Fibrovascular proliferation and retinal detachment after intravitreal injection of activated macrophages in the rabbit eye

Injection of activated macrophages into the posterior vitreous of the rabbit induced vigorous fibrovascular proliferation over the optic disk and medullary rays, as demonstrated by 3H-thymidine autoradiography. One week after injection, endothelial cells and pericytes of the capillaries near the inner surface of the optic disk and rays were labeled; fibroblast-like cells, which were also labeled, migrated and formed vitreous strands. By the second week after injection, the fibrovascular tissue proliferated most actively, and traction medullary ray detachment and peripapillary retinal fold formation were observed. The cellular proliferation was accompanied by inflammatory cell infiltration. Glial cells within the optic disk, as well as retinal pigment epithelial cells beneath the detached retina, were labeled by 3H-thymidine. These results demonstrate that the fibrovascular proliferation originates from the vessel complex of the optic disk and medullary rays in this experimental model of retinal detachment.     

The development of vitreous membranes and retinal detachment induced by intravitreal carbon microparticles

We induced intravitreal cellular proliferation by injection of carbon microparticles (size 20–70 nm) into the vitreous of 21 eyes of 11 cynomolgus monkeys. Pathological changes were evaluated by light and electron microscopy. At 1 week, there was conspicuous cyclitis showing exudative separation of the nonpigmented and pigmented ciliary epithelium, inflammatory cells, mononuclear phagocytes, and premacular vitreous detachment. At 3 weeks, continued macrophagic response was accompanied by fibrovascular proliferation with ingrowth of vessels from the ciliary body into the vitreous. At 4–5 weeks, deposition of extracellular fibrous material and traction retinal detachment (RD) were found. At 10 weeks, all eyes had extensive RD with pre- and subretinal collagenous cellular membranes. Carbon-laden macrophages were aggregated over the optic disc and fovea with prepapillary neovascularization and cystoid macular edema. Thus, intravitreal fibrovascular proliferation, vitreous contraction, and RD were induced by inflammatory and phagocytic response to carbon particles.Presented in part before the Association for Research in Vision and Ophthalmology, Sarasota, Florida, 30 April 1986     

Perfluorooctylbromide (PFOB) as a vitreous substitute in non-human primates

We evaluated the toxicity of perfluorooctylbromide in the primate eye as a short-term postoperative vitreous substitute. Four eyes of 4 African green monkeys underwent complete vitrectomy and vitreous replacement with 1.5–2.0 ml of PFOB. One additional animal received BSS as a control vitreous substitute in one eye. Animals were examined twice weekly for clarity and consistency of the vitreous replacement substance. Anterior segment and lenses remained clear in all eyes, although in the immediate postoperative period one eye became inflamed and had a culture-negative vitritis. The other eyes showed a minimal anticipated postoperative vitreous inflammation. Emulsification of the PFOB began within 3 days of injection and progressed up to 3 weeks, precluding fundus examination and fluorescein angiography after 2 weeks. Eyes were enucleated and light microscopy performed at 2 days, 10 days, 33 days, and 45 days. No toxic effects to the retinal cells were detectable by histological examination, but perivasculitis of retinal vessels was noted at 45 days. Indirect examination was normal up to 10 days; thereafter, the fundus view was obscured by the emulsified PFOB. Because of cellular migration into the vitreous cavity and retinal perivasculitis, observed histologically, PFOB seems most suitable for intraoperative rather than postoperative use.Supported in part by U.S. Public Health Service grants EY07541 and EY02377 and NEI1F32EY06193-03 from the National Eye Institute, National Institutes of Health, Bethesda, MD, USA.     

