Intraocular silicone implant to treat chronic ocular hypotony: an in vivo trial.

PURPOSE: The management of chronic ocular hypotony and complicated proliferative vitreoretinopathy-related retinal detachment represents a challenge. Being non-absorbable and non-biodegradable, a silicone oil implant is expected to restore the volume and the intraocular pressure of the globe, as well as to approximate the detached retina. Further advantages could be a long-term tamponade potential, absence of toxicity, and prevention of silicone oil emulsification or anterior chamber oil-prolapse. The aim of this study was to assess the histological tolerance of the silicone oil implant in a pig model. METHODS: A seamless silicone balloon implant with optional surface modifications was developed. Mini pigs were used as experimental animals, and three variants of silicone implants with different surfaces were tested: uncoated, NCO-sP(EO-stat-PO) coated, and heparin-NCO-sP(EO-stat-PO) coated silicone implants. An extracapsular lens extraction was achieved via a standard phacoemulsification followed by a standard three-port vitrectomy. The implant was then placed in the posterior segment and filled with 5000 centistoke silicone oil. One month later, the pigs were euthanized, the eyes were enucleated, and histological specimens were prepared for microscopy. RESULTS: The analysis of the histology revealed that adverse histological changes in conjunctiva, cornea, iris, and ciliary body could be excluded in all eyes operated on regardless of which variant of implant had been employed. The retina as the implant-contacting ocular tissue showed overall good tolerance, although some inflammatory reaction and fibrous proliferation was evident in some cases. CONCLUSIONS: The silicone oil implant is a promising candidate and has the potential to fulfill clinical requirements to act as a long-term intraocular tamponade agent. The heparin-NCO-sP(EO-stat-PO) coating approach could lead to a novel bioactive surface for intraocular devices with excellent properties to hinder cell adhesion and protein adsorption, although further studies will be necessary to evaluate long-term biocompatibility and long-term resistance to biological attacks.

Intraocular silicone implant to treat chronic ocular hypotony-preliminary feasibility data.

PURPOSE: Ocular hypotony secondary to proliferative vitreoretinopathy-related retinal detachment, trauma or inflammation is difficult to treat. Besides endotamponades such as silicone oil, vitreous implants such as iris diaphragms or balloons have been developed to stabilize the eye and to prevent phthisis of the globe. Vitreous implants tested thus far exhibit a seam at the attachment site of the hemispheres, or micropores. This manuscript reports the development of a seamless silicone balloon implant without micropores, which can be filled with silicone oil and surface-modified to improve its biocompatibility. Developed for intraocular placement in the management of chronic hypotony and phthisis prevention, it may also be suitable for tamponading retinal detachments. METHODS: Silicone was used as the basic structure for the fabrication of a seamless balloon-shaped intraocular implant, which was coated by employing a six-arm star-shaped (sP) macromer of a copolymer of 80 % ethylene oxide (EO) and 20 % propylene oxide (PO) with conjugated functional terminal isocyanate groups, NCO-sP(EO-stat-PO), with and without heparin. Three variants of implants, which differ in their surfaces, were manufactured: uncoated silicone, NCO-sP (EO-stat-PO) coated silicone and heparin-NCO-sP (EO-stat-PO) coated silicone implants. To exert a tamponade effect, the implant was filled with silicone oil and its properties were studied. RESULTS: Seamless thin balloon implants made of silicone, which are considered biocompatible and intrinsically resistant to biological attacks in vivo, could be fabricated in different sizes. The silicone oil-filled implant can mimic the mechanism of buoyant force and high surface tension of silicone oil, which is the only long-term vitreous substitute currently available. The silicone oil-filled implant can also mimic the natural vitreous body by occupying the entire posterior segment. CONCLUSIONS: The intraocular silicone implant as an alternative long-term treatment of chronic ocular hypotony might offer a new option for clinical ophthalmological practice. In vivo studies need to be performed to collect more data on the implant's long-term mechanical and optical properties, as well as long-term biocompatibility.

