Subretinal Fluid In Patients Research Articles

FREQUENCY AND ASSOCIATIONS OF A TAUT THICKENED POSTERIOR HYALOID, PARTIAL VITREOMACULAR SEPARATION, AND SUBRETINAL FLUID IN PATIENTS WITH DIABETIC MACULAR EDEMA

To determine prospectively among patients with diabetic macular edema (DME) the frequency of a clinically evident taut thickened posterior hyaloid (TTPH), optical coherence tomography (OCT) signs suggestive of partial vitreomacular separation (PVMS), and OCT evidence of subretinal fluid (SRF) and to investigate for associations between these findings. In a prospective case series, patients with DME despite previous laser treatment were examined for the presence of a TTPH. OCT was performed to investigate for PVMS and SRF. One hundred forty patients and eyes were included in the study. A TTPH was present in six patients (4%). PVMS was present in 14 (10%) of 140 patients with DME, of whom 5 also had a TTPH. SRF was present in 15 (11%) of 140 patients, of whom 4 had TTPH. OCT showed that 66% of patients with SRF and DME had neither a clinical TTPH nor partial posterior hyaloid separation. A TTPH was found in 4% of subjects with DME. Partial posterior hyaloid separation and SRF may be found in patients who do not have a TTPH. SRF in patients with DME may not be tractional.

Dexamethasone concentration in the subretinal fluid after a subconjunctival injection, a peribulbar injection, or an oral dose

Purpose To determine dexamethasone concentrations in the subretinal fluid of patients after a peribulbar injection, a subconjunctival injection, or an oral dose of dexamethasone and to compare the results with those of previous similar studies of dexamethasone concentrations in the vitreous. Design Prospective, nonrandomized, comparative trial. Participants One hundred forty-eight patients with a rhegmatogenous retinal detachment. Methods Fifty patients received a peribulbar injection of 5 mg dexamethasone disodium phosphate, 49 received a subconjunctival injection of 2.5 mg dexamethasone disodium phosphate, and 49 received an oral dose of 7.5 mg dexamethasone at various time intervals before surgery. At the time of surgery, a subretinal fluid sample was taken from each patient. Main outcome measures The dexamethasone concentration in the subretinal fluid measured by radioimmunoassay. Results The estimated maximum dexamethasone concentrations in the subretinal fluid after the peribulbar injection, the subconjunctival injection, and the oral dose were, respectively, 82.2 ng/ml (standard error, 17.6), 359 ng/ml (standard error, 80.2), and 12.3 ng/ml (standard error, 1.61). Corrected for dose, the maximum dexamethasone concentrations after subconjunctival injection and peribulbar injection were, respectively, 120 (95% confidence interval, 54/180) and 13 (95% confidence interval, 6.8/20) times greater than after oral administration. Conclusions A subconjunctival injection of dexamethasone disodium phosphate is more effective in delivering dexamethasone into the subretinal fluid of patients with a rhegmatogenous retinal detachment compared with peribulbar injection or oral administration. The subretinal dexamethasone concentrations were higher than concentrations measured in the vitreous in previous studies with a similar setup after all three delivery methods.

Comparative Studies of Morphological Changes and Interleukin Concentration in Subretinal Fluid of Patients with Retinal Detachment

Morphological evaluation was performed with the light and scanning electron microscope of subretinal fluids (SRF) collected during operations from 36 patients with rhegmatogenous retinal detachment. Duration of the disease was 3 weeks, 5–8 weeks, 10 weeks and 6 months. The immunoenzymatic method was used to establish the presence of interleukins IL-1β, IL-2, IL-4 and IL-6 in SRF. It was revealed that the differentiation of the morphological picture of SRF depended on the duration of detachment. Most cell-rich SRF came from the 3-week detachment. Mononuclear cells were predominant in that period (macrophages, lymphocytes). In the later period (over 8 weeks) a decrease in the number of cells and a change in cellular composition were noted in the fluids examined, while after six months of detachment normal cellular elements were absent. In all time intervals analyzed, no significant increase in IL-1β, IL-2 and IL-4 was noted in SRF. However, a significant quantity of IL-6 was found, particularly in the 5- to 8-week detachment. The authors assume that the presence of a large number of inflow cells in ‘fresh’ detachment can trigger a variety of inflammation-based immunological processes which stimulate the development of vitreoretinal proliferation.