Experimental traction retinal detachment in the cat

We developed a reproducible model of traction retinal detachment (TRD) in the cat eye by creating a serous retinal detachment and then injecting 2.5 × 10⁵ kitten dermal fibroblasts into the vitreous cavity at the site of a retinal wound. Serous detachments were produced by exposing an area of retina to focused light after intravenous injection of rose bengal (a photosensitizing dye). TRD developed rapidly within the first 2 weeks after fibroblast injection, accompanied by the formation of vitreoretinal strands and, to a lesser degree, epiretinal and/or subretinal proliferation. Histopathology demonstrated fibroblasts within the vitreous or along the posterior hyaloid face. Focal deposits of fibroblasts were occasionally found on the inner surface of the retina and/or in the subretinal space. Fibroblast proliferation was confirmed by uptake of radiolabeled thymidine. Deposition of collagen was noted at as early as 3 days after fibroblast injection. Neovascularization was not observed. Control eyes that did not receive fibroblasts showed resolution of serous detachment without retinal traction. In all eyes, retinal degeneration and thinning were seen in the area of previous photodynamic treatment. In this model of TRD, anteroposterior traction (due to vitreous strands) predominates, as is observed in experimental posterior penetrating ocular injury induced by intravitreal blood injection, which also results in vitreous strand formation. Our model, however, enables clinical assessment of TRD in the cat without the media opacification produced by vitreous blood. Offprint requests to: D.L. HatchellSupported by VA medical research funds, NIH research grant EY02903, core grant EY05722, the Helena Rubinstein Foundation, New York, and Research to Prevent Blindness, Inc., New York. Dr. D.L. Hatchell is a Research to Prevent Blindness, Inc., Senior Scientific Investigator. The authors have no commercial or proprietary interest in the chemicals, drugs, or devices used in this study     

Calcein: A new dye for evaluation of the blood-retinal barrier by fluorophotometry

A vitreous fluorophotometry study was performed on rabbits to compare the characteristics of carboxyfluorescein and calcein with those of sodium fluorescein. Our results demonstrated that carboxyfluorescein and calcein attained mid vitreous concentrations similar in magnitude to fluorescein approximately one hour after injection of the dye. As long as three to four hours after injection of the dye, the mean fluorescence levels of calcein in the chorioretina were much higher than those of sodium fluorescein and carboxyfluorescein. These results point out that calcein has potential experimental and clinical use as a probe of the blood-ocular barrier as well as in experimental and clinical angiography of the fundus.Supported in part by U.S. Public Health Service grants EY07541 and EY02377 from the National Eye Institute, National Institutes of Health, Bethesda, MD, USA     

Natural history of penetrating ocular injury with retinal laceration in the monkey

In one eye each of four cynomolgus monkeys, an 8-mm penetrating injury was made through the equator; there was retinal perforation with vitreous loss. None of the four eyes with this injury developed posterior vitreous detachment or retinal detachment during a follow-up period of 8 months to 1 year.Another group of 26 monkeys had the same injury but also had 0.5 ml autologous whole blood injected into the vitreous at the time of injury. The eyes were examined weekly and enucleated at scheduled intervals from 1 day to 52 weeks post-injury. Posterior vitreous detachment occurred at the earliest at 2 weeks post-injury, and was ultimately present in 91% of the eyes. Vitreous detachment can occur either as a separation at the level of the internal limiting membrane or as a cleavage within the cortical vitreous. Retinal detachment occurred at the earliest at 8 weeks post-injury, and eventually was present in 50% of the eyes. The retinal detachment was tractional; no retinal breaks were detected in any of the eyes.This study was supported by grants EY02061 and EY03040 from the National Institutes of HealthPresented at the 1984 meeting of the Club Jules Gonin in Lausanne, Switzerland     

