Extraretinal Neovascularization Research Articles

THE EFFECTIVENESS OF INTRAVITREAL ANTI-VEGF INJECTION IN EALES' DISEASE: A CASE REPORT

Introduction : Eales’ Disease (ED) is an idiopathic inflammatory retinal vasculitis, affecting retinal veins of small and large caliber that results in extraretinal neovascularization with vitreous hemorrhage. The etiopathogenesis of ED is poorly understood. However, many studies have attributed inflammation as a response to mycobacterium tuberculosis. Treatment of this disease can be done with corticosteroids, anti-VEGF therapy, laser photocoagulation, and vitreoretinal surgery.
 Case Illustration : We reported a patient, a 31-year-old woman with complaints of blurred vision and floaters in both eyes. An initial examination showed the visual acuity of the RE was 0,1F1 and the LE was 0,1. Examination of the posterior segment found perivascular exudate and peripheral retinal neovascularization. We performed an OCT examination on both eyes and found that there was extensive macular edema, especially in the RE. Patient was diagnosed with ED and received steroidsas an initial treatment. But there was no improvement in both eyes. In addition, patient received two anti-VEGF injections in the RE and one injection in the LE and showed good improvement. After that injection, the posterior segment showed very minimal lesions on the macula and repeated OCT results showed normal central macular thickness.
 Discussion : Anti-VEGF may also play a role in the treatment and management of ED. This is because, besides inflammation, there is an increased expression of VEGF in vitreous patients with ED. Several case reported there is significant improvement in anti-VEGF injection in the management of patients with ED.
 Conclusion : Intravitreal anti-VEGF injection shows good results in ED that did not improve with steroid treatment.

A pilot optical coherence tomography angiography classification of retinal neovascularization in retinopathy of prematurity

Extraretinal neovascularization is a hallmark of treatment-requiring retinopathy of prematurity (ROP). Optical coherence tomography angiography (OCTA) offers vascular flow and depth information not available from indirect ophthalmoscopy and structural OCT, but OCTA is only commercially available as a tabletop device. In this study, we used an investigational handheld OCTA device to study the vascular flow in and around retinal neovascularization in seven preterm infants with treatment-requiring ROP and contrasted them to images of vascular flow in six infants of similar age without neovascular ROP. We showed stages of retinal neovascularization visible in preterm infants from 32 to 47 weeks postmenstrual age: Intraretinal neovascularization did not break through the internal limiting membrane; Subclinical neovascular buds arose from retinal vasculature with active flow through the internal limiting membrane; Flat neovascularization in aggressive ROP assumed a low-lying configuration compared to elevated extraretinal neovascular plaques; Regressed neovascularization following treatment exhibited decreased vascular flow within the preretinal tissue, but flow persisted in segments of retinal vessels elevated from their original intraretinal location. These findings enable a pilot classification of retinal neovascularization in eyes with ROP using OCTA, and may be helpful in detailed monitoring of disease progression, treatment response and predicting reactivation.

PREVALENCE, PATHOGENESIS, CLASSIFICATION, IMAGING, SCREENING AND MANAGE-MENT OF DIABETIC RETINOPATHY- A CRITICAL REVIEW

Diabetic retinopathy is that the leading reason for sightlessness among people between twenty-five and seventyfour years older within the industrialised world. Diabetes mellitus (DM) includes a heterogeneous cluster of disorders of carbohydrate, protein, and metastasis manifesting hyperglycemia. Diabetic retinopathy could be microangiopathy ensuing from the chronic effects of the disease, and shares similarities with the microvascular alterations that occur in different tissues at risk of DM equivalent to the kidneys and also the peripheral nerves. Diabetic retinopathy is assessed into nonproliferative and proliferative stages. Nonproliferative diabetic retinopathy (NPDR) involves progressive intraretinal microvascular alterations that may result in, and a lot of advanced proliferative stages outlined by extraretinal neovascularization. Imaging modalities in common clinical use for the management of NPDR and DME embrace structure photography, fluorescein angiography (FA), and optical coherence tomography (OCT). The suggested schedule for screening and surveillance for NPDR reflects data concerning the epidemiology and natural history of the disease. Diabetic retinopathy could be a leading explanationfor vision loss in working-age Americans and a major cause of sightlessness worldwide. The International Diabetes Federation estimates that as several as 592 million individuals worldwide can have DM in 2035, a rise from or so 387 million people calculable to possess the disease in 2014. Here, we tend to present a review of the presentunderstanding and new insights into biochemical mechanisms within the pathological process in DR, classification, furthermore as clinical treatments for DR patients. Keywords: Diabetic retinopathy, diabetes mellitus, retinal degeneration, fluoresces in angiography, optical coher- ence tomography, VEGF, focal/grid laser photocoagulation.