Thrombophilia in patients with retinal vein occlusion: a retrospective analysis.

BACKGROUND: To assess the prevalence of thrombophilia in patients with central (CRVO) and branch retinal vein occlusion (BRVO). METHODS: In 139 patients with CRVO (n = 88) and BRVO (n = 51) and in 40 healthy controls factor VIII, fibrinogen, antithrombin III, protein C, protein S, activated protein C resistance, anticardiolipin antibodies (ACA), homocysteine, factor V Leiden, prothrombin G20210A and methylene tetrahydrofolate reductase (MTHFR) C677T mutation were assessed retrospectively. RESULTS: Elevated factor VIII activity and the homozygous MTHFR C677T mutation were significantly more often found in CRVO and BRVO cases compared to controls. Age-, gender- and C-reactive protein-adjusted logistic regression analysis did not show a significant additive effect of elevated factor VIII activity on the risk of developing CRVO/BRVO. Elevated fibrinogen levels and ACA were significantly more often found in CRVO than amongst controls. No significant differences were found concerning the remaining variables. CONCLUSIONS: We suggest elevated fibrinogen levels, ACA and the homozygous MTHFR C677T mutation as potential risk factors for CRVO/BRVO.

Human complement factor H and factor H-like protein 1 are expressed in human retinal pigment epithelial cells.

BACKGROUND: A common haplotype in the gene for the regulator of the alternative pathway of complement activation factor H has been linked to individual predisposition to age- related macular degeneration (AMD). METHODS: In this study, retinal pigment epithelial (RPE) cells, i.e. immortalized ARPE-19 as well as primary human RPE cells, were investigated for expression of factor H and FHL-1 by immunohistochemistry and in situ hybridization analysis. RESULTS: Factor H and the alternative spliced product FHL-1 are expressed in RPE cells, i.e. in immortalized ARPE-19 and primary human RPE cells. Factor H and FHL-1 expression was induced in a dose-dependent manner in ARPE-19 cells upon treatment with the inflammatory marker interleukin-6 (IL-6). In situ hybridization experiments confirmed an elevated expression rate of the factor H gene in IL-6-treated ARPE-19 cells. AMD is characterized by complement-associated inflammatory processes in the retina. Thus, local synthesis of complement regulators affects the protection of retinal cells and may be involved in the pathogenesis at the RPE-choroid interface.

Effects of coagulation on the autofluorescence pattern of ARPE-19 cells: an in vitro study.

OBJECTIVE: Changes in fundus autofluorescence (AF) are observed in various retinal disorders. Lipofuscin accumulation within the retinal pigment epithelium (RPE) is a source of fundus AF (FAF); however, the causes of short-term increases in FAF observed in inflammatory conditions or after laser treatment are unknown. Here, we describe an RPE cell culture model that is useful for investigations of FAF. METHODS: ARPE-19 cells were cultured in 2-well chamber slides. Cells were exposed to isolated rabbit photoreceptor outer segments (POS) to mimic in vivo phagocytic activity. The AF of RPE cells exposed to POS was measured before and after focal coagulation of the cultures. AF was measured over a period of 4 weeks. Cell lysates were examined by two-dimensional (2D) gel electrophoresis and mass spectrometry analysis. RESULTS: The exposure of ARPE cells to POS did not lead to increased AF; however, after coagulation, cells exposed to POS showed a statistically significant increase in AF (p < 0.05). 2D electrophoresis of the cell lysates revealed changes in 3 proteins. One of these proteins, identified by mass spectrometry as ezrin-radixin-moesin-binding phosphoprotein 50, was reduced in the coagulated cell population. CONCLUSIONS: We have established an in vitro model of RPE cells in culture that can be used to evaluate the development of AF and changes in cellular proteins that accompany laser photocoagulation.

