Development Of Tractional Retinal Detachment Research Articles

Safety and efficacy of intravitreal anti vascular endothelial growth factor for severe posterior retinopathy of prematurity with flat fibrovascular proliferation.

Intravitreal anti-vascular endothelial growth factor (IVA) injection is known to cause contraction of fibrovascular proliferation (FVP), when present in severe retinopathy of prematurity (ROP). To assess the structural outcomes of IVA injection in the treatment of severe posterior ROP with significant FVP. It was a retrospective study in which 36 eyes of 18 preterm babies who developed > 4 clock hours of FVP in zone I or posterior zone II, were treated with either intravitreal 0.625 mg bevacizumab or intravitreal 0.2 mg of ranibizumab. Favorable structural outcome included resolution of plus disease and FVP without the development of tractional retinal detachment. Secondary outcome measure included either full retinal maturation at follow-up or development of recurrent disease requiring additional treatment. Adverse outcomes included progression to retinal detachment. The mean gestational age of the 18 preterm babies was 30 wk (range 27-36), and mean birth weight was 1319 g (range 650-1980 g). Mean post-menstrual age (PMA) at the time of primary treatment was 35.5 wk (range 31-41 wk). All eyes showed regression of plus disease and FVP. 5 eyes of 3 babies showed reactivation of disease and were treated with repeat IVA (n = 2 eyes) or peripheral laser photocoagulation (n = 3 eyes) respectively. 16 out of 36 (44%) reached retinal vascular maturation at final follow up at 5 years. There was good resolution of severe posterior ROP with FVP with IVA, with retinal maturity of 44% at 5 year follow-up and a reactivation rate of 13.8%. When the IVA injection is given prior to 37 wk PMA, while disease is in phase 2, it is less likely to cause contracture of pre-existing FVP.

From the Hypotheses to Clinical Evidence in Retinal Therapy.

The off-label, therapeutic use of intravitreal bevacizumab (IVB) in vascular retinal diseases such as diabetic macular edema and proliferative diabetic retinopathy (PDR) has increased significantly due to its ability to reduce retinal neovascularization and slow progression of disease. Here, we will review the literature and investigative developments on the use of IVB as a preoperative adjuvant to vitrectomy in severe PDR, specifically focusing on its ability to reduce intra- and postoperative complications and its risk for progression or development of traction retinal detachment. In particular, this review will highlight the natural progression of evidence from case series and observations to prospective, randomized clinical trials.

Imaging the pediatric retina: An overview.

Recent decade has seen a shift in the causes of childhood blinding diseases from anterior segment to retinal disease in both developed and developing countries. The common retinal disorders are retinopathy of prematurity and vitreoretinal infections in neonates, congenital anomalies in infants, and vascular retinopathies including type 1 diabetes, tumors, and inherited retinal diseases in children (up to 12 years). Retinal imaging helps in diagnosis, management, follow up and prognostication in all these disorders. These imaging modalities include fundus photography, fluorescein angiography, ultrasonography, retinal vascular and structural studies, and electrodiagnosis. Over the decades there has been tremendous advances both in design (compact, multifunctional, tele-consult capable) and technology (wide- and ultra-wide field and noninvasive retinal angiography). These new advances have application in most of the pediatric retinal diseases though at most times the designs of new devices have remained confined to use in adults. Poor patient cooperation and insufficient attention span in children demand careful crafting of the devices. The newer attempts of hand-held retinal diagnostic devices are welcome additions in this direction. While much has been done, there is still much to do in the coming years. One of the compelling and immediate needs is the pediatric version of optical coherence tomography angiography. These needs and demands would increase many folds in future. A sound policy could be the simultaneous development of adult and pediatric version of all ophthalmic diagnostic devices, coupled with capacity building of trained medical personnel.

Analysis of Predisposing Clinical Features for Worsening Traction After Treatment of Familial Exudative Vitreoretinopathy in Children

