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At least 397 records · Page 22Linked to original sources
PubMed1986

Experimental retinal vascular occlusion. III. An ultrastructural study of simultaneous occlusion of central retinal vein and artery.

The retinal changes following the simultaneous occlusion of retinal vessels were examined at an ultrastructural level. The preservation of endothelial cells that prevented leakage of blood and horseradish peroxidase tracer material in the surrounding retinal tissues explained the lack of hemorrhages observed clinically. Mueller cell death resulted in severe structural disorganization of the retina, with disruption of the inner limiting membrane, involvement of the outer retinal layers, and fleurette formation. The retinal macrocysts were derived from ischemic infarction.

Animals↗
PubMed2001

[The effect of gabapentin and gabapentin-lactam on retinal ganglion cell survival. Situation after acute retinal ischemia in animal models].

BACKGROUND: Reduction in the excitatory and potentially toxic neurotransmitter glutamate can protect retinal ganglion cells. What are the effects of the antiepileptic drug gabapentin, for which antiglutamatergic effects have been described, and the new substance gabapentin-lactam (GBP-L) on retinal ganglion cell survival after retinal ischemia? METHODS: In 3 groups of 10 rats each, ischemia was induced by elevating the intraocular pressure of the left eye to 120 mmHg for 1 h. Saline, gabapentin (2 x 50 mg/kg intraperitoneally) and GBP-L (2 x 50 mg/kg intraperitoneally) were injected before and 5 h after ischemia. Two weeks later ischemic damage was quantified histologically by counting the number of neurons in the ganglion cell layer. In vitro transmitter release experiments were performed to obtain information on the effect of gabapentin and GBP-L on ischemia-induced glutamate release and the mechanism of action of GBP-L. RESULTS: In the control group 17% of the retinal ganglion cells survived ischemia. GBP-L doubled the number of the surviving cells while gabapentin was not effective in these experiments. In vitro gabapentin and GBP-L reduced ischemia-induced glutamate release by 35.7% and 42.5%, respectively. The blockade of ATP-sensitive potassium channels antagonized the effect of GBP-L completely. CONCLUSION: GBP-L is neuroprotective in retinal ischemia and diminishes the release of the excitatory neurotoxic amino acid glutamate. The effect of GBP-L might be mediated by ATP-sensitive potassium channels. Also gabapentin reduced glutamate release but was not neuroprotective in vivo.

Acetates↗
PubMed1987

Prevalence, pathophysiology, and treatment of rhegmatogenous retinal detachment in treated cytomegalovirus retinitis.

Seventeen patients with the acquired immune deficiency syndrome and cytomegalovirus retinitis were treated with the antiviral drug ganciclovir (9-[1,3-dihydroxy-2-propoxy-methyl]-guanine, DHPG). Eight eyes of five patients developed rhegmatogenous retinal detachment after initiation of treatment. Multiple breaks in areas of peripheral, healed, atrophic retina accounted for the detachments. All seven eyes that underwent surgery had extensive retinal detachments that were reattached with vitrectomy and silicone oil. Retinotomy and retinal tacks were necessary in two cases that were complicated by severe proliferative vitreoretinopathy. In the fellow eye of one patient, laser treatment was used prophylactically to wall off a peripheral patch of healed retinitis. Endoretinal biopsies and culture were taken in five eyes; evidence of persistent cytomegalovirus was seen in two cases despite concurrent and clinically effective antiviral therapy.

AIDS-Related Complex↗
PubMedDate not supplied

Surgical management of retinal detachment secondary to acute retinal necrosis: clinical features, surgical techniques, and long-term results.

PURPOSE: To describe the clinical features of complicated retinal detachment secondary to acute retinal necrosis (ARN) and to present the long-term results of vitreous surgery in these cases. METHODS: A retrospective study was conducted on 16 immunocompetent patients (18 eyes). The average follow-up period was 60 months. RESULTS: Proliferative vitreoretinopathy (PVR) grade C, with the predominance of anterior PVR, and characteristic changes in the vitreous base area were present in all cases before surgery. All eyes underwent vitrectomy, membrane peeling, endolaser photocoagulation, and intraocular tamponade without scleral buckling. Additional procedures were performed in 13 eyes. Retinal reattachment was achieved in the 18 eyes (100%) in the short term. Variable degrees of reproliferation occurred in all cases after surgery. Other delayed complications included ocular hypotony, macular pucker, peripheral retinal neovascularization, and severe preretinal fibrosis. Improvement of visual acuity occurred in 13 eyes (72.2%). Eleven eyes (61.1%) achieved final ambulatory visual acuity of 5/200 or better. CONCLUSIONS: Rhegmatogenous retinal detachment secondary to ARN has characteristic clinical features. Severe proliferative vitreoretinopathy with the predominance of anterior PVR develops rapidly. Reproliferation is the most important late postvitrectomy complication necessitating multiple surgical procedures in these cases. The visual results remain unfavorable due to the destructive nature of ARN.

Adult↗
PubMedDate not supplied

Gray-white, spherical deposition on retinal vessel associated with acute retinal necrosis and diabetic retinopathy in HTLV-I carriers.

