Marcel Pfister

Comparison of cytokine levels from undiluted vitreous of untreated patients with retinal vein occlusion

Purpose:  To compare cytokines in undiluted vitreous of treatment‐naïve patients with macular oedema without vitreomacular traction secondary to branch (BRVO), central (CRVO) and hemi‐central (H‐CRVO) retinal vein occlusion.

Proteomics of Vitreous Humor of Patients with Exudative Age-Related Macular Degeneration

Background There is absence of specific biomarkers and an incomplete understanding of the pathophysiology of exudative age-related macular degeneration (AMD). Methods and Findings Eighty-eight vitreous samples (73 from patients with treatment naïve AMD and 15 control samples from patients with idiopathic floaters) were analyzed with capillary electrophoresis coupled to mass spectrometry in this retrospective case series to define potential candidate protein markers of AMD. Nineteen proteins were found to be upregulated in vitreous of AMD patients. Most of the proteins were plasma derived and involved in biological (ion) transport, acute phase inflammatory reaction, and blood coagulation. A number of proteins have not been previously associated to AMD including alpha-1-antitrypsin, fibrinogen alpha chain and prostaglandin H2-D isomerase. Alpha-1-antitrypsin was validated in vitreous of an independent set of AMD patients using Western blot analysis. Further systems biology analysis of the data indicated that the observed proteomic changes may reflect upregulation of immune response and complement activity. Conclusions Proteome analysis of vitreous samples from patients with AMD, which underwent an intravitreal combination therapy including a core vitrectomy, steroids and bevacizumab, revealed apparent AMD-specific proteomic changes. The identified AMD-associated proteins provide some insight into the pathophysiological changes associated with AMD.

Profile of ocriplasmin and its potential in the treatment of vitreomacular adhesion.

The recent approval by the US Food and Drug Administration of ocriplasmin for the treatment of symptomatic vitreomacular adhesion (VMA), often associated with vitreomacular traction (VMT) and macular hole (MH), has brought new attention to the field of pharmacologic vitreolysis. The need for an enzyme to split the vitreomacular interface, which is formed by a strong adhesive interaction between the posterior vitreous cortex and the internal limiting membrane, historically stems from pediatric eye surgery. This review summarizes the different anatomic classifications of posterior vitreous detachment or anomalous posterior vitreous detachment and puts these in the context of clinical pathologies commonly observed in clinical practice of the vitreoretinal specialist, such as MH, VMT, age-related macular degeneration, and diabetic macular edema. We revisit the outcome of the Phase II studies that indicated ocriplasmin was a safe and effective treatment for selected cases of symptomatic VMA and MH. Release of VMA at day 28 was achieved by 26.5% of patients in the ocriplasmin group versus 10.1% in the placebo group (P<0.001). Interestingly, for MHs, the numbers were more remarkable. Predictive factors for successful ocriplasmin treatment were identified for VMT (VMA diameter smaller than 1,500 μm) and MH (smaller than 250 μm). In comparison with the highly predictable outcome after vitrectomy, the general success rate of ocriplasmin not under clinical trial conditions has not fully met expectations and needs to be proven in real-world clinical settings. The ocriplasmin data will be compared in the future with observational data on spontaneous VMA release, will help retina specialists make more accurate predictions, and will improve outcome rates.

Inflammatory and Angiogenic Protein Detection in the Human Vitreous: Cytometric Bead Assay

Introduction. To evaluate clinical feasibility and reproducibility of cytometric bead assay (CBA) in nondiluted vitreous samples of patients with age-related macular degeneration (ARMD), diabetic macular edema (DME), and central retinal vein occlusion (CRVO). Methods. Twelve patients from a single clinics day qualified for intravitreal injections (ARMD n = 6, DME n = 3, CRVO n = 3) and underwent a combination treatment including a single-site 23 gauge core vitrectomy which yielded a volume of 0.6 mL undiluted vitreous per patient. Interleukin-6 (IL-6), vascular endothelial growth factor isoform A (VEGF-A), and monocyte chemo-attractant protein-1 (MCP-1) were assessed directly from 0.3 mL at the same day (fresh samples). To assess the reproducibility 0.3 ml were frozen for 60 days at −80°, on which the CBA was repeated (frozen samples). Results. In the fresh samples IL-6 was highest in CRVO (median IL-6 55.8 pg/mL) > DME (50.6) > ARMD (3.1). Highest VEGF was measured in CRVO (447.4) > DME (3.9) > ARMD (2.0). MCP-1 was highest in CRVO (595.7) > AMD (530.8) > DME (178). The CBA reproducibility after frozen storage was examined to be most accurate for MCP1 (P = 0.91) > VEGF (P = 0.68) > IL-6 (P = 0.49). Conclusions. CBA is an innovative, fast determining, and reliable technology to analyze proteins in fluids, like the undiluted vitreous, which is important to better understand ocular pathophysiology and pharmacology. There is no influence of intermittent storage at −80° for the reproducibility of the CBA.