To determine the incidence of worsening vitreoretinal traction after laser treatment for familial exudative vitreoretinopathy (FEVR) and to determine whether any baseline clinical features are associated with worsening. Retrospective cohort comparison study in a university tertiary referral center. All patients 0-21 years of age treated with laser from January 1, 2001, to June 1, 2018, were studied. Worsening traction after treatment was defined as the occurrence within 6months of worsening or development of tractional retinal detachment, folds, dragging, breaks, rhegmatogenous detachment, or worsening tractional membranes. Comparisons of baseline features between groups with and without worsening were performed to determine features associated with higher risk. A total of 46 eyes from 28 patients met inclusion criteria. Of the 46 eyes, 6 (13%) had worsening after treatment. There were no significant differences in age or other baseline demographics between the cohorts with and those without worsening traction. The presence of proliferative tissue in contact with the lens was found in 2 of 6 patients with worsening compared to 1 of 40 (3%) without worsening (P= .04). Mean follow-up was 57.8months (range, 6.6-134months). At the 6-month follow-up, median logMAR visual acuity in the cohorts with and without worsening was 1.7 (Snellen 20/1002; n= 5) and 0.24 (Snellen 20/35; n= 16), respectively. Laser treatment resulted in worsening traction in a substantial proportion of eyes with FEVR. Children with proliferative tissue in contact with the lens may be at higher risk of worsening after laser. Potential measures to reduce risk will require further study to establish efficacy.

Ziv-aflibercept versus bevacizumab administration prior to diabetic vitrectomy: a randomised and controlled trial

PurposeTo compare the effectiveness of intravitreal ziv-aflibercept (IVZ) to intravitreal bevacizumab (IVB) administered preoperatively to patients undergoing pars plana vitrectomy (PPV) for severe manifestations of proliferative diabetic retinopathy (PDR).DesignRandomised clinical...

Bevacizumab before Diabetic Vitrectomy: A Clinical Trial Assessing 3 Dosing Amounts

To evaluate the optimal dosing of preoperative intravitreal bevacizumab (IVB) in patients undergoing pars plana vitrectomy (PPV) for manifestations of proliferative diabetic retinopathy (PDR). Randomized clinical trial. Two hundred six patients with severe manifestations of PDR underwent PPV at a single university-based hospital. Patients were randomized into 1 of 3 treatment groups: group A received 0.625 mg IVB (0.025 ml) 1 to 10 days before PPV, group B received 1.25 mg IVB (0.05 ml) 1 to 10 days before PPV, and group C received 2.5 mg IVB (0.1 ml) 1 to 10 days before PPV. The primary outcome was best-corrected visual acuity (BCVA) at 6 months. Secondary outcome measures were rates of perioperative tractional retinal detachment (TRD) development, intraoperative and postoperative complications, and incidence of unplanned PPV at 6 months. One hundred sixty-seven patients underwent PPV and completed 6 months of follow-up. There were no significant differences between treatment groups regarding baseline characteristics, final BCVA, intraoperative complications, postoperative complications, or unplanned PPV rates. There were no patients in group A(0.0%), 3 patients in group B (7.0%), and 5 patients in group C (8.5%) who demonstrated perioperative TRD after IVB administration, but before PPV (P= 0.0283). This difference was significant between groups A and B (P= 0.0494) and between groups A and C (P= 0.0080). This randomized clinical trial demonstrated that patients receiving the 0.625-mg dose of IVB before PPV for the treatment of PDR-related manifestations showed similar visual acuity, but a lower incidence of perioperative TRD development compared with patients receiving the 1.25-mg and 2.5-mg doses. Clinicians should consider adopting the lowest effective dose, 0.625 mg, into clinical practice. The current study is limited by the lack of a control group receiving no IVB before PPV.

Role of Retinal Pigment Epithelial Cell β-Catenin Signaling in Experimental Proliferative Vitreoretinopathy

Proliferative vitreoretinopathy is caused by the contraction of fibrotic membranes on the epiretinal surface of the neurosensory retina, resulting in a traction retinal detachment and loss of visual acuity. Retinal pigment epithelial (RPE) cells play an important role in formation of such fibrotic, contractile membranes. We investigated the role of Wnt/β-catenin signaling, a pathway implicated in several fibrotic diseases, in RPE cells in proliferative vitreoretinopathy. In vitro culture of swine RPE sheets resulted in nuclear translocation of β-catenin in dedifferentiated RPE cells. FH535, a specific inhibitor of β-catenin signaling, reduced the outgrowth of cultured RPE sheets and prevented dedifferentiated RPE cell proliferation and migration. It also inhibited formation of contractile membranes by dedifferentiated RPE cells on collagen I matrices. Expression and function of the β-catenin signaling target connexin-43 were down-regulated by FH535, and functional blockade of connexins with carbenoxolone also prevented the in vitro formation of fibrotic, contractile membranes. Intravitreal injection of FH535 in swine also inhibited formation of dense, contractile membranes on the epiretinal surface and prevented development of traction retinal detachment. These findings demonstrate that β-catenin signaling is involved in formation of contractile membranes by dedifferentiated RPE cells and suggest that adjunctive treatment targeting this pathway could be useful in preventing proliferative vitreoretinopathy.