Prognostic Value Estimation of Monoamines Systemic Level in Retinopathy of Prematurity in Experiment.

The aim of the investigation was to study a systemic level of L-DOPA, dopamine, and norepinephrine, and assess their prognostic value in retinopathy of prematurity (ROP) development on an experimental disease model.Materials and MethodsThe investigation was carried out on infant Wistar rats (n=36) divided into a study group (rat infants with experimental ROP, n=17) and a control group (n=19). The animals of both groups were sacrificed on days 14, 21–23, and on days 28–30. The choice of the indicated periods corresponded to the key stages of ROP development in an experiment and was based on the findings of our previous histological studies. Dopamine, L-DOPA, and norepinephrine levels in infant rat blood plasma samples were determined.ResultsOn day 14 of the experiment (the period corresponds to the pathological neovascularization induction in the applied model and preclinical ROP in children), mean L-DOPA level in infant rats with ROP (0.31 ng/ml) was significantly decreased compared to that in the controls (0.42 ng/ml) (p≤0.01). On days 21–23 of the experiment (the period corresponds to the growth of pathological extraretinal neovascularization in the applied model and ROP stage 3 in children) the systemic level of L-DOPA was still statistically reduced in the study group (0.87 ng/ml) compared to the control group (1.53 ng/ml) (p≤0.01). On days 28–30 of the experiment (the period corresponds to the regress of neovasculature in the applied model and a spontaneous ROP regress stage in children) the L-DOPA level in blood plasma in the study group (0.33 ng/ml) showed an insignificant upward tendency in reference to the controls (0.21 ng/ml). Mean dopamine and norepinephrine levels had no difference in the groups under study of infant rats within all follow-up periods.ConclusionLow systemic level of L-DOPA at the preclinical stage of experimental ROP should be considered as a laboratory prognostic criterion of a developing pathological process; it will enable to use the criterion when working out the measures to optimize the existing screening system for the disease in children.

The spectrum of genetic mutations in patients with asymptomatic mild familial exudative vitreoretinopathy

Familial exudative vitreoretinopathy (FEVR) is a disease exhibits a wide range of clinical signs, ranging mild peripheral retinal vascular anomalies to severe retinal detachments. Individuals with mild FEVR are frequently asymptomatic with good visual function and are often undiagnosed. However, little is known about the genetic characters of the cohort. The purpose of this study was to investigate the clinical characteristics and genetic spectrum of in patients with asymptomatic mild FEVR. Herein, sixty-two patients (124 eyes) with asymptomatic mild FEVR were studied in a case series. Comprehensive ophthalmic examinations and genetic testing were performed in all patients. Clinical examinations showed that the avascular zone was seen in all 124 eyes and was the most common abnormality observed. Increased vessel branching and straightened peripheral vessel branches were found in 122 (98.4%) eyes. Late-phase angiographic posterior and peripheral leakage (LAPPEL) was observed in 80 (64.5%) eyes and V-shape degeneration was noted in 36 (29.0%) eyes. Other manifestations including extensive anastomoses, retinal ridges, and extraretinal neovascularization, which were detected in 30 (24.2%), 10 (8.1%) and 2 (1.6%) eyes respectively. Overall, pathogenic mutations were identified in 48.4% (30/62) of individuals with asymptomatic mild FEVR. Mutations in FZD4, LRP5, TSPAN12, and KIF11 were detected in 21.0% (13/62), 12.9% (8/62), 12.9% (8/62), and 1.6% (1/62) of our patients respectively. Ten novel mutations were found. In conclusion: Pathogenic mutations in the known FEVR-associated genes were detected in nearly half (48.4%) of the asymptomatic mild FEVR cohort. Among these mutations, FZD4 was predominant, appearing in 21.0% of all individuals. Patients with asymptomatic mild FEVR should receive timely examinations, lifelong monitoring, and some of them need preventive therapy and treatment. Additionally, we discovered 10 novel variants, which may enable a deeper understanding of this disease.