Surface-modified silicone foils for intraocular implantation.

BACKGROUND: Implantation of silicone materials like iris diaphragms into the eye can be complicated by cell migration and attachment. We studied polydimethylsiloxane (PDMS) foils coated with isocyanate terminated, star-shaped poly(ethylene glycol-stat-propylene glycol) (NCO-sP(EO-stat-PO)) equipped with heparin towards the inhibition of cell attachment without influencing cell viability. METHODS: Mouse fibroblasts L929 were cultured and seeded onto sterilized pieces of either uncoated NCO-sP(EO-stat-PO) or heparin-NCO-sP(EO-stat-PO) loaded foils. Polyvinylchloride (PVC) foils served as the positive control and biomembranes as the negative control. The cultured cells were examined after 24 h for cell viability and adhesion by fluorescence microscopy; morphological cell changes were documented after hemalaun staining. Cell density was measured and quantification of cell proliferation was assessed by a BrdU test; quantification of cell activity was analyzed by a WST-1 test. RESULTS: The fibroblasts' cell viability was excellent on all tested foils except the toxic PVC foil. NCO-sP(EO-stat-PO) coating provided significantly reduced cell activity. On heparin-loaded coatings, cells were viable and less dense but showed almost the same cell proliferation and cell activity as on the negative control. NCO-sP(EO-stat-PO) coated, heparin loaded foils proved high biocompatibility and reduced cell adhesion. CONCLUSIONS: Both NCO-sP(EO-stat-PO)-coated foils with and without heparin seemed to be a viable implantation material for less cell migration, attachment, and reduced implant complications. Conclusive we give a recommendation for further studies on the intraocular implantation in particular for the NCO-sP(EO-stat-PO)-coated foils.

Improving the quality of multifocal visual evoked potential results by calculating multiple virtual channels.

PURPOSE: To introduce a method for improvement of multifocal VEP (mfVEP) recordings by prediction of waveforms at multiple positions on the surface of the skull. METHODS: Fifteen healthy participants (mean age 24 ± 3.8 years) underwent mfVEP recordings from 3 surface positions. Two methods of a best-of-mfVEP approach were used and compared. In the first, a standard procedure, further data from 3 calculated channels were used. In the second approach, mfVEPs were obtained by using data derived from 40 virtual electrode positions on the basis of predictions from dipole source calculations. RESULTS: The mean signal-to-noise ratios (SNRs) of the best-of-mfVEPs of both methods were compared. The SNR was significantly higher for mfVEP data using additional virtual recordings revealed by dipole source determination (2.87 vs. 3.36; P < 0.035). CONCLUSION: We conclude that multichannel prediction of mfVEP responses based on dipole source calculation significantly improves the quality of the examination results compared with the currently prevalent standard method.

Detection of heat shock protein 70 in choroidal neovascular membranes secondary to age related macular degeneration.

BACKGROUND: Heat shock proteins are acute phase proteins that are upregulated in inflammation or following thermal stress. We analyzed the presence of the heat shock protein 70 (Hsp 70) in choroidal neovascular (CNV) membranes secondary to AMD after treatment with verteporphin photodynamic therapy (PDT) or transpupillary thermo therapy (TTT) to determine whether treatment correlated with the presence of Hsp70. RESULTS: CNV membranes were removed by pars plana vitrectomy (ppV) and subretinal extraction. The membranes were analysed by light microscopy and the presence of Hsp 70 was examined using histochemistry. HeLa Cells served as controls.Of the 14 membranes analysed 11 were Hsp70 positive and 3 negative. In the no pre-treatment group of 8 membranes 6 were Hsp70 positive and 2 negative; in the PTD group all 4 membranes were positive and in the TTT group 1 membrane was positive and 1 membrane was negative for Hsp70. CONCLUSION: Hsp70 is present in the most CNV membranes secondary to AMD. Pre-treatment of the membrane with PTD or TTT does not appear to influence the expression of Hsp70.