Autocrine CCL2, CXCL4, CXCL9 and CXCL10 signal in retinal endothelial cells and are enhanced in diabetic retinopathy

This study aimed at examining the presence and role of chemokines (angiogenic CCL2/MCP-1 and angiostatic CXCL4/PF-4, CXCL9/Mig, CXCL10/IP-10) in proliferative diabetic retinopathy (PDR). Regulated chemokine production in human retinal microvascular cells (HRMEC) and chemokine levels in vitreous samples from 40 PDR and 29 non-diabetic patients were analyzed. MCP-1, PF-4, Mig, IP-10 and VEGF levels in vitreous fluid from PDR patients were significantly higher than in controls. Except for IP-10, cytokine levels were significantly higher in PDR with active neovascularization and PDR without traction retinal detachment (TRD) than those in inactive PDR, PDR with TRD and control subjects. Exploratory regression analysis identified associations between higher levels of IP-10 and inactive PDR and PDR with TRD. VEGF levels correlated positively with MCP-1 and IP-10. Significant positive correlations were observed between MCP-1 and IP-10 levels. In line with these clinical findings Western blot analysis revealed increased PF-4 expression in diabetic rat retinas. HRMEC produced MCP-1, Mig and IP-10 after stimulation with IFN-γ, IL-1β or lipopolysaccharide. IFN-γ synergistically enhanced Mig and IP-10 production in response to IL-1β or lipopolysaccharide. MCP-1 was produced by HRMEC in response to VEGF treatment and activated HRMEC via the ERK and Akt/PKB pathway. On the other hand, phosphorylation of ERK induced by VEGF and MCP-1 was inhibited by PF-4, Mig and IP-10. In accordance with inhibition of angiogenic signal transduction pathways, PF-4 inhibited in vitro migration of HRMEC. Thus, regulatory roles for chemokines in PDR were demonstrated. In particular, IP-10 might be associated with the resolution of active PDR and the development of TRD.

The novel use of decorin in prevention of the development of proliferative vitreoretinopathy (PVR)

The cytokine transforming growth factor-ß (TGF-ß) is a pivotal contributor to tissue fibrosis and a key cytokine in the pathogenesis of cellular transdifferentiation, epithelial-mesenchymal transition (EMT), and cell adhesion. This study evaluates the effect of decorin, a naturally occurring TGF-ß inhibitor, in an experimental rabbit model for proliferative vitreoretinopathy (PVR). Traumatic PVR was induced in 50 rabbits divided into ten groups (n = 5). One group (GI) reveals a control with no treatment after trauma. Groups (GII-GIV) consisted of subgroups receiving phacovitrectomy at three different time points; (a) at the time of trauma, (b) 1 week following trauma, and (c) 2 weeks following trauma. GIII and GIV received 100 μg or 200 μg decorin, respectively. PVR severity was scored from 0 to 4. The amount of fibrosis was quantified using JMicroVision© software. The control group GI developed severe PVR with tractional retinal detachment (TRD); (PVR score ≥2) in four rabbits out of five. Vitrectomy had a positive effect (p < 0.05) on PVR development when preformed immediately, however the developed fibrosis was high. The best results were obtained when surgery was used in conjunction with decorin that reduced both the PVR score and fibrosis development significantly (p < 0.05). Depending on dosage and time of vitrectomy, PVR could be completely avoided (PVR score = 0) in 16 rabbits out of 30. TRD was prevented in 13 rabbits out of 15 in GIII to 14 rabbits out of 15 in GIV. In decorin-treated eyes, vitrectomy outcome was best when preformed at 1 week after trauma. There were no drug-related toxic effects evident on clinical and histopathological examination. In conclusion, in this rabbit model of PVR, adjuvant decorin application during vitrectomy effectively reduces fibrosis and TRD development. In conjunction with no obvious histopathological toxicity signs, decorin represents a promising substance to inhibit PVR reactions.

