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Biomedical subjects

A Patz

Publications and source records attributed to A Patz.

At least 55 records · Page 3Linked to original sources
PubMed1984

Retinal neovascularisation: early contributions of Professor Michaelson and recent observations.

The late Professor I. C. Michaelson's pioneer contributions to the development and pathophysiology of the retinal vasculature have laid the groundwork for a generation of ophthalmic research scientists to pursue this exciting field of investigation. In more recent studies it has been found that, in diabetic retinopathy, branch vein occlusion, sickle cell retinopathy, and retrolental fibroplasia, retinal neovascularisation follows the development of retinal capillary closure. The capillary closure or nonperfusion has been demonstrated by fluorescein angiography. A working hypothesis to explain the clinical and experimental observations is that these areas of nonperfused retina are ischaemic or hypoxic and liberate a theoretical angiogenic or vasoproliferative substance which stimulates the development of retinal neovascularisation. In postulating this working hypothesis it is important to recognise, firstly, that this hypothesis remains to be proved, and, secondly, that retinal neovascularisation may develop from other stimuli such as intraocular inflammation where retinal ischaemia is not apparent.

Angiogenesis Inducing Agents↗
PubMed1984

Current concepts of the effect of oxygen on the developing retina.

The role of oxygen in the development of retrolental fibroplasia and the mechanism of oxygen changes in the developing retina are discussed. The primary effect of oxygen is one of Vascular closure and the secondary response, which occurs after removal from increased oxygen, is retinal neovascularization. A brief discussion of recent observations on the potential role of vitamin E in the prevention of retrolental fibroplasia is presented.

Animals↗
PubMed1983

Current therapy of retrolental fibroplasia. Retinopathy of prematurity.

Retrolental fibroplasia, frequently referred to now as the "retinopathy of prematurity," has shown an increased incidence in recent years. This is apparently due to advances in neonatal care, which have resulted in a four- to five-fold improvement in the survival of the extremely low birthweight infants and it is these infants who are at the highest risk of developing retrolental fibroplasia. The use of large supplements of vitamin E, a known antioxidant, is discussed along with other forms of therapy.

Child↗
PubMed1983

An ocular clinicopathologic correlative study of six patients from the Diabetic Retinopathy Study.

The authors studied the eyes postmortem from six patients who were enrolled in the multicenter Diabetic Retinopathy Study and treated by photocoagulation. All were patients of the Wilmer Institute, The Johns Hopkins Hospital. Of these six patients, four had equal or better vision in the treated eye at their last visit. Two patients had worse vision, due primarily to cystoid macular edema. All but one patient had clinically significant field loss in the treated eye, and this correlated with the retinal damage induced by photocoagulation. This treatment produced local retinal and choroidal effects and did not alter the histopathologic appearance of the anterior segment of the eye.

Adult↗
PubMed1983

Irreversible visual loss in Waldenström's macroglobulinaemia.

A patient with Waldenström's macroglobulinaemia presented with visual reduction in both eyes. The funduscopic and angiographic demonstrations of venous engorgement ('string of sausages'), retinal haemorrhages at all levels, retinal and disc oedema, and serous detachment of the maculas were consistent with this diagnosis. The cryoprecipitation of the immunoglobulin at a temperature slightly below body temperature precluded routine blood studies and plasmapheresis. Plasmapheresis was ultimately performed without difficulty with the patient and equipment at 88 degrees F (31 degrees C). Despite marked improvement in the funduscopic and angiographic appearance of the retina, perifoveal capillary nonperfusion and serous elevation of the macula persisted. Even when the maculas flattened in both eyes, no visual recovery occurred. Early diagnosis, even on a clinical basis when laboratory studies cannot be performed, and early plasmapheresis to reduce serum viscosity are warranted to prevent intravascular occlusion in the perifoveal capillary bed, deposition of immunoglobulin in the retina, and transudation in the subretinal space.

Blood Viscosity↗
PubMed1983

Vitreous: an inhibitor of retinal extract-induced neovascularization.

One of the major problems in assessing neovascularization in mammalian experimental animal models is the immunologic response of the host to stimuli from nonautologous species. Hence, crude bovine vitreous and retinal extracts may produce a complex immune reaction when tested in the rabbit. To circumvent this problem, the chicken chorioallantoic membrane (CAM) assay is most appropriate. In this study the CAM assay for angiogenesis has been modified to study antiangiogenic substances. The modified assay is described in detail and used to demonstrate for the first time the inhibition by adult bovine vitreous of neovascularization induced by extracts of adult bovine retina. In addition to vitreous, three common glycosaminoglycans (keratan sulfate, chondroitin sulfate C, and hyaluronic acid) were assayed for antiangiogenic activity. The results indicate that vitreous inhibition of retinal extract-induced neovascularization is dose dependent, while the sulfated glycosaminoglycans tested had no antiangiogenic activity. A commercial preparation of bovine vitreous hyaluronic acid exhibited a slight, but not statistically significant, inhibitory activity. When vitreous extracts were digested with hyaluronidase, no loss of antiangiogenic activity occurred. These results suggest that the inhibitor of angiogenesis from adult vitreous is probably not a common glycosaminoglycan. The results are consistent with the hypothesis that antiangiogenic substance(s) in vitreous and angiogenic components from retina may act as natural antagonists in controlling the process of retinal neovascularization.