Vitreoretinal juncture over retinal vessels

Summary Previous studies have attributed changes in the retinal surface over or adjacent to large superficial retinal vessels to a variety of conditions, the most common being anomalous vitreoretinal attachments. The fundamental nature of the lesions and their pathogenesis, however, has remained controversial. The present study was undertaken to categorize the ultrastructural alterations of the vitreoretinal juncture over retinal vessels in the posterior fundus of man, and to clarify the relationship of these fundamental changes to clinically significant lesions in this region.Results show no difference in vitreoretinal, or more specifically vitreolaminar attachments over vessels when compared with adjacent regions. The cause of the more significant anomalies, notably surface breaks and their sequelae, is apparently multifactorial and related to a sequence of events. Initially three events predispose to or cause small surface breaks: developmental thinning of the inner limiting lamina; subsurface retinal degeneration; and transmigrating macrophages. These small surface breaks, when complicated by vitreous incarceration or by simple epiretinal membrane formation, can during posterior vitreous detachment cause peeling of the retinal surface, and the resulting large surface breaks may in turn provoke more complex proliferative lesions of the vitreoretinal juncture.This investigation was supported in part by U.S. Public Health Service research grants EY 00331, EY 01090, and EY 00725 from the National Eye Institute, National Institutes of Health     

Vitreous macrophage elicitation: generation of stimulants for pigment epithelium in vitro

Vitreous and macrophage samples were tested for the ability to stimulate proliferation and cell migration in cultured rabbit retinal pigment epithelium (RPE). A macrophage invasion was elicited by the intravitreal injection of latex particles in rabbits and after 3 days the vitreal macrophages were collected. The macrophages themselves, macrophage-conditioned culture medium, and macrophage-incubated vitreous had modest effects on RPE proliferation, but significantly stimulated RPE migration. A portion of the migration activity may be due to macrophage-derived proteases acting on normal vitreous. Mitogenic and additional migration-stimulating activity may also arise from adjacent tissues or from a breakdown of the blood-vitreous barrier that accompanies a macrophage invasion. A macrophage ingress into the vitreous may provide part of the stimulation for the migration and proliferation of RPE in conditions such as proliferative vitreoretinopathy.     

Subretinal strands: Ultrastructural features

This report describes the histologic and ultrastructural features of 13 subretinal strands removed during vitreous surgery for retinal detachment with proliferative vitreoretinopathy. On the surface of the subretinal strands, retinal pigment epithelial cells were found that maintained their cellular characteristics. Inside the strand were modified pigment epithelial cells, fibroblasts, fibrocytes, myofibroblasts, macrophages, basal lamina material, fibrin, and often large amounts of collagen. In some strands, the basal lamina material was similar to the types found in Drusen and in the inner layer of bruch's membrane. Glial cells were rarely found in these strands.Supported by the National Institute of Health, EY02903, Research to Prevent Blindness, Inc., New York, and the Helena Rubinstein Foundation, New York     

Triamcinolone acetonide facilitates removal of the epiretinal membrane and separation of the residual vitreous cortex in highly myopic eyes with retinal detachment due to a macular hole

PURPOSE: To study the usefulness of intravitreal triamcinolone acetonide injection during vitrectomy in highly myopic eyes with retinal detachment due to a macular hole. METHODS: Pars plana vitrectomy was performed in 6 patients with retinal detachment resulting from a highly myopic eye with a macular hole. After separation of the posterior hyaloid and removal of any visible epiretinal membrane, triamcinolone acetonide was injected over the posterior pole. Excised specimens were evaluated by transmission electron microscopy. RESULTS: Upon injection of triamcinolone acetonide, the entire epiretinal membrane and residual vitreous cortex could be visualized in all patients. The epiretinal membrane and residual posterior vitreous cortex were completely removed. Successful reattachment was performed without retinal damage in all cases. Electron microscopy revealed a cellular epiretinal membrane within a collagenous matrix lining the smooth internal surface of the internal limiting membrane. No complications related to the use of triamcinolone acetonide were encountered. CONCLUSION: Intraoperative visualization of the epiretinal membrane and residual posterior vitreous cortex with triamcinolone acetonide was found to be a useful adjunct to vitrectomy. Using triamcinolone acetonide during vitrectomy may facilitate both removal of the epiretinal membrane around the macular hole and separation of the residual vitreous cortex from the retina in highly myopic eyes with retinal detachment.     