Intravitreal bevacizumab for surgical treatment of severe proliferative diabetic retinopathy

The purpose of this study is to evaluate the role, the safety and the effectiveness of intravitreal bevacizumab (IVB) injections as an adjunct to vitrectomy in the management of severe proliferative diabetic retinopathy (PDR). Case-Control Study Randomized controlled trial performed on 72 eyes of 68 patients affected by vitreous haemorrhage (VH) and tractional retinal detachment (TRD), which occurred as a consequence of active proliferative diabetic retinopathy (PDR). We randomly assigned eligible patients in a 1: 1: 1 ratio to receive a sham injection or an intravitreal injection of 1.25 mg of bevacizumab, either 7 or 20 days before the vitrectomy. In order to obtain three homogeneous groups of surgical complexity, we assigned to the following preoperative parameters a score from 0 to 3: a) vitreous haemorrhage, b) prior retinal laser-photocoagulation, c) morphological types of retinal detachment such as focal, hammock, central diffuse, table-top. Complete ophthalmic examinations and color fundus photography were performed at baseline and 1, 6, 12, and 24 weeks after the surgery. Intraoperative management, safety, efficacy of IVB at different time injection as an adjunct to vitrectomy in the management of severe PDR RESULTS: Group A (sham injection): intraoperative bleeding occurred in 19 cases (79.1%), the use of endodiathermy was necessary in 13 patients (54.1%), relaxing retinotomy was performed on one patient (4.1%), and in four cases (16.6%) iatrogenic retinal breaks occurred. The surgical mean time was 84 minutes (SD 12 minutes). Group B (bevacizumab administered 7 days before vitrectomy): intraoperative bleeding occurred in two cases (8.3%) and the use of endodiathermy was necessary in two patients (8.3%). No iatrogenic breaks occurred during the surgery. The surgical mean time was 65 minutes (SD 18 minutes). Group C (bevacizumab administered 20 days before vitrectomy): intraoperative bleeding occurred in three cases (12.5%), the use of endodiathermy was necessary in three patients (1.5%), and an iatrogenic break occurred in one patient (4.1%) while the delamination of fibrovascular tissue was being performed. The surgical mean time was 69 minutes (SD 21 minutes). The average difference in the surgical time was statistically significant between group A and group B (p = 0.025), and between group A and group C (p = 0.031). At the end of the surgery, the retina was completely attached in all eyes. At the 6-month follow-up, we observed the development of tractional retinal detachment (TRD) in one out of 24 patients from group C (4%). A preoperative intravitreal injection of bevacizumab may represent a new strategy for the surgical treatment of severe PDR by reducing retinal and iris neovascularization: this would make surgery much easier and safer, thus improving the anatomical and functional prognosis. According to our study, the best surgical results are achieved performing the IVB 7 days preoperatively.

Morbus Eales – 10 Jahre Erfahrung mit einem seltenen Krankheitsbild

Eales' disease is an uncommon vasoproliferative retinal disease affecting otherwise healthy young men. We report on our treatment results in a large patients group with long-term follow-up. The treatment results in 50 eyes (35 patients) with Eales' disease, that were consecutively treated from May 1995 to August 2005, were analysed retrospectively. Recorded data included age, sex, race, association of systemic disease, medications, laboratory evaluation and the surgical treatment. Mean follow-up was 5.8 years (minimum: 3.2, maximum: 8.6 years). Systemic and laboratory evaluations detected a factor V Leiden mutation (4x), vestibuloauditory problems (1x) and migraine (1x). 10 eyes with peripheral non-perfusion, teleangiectasia and mild neovascularisations were treated by scatter laser photocoagulation alone. 18 eyes with advanced neovascularisations/vitreous haemorrhages received cryocoagulation too. 14 eyes with persistent or recurrent bleedings despite coagulation therapy and/or development of tractional retinal detachment were treated by vitrectomy. 5 of them received a silicone oil endotamponade. All eyes could be stabilised without further bleedings. Visual acuity increased in 25 eyes. Only 5 eyes showed a visual loss. The visual results (rate of improvements and the stages of visual acuity as well) were the best in those eyes that received vitrectomy. These results suggest that early retinal laser and cryocoagulation and - if necessary - vitrectomy in due time may led to a stabilised retina without further bleedings and visual improvement too. Coagulopathy could play a role in the pathogenesis of Eales' disease.

Efficacy of intravitreal injection of bevacizumab for severe retinopathy of prematurity: a pilot study

Aim:The aim of the study was to evaluate the short-term efficacy of intravitreal injections of bevacizumab for severe retinopathy of prematurity (ROP).Methods:A retrospective chart review was conducted of 23 consecutive...

Tractional retinal detachment following intravitreal bevacizumab (Avastin) in patients with severe proliferative diabetic retinopathy

Aims:The aim of this study was to report the development or progression of tractional retinal detachment (TRD) after the injection of intravitreal bevacizumab (Avastin) used as an adjuvant to vitrectomy...