Correlation of inflammatory and proangiogenic cytokines from undiluted vitreous samples with spectral domain OCT scans, in untreated branch retinal vein occlusion

Purpose To assess the levels of inflammatory and angiogenic cytokines in undiluted vitreous from treatment-naïve patients with macular edema secondary to nonischemic branch retinal vein occlusion (BRVO), with flow cytometric bead array (CBA) and to correlate the results with subjective and multiple spectral-domain optical coherence tomography (SD-OCT) parameters. Methods A total of 43 eyes from 43 patients (mean age 69.7 years, 23 male) were divided into groups of new, “fresh” (n = 28; mean duration after onset 4.1 months) and older BRVO (n = 15; 11.6 months). Because of macular edema, these patients underwent an intravitreal therapy combining a single-site 23 g core vitrectomy with bevacizumab and dexamethasone. Undiluted vitreous was then analyzed for interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and vascular endothelial growth factor isoform A (VEGF-A) levels with CBA and correlated with visual acuity (VA), clinical parameters of BRVO (type and perfusion status), and morphologic parameters, such as central macular thickness, central retinal thickness, thickness of the neurosensory retina, thickness of the serous retinal detachment, and the disruption of the ellipsoid line (photoreceptor inner and outer segments) and the external limiting membrane, as measured with SD-OCT. Twenty-eight undiluted vitreous samples from patients with idiopathic, nonuveitis vitreous floaters served as the controls. Results The mean IL-6 was 23.2 pg/mL (standard deviation, ±48.8), MCP-1 was 602.6 (±490.3), and VEGF-A was 161.8 (±314.3), and this was higher than in the control group, which had a mean IL-6 of 6.2 ± 3.4 pg/mL (P = 0.17), MCP-1 of 253.2 ± 73.5 (P < 0.0000001), and VEGF-A of 7.0 ± 4.9 (P < 0.003). In all BRVO samples, IL-6 correlated positively with MCP-1 and VEGF-A (correlation coefficient r = 0.79 and r = 0.46, respectively). VEGF-A was the only cytokine to correlate significantly with SD-OCT parameters (thickness of the neurosensory retina r = 0.31; disruption of the ellipsoid line r = 0.33). In the older BRVO group, there was a positive correlation between cytokines (IL-6 with MCP-1, r = 0.77; Il-6 with VEGF-A, r = 0.68; MCP-1 and VEGF-A, r = 0.68), whereas only IL-6 correlated with MCP-1 in the fresh group (r = 0.8). Conclusion The inflammatory markers and VEGF-A were elevated in the vitreous fluid of patients with BRVO, and these correlated with one another. VEGF-A was more often correlated with the morphologic changes assessed by SD-OCT, whereas the inflammatory markers had no significant influence on SD-OCT changes.

Comparison of Reaction Response Time between Hand and Foot Controlled Devices in Simulated Microsurgical Testing

Purpose. We hypothesized that reaction times (RTs) for a switch release are faster for hand-controlled than for foot-controlled switches for physiological and anatomical reasons (e.g., nerve conduction speed). The risk of accidental trauma could be reduced if the surgeon reacted quicker and therefore improve the surgical outcome. Method. We included 47 medical professionals at USC. Demographics and handedness were recorded. Under a microscope, a simple reaction time test was performed, testing all extremities multiple times in a random order. Additionally, a subjective questionnaire was administered. Results. The mean RTs for hands are 318.24 ms ± 51.13 and feet 328.69 ± 48.70. The comparison of hand versus foot showed significant shorter RTs for the hand (P = 0.025). Partially significant differences between and within the experience level groups could be demonstrated by level of education (LE) and microscopic surgeries/week (MSW) (P = 0.57–0.02). In the subjective questionnaire, 91.5% (n = 43/47) of test subjects prefer to use hand controls. Conclusion. Our data show that the RT for hands is faster than feet. Similarly the subjective questionnaire showed a greater preference for hand actuation. This data suggest a hand-controlled ophthalmic instrument might have distinct advantages; however, clinical correlation is required.

Correlation from undiluted vitreous cytokines of untreated central retinal vein occlusion with spectral domain optical coherence tomography.