CFH, C3 and ARMS2 are significant risk loci for susceptibility but not for disease progression of geographic atrophy due to AMD.

BACKGROUND: Age-related macular degeneration (AMD) is a prevalent cause of blindness in Western societies. Variants in the genes encoding complement factor H (CFH), complement component 3 (C3) and age-related maculopathy susceptibility 2 (ARMS2) have repeatedly been shown to confer significant risks for AMD; however, their role in disease progression and thus their potential relevance for interventional therapeutic approaches remains unknown. METHODOLOGY/PRINCIPAL FINDINGS: Here, we analyzed association between variants in CFH, C3 and ARMS2 and disease progression of geographic atrophy (GA) due to AMD. A quantitative phenotype of disease progression was computed based on longitudinal observations by fundus autofluorescence imaging. In a subset of 99 cases with pure bilateral GA, variants in CFH (Y402H), C3 (R102G), and ARMS2 (A69S) are associated with disease (P = 1.6x10(-9), 3.2x10(-3), and P = 2.6x10(-12), respectively) when compared to 612 unrelated healthy control individuals. In cases, median progression rate of GA over a mean follow-up period of 3.0 years was 1.61 mm(2)/year with high concordance between fellow eyes. No association between the progression rate and any of the genetic risk variants at the three loci was observed (P>0.13). CONCLUSIONS/SIGNIFICANCE: This study confirms that variants at CFH, C3, and ARMS2 confer significant risks for GA due to AMD. In contrast, our data indicate no association of these variants with disease progression which may have important implications for future treatment strategies. Other, as yet unknown susceptibilities may influence disease progression.

Retinal pigment epithelium tears after intravitreal bevacizumab in pigment epithelium detachment.

PURPOSE: To evaluate pigment epithelium detachment (PED) secondary to exudative age-related macular degeneration (AMD) treated with intravitreal injection of bevacizumab with regard to incidence of retinal pigment epithelium tears (RIPs). DESIGN: Retrospective, interventional case series. METHODS: Institutional study of 31 eyes with PED in exudative AMD receiving intravitreal bevacizumab. Main outcome measures were Early Treatment of Diabetic Retinopathy Study (ETDRS) visual acuity, PED vascularization and size measured by angiography and optical coherence tomography (OCT) imaging, and incidence of RIP. RESULTS: Vision improved in six eyes and remained stable in 22 eyes (follow-up, 12.3 +/- 10.3 weeks). Twenty-eight eyes showed a vascularized PED. Four eyes (12.9%) experienced an RIP without vision loss. All RIP cases were vascularized in more than 50% of total lesion size. CONCLUSIONS: In short-term follow-up, the risk for RIP after bevacizumab injection in eyes with PED seems to be moderately, but not statistically significantly, increased in PED lesions vascularized more than 50%.

Amplitude calculation in multifocal ERG: comparison of repeatability in 30 Hz flicker and first order kernel stimulation.

BACKGROUND: In multifocal flicker stimulation, each step of the M-sequence consists of four consecutive flashes with a frequency of 30 Hz. The resulting amplitudes can be calculated by means of a discrete fourier transformation (DFT). With this method, amplitudes can be calculated without having to localise peaks and troughs and set cursors. The purpose of this study is to compare the re-test stability of this method to conventional mfERG stimulation. METHODS: We examined 27 healthy subjects using a RETI-scan device (Roland Consult, Wiesbaden). We used 61 hexagons within a 30 deg. visual field. We compared the classic first order kernel (FOK) stimulation with the multifocal 30 Hz Flicker (mfFlicker-ERG) stimulation. Repeatability was calculated using coefficients of variation. RESULTS: Both methods had coefficients of 15% for the sum P1-amplitude and the DFT results, respectively. The amplitudes calculated by flicker and DFT were approximately 25% smaller than the FOK amplitudes. CONCLUSIONS: This study showed no difference of re-test repeatability between the mfFlicker-ERG and the conventional first order kernel method. Since the mfFlicker-ERG method does not require a definition of peaks and troughs in order to calculate the amplitudes, we believe that a common source of error is eradicated, especially when dealing with distorted or atypical curves.