Involution of retinopathy of prematurity and neurodevelopmental outcomes after intravitreal bevacizumab treatment.

This single-centered, retrospective cohort study investigated the timing of involution of retinopathy of prematurity (ROP) and retinal vascularization to zone III after intravitreal bevacizumab (IVB) treatment and its possible impacts on postnatal growth and neurodevelopment. Premature infants with birth weight ≤1500 g, born between 2008 to 2014 and diagnosed with ROP were enrolled. All patients with type 1 ROP underwent IVB as 1st line treatment and were recruited as the study group; those with any stage of ROP except type 1 ROP without treatment served as controls. Neurodevelopmental outcomes were assessed using the Bayley Score of Infant Development (BSID) editions II or III. The study group included 35 eyes from 18 patients; the control group included 86 patients. Twenty-three eyes (65.7%) exhibited ROP regression after a single dose of IVB. The majority of plus sign and extraretinal neovascularization regressed within two weeks. The length of time for retinal vascularization to reach zone III was significantly longer in the treatment group compared with the control (mean post-menstruation age 54.5 vs. 47.0 weeks, p<0.001). Long-term follow-up showed no significant differences in body weight and neurodevelopment between the study and control groups up to the 2-year corrected age.

Next-Generation Sequencing in the Familial Exudative Vitreoretinopathy-Associated Rhegmatogenous Retinal Detachment.

The purpose of this study was to investigate the genetic mutation spectrum in Chinese patients with familial exudative vitreoretinopathy-associated rhegmatogenous retinal detachment (FEVR-RRD) and to analyze the preliminary genotype-phenotype association. In this consecutive, cross-sectional study, 54 patients with FEVR-RRD were studied. Comprehensive ophthalmic examinations and targeted next-generation sequencing were performed in all patients. The genotype-phenotype association was also analyzed. Causative mutations were identified in 38.9% (21/54) of patients (14/54 in LRP5, 4/54 in FDZ4, and 3/54 in TSPAN12). The study identified 22 potentially pathogenic mutations in 21 unrelated FEVR probands, and 14 were novel (10/15 in LRP5, 1/4 in FZD4, and 3/3 in TSPAN12). Furthermore, to explore the genotype-phenotype association, late-phase angiographic posterior and peripheral leakage (LAPPEL) was identified in 100% (4/4) of patients with FZD4 mutations and 100% (3/3) of patients with TSPAN12 mutations but only in 42.9% (6/14) of patients with LRP5 mutations. Extraretinal neovascularization (ERNV) was found in 100% (4/4) of patients with FZD4 mutations and in 66.7% (2/3) of patients with TSPAN12 mutations, but only in 21.4% (3/14) of patients with LRP5 mutations. The positive rate for pathogenic mutations in the known FEVR-associated genes was 38.9% (21/54). Among the mutations, LRP5 mutation was the predominant, accounting for 66.7% (14/21) of genetic positive patients. Patients with FEVR-RRD due to LRP5 mutations have less retinal vascular leakage or neovasculization than do patients with FEVR-RRD due to TSPAN12/FZD4 mutations. Moreover, 14 novel variants were found, which provided a deeper understanding of this disease.

Three-dimensional pattern of extraretinal neovascular development in retinopathy of prematurity