Epiretinal pathology of vitreomacular traction syndrome

AIMS: To investigate the ultrastructure of the vitreoretinal interface in patients with vitreomacular traction syndrome. METHODS: 14 patients with vitreomacular traction syndrome underwent standard pars plana vitrectomy. After induction of posterior vitreous detachment, epiretinal tissue and the inner limiting membrane (ILM) of the retina were removed, and processed for transmission electron microscopy. RESULTS: Ultrastructural analysis revealed two basic patterns of vitreoretinal pathology in eyes with vitreomacular traction syndrome. Seven specimens showed mostly single cells or a cellular monolayer covering closely the vitreal side of the ILM, not resulting in a biomicroscopically detectable epiretinal fibrocellular proliferation. The other seven specimens revealed premacular fibrocellular tissue which was separated from the ILM by a layer of native collagen, resembling the clinical features of idiopathic epiretinal membranes. In both groups of eyes, the myofibroblast was the predominant cell type. Fibrous astrocytes and fibrocytes were less frequent. Retinal pigment epithelial cells and macrophages were absent. Deposits of newly formed collagen were present only adjacent to fibrocellular multilayers. CONCLUSIONS: There are two distinct clinicopathological features of vitreomacular traction syndrome which suggest different forms of epiretinal fibrocellular proliferation: (1) epiretinal membranes interposed in native vitreous collagen and (2) single cells or a cellular monolayer proliferating directly on the ILM. The presence of remnants of the cortical vitreous which remain attached to the ILM following posterior vitreous separation may determine the clinicopathological feature of the disease. The predominance of myofibroblasts may help to explain the high prevalence of cystoid macular oedema and progressive vitreomacular traction characteristic for this disorder.     

Effect of piroxicam on the blood-retina barrier in experimentally induced diabetes in rats

The effect of piroxicam on the blood-retina barrier was evaluated in rats with experimentally induced diabetes. Diabetes was induced in rats by intraperitoneal injection of streptozocin (STZ). Diabetic rats were divided into two equal groups: those treated with piroxicam, a long-acting platelet inhibitor, and an untreated control group. Vitreous fluorophotometry (VFP) was performed both before and two weeks after induction of diabetes and piroxicam intake. Streptozocin-induced diabetes caused an alteration in the blood-retinal barrier evidenced by an increase in vitreous fluorescein concentration in diabetic rats compared with normal rats. Piroxicam intake did not lead to significant change in vitreous fluorescein concentrations. However, the examination had to be terminated at two weeks because of cataract formation. The piroxicam treated group showed less incidence of lens opacity formation (59.1% compared to 81.8% in the untreated group, p = 0.0006). Piroxicam administration appears to protect the diabetic rat eye against lens opacification.This work was supported in part by U.S. Public Health Service Grants EY02377, EY07541 and EY08137 from the National Eye Institute, National Institutes of Health, Bethesda, MD and by the Juvenile Diabetes Foundation International and Pfizer, Inc.     

Intravitreal penetration of oral pefloxacin in humans

We measured vitreous and serum levels of pefloxacin after oral administration. Twenty patients with retinal detachments undergoing vitrectomy were recruited into this study. Each patient received 400 mg pefloxacin orally 1 to 12 hours before vitrectomy. Vitreous fluid (0.1 mL) was aspirated at surgery. Vitreous levels of pefloxacin were determined by high-performance liquid chromatography. Six hours after oral administration, an average level of 1.37 g/mL of pefloxacin was measured in the vitreous samples. These levels were well above the minimum inhibitory concentration (MIC) for most organisms termed sensitive to pefloxacin. Oral administration of pefloxacin may play an important role in the prevention or management of endophthalmitis.Supported in part by U.S. Public Health Service grants EY07541 and EY02377 from the National Eye Institute, National Institutes of Health, Bethesda, MD, USA.     