Lipid peroxidation products and antioxidants in human disease.

Lipid peroxidation (LPO) is a free radical-related process that in biologic systems may occur under enzymatic control, e.g., for the generation of lipid-derived inflammatory mediators, or nonenzymatically. This latter form is associated mostly with cellular damage as a result of oxidative stress, which also involves cellular antioxidants in this process. This article focuses on the relevance of two LPO products, malondialdehyde (MDA) and 4-hydroxynonenal (HNE), to the pathophysiology of human disease. The former has been studied in human serum samples of hepatitis C virus-infected adults and human immunodeficiency virus-infected children. In these two cases it is shown that the specific assay of serum MDA is useful for the clinical management of these patients. The presence of MDA in subretinal fluid of patients with retinal detachment suggests the involvement of oxidative stress in this process. Moreover, we were able to report the dependence of this involvement on the degree of myopia in these patients. The assay of MDA contents in the peripheral nerves of rats fed a chronic alcohol-containing diet or diabetic mice also confirms the pathophysiologic role of oxidative stress in these experimental models. In these two cases, associated with an increase in tissue LPO products content, we detected a decrease of glutathione peroxidase (GSHPx) activity in peripheral nerve, among other modifications. We have demonstrated that in vitro HNE is able to inhibit GSHPx activity in an apparent competitive manner, and that glutathione may partially protect and/or prevent this inactivation. The accumulation of LPO products in the brain of patients with Alzheimer's disease has also been described, and it is on the basis of this observation that we have tried to elucidate the role of oxidative stress and cellular antioxidants in beta-amyloid-induced apoptotic cell death of rat embryo neurons. Finally, we discuss the possible role of the observed vascular effects of HNE on human arteries.

Proteinases in subretinal fluid.

Degradation of the extracellular matrix by secreted proteases is connected to cell migration and proliferation in invasive growth and in scar tissue formation. In retinal detachment, retinal pigment epithelium (RPE) cells loosened from their monolayer are often seen in the subretinal fluid (SRF) and the vitreous, where they may participate in the scar tissue formation of proliferative vitreoretinopathy. To evaluate the role of SRF constituents on the release of RPE cells, we analyzed SRF in patients with retinal detachment for the presence of enzymes able to degrade extracellular matrix. SRF was collected altogether from 16 patients undergoing retinal reattachment surgery and analyzed for activities against some of the key enzymes in extracellular proteolysis, namely collagenases, gelatinases, elastase and cathepsin G. Seventy-two-kilodalton gelatinase was found in all SRF samples studied, whereas the neutrophil-type 92-kDa gelatinase could not be detected. Low collagenase, elastase and cathepsin G activities could also be detected in some samples. The predominant type of matrix metalloproteinase present in SRF is the 72-kDa MMP-2. The proteolytic activity in SRF may be connected to the release of RPE cells into SRF and to degradation of components of the vitreous exposed to SRF.

Secretion of plasminogen activators by cells cultured from subretinal fluid

Secretion of plasminogen activators was examined in 11 cells cultures from subretinal fluid of patients with retinal detachment. The plasminogen activator production was compared to 4 retinal pigment epithelial cell cultures from post-mortem donors with no known retinal pathology. Plasminogen activator activity was evaluated by zymography and was corrected for the total cell protein in the cultures. Cells from subretinal fluid had more proteolytic activity and secreted more active urokinase-type plasminogen activator than retinal pigment epithelial cells of donor origin. It is possible that cells from subretinal fluid are modulated by the conditions in subretinal fluid to secrete more urokinase-type plasminogen activator, generally considered to be a sign of invasive growth or that the subretinal fluid cultures contain other cell types than solely retinal pigment epithelial cells, such as pigmented macrophages, with an active plasminogen activator production. Alternatively, retinal pigment epithelial cells detached into the subretinal fluid may represent a selected population of retinal pigment epithelial cells with a more active extracellular proteolysis.