The application of three-dimensional (3D) visualization techniques to evaluate the earliest visible onset of abnormal retinal vascular development in preterm infants with retinopathy of prematurity (ROP), using bedside non-contact optical coherence tomography (OCT) imaging to characterize morphology and sequential structural changes of abnormal extraretinal neovascularization. Thirty-one preterm infants undergoing routine ROP screening with written informed consent for research imaging were enrolled in this prospective observational study. We imaged the macula and temporal periphery of preterm infants using a handheld OCT system (Envisu 2300 or handheld swept-source research system). The scans obtained were segmented and, using enhanced ray casting, were converted to 3D volumes to which color filter was applied. Using colorized 3D visualization, we defined extraretinal neovascular structures as buds, bridging networks, and placoid lesions. We could longitudinally follow progression and regression of extraretinal neovascularization in stage 3 ROP after treatment in one infant over 12weeks and document the appearance of early buds, and formation of florid neovascularization. From stages 2 to 3 ROP, we observed progression from sessile buds to a complex plaque that corresponded to stage 3 ROP on clinical examination. We demonstrated regression of neovascular complexes to small pre-retinal tufts after treatment with anti-VEGF. The extension of OCT processing to include surface flattening and colorization that further improved structural analysis rendered better understanding of extraretinal tissue. Our ability to image similar areas in the same infant over multiple visits enabled us to study the evolution of these structural components and follow pathological vascular events longitudinally in development and regression after treatment. These methods can be applied to further study which are likely contribute to our understanding of the pathophysiology of neovascularization in ROP.

Avastin Treatment Reduces Retinal Neovascularization in a Mouse Model of Retinopathy of Prematurity

Purpose: This study was designed to evaluate the effect of one intraperitoneal (IP) injection of bevacizumab (Avastin) on the severity of oxygen-induced retinopathy (OIR) in a mouse model.Materials and methods: Twenty-eight eyes of 14 mice with OIR were studied. There were nine mice in the bevacizumab-treated group (study group) and five mice in the saline-treated group (controls). The mouse OIR model consisted of a 5-day exposure to 75% oxygen. On postnatal day 12 (P12), Avastin 2.5 mg/kg was administered IP to the study group and 2.5 mg/kg normal saline was administered IP to the controls. All 14 mice underwent fluorescein angiography of the retinal vasculature on P17 and the following parameters were scored (Modified Retinopathy Scoring System, MRSS): blood vessel growth, formation of blood vessel tufts, extraretinal neovascularization, degree of central constriction, and tortuosity of vessels. In addition, the neovascular vessels were quantified on the hematoxylin and eosin (H&S)-stained paraffin sections of the eyes in a masked fashion.Results: The MRSS score in the Avastin-treated mice was significantly lower than that of the saline-treated mice (3.06 ± 1.63 versus 7.1 ± 2.01, respectively, p = 0.0021). The neovascularization count was also significantly lower in the study group (3.44 ± 1.81 versus 9.34 ± 3.23 for the controls, p = 0.0013).Conclusions: IP Avastin treatment reduced the extent of oxygen-induced retinopathy in a mouse model of retinopathy of prematurity.

RhoA Activation and Effect of Rho-kinase Inhibitor in the Development of Retinal Neovascularization in a Mouse Model of Oxygen-induced Retinopathy

Purpose: To study RhoA activation and the effect of the Rho-kinase inhibitor in the development of retinal neovascularization in a mouse model of oxygen-induced retinopathy (OIR).Methods: C57BL/6 mice at postnatal day (P7) were exposed to hyper-oxygen for 5 days and returned to room air for 5 days to induce OIR. RhoA-GTP, an active form of RhoA, in retinas at P12, P13 and P17 was detected. Mice received a single intravitreal injection of Y27632 (5 µM or 50 µM), a Rho-kinase inhibitor, in one eye during the transition from oxygen to room air at P12. Contralateral eyes were used as the control. Fluorescein-conjugated dextran angiography of retinal whole mount was prepared to score features of neovascular retinopathy at P17. The preretinal neovascular nuclei quantification was performed in frozen sections as well to evaluate the neovascularization.Results: The retinal RhoA-GTP in OIR mice significantly increased from 0.24 ± 0.06 at P12 to 0.38 ± 0.12 at P13 (p < 0.05). The median total retinopathy score of 5.7 was significantly lower in eyes treated with Y27632 than controls (p < 0.001). Significant improvement was found in the specific categories of vascular tufts (p < 0.01) and extraretinal neovascularization (p < 0.05) in treated eyes. Those treated eyes also had a significantly decreased number of neovascular nuclei (p < 0.01).Conclusions: These results suggest that Rho/Rho-kinase signaling pathways are involved in the early process of hypoxia-induced retinal neovascularization and Y27632 might have therapeutic potential for the treatment of retinal neovascularization.