Experimental epiretinal membranes induced by intravitreal carbon particles

We injected 20-nm carbon particles into the vitreous of 14 young rabbits that were killed eight to ten weeks later. Histologic examination showed partial posterior vitreous detachments, epiretinal cellular proliferation, and membranes in all eyes and retinal detachments in five eyes. Electron microscopy disclosed that the epiretinal membranes were formed mainly by Müller cell expansions, astrocytes, and macrophages. Müller cells penetrated the internal limiting membrane and removed carbon particles from the vitreous by endocytosis. The experiments indicated that gaps are produced in the internal limiting membrane by glial cells and macrophages that invade the vitreous in an attempt to remove foreign material. The experimental epiretinal membranes resembled idiopathic preretinal gliosis or macular pucker.     

Measurement of cellular proliferation within the vitreous during experimental proliferative vitreoretinopathy

Cellular proliferation is an important component in the pathogenesis of complex retinal detachments caused by proliferative vitreoretinopathy (PVR). We used flow cytometry to measure the proliferation of cells recovered from the vitreous cavity in an experimental model of tractional retinal detachment induced by homologous fibroblast injection. Two distinct populations of cells were detected. One population comprised smaller, dense cells representing mostly leukocytes. A second population of larger cells contained not only the injected fibroblasts but also high concentrations of host-derived cells with significant proliferative activity, whose number increased for 3 days following injection. Flow cytometry was useful for analysis of the recovered cells for concentration, morphologic features and proliferation. This technique may be applicable in the identification of patients at high risk for the development of PVR.Presented in part at the annual meeting of the Association for Research in Vision and Ophthalmology, Sarasota, Florida, May 1, 1990. This work was supported by USPHS grants EY00308 (SWC) and EY02180 Offprint requests to: S.W. Cousins     

Double visualization using triamcinolone acetonide and trypan blue during stage 3 macular hole surgery

PURPOSE: To study the usefulness of intravitreal injection of triamcinolone acetonide and trypan blue for facilitating visualization and dissection of the posterior vitreous cortex and internal limiting membrane (ILM) during vitrectomy in idiopathic stage 3 macular holes. METHODS: Pars plana vitrectomy was performed in 10 eyes of 10 patients with idiopathic stage 3 macular holes. After core vitrectomy had been performed, triamcinolone acetonide was injected over the posterior pole. After separation of the visualized posterior vitreous cortex, trypan blue was injected over the macular area. Excised specimens were examined by electron microscopy. RESULTS: Upon injection of triamcinolone acetonide, the posterior vitreous cortex and residual vitreous cortex could be visualized in all patients. The posterior vitreous cortex and residual vitreous cortex were completely removed. The ILM of the retina was stained faint blue and was successfully removed in all patients. Electron microscopy revealed that the triamcinolone-acetonide-visualized layer and the trypan-blue-stained layer had different histological features. No complications related to the use of triamcinolone acetonide and trypan blue were encountered. CONCLUSION: Double visualization of the posterior vitreous cortex and ILM using triamcinolone acetonide and trypan blue during vitrectomy may facilitate separation of the posterior vitreous cortex from the retina and removal of the ILM around the macular hole in patients with idiopathic stage 3 macular holes.     