Fundus near infrared fluorescence correlates with fundus near infrared reflectance.

PURPOSE: To analyze the occurrence of near infrared (NIR) fluorescence in relation to NIR reflectance, blue-light-excited autofluorescence, angiograms, and funduscopy. METHODS: Observational consecutive case series in patients with macular diseases. Imaging was performed with a confocal scanning laser ophthalmoscope for NIR reflectance, blue-light-excited autofluorescence, NIR fluorescence, and fluorescein and indocyanine green (ICG) angiograms. In cases in which NIR fluorescence was observed, five to nine images were averaged. The leakage of the scanning laser ophthalmoscope was analyzed. RESULTS: In the 291 eyes analyzed, NIR fluorescence was observed in 51 and was graded weak in 27 with wet age-related macular degeneration (AMD, 10 cases), dry AMD with pigment clumping (n=7), chronic central serous choroidopathy (CSC; n=5), choroidal nevi (n=2), subretinal hemorrhages (n=2), and chloroquine maculopathy (n=1). Strong NIR fluorescence was found in 24 eyes, with wet AMD (n=14), subretinal hemorrhages (n=8), and choroidal nevi (n=2). Except for four eyes, we observed a strong correlation of NIR fluorescence and increased NIR reflectance at identical fundus location (92.2%). NIR fluorescence corresponded with increased blue-light-excited autofluorescence in 21 of 31 patients with AMD and in 4 of 5 patients with chronic CSC, but in none of the 4 patients with nevi. Funduscopy showed that structures with NIR fluorescence were pigmented or consisted of degraded blood. Barrier filter leakage of the imaging system was 6.2x10(-6). CONCLUSIONS: The high correlation of NIR fluorescence and reflectance indicated that part of the observed NIR fluorescence is pseudofluorescence, whereas gray-scale analysis indicated that both NIR autofluorescence and pseudofluorescence contribute to the NIR fluorescence images. Quantification of leakage of the imaging system indicated a significant part of the observed NIR fluorescence is NIR autofluorescence. As NIR fluorescence derives from pigmented lesions, melanin is a possible source if NIR reflectance is also increased. Comparison with blue-light-excited autofluorescence showed differences between AMD and patients with nevi. NIR autofluorescence was also detected in single cases of maculopathy without corresponding NIR reflectance.

Translocation of iris pigment epithelium in patients with exudative age-related macular degeneration: long-term results.

PURPOSE: To report the practicability and efficacy of autologous iris pigment epithelium (IPE) translocation in exudative age-related macular degeneration (ARMD) over 1 year. METHODS: The consecutive interventional case series included 56 patients with exudative ARMD. During vitrectomy the submacular neovascular membrane (CNV) was removed and IPE cells, harvested from a peripheral iridectomy, were injected into the submacular space. Included were patients with subfoveal occult CNV (11 eyes), classic CNV (10 eyes), mixed CNV (17 eyes), CNV with a pigment epithelial detachment (13 eyes) or CNV with a hemorrhage (5 eyes). Outcome measures were visual acuity, foveal fixation, size of CNV and rate of recurrence based on fluorescence angiographic imaging. RESULTS: All patients underwent successful surgical removal of the CNV with consecutive subretinal IPE injection. Visual acuity was better than 20/100 in 19 patients preoperatively and in 18 patients postoperatively. A visual acuity of 20/100 or less was found in 37 patients preoperatively and in 38 patients postoperatively. Mean preoperative visual acuity (1.0+/-0.3 logMAR units) did not change significantly after 1 year (1.0+/-0.3 logMAR units). Ten eyes (18%) developed a recurrence. Fixation within the surgically denuded area could be demonstrated in 25 eyes (45%). CONCLUSIONS: Autologous IPE translocation for ARMD over one year can preserve foveal function on a low level, but cannot improve visual acuity. IPE translocation is technically feasible with a low rate of complications. Continued research seems justified to improve functional outcome.