INTRAVITREAL BEVACIZUMAB AS SUPPLEMENTAL TREATMENT OR MONOTHERAPY FOR SEVERE RETINOPATHY OF PREMATURITY

To investigate the benefit of intravitreal bevacizumab as supplemental or primary treatment for retinopathy of prematurity. The files of nine consecutive infants treated with intravitreal bevacizumab for bilateral severe posterior retinopathy of prematurity were reviewed. Gestational age was 24 weeks to 27 weeks, and birth weight was 660 g to 1,131 g. Indications for treatment were retinopathy of prematurity progression from Stage 3 to 4A or 2 to 3 with extraretinal neovascularization despite laser treatment; active neovascular Stage 4A disease after laser and cryo-treatment; anterior segment neovascularization and bleeding after laser treatment; and aggressive posterior disease with tunica vasculosa lentis and vitreous haze, which prevented laser treatment. One patient (two eyes) underwent lens-sparing vitrectomy after bevacizumab treatment; one eye acquired macular fold. One patient underwent bilateral scleral buckle. Bevacizumab treatment was associated with subsidence of the active vascular component in all eyes. Anatomical results were favorable in 17 eyes. There were no local or systemic complications. Intravitreal bevacizumab may serve as a supplemental therapeutic agent for severe laser-refractory retinopathy of prematurity or as monotherapy when media opacities preclude diode laser photocoagulation or the patient is too sick for lengthy laser treatment.

The effect of thalidomide on neovascularization in a mouse model of retinopathy of prematurity

Abnormal angiogenesis is the hallmark feature of retinopathy of prematurity (ROP), and contributes to the severe visual loss that accompanies this disease. Thalidomide is a well-known anti-angiogenic drug. We tested the assumption that injection of intraperitoneal thalidomide could reduce the severity of oxygen-induced retinopathy (OIR) in a mouse model. Forty-three baby wild type mice were used in this study. The mouse model of oxygen-induced retinopathy consisted of a 5-day exposure to 75% oxygen from postnatal day 7 to 12 (P12) followed by 5 days in room air (relative hypoxia). Control mice were those with normally developing retinal vasculature exposed to room air from birth until postnatal day 17 (P17). Thalidomide (200 mg/Kg) was administered daily intraperitoneally to control and ROP mice in two protocols: (1) from P12 to P16, and (2) from P11 to P15 . Fluorescein-conjugated dextran angiography of retinal vasculature was performed on P17, and retinal whole mounts were prepared to score features of retinopathy. The parameters that were scored in a masked fashion included blood vessel growth, blood vessel tufts formation, extra retinal neovascularization, degree of central constriction, and tortuosity of vessels. These parameters constitute the Modified Retinopathy Scoring System (MRSS). In addition, quantification of the number of blood vessel tufts was performed in a masked fashion with hematoxylin & eosin (H&S) staining of paraffin-embedded eye sections. The retinopathy score by MRSS in the thalidomide treated mice was similar to that of untreated mice that were exposed to oxygen (9.3 +/- 1.9 vs 10.15 +/- 1.6; p = 0.21). The neovascularization count was also similar between the two groups (10.4 +/- 5.6 vs 9.6 +/- 4.8; p = 0.56). In the control group left in the room air, the retinopathy score was 0.19 +/- 0.37 (p = 0) and the neovascularization count was also very low (2.92 +/- 2.14; p = 0). Although thalidomide might have a proven anti-angiogenic and anti-inflammatory effect, our model did not show a significant effect on the retinopathy. The reason might be an ineffective level of the drug in the retina due to ineffective metabolism of the drug, or due to blockage of the drug by the blood-retina barrier, or the involvement of other factors besides those influenced by thalidomide in the process.