血液不同成分对眼后节穿孔伤眼内细胞增生的影响

将自体血液的不同成分,即血红蛋白、白细胞和血清分离后分别注入兔眼穿孔伤模型的玻璃体内,结果表明血红蛋白和白细胞都使90%以上的眼出现玻璃体内纤维血管增生。增生的细胞主要来源于巩膜伤口,一些来源于无色素睫状上皮和视盘表面。白细胞注入组眼内增生较明显。血红蛋白注入后出现以巨噬细胞为主的炎症反应。血清对眼内增生的影响不显著。提示炎细胞在外伤性眼内细胞增生中起重要作用。     

Noninvasive monitoring of intraocular pharmacokinetics of daunorubicin using fluorophotometry

Purpose. Daunorubicin is a cytotoxic drug, which, in nontoxic doses, is effective in preventing cellular proliferation in experimental vitreoretinopathy. We studied dose and clearance of daunorubicin in various ocular tissues using fluorophotometry techniques. Methods. In vitro tests: The emission of fluorescence from the daunorubicin solution having a concentration range of 0.1 to 10 g/mL in phosphate buffer was measured using an excitation wavelength range of 489 ± 10 nm. The emission of fluorescence was measured at 514 nm; the linearity of the response was determined using linear regression analysis. There is a fluorescence peak of daunorubicin at 485 nm. The validity and reproducibility of the method were examined. In vivo tests: The rabbits were randomized into three groups and daunorubicin concentrations of 4, 6, or 8 g/mL were injected into the vitreous. Fluorophotometry scanning from the retina to the anterior chamber was performed with a commercially available fluorophotometer at various times up to 48 hours after injection to quantify fluorescence emission of daunorubicin. Results. The standard curve of fluorescence versus concentration of daunorubicin was linear in the range of 0.1 to 8 g/mL. It was sensitive up to 0.1 g. The daunorubicin time concentration profile showed a dose response relationship over the 48-hour period studied. The half-life of daunorubicin in the vitreous was about 5 hours. Conclusion. We performed fluorophotometry using a fluorophotometer whose exciter emits light at 489 nm, which is very close to an absorption peak of daunorubicin. These two values are close enough to obviate the need for modifying the commercial fluorophotometer. Therefore the concentration of daunorubicin in the vitreous cavity can be measured noninvasively.Supported in part by U.S. Public Health Service grants EY07541, EY08137, and EY02377 from the National Eye Institute, National Institutes of Health, Bethesda, MD, USA.     

Heterotransplantation of human uveal melanoma

Cell lines established from the biopsy specimen of a patient with a spindle B choroidal melanoma were transplanted into the posterior choroid of 30 immunosuppressed, pigmented New Zealand rabbits. Growth of the tumor xenografts could be seen 7 to 10 days after transplantation. Tumor xenografts were reproducible and reached an average size of 5 mm in height and 8 mm in their basal dimension by 4 weeks. Histopathology of the original tumor revealed primarily spindle B cells, while the tumor xenografts contained epithelioid, spindle B, and clear cell melanoma cells. Of particular interest was the presence of an extensive and intact vasculature and the absence of a capsule surrounding the lesions in situ. The use of human uveal melanoma cells, the ease of transplantation, and the posterior location of the tumor may make this animal model of use in studies on new diagnostic and therapeutic modalities.This study was supported in part by NIH Grant R01EY08001-01A2 from the National Institutes of Health     

23G玻切术治疗PDR术后早期出血的危险因素分析

目的：分析23G玻璃体切割术治疗增生型糖尿病视网膜病变(PDR)术后早期发生出血的危险因素。

方法：回顾性分析2016-06/2018-01于我院行23G玻璃体切割术治疗的PDR患者100例100眼的临床资料,根据术后早期(1mo内)是否发生玻璃体出血分为早期玻璃体出血组(27例)和无玻璃体出血组(73例),分析术后早期发生玻璃体出血的危险因素。

结果：两组患者年龄、术前抗VEGF治疗、术前存在纤维血管膜增殖、术中视盘新生血管出血、术中注入气体情况有明显差异(P<0.01),其中术前存在纤维血管膜增殖、术中存在视盘新生血管出血是导致术后早期出血的独立危险因素。

结论：23G玻璃体切割术治疗PDR术后早期玻璃体出血主要发生于眼底病变严重者,术前存在纤维血管膜增殖及术中视盘新生血管出血会增加其发生风险。