Animals↗
PubMed1982

Idiopathic preretinal gliosis.

Of 89 patients with idiopathic preretinal gliosis examined between 1970 and 1978, 52 were examined within six months of the onset of symptoms. Forty-seven patients were men and 42 were women; 83 (93%) were more than 50 years old. Initial visual acuities were 6/12 (20/40) or better in 60 of 98 eyes (61%). Nine patients had initial bilateral involvement, and the second eye became involved in one other patient during the follow-up period. Posterior vitreous detachment was present in 59 of the 64 eyes (92%) for which the state of the vitreous had been recorded; 16 of 74 eyes (21%) had fluorescein leakage into the macula. During a mean follow-up period of 31.1 months, the appearance of the fundus remained unchanged in 65 of 72 eyes (90%). Fifty-one of the 72 eyes (71%) had final visual acuities within one line of those recorded at the first examination. Spontaneous improvement of two lines or more occurred in only two patients, accompanied in both cases by an apparent decrease in the severity of the retinal wrinkling. Although these data indicated that idiopathic preretinal gliosis is generally a nonprogressive condition that does not cause serious visual loss, those patients followed up for more than three years did have a small overall decline in visual acuity.

Adult↗
PubMed1982

Clinical and experimental studies on retinal neovascularization. XXXIX Edward Jackson Memorial Lecture.

Retinal neovascularization is a serious complication of the retinopathy associated with diabetes, branch vein occlusion, sickle cell anemia, and retrolental fibroplasia. Retinal capillary nonperfusion, demonstrated on fluorescein angiography, precedes the development of neovascularization in each of these conditions. Our working hypothesis is that the nonperfused (ischemic or hypoxic) retina liberates a vasoproliferative or angiogenic substance. Although I have delineated the clinical and experimental observations relating to the hypothesis of an ischemic-mediated angiogenesis substance, other postulated mechanisms for the development of retinal neovascularization may be involved. Recent observations on the experimental model of retrolental fibroplasia have demonstrated the markedly abnormal persistence and apparent proliferation of the hyaloid vessels in mice following oxygen-induced retinal vascular closure.

Animals↗
PubMed1982

Natural course of choroidal neovascular membranes within the foveal avascular zone in senile macular degeneration.

We divided 96 eyes (93 patients) with senile macular degeneration and choroidal neovascular membranes into two groups--those with juxtafoveal membranes (1 to 250 mu from the center of the foveal avascular zone) and those with subfoveal membranes (0 mu from the center of the zone). After an average follow-up period of 21 months, one of 38 eyes in the juxtafoveal group (3%) had improved two or more lines on the Snellen chart, three eyes (8%) had remained the same, and 34 eyes (89%) had lost two or more lines on the Snellen chart. Although 35 of the 38 eyes (92%) had had initial visual acuities of 6/30 (20/100) or better, 27 eyes (71%) had become legally blind. Of the 58 eyes in the subfoveal group, 18 (31%) had remained the same or improved and 40 (69%) had lost two or more lines on the Snellen chart; 41 (70%) had final visual acuities of 6/60 (20/20) or worse. Of the 26 eyes in the subfoveal group that had had initial visual acuities of 6/60 (20/100) or better (45%). four (15%) had stayed the same and 22 (85%) had lost two or more lines on the Snellen chart. Fourteen of the 26 eyes (54%) had final visual acuities of 6/60 (20/200) or worse. Exudative maculopathy developed in the second eye in 13% of patients who initially had unilateral choroidal neovascularization after 12 months, in 22% after 24 months, and in 29% after 36 months, using life table analysis.

Adult↗
PubMed1982

Acute retinal necrosis syndrome.

Six patients with the acute retinal necrosis (ARN) syndrome are described. Ophthalmoscopic examination demonstrated occlusion of peripheral retinal vessels and patchy areas of peripheral retinal whitening spreading rapidly over a period of weeks to markedly decreased vision. In four patients, the disease was bilateral. Histologic examination of vitrectomy specimens from three cases and one enucleated eye revealed chronic granulomatous inflammation. Extensive medical evaluations were noncontributory, with no evidence of compromised immune systems. No patient demonstrated a response to any form of therapy. The etiology is unknown.

Acute Disease↗
PubMed1982

Current status of retrolental fibroplasia.

The improved survival of very premature infants is probably responsible for the moderate increase in incidence of RLF in the past few years. Because of the new cases of RLF, ophthalmologists should continue to focus their attention on this retinopathy of the premature infant. The pathogenesis of RLF and the role of oxygen, along with a brief discussion of newer concepts, are discussed.

Humans↗