Tiny, gray-white, spherical deposits were found on the retinal vessels and vitreoretinal interface of the fovea in a 55-year-old woman with acute retinal necrosis due to varicella-zoster virus, and in a 47-year-old man with preproliferative diabetic retinopathy. Both patients developed massive vitreous opacities due to uveal inflammation or hemorrhages that rendered the fundus difficult to visualize. A therapeutic vitrectomy revealed gray-white, tiny spherical deposits, about blood-vessel-diameter, which were scattered on seemingly intact retinal arteries and veins in the posterior fundus and over the vitreoretinal interface overlying the fovea. The deposits were loosely adherent to vessel walls and were easily aspirated, and the residual materials resolved in the early postoperative days. These characteristic retinal vascular deposits resembled those seen in patients with HTLV-I associated uveitis. The two patients reported herein were otherwise asymptomatic carriers of HTLV-I. The findings provide additional information about the etiological role of HTLV-I in the development of characteristic retinal vascular deposition, although its pathogenesis remains to be elucidated.

Carrier State↗
PubMed1982

Retinal ischemia and risk of neovascularization following central retinal vein obstruction.

The predominant risk factor for the development of neovascular complications involving the retina (NVR), the optic disc (NVD), and iris (NVI) following central retinal vein obstruction (CRVO) is the extent, location, and duration of retinal ischemia (ischemic drive). The extent of retinal capillary nonperfusion (ischemic index) was quantitated by microcomputer analysis of 200 standard fundus-iris fluorescein angiograms. The results were correlated with the development of neovascularization in eyes not receiving prophylactic argon laser panretinal photocoagulation (PRP). Of the 85 eyes with intact capillary perfusion (hyperpermeable group), none developed NVR/NVD and only one eye (1%) developed neovascular glaucoma (NVG). Twenty-nine eyes exhibited moderate degrees of retinal ischemia (indeterminate group), and three eyes (10%) developed NVR/NVD, with two eyes (7%) developing NVG. Of the 86 eyes with extensive retinal capillary nonperfusion (ischemic group), 28 eyes (33%) developed NVR/NVD and NVG occurred in 39 eyes (45%). The inherent difficulties in following high risk patients clinically and angiographically at frequent intervals over extended periods of time, the tendency for rapid progression of early NVI to NVG, and the relatively poor results following treatment in advanced cases make the early recognition of eyes at high risk to develop NVG essential and the initiation of prophylactic PRP as the treatment of choice in this disorder.

Fluorescein Angiography↗
PubMed1993

Central retinal vein occlusion associated with retinal arteriovenous malformation.

PURPOSE/BACKGROUND: Retinal arteriovenous malformations can be seen in a variety of ways and have multiple, associated, ocular changes that can affect vision. The authors report two cases of retinal arteriovenous malformation. In each case, a central retinal vein occlusion developed. METHODS: Each patient underwent clinical examination and fluorescein angiography. One patient was followed over a long period of time. CONCLUSION: The authors propose that a turbulent flow, high intravascular volume, and arteriolar pressure in the venous side of the retinal arteriovenous malformation may lead to vessel wall damage, thrombosis, and occlusion. They also suggest that compression of the central retinal vein by the mass effect of the arteriovenous malformation on the optic nerve further leads to turbulence and thrombosis.

Arteriovenous Malformations↗
PubMed1985

[The physiopathology of retinal circulation: consequences of acute retinal vascular occlusion].

A constant oxygen supply from the retinal and choroidal vascular system is essential for the maintenance of the retinal electrical activity. Arterial or venous retinal obstruction modifies the hemodynamics in the retinal circulation and produces hypoxia in the affected area. In the case of arterial obstruction, severe hypoxia (anoxia) rapidly (in less than 45 min) produces irreversible cell damage in the inner area of the retina. With venous obstruction, the hypoxia is moderate and the retinal damage is partial. In some cases, hypoxia regresses because the formation of collateral vessels most probably provides adequate perfusion. In cases of irreversible venous obstruction, insufficient formation of collateral vessels results in the development of ischemic regions in the retina and severe hypoxia. In these cases preretinal neovascularization may develop.

Animals↗
PubMedDate not supplied

The role of a second isolated retinal artery in branch retinal vein obstruction.

PURPOSE: To evaluate the prevalence of a second isolated retinal artery in eyes with and without branch retinal vein obstruction (BRVO). METHODS: A retrospective study of the color photographs and fluorescein angiograms of 100 patients with unilateral BRVO (64 superotemporal and 34 inferotemporal) and a control group of 33 patients (66 eyes) with different ailments was made. The prevalence of a second isolated retinal artery, which coursed closer to the macular region, in BRVO eyes, fellow eyes and eyes of the control group was evaluated. The types and sites of arteriovenous crossings were also recorded for comparison. RESULTS: The eyes with BRVO, which involved the superotemporal quadrant, had significantly larger numbers of arteriovenous crossings than did fellow eyes (p = 0.02) and control eyes (p = 0.001). In the superotemporal quadrant, a significantly higher percentage (35 of 66, 53%) of the control eyes had a second isolated retinal artery than did BRVO eyes (16 of 64 cases, 25%, p = 0.001). CONCLUSIONS: The second isolated retinal artery, which has not been previously mentioned in the literature, may lower the chance of arteriovenous crossings and play a protective role in BRVO.