Indocyanine-green-assisted internal limiting membrane peeling in macular hole surgery--a follow-up study.

BACKGROUND: Macular hole surgery including vitrectomy and peeling of epiretinal membranes and the internal limiting membrane (ILM) has become a standard procedure in retinal surgery. Poor visualization of the ILM is an obstacle for successful surgery. Recently, indocyanine green (ICG) has been reported to be a helpful intraocular substance in identifying these membranes. PATIENTS AND METHODS: Eighteen eyes with macular holes stages 2-4 were included. Intraoperatively, the ILM was stained with three drops of 1:9-diluted ICG. After 1 min incubation, the vitreous cavity was rinsed with Ringer's lactate solution, and the ILM was peeled. Autologous thrombocytes were applied to the macular hole and the eye was endotamponaded with 20% SF-6 gas. Preoperatively, 6 weeks postoperatively, and in 3-month intervals thereafter, visual acuity, fundus photographs, scanning laser ophthalmoscope imaging, and Humphrey 24-2 static perimetry was performed. RESULTS: Intraoperatively, the ILM could be nicely visualized by ICG, which allowed easier and less traumatic peeling. At 6 weeks follow-up, visual acuity had improved in 14 of 18 patients, and the macular hole was closed 6 weeks after surgery. Scanning laser imaging revealed a strong signal. During prolonged follow-up, visual acuity declined due to cataract formation. CONCLUSION: ICG as an intraocular tool for staining of the ILM is helpful in macular hole surgery. We observed no negative effects on retinal function, but patients should be followed.

[Treatment of Acute Central Retinal Artery Occlusion (CRAO) by Hyperbaric Oxygenation Therapy (HBO)--Pilot study with 21 patients]. / Behandlung akuter retinaler Zentralarterienverschlüsse (ZAV) mit der hyperbaren Sauerstofftherapie (HBO)--Pilotstudie an 21 Patienten.

BACKGROUND: Central retinal artery occlusion causes severe loss of vision. Treatment trials include massage of the globe, paracentesis, antiglaucomatous eye drops, haemodilution or lysis therapy, which in individual cases did improve the visual outcome, although in general the prognosis remains poor. In this study we applied hyperbaric oxygenation treatment additionally to haemodilution to overcome retinal ischaemia until spontaneous recanalisation of the central retinal artery occurs. PATIENTS AND METHODS: Patients with central retinal artery occlusion and onset of symptoms up to 12 h were included. Following initial ocular massage and application of antiglaucomatous eyedrops, hyperbaric oxygenation treatment was performed twice daily for up to three days. RESULTS: 21 patients could be included. The time lag between onset of symptoms and admission was between 4 and 12 h. Initial visual acuity ranged from light perception to 0.08. On discharge 19 patients reported on a subjective visual improvement which could be confirmed in 13 patients. In 9 patients an initial increase of visual acuity under hyperbaric oxygenation treatment could be observed which however was again reduced by at least one line on discharge. No patient experienced vision loss below admission vision. CONCLUSIONS: Hyperbaric oxygenation treatment seems to improve the visual outcome in central retinal artery occlusion. Major parameters for visual prognosis are the time lag from the onset of symptoms to the beginning of hyperbaric oxygenation treatment and the time lag until retinal reperfusion begins. Hyperbaric oxygenation treatment can compensate retinal ischaemia; however, the lack of glucose and accumulation of toxic metabolites is not addressed. A combination of hyperbaric oxygenation treatment with administration of glutamate antagonists or intravitreal glucose application might further improve the visual outcome.