarkers in diabetic retinopathy: a systematic review and meta-analysis

The aim of this study was to perform a systematic meta-analysis of biomarkers investigated with diabetic retinopathy (DR) in the vitreous, and to explore the molecular pathway interactions of these markers found to be consistently associated with DR. Relevant databases [PubMed and ISI web of science] were searched for all published articles investigating molecular biomarkers of the vitreous associated with DR. Based on set exclusion/inclusion criteria available data from studies with human vitreous samples were extracted and used for our meta-analysis. The interactions of significant biomarkers in DR were investigated via STRING and KEGG pathway analysis. Our meta-analysis of DR identifies eleven biomarkers as potential therapeutic candidates alternate to current anti-VEGF therapy. Four of these are deemed viable therapeutic targets for PDR; ET receptors (ET A and ET B), anti-PDGF-BB, blocking TGF-β using cell therapy and PEDF. The identification of supplementary or synergistic therapeutic candidates to anti VEGF in the treatment of DR may aid in the development of future treatment trials.

The effect of erythropoietin on the severity of retinopathy of prematurity

AIMS

Exogenous human erythropoietin (EPO) artificially synthesised through recombinant DNA technology (rHuEPO) is currently used as a substitute for blood transfusion in preterm and low birth weight neonates. The objective of this study is to determine whether the use of rHuEPO is associated with an increased severity of retinopathy of prematurity (ROP) in preterm neonates.

METHOD

This retrospective review studies neonates who were admitted to a tertiary perinatal unit and screened for ROP during the 10-year period from January 2003 to December 2012.

RESULTS

: During the 10-year period, 688 preterm neonates underwent ROP screening, with 198 identified as having ROP. The incidence of stage 1 ROP was 51.5% (102/198), followed by 35.9% (71/198) for stage 2, and 12.6% (25/198) for stage 3 and greater. Plus disease was seen in 14 neonates (7.1%). Treatment (laser photocoagulation) was administered in 64% of neonates (16/25) with stage 3 of the disease and above because of progression to threshold ROP. Twenty-six (13%) of the neonates received rHuEPO treatment. There were no statistically significant differences in birth weight (910.4 vs 885 g; P=0.71), gestational age (26.5 vs 25.8 weeks; P=0.09), and duration of ventilation (512 vs 501.4 h; P=0.92) between neonates who did not receive rHuEPO compared with those who were treated with rHuEPO. Multivariate regression analysis showed that the use of EPO was associated with increased severity of ROP.

CONCLUSIONS

EPO therapy appears to increase the risk of development and worsening of ROP.

How to administrate erythropoietin, intravenous or subcutaneous?

AIM

To determine whether adding recombinant erythropoietin to the intravenous (IV) solution and administering it as a 24-h continuous infusion would result in an erythropoietic effect not inferior to that seen with subcutaneous (SC) administration.

METHODS

Infants weighing ≤1500 grams and ≤32 weeks of gestational age were randomly assigned at 72 h of life to receive erythropoietin (300 units/kg, 3 times a week until 36 complete weeks of postmenstrual age or discharge), either subcutaneously [erythropoietin subcutaneous (ESC) group] or added to IV fluids [erythropoietin intravenous (EIV) group].

RESULTS

One hundred infants were randomized (50 in the EIV group and 50 in the ESC group). The incidence of transfusions was comparable in the two groups, similar in baseline characteristics and haematologic values at study entry. Phlebotomy losses did not differ between groups, and at the end of the study, there were no differences in reticulocyte counts, transferrin saturation and ferritin. No differences in the incidence of side effects were observed.

CONCLUSIONS

In preterm infants, continuous intravenous administration of erythropoietin was not inferior to SC dosing.

Infantile hemangiomas and retinopathy of prematurity: clues to the regulation of vasculogenesis

Retinopathy of prematurity (ROP) and infantile hemangiomas are vascular disorders that may share common mechanisms. This study examined a potential clinical association between these disorders in populations of preterm infants at two hospitals in the USA and Hungary. Clinically collected data from infants with gestational ages less than 32 weeks born between May 1, 2007 and December 31, 2010 seen in the University of Iowa Children's Hospital or the Department of Obstetrics and Gynecology, University of Pécs, were abstracted from electronic medical records and entered into a study database. Demographic and clinical variables were examined as potential covariates to the disorders of interest. Data were initially analyzed by center and then combined through meta-analysis. Six hundred eighty-four subjects were studied: 236 from Pécs and 448 from Iowa. There were no significant demographic differences between populations. Univariate analysis on each study population yielded covariates to ROP in each population, including infantile hemangioma, which were entered into a logistic regression model. These models were combined through random-effects meta-analysis and demonstrated a significant relationship between infantile hemangioma and ROP (odds ratio = 1.84, 95 % confidence interval 1.08-3.12).

CONCLUSION

Infantile hemangioma and ROP co-occur in premature infant populations. Further studies are needed to investigate the pathogenesis of both disorders.

Hypoxia-induced oxidative stress in ischemic retinopathy

Oxidative stress plays a crucial role in the pathogenesis of retinal ischemia/hypoxia, a complication of ocular diseases such as diabetic retinopathy (DR) and retinopathy of prematurity (ROP). Oxidative stress refers to the imbalance between the production of reactive oxygen species (ROS) and the ability to scavenge these ROS by endogenous antioxidative systems. Free radicals and ROS are implicated in the irreversible damage to cell membrane, DNA, and other cellular structures by oxidizing lipids, proteins, and nucleic acids. Anti-oxidants that can inhibit the oxidative processes can protect retinal cells from ischemic/hypoxic insults. In particular, treatment using anti-oxidants such as vitamin E and lutein, inhibition of nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase) or related signaling pathways, and administration of catalase and superoxide dismutase (SOD) are possible therapeutic regimens for DR, ROP, and other retinal ischemic diseases. The role of oxidative stress in the pathogenesis of DR and ROP as well as the underlying mechanisms involved in the hypoxia/ischemia-induced oxidative damage is discussed. The information provided will be beneficial in understanding the underlying mechanisms involved in the pathogenesis of the diseases as well as in developing effective therapeutic interventions to treat oxidative stress-induced damages.