Intravitreal injection of the heparin analog 5-amino-2-naphthalenesulfonate reduces retinal neovascularization in mice

The effect of the heparin analog 5-amino-2-naphthalenesulfonate (5-amino-2-NMS) on retinal neovascularization was investigated in the mouse model for oxygen-induced retinopathy (OIR). From postnatal day 7 (P7) until P12, mice were kept in a 75% oxygen environment. On P12, they received an intravitreal injection of 10 mM 5-amino-2-NMS in one eye and PBS as control substance in the fellow eye. The animals were intracardially perfused with fluorescein-dextran solution on P17. Retinal whole mounts were prepared and ischemic retinopathy was evaluated in 30 animals using a standardized retinopathy score. A single intravitreal injection of 5-amino-2-NMS reduces significantly angioproliferative changes (blood vessel tufts, extra-retinal neovascularization, and blood vessel tortuosity) compared to the contralateral control eye ( p = 0.025). The median retinopathy score (maximal 13) for the 5-amino-2-NMS treated eyes was 6 versus 8 for the control eyes. 5-Amino-2-NMS binds to the heparin-binding site of FGF1 and FGF2 and thus may be a promising substance for the local treatment of retinal neovascularization.

An increase in superoxide dismutase ameliorates oxygen-induced retinopathy in transgenic mice.

Oxygen therapy is a well-recognized risk factor for retinopathy of prematurity. We examined whether an increase in the naturally occurring enzyme copper-zinc superoxide dismutase (CuZnSOD), which controls oxygen, can reduce the severity of oxygen-induced retinopathy in a mouse model. Seven transgenic mice overexpressing CuZnSOD and six wild-type mice were exposed to 75% oxygen from postnatal day 7 to 12. Seven transgenic mice and five mice of the wild type were kept in room air and served as controls. Fluorescein-conjugated dextran angiography of retinal vasculature was performed and flat-mounted preparations were evaluated by scoring blood vessel growth, blood vessel tuft formation, extraretinal neovascularization, degree of central constriction, and tortuosity of vessels. In addition, quantification of the number of blood vessel tufts was performed in a masked fashion with haematoxylin and eosin staining of paraffin-embedded eye sections. The mean retinal score+/-SD obtained by the wild-type mice was 9.4+/-2.0, whereas the transgenic mice overexpressing CuZnSOD obtained a value of 2.4+/-1.6 (P=0). The two control groups (wild type and transgenic) that were kept in room air, each obtained a score of 0. Significantly fewer extraretinal vascular tufts were seen in the transgenic mice (0.26+/-0.34) than in the wild-type mice (4.27+/-1.6) after both groups were exposed to oxygen (P<0.001). The results suggest that high SOD activity protects neonatal mice against oxygen-induced retinopathy, and support the assumption that oxygen radicals are a major causative factor in oxygen-induced retinopathy.

Reduced retinal angiogenesis in MMP-2-deficient mice.

To study the putative role of endogenous matrix metalloproteinases (MMPs) in retinal neovascularization, an established mouse model was used to compare the retinal neovascularization observed in wild-type mice with that in mice without the MMP-2 or -9 genes. C57Bl/6 (MMP-2(+/+) and -9(+/+)), MMP-2-deficient (MMP-2(-/-)), and MMP-9-deficient (MMP-9(-/-)) mice were used. After oxygen-induced retinopathy was induced in the mice, their eyes were rapidly removed and frozen in optimal cutting temperature embedding compound. Sections were histochemically stained with specific markers for vascular cells and angiogenesis-related factors. The area of new retinal vessels was measured using image-analysis software and compared between groups. Retinal neovascularization was not significantly different between wild-type and MMP-9(-/-) mice. The MMP-2(-/-) mice had significantly less extraretinal neovascularization than did wild-type mice. The mean number of extraretinal neovascular buds per cross section was significantly lower in MMP-2(-/-) mice than in wild-type mice (P < 0.05). The expression of other angiogenesis-related factors, vascular endothelial growth factor and pigment epithelium-derived factor, was not different between wild-type and MMP-2(-/-) mice. MMP-2 may be essential in the regulation of retinal neovascularization. Pharmacologic intervention using MMP inhibitors may be a future therapeutic approach for angiogenic retinal diseases.