The role of specific ROCK inhibitor in the prevention of experimental PVR in rabbits

To determine the effect of Y27632, a specific inhibitor of p160 Rho-associated coiled-coil forming protein kinase (ROCK), on experimental rabbit PVR. Cultured rabbit retinal pigment epithelial cells were used in the experiments. The effects of Y27632 on RPE alpha-SMA (smooth muscle actin) stress fiber formation were studied by immuno-fluorescent staining. An in vitro type I collagen gel contraction assay and MTT assay were used to detect the effect of Y27632 on RPE cell contractile force and proliferation. Cultured 6 th passage rabbit RPE cells were injected intravitreally to induce the PVR model and then followed injection of 50 micromol/L of Y27632. The presence of tractional retinal detachment (TRD) was assessed to evaluate the effect of this agent in vivo. Electroretinography and histological studies were performed after intravitreal injection of Y27632 into untreated eyes to evaluate toxicity. The results showed that Y27632 disrupted SMA stress fiber formation in the cultured RPE cells and impaired contractile force generated by RPE cells (t = 16.212, P < 0.01). Development of TRD was significantly reduced (P < 0.01) with 50 micromol/L of Y27632. No obvious histological or retinal functional damage was found in the Y27632-treated group. p160 ROCK specific inhibitor Y27632 decreased contractile force generated by RPE cells and attenuated PVR without significant side effect in rabbit. This reagent could be potential therapeutically method in the treatment of PVR.

Platelet-derived Growth Factor Receptor Kinase Inhibitor AG1295 and Inhibition of Experimental Proliferative Vitreoretinopathy

Purpose: Receptor tyrosine kinase (RTK) activation is critical for growth factor-mediated cell proliferation. The present study was designed to determine the effect of tyrphostin AG1295, a selective blocker of platelet-derived growth factor (PDGF) RTK, on proliferative vitreoretinopathy (PVR) development. Methods: Rabbit conjunctival fibroblasts cells (1 × 10 4) were seeded into 96-well plates and maintained in Dulbecco's modified essentialmedium (DMEM) with 0.5% fetal bovine serum. The cells were exposed to 50 ng/mL PDGF-AAor PDGF-BBor phosphate-buffered saline with or without AG1295 (1 μM, 10 μM, and 100 μM). After 3 days, the viable cells in each well were measured by 3,(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Homologous rabbit conjunctival fibroblasts were injected intravitreally, followed by injection of 100 μM of AG1295. The development of tractional retinal detachment (TRD) was assessed to evaluate the effect of AG1295 in vivo. Electroretinography and histologic studies were performed after intravitreal injection of AG1295 into untreated eyes to evaluate toxicity. Results: Two concentrations of AG1295 (10 and 100 μM) significantly inhibited rabbit conjunctival fibroblast cell growth stimulated by PDGF-AA or PDGF-BB in vitro. Development of TRD was significantly attenuated ( P < .01) with 100 μM of AG1295 until day 21. No significant histologic or retinal functional damage was found in the AG1295-treated group. Conclusions: PDGF receptor specific inhibitor AG1295 attenuated PVR without significant side effects in rabbits. This reagent could be a useful treatment to prevent PVR.

Transscleral diode laser in the treatment of retinopathy of prematurity.

To assess the outcome of contact transscleral diode laser (TSDL) in the treatment of threshold retinopathy of prematurity (ROP). TSDL was performed in 14 eyes of 8 babies who presented to the paediatric ophthalmic service at King's College Hospital between 1996 and 1997 with threshold ROP (median post-conceptual age 26 + 1 weeks, median birthweight 835 g) by a single surgeon. Follow-up ranged from 9 to 41 weeks (median 21 weeks). In 11 eyes (79%) regression of ROP occurred after a single laser treatment with a good anatomical outcome. In 3 eyes (21%) there was an unfavourable response with the development of traction retinal detachment. These include both eyes of one baby who rapidly progressed to stage IV ROP. One other eye developed a fibrotic band a few months after treatment. No significant complications of laser treatment were observed. These initial results indicate that TSDL photocoagulation is an effective and technically straightforward alternative to cryotherapy in the treatment of ROP.