Monoclonal antibodies to uveal melanoma.

Rat monoclonal antibodies were prepared against antigens expressed by uveal melanomas. Uncultured cells from primary human uveal melanomas were used for the rat inoculations and for the screening of hybridomas by enzyme-linked immunosorbent assay (ELISA). One of the monoclonal antibodies, designated 4A3, recognised a cytoplasmic antigen which was relatively specific for melanoma cells and which could be detected by immunohistochemistry in formalin-fixed, paraffin embedded tumour tissue. Western blotting showed the antigen to have a molecular weight of approximately 55-60 kD, with a doublet configuration which showed inter-tumour variation. The antigen was also detected by Western Blotting in the subretinal fluid of patients with uveal melanoma.

Lysosomal Hyaluronidase in the Subretinal Fluid of Patients with Rhegmatogenous Retinal Detachments

A biochemical analysis of 66 samples of subretinal fluid from patients with primary rhegmatogenous retinal detachment showed that 46 contained hyaluronic acid. Seventeen samples that did not contain hyaluronic acid disclosed hyaluronidase activity. Hyaluronidase activity in the subretinal fluid increased with the duration of the detachment but there was no correlation between enzyme activity and the age of the patient or the extent of the retinal detachment.

Source of subretinal fluid on the basis of ascorbate analyses.

Biochemical analyses of subretinal fluid revealed a consistently high ascorbate level in the subretinal fluid of patients with rhegmatogenous retinal detachment. The average values and SDs of ascorbate in anterior chamber aqueous humor, subretinal fluid, and blood were 14.7 +/- 1.8, 27.4 +/- 2.1, and 1.8 +/- 0.2 mg/dL, respectively. The ascorbate concentration in subretinal fluid was always higher than that in aqueous humor. The high ascorbate level in subretinal fluid led to the hypothesis that aqueous humor contributes to the formation of subretinal fluid. Presumably and constant absorption of subretinal fluid by the choroid directs a portion of the aqueous humor from the posterior chamber into the subretinal space. The posterior movement of aqueous humor causes reduced ascorbate concentration in the anterior chamber and relative hypotony of eyes with rhegmatogenous retinal detachment. Closing the retinal break results in an interruption of the posterior movement of aqueous humor and rapid absorption of the remaining subretinal fluid by the choroid.

Subretinal Fluid Butyrylcholinesterase: 1. Source of the Enzyme and Factors Affecting Its Concentration in Subretinal Fluid From Primary Rhegmatogenous Retinal Detachments

Three sources have been postulated for subretinal fluid (SRF) in primary rhegma­ togenous retinal detachment: vitreous,' de­ generating retina, and plasma transudate from the choriocapillaris.' The theory gen­ erally accepted has been that SRF is liquid vitreous which has percolated through a reti­ nal hole and dissected neural retina off the pigment epithelium.' However, there has been considerable morphologic and biochem­ ical evidence for multiple origins of SRF. Magitot described detached nerve and protoplasmic debris on light micros­ copy of SRF, and concluded that these ele­ ments came from the retina. Manna, Meyer, and Mielnik observed retinal pigment epi­ thelial and neuroretinal cells in the SRF of patients with recent rhegmatogenous detach­ ments, and ghost in fluid from cases of longer duration. Lindner demonstrated the anatomic con­ tinuity of vitreous and SRF through the ret­ inal hole. Proteins which are antigenically specific for vitreous have been identified in SRF. Ascorbic and lactic acids have been found in much higher concentrations in vitreous than in plasma, with SRF levels ly­ ing generally in between. Hyaluronic acid is present in vitreous but absent from plasma. It has always been found in SRF from primary rhegmatogenous detachments, at levels higher or lower than in vitreous.· Paufique showed that in some rhegma­ togenous detachments there appeared to be a leakage of acellular transudate from the cho­ riocapillaris into the subretinal space, com-