Somatostatin Analogs Inhibit Neonatal Retinal Neovascularization

The goal of this study was to determine the effect of two somatostatin analogs, Woc4D and octreotide, on oxygen induced retinopathy in the mouse. Oxygen induced retinopathy was produced in C57BL6 mice. Octreotide and Woc4D were administered from post-natal day 12–16. Retinopathy was assessed by a retinal scoring system utilizing fluorescein perfused retinal whole mounts. Animals treated with Woc4D and octreotide, respectively, had median retinopathy scores of 4(3,5) [median(25th, 75th quartile)] with P=0.01 and 3.5(2.9,4.3) withP=0.01 compared to oxygen and sham treated oxygen animals with scores of 6.6(5.3,8.5) and 7.4(5.8,8.6), respectively. Woc4D and octreotide treated animals had decreased blood vessel tufts and decreased extra-retinal neovascularization when compared to oxygen treated animals. Pituitary growth hormone (GH) mRNA expression was increased 8.3-fold by Woc4D treatment and 106-fold by oxygen exposure, and GH and mRNA was markedly reduced by Woc4D as well as octreotide. Growth as measured by animal weight was unaffected by either treatment. Woc4D and octreotide inhibited retinal neovascularization in an equally effective manner in the mouse model of oxygen induced retinopathy.

Retinopathy of Prematurity: History, Classification, and Pathophysiology

After completing this article, readers should be able to: 1. Describe the onset of retinopathy of prematurity (ROP). 2. Explain the role of oxygen in ROP. 3. Compare and contrast zones I, II, and III disease. 4. Describe the stages of ROP. 5. Characterize “plus” disease. 6. Describe the infants in whom severe ROP leading to the need for surgery is common. 7. Describe the timeframe at which ROP is visible in the eye. ### The First ROP In 1942, Terry described the first infant who had grey, blood vessel-covered membranes behind the pupil. As more cases were described, the name retrolental fibroplasia (RLF) was coined (Fig. 1⇓ ). Distressingly, it became common around the world in special units for preterm infants. Pathologic specimens were rare (Fig. 2⇓ ) , but serial examinations of preterm infants following birth revealed that infants were not born with RLF; they developed it after birth. By the end of the 1940s, many innovations in the new preterm infant nurseries had been implicated, some were exonerated, and it was time to examine the role of oxygen. Figure 1. End-stage ROP. The white pupils (leukocoria) of stage 5 ROP result from total retinal detachment, with the mass of fibrous neovascularization and the retina pushing up against the lens from behind. This is the source of the historical name retrolental fibroplasia. Photograph courtesy of A. Patz, MD, used with permission. Reprinted with permission from Pediatrics . 1957;19:502–504. Figure 2. A. Artist’s rendering of stage 5 retinal detachment. B. Pathologic specimen of an eye with stage 5 ROP. In this cross section, the lens is displaced into the anterior chamber by the mass of tissue in the vitreous composed of the detached retina and the large number of extraretinal vessels and accompanying scar tissue (fibroplasia). The retina remains attached at the posterior pole at the optic disc and around the rim …

What Can We Learn From STOP-ROP and Earlier Studies?

The results of the STOP-ROP study, published elsewhere in this month's issue,1suggest that the effect of supplemental oxygen on the conversion rate of prethreshold retinopathy of prematurity (ROP) to threshold disease may be less pronounced than that found in 2 previous studies, one by Gaynon et al2 at Stanford and the other by Seiberth et al3 in Germany. For the STOP-ROP group as a whole, the reduction in the rate of conversion from prethreshold ROP to threshold was from 48.5% for the conventional oxygen group down to 40.9% for the supplemental oxygen group. STOP-ROP did show a trend toward better outcome, which for the group as a whole, did not reach statistical significance, given the ultimate sample size of 649 infants, down from the initially planned 880 infant enrollment. Results were more dramatically beneficial for those infants without plus disease. Taking this group as a whole, the conversion rate to threshold dropped from 46% for the conventional group to 32% for the supplemental group. This is consistent with the notion that plus disease (tortuous and engorged retinal vessels) is a sign of high blood flow through arteriovenous shunting attributable to intraretinal (stage 2+) or extraretinal (stage 3+) neovascularization. Lack of, or resolution of, plus disease is a favorable sign suggesting that any neovascularization present, as a component of prethreshold ROP, may be resolving. The time it took for threshold disease to appear was longer for the supplemental group as compared with the conventional group, both for the study as a whole as well as for patient subsets stratified according to disease severity, suggesting a moderating effect of supplemental oxygen on disease momentum. At the same time there was evidence that to some extent, chronic lung disease was worse in those infants in STOP-ROP given supplemental oxygen …

Dexamethasone reduces oxygen induced retinopathy in a mouse model.