Contraction of extracellular matrix by transdifferentiated retinal pigment epithelial cells, inducers and inhibitors

Transdifferentiated retinal pigment epithelial cells (RPE) display enhanced contractile potentials and have been implicated in the development of tractional retinal detachment. This study determines the activity of contraction-promoting factors, examines some involved mechanisms and evaluates inhibitors. Using an in vitro contraction assay, we demonstrated that collagen matrix contraction by transdifferentiated RPE cells is effectively stimulated by serum, platelet-derived growth factor and insulin-like growth factor-1. Endothelin-1 and transforming growth factor-beta 1 and -beta 2 have a more discrete or marginal effect. Tractional forces promoted by these peptides are completely protein synthesis dependent. Contraction stimulated by serum is only partly dependent on de novo protein synthesis, suggesting different active factors and/or pathways. Staurosporine, a broad-spectrum kinase inhibitor, effectively inhibited collagen matrix contraction by transdifferentiated RPE cells regardless of the promoter.

Inhibition of cell-induced vitreous contraction by synthetic peptide derived from the collagen receptor binding sequence.

Cell-mediated tractional retinal detachment (TRD) is the end result of various intraocular proliferative disorders. Interactions between cells and extracellular matrix via cellular surface receptors, integrins, play an important role. Anti-adhesion therapy has been suggested as a promising way to treat the integrin-dependent pathological events. We tested three synthetic peptides, Gly-Arg-Gly-Asp-Ser (GRGDS), derived from the fibronectin receptor binding domain; Try-Ile-Gly-Ser-Arg (YIGSR), from the laminin receptor binding domain, and Ala-Asp-Gly-Glu-Ala (ADGEA), from the collagen receptor binding domain, to evaluate their inhibitory effect on cell-mediated matrix attachment and vitreous contraction in vitro, and on cell-induced TRD in rabbit eyes in vivo. Indirect immunofluorescent stain demonstrated both bovine retinal pigment epithelial (RPE) cells and rabbit dermal fibroblasts expressed the alpha 2 beta 1, alpha 5 beta 1 and alpha 6 beta 1 integrins, the collagen, fibronectin, and laminin receptors, respectively. GRGDS exhibited a broad spectrum of inhibitory activity on RPE cell attachment to extracellular matrices. YIGSR specifically inhibited RPE cell attachment to laminin, whereas ADGEA inhibited RPE cell attachment to collagen type I and IV. ADGEA inhibited RPE cell-induced vitreous contraction in a dose-dependent manner, whereas GRGDS and YIGSR had no effect. ADGEA (1250 micrograms/mL) delayed the development of TRD but did not prevent it. ADGEA was nontoxic to cells and retina, as demonstrated by cytotoxicity tests and histological examination. The synthetic peptide, ADGEA, and its analogs may be potential candidates for the treatment of cell-mediated collagenous contraction in the ocular tissues.

Blood Coagulation Factor XIII Contributes to the Development of Traction Retinal Detachment

The blood coagulation factor XIII catalyzes the crosslinking of fibrin monomers at the end of the coagulation cascade. Additional functions are the enzymatic coupling of fibrinectin to itself, fibrin, and collagen. We located the two subunits of factor XIII in 20 surgically obtained periretinal membranes, using double label immunofluorescence microscopy. Both subunits of factor XIII could be detected in all specimens. The positive staining in all specimens examined prompted us to determine the source of factor XIII. The abundant fibroblastic cells did not contain factor XIII. Macrophages, half of which stained for the alpha-subunit of factor XIII could not account for the presence of factor XIII because these cells were not present in all specimens, and did not stain for the beta-subunit. Factor XIII is probably derived from the exudation of plasma and platelets through disrupted blood-ocular barriers. This is confirmed by the detection of both subunits in vitreous aspirates from patients with proliferative intraocular disorders (n = 15) by Western blotting.

Blood coagulation factor XIII contributes to the development of traction retinal detachment

The blood coagulation factor XIII catalyzes the crosslinking of fibrin monomers at the end of the coagulation cascade. Additional functions are the enzymatic coupling of fibrinectin to itself, fibrin, and collagen. We located the two subunits of factor XIII in 20 surgically obtained periretinal membranes, using double label immunofluorescence microscopy. Both subunits of factor XIII could be detected in all specimens. The positive staining in all specimens examined prompted us to determine the source of factor XIII. The abundant fibroblastic cells did not contain factor XIII. Macrophages, half of which stained for the alpha-subunit of factor XIII could not account for the presence of factor XIII because these cells were not present in all specimens, and did not stain for the beta-subunit. Factor XIII is probably derived from the exudation of plasma and platelets through disrupted blood-ocular barriers. This is confirmed by the detection of both subunits in vitreous aspirates from patients with proliferative intraocular disorders (n = 15) by Western blotting.