Adult↗
PubMed2000

Retinal arteriolar tortuosity with recurrent retinal hemorrhages--case report.

Retinal arteriolar tortuosity with retinal hemorrhage was first described in 1958. A 45 year-old Taiwanese man had experienced recurrent retinal hemorrhages in each eye in the previous 20 years. The hemorrhages resolved spontaneously without any subjectively obvious sequelae. He has no history of hypertension or any vascular occlusive diseases. There were also no similar cases in his family. The medical examination and laboratory tests did not reveal any significant etiologic factors. Ophthalmologically, the retinal vein was normal but all retinal arterioles were tortuous from the posterior pole to the periphery. Fluorescein angiography revealed the same findings. To our knowledge, this is the first case report in Taiwan.

Arterioles↗
PubMed1975

[Recurring retinal haemorrhages with tortuosity of the retinal arteriols (author's transl)].

Four young and healthy adults with tortuosity of the retinal arterioles of the posterior pole and recurring superficial retinal haemorrhages are described. Two of them had a suspected mild thrombocytopathy without clinical manifestations in other organs. Inheritance of the syndrome was not demonstrated and the pathogenic mechanism still remains obscure. All the described patients had been at risk of a retinopathy of praematurity. Knowing that familial retinal haemorrhages without retinal tortuosity do occur and retinal tortusity may persist as a minimal change of retinopathy of praematurity, it is suggested that this syndrome might be a combination of two entities.

Adult↗
PubMedDate not supplied

Retinal neovascularization and an angioma-like lesion after demarcation photocoagulation for rhegmatogenous retinal detachment.

Laser photocoagulation might aggravate the ischemia of an area of retinal detachment and predispose the retina to formation of neovascularization and an angioma-like lesion. We present a case of retinal neovascularization (RNV) and an angioma-like lesion occurring after demarcation photocoagulation for rhegmatogenous retinal detachment (RRD). A 20-year-old woman suffered from a retinal atrophic hole with localized shallow retinal detachment in the right eye. Laser photocoagulation was performed to wall off the area of detachment. Fifteen months later, RNV and an angioma-like lesion had developed in the previously detached retina. Treatment with demarcation photocoagulation for RRD may run a risk of formation of RNV and angioma-like lesion if the retina is not reattached.

Adult↗
PubMed1990

[Acute retinal necrosis--a herpetic retinitis?].

Acute retinal necrosis (ARN) is characterized by unilateral or bilateral severe vaso-occlusive retinitis. In a large number of cases the patients become blind in the affected eyes as a direct result of the acute inflammation or the subsequent retinal detachment. The etiology is poorly understood; herpesvirus-induced vasculitis is presumed and has been demonstrated by some authors. However, the author's own investigations in seven patients show that even vitreous biopsy reveals a herpetic origin only in a minority of cases. Intravenous treatment with acyclovir and steroids prevented progression of the retinitis but did not reduce the risk of retinal detachment.

Acyclovir↗
PubMed1989

[The clinical characteristics of different types of peripheral retinal degeneration and their relationship to retinal breaks and detachment].

Clinico-statistical analysis of case histories of 6114 patients with retinal detachment has revealed peripheral degeneration of the retina in 2739 twin eyes, of them in 67 patients breaks and tears of the retina were not followed by its detachment. A working-scheme classification of this pathology is worked out and clinical description of different forms of degeneration predisposing to retinal detachment is made. To prevent retinal detachment, indications to laser coagulation are worked out. Among 1754 patients with monolateral detachment of the retina in twin eyes subjected to prophylactic laser coagulation of the retina, only in 5 cases subsequent retinal detachment was recorded. It is shown that prophylactic laser coagulation of the retina allows to minimize the threat of retinal detachment in predisposed eyes.

Adolescent↗
PubMed1987

Permeability of the blood-retinal barrier to carboxyfluorescein in eyes with rhegmatogenous retinal detachment.

Outward and inward permeability of carboxyfluorescein across the blood-retinal barrier were measured fluorophotometrically in seven cynomolgus monkey eyes with experimental rhegmatogenous retinal detachment. Probenecid was used to inhibit outward transport of carboxyfluorescein. The outward permeability was 1.98 +/- 0.31 microliter/min in eyes with retinal detachment and 0.84 +/- 0.15 microliter/min in control eyes with vitrectomy alone (P less than 0.01). The inward permeability, determined separately following intravenous injection, was significantly lower than the outward permeability: 0.14 +/- 0.02 microliter/min for eyes with retinal detachment and 0.04 +/- 0.01 microliter/min for control eyes. Since the outward permeability minus the inward permeability in the presence of probenecid represents that fraction of tracer moving due to fluid flow, it may be concluded that outward flow of fluid across the blood-retinal barrier is a substantial contributor to carboxyfluorescein loss from the vitreous cavity following intravitreal injection.

Animals↗