Dexamethasone is widely used in the postnatal period. Its impact on retinopathy of prematurity (ROP) is extremely controversial; published studies have found a detrimental, protective, or no effect on ROP. The goal of this study was to test the hypothesis that use of dexamethasone during the injury phase (oxygen exposure) reduces the severity of oxygen-induced retinopathy (OIR) in a mouse model. C57BL6 mice pups were exposed to either room air or hyperoxia (75% FiO2) from postnatal d 7 through 12 (PN7-12) with or without dexamethasone (0.5 mg/kg/d s.c.) and killed on PN17-21. Retinopathy was assessed by a scoring system of retinal flat mount preparations and periodic acid-Schiff (PAS) staining of retinal sections. Pups exposed to dexamethasone and oxygen had a lower median retinopathy score of 5 (4, 6) [median (25th, 75th quartile)] compared with animals exposed to oxygen alone with median score of 9 (6, 10) with p < 0.001. PAS staining for extra retinal neovascularization in the dexamethasone and oxygen treated animals showed a significant reduction in number of nuclei extending beyond the inner limiting membrane when compared with oxygen exposed alone (p = 0.04). Animals treated with dexamethasone had decreased weight gain compared with control animals. Dexamethasone did not appear to affect the normal development of retinal vasculature as assessed by the scoring system when compared with control animals. Thus, dexamethasone decreases severity of OIR without having an adverse effect on normal retinal vascular development in the mouse model. We speculate that dexamethasone decreases the injury response that occurs during the hyperoxic phase, thus protecting the developing vasculature and improving the subsequent retinopathy.

Diltiazem reduces retinal neovascularization in a mouse model of oxygen induced retinopathy

Purpose. To assess the effect of diltiazem, a calcium channel blocking agent, on oxygen induced retinopathy (OIR) in a mouse model using neovascular nuclei quantitation and a quantitative scoring system based on examining fluorescein perfused retinal whole mount preparations. Methods. The mouse model of oxygen induced retinopathy consisting of a 5 day exposure to 75% oxygen from postnatal day 7 to 12 was used to produce retinal neovascularization. Fluorescein conjugated dextran angiography of retinal vasculature was performed and retinal whole mounts were prepared to score features of retinopathy. The parameters that were scored in a masked fashion included blood vessel growth, blood vessel tuft formation, extra retinal neovascularization, degree of central vasoconstriction, retinal hemorrhage, and tortuosity of vessels. Diltiazem (0.05-0.5 mg/kg/day subcutaneously for five days) was administered to mice pups during exposure to oxygen to determine if calcium channel blockade altered retinopathy. In addition, quantification of retinal neovascular nuclei was performed in a masked fashion with periodic acid Schiff (PAS) staining of frozen eye sections. Results. Animals that were exposed to hyperoxia for five days had a median (25th, 75th quartile) retinopathy score of 9 (8,11) versus control animals that had a retinopathy score of 1 (0,1) with p < 0.001. Subscores for blood vessel growth, blood vessel tufts, extra-retinal neovascularization, central vasoconstriction, hemorrhage, and blood vessel tortuosity were all significantly different between control and treated animals. In addition, quantification of neovascular nuclei showed a significant increase in the number of nuclei extending beyond the inner limiting membrane into the vitreous in hyperoxic treated animals. Diltiazem at doses of 0.2 and 0.5 mg/kg/day improved the retinopathy as measured by the total retinopathy score [5 (4,6) and 4 (3.75,5.25), respectively]. The average number of extraretinal neovascular nuclei per retinal section (mean ± standard deviation) was significantly decreased by diltiazem at doses of 0.2 and 0.5 mg/kg/day (31.4 ± 18.8 and 20.9 ± 6.9, respectively) when compared to hyperoxic treated animals (56.1 ± 21.5). Conclusions. Diltiazem reduces oxygen induced retinopathy in the mouse as measured by a scoring system based on a retinal whole mount method of retinal neovascularization and by quantification of extra retinal neovascular nuclei.