Purpose: To correlate inflammatory and proangiogenic key cytokines from undiluted vitreous of treatment-naïve central retinal vein occlusion (CRVO) patients with SD-OCT parameters. Methods: Thirty-five patients (age 71.1 years, 24 phakic, 30 nonischemic) underwent intravitreal combination therapy, including a single-site 23-gauge core vitrectomy. Twenty-eight samples from patients with idiopathic, non-uveitis floaterectomy served as controls. Interleukin 6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and vascular endothelial growth factor (VEGF-A) levels were correlated with the visual acuity (logMar), category of CRVO (ischemic or nonischemic) and morphologic parameters, such as central macular thickness-CMT, thickness of neurosensory retina-TNeuro, extent of serous retinal detachment-SRT and disintegrity of the IS/OS and others. Results: The mean IL-6 was 64.7pg/ml (SD ± 115.8), MCP-1 1015.7 ( ± 970.1), and VEGF-A 278.4 ( ± 512.8), which was significantly higher than the control IL-6 6.2 ± 3.4pg/ml (P=0.06), MCP-1 253.2 ± 73.5 (P<0.0000001) and VEGF-A 7.0 ± 4.9 (P<0.0006). All cytokines correlated highly with one another (correlation coefficient r=0.82 for IL-6 and MCP-1; r=0.68 for Il-6 and VEGF-A; r=0.64 for MCP-1 and VEGF-A). IL-6 correlated significantly with CMT, TRT, SRT, dIS/OS, and dELM. MCP-1 correlated significantly with SRT, dIS/OS, and dELM. VEGF-A correlated not with changes in SD-OCT, while it had a trend to be higher in the ischemic versus the nonischemic CRVO group (P=0.09). Conclusions: The inflammatory cytokines were more often correlated with morphologic changes assessed by SD-OCT, whereas VEGF-A did not correlate with CRVO-associated changes in SD-OCT. VEGF inhibition alone may not be sufficient in decreasing the inflammatory response in CRVO therapy.

Cytokine determination from vitreous samples in retinal vascular diseases

PURPOSE The aim of this study was to determine cytokine levels from vitreous samples of treatment-naive patients with diabetic retinopathy (DRP), retinal vein occlusion (RVO) and exudative age-related macular degeneration (ARMD). METHODS In this study 187 patients (median age 67 years, 101 males) were treated with a combined drug therapy including a 23-gauge core vitrectomy. Interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1) and intravitreal vascular endothelial growth factor (VEGF-A) levels were determined a using cytometric bead assay (CBA) and compared to those of the control group. RESULTS Compared to the control group all diseases had significantly elevated cytokine levels, except VEGF in ARMD. In DRP samples of patients with diffuse diabetic macula edema (DME) higher VEGF-A and MCP-1 levels were found than in patients with focal DME. Ischemic DRP had higher VEGF levels than non-ischemic DRP. All measured cytokines were significantly higher in central retinal vein occlusion (CRVO) than in branch retinal vein occlusion (BRVO). CONCLUSIONS Differences in intravitreal cytokine levels in DRP, RVO and ARMD could be demonstrated. The knowledge of depicted specific characteristic dysregulation of cytokines could allow more targeted future therapies.

INTRAOCULAR PRESSURE CHANGES DURING VITRECTOMY USING CONSTELLATION VISION SYSTEM'S INTRAOCULAR PRESSURE CONTROL FEATURE.

Purpose: To evaluate intraocular pressure (IOP) changes during experimental vitrectomy and the efficacy of Constellation Vision Systems IOP control (IOPc) feature in reestablishing baseline pressure. Methods: Using a pressure transducer in freshly enucleated porcine eyes, a broad range of parameters (baseline pressures, aspiration levels, and cut rates) were tested with 23- and 25-gauge probes and IOPc turned ON versus OFF. Results: IOPc turned ON was significantly more effective than IOPc turned OFF in controlling IOP drop and stabilizing pressure during vitrectomy using a wide range of baseline pressures (20–70 mmHg). The 23-gauge system consistently presented a reduced drop from baseline compared with the 25-gauge system. The overall average drop for the 23- and 25-gauge systems was 12.79 mmHg and 21.17 mmHg, respectively. Both gauge sizes reestablished baseline pressure approximately 1.6 seconds after the initial pressure drop generated at the beginning of aspiration. A peak of IOP (overshooting) was observed when the pressure was returning to baseline using both 23- and 25-gauge systems. Conclusion: Using IOPc feature turned ON, 23- and 25-gauge probes were effective in reestablishing and sustaining baseline infusion pressures, although 23-gauge probes showed less IOP fluctuation than did 25-gauge probes.

Zytokinbestimmung aus Glaskörperproben bei retinalen Gefäßerkrankungen

PURPOSE The aim of this study was to determine cytokine levels from vitreous samples of treatment-naive patients with diabetic retinopathy (DRP), retinal vein occlusion (RVO) and exudative age-related macular degeneration (ARMD). METHODS In this study 187 patients (median age 67 years, 101 males) were treated with a combined drug therapy including a 23-gauge core vitrectomy. Interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1) and intravitreal vascular endothelial growth factor (VEGF-A) levels were determined a using cytometric bead assay (CBA) and compared to those of the control group. RESULTS Compared to the control group all diseases had significantly elevated cytokine levels, except VEGF in ARMD. In DRP samples of patients with diffuse diabetic macula edema (DME) higher VEGF-A and MCP-1 levels were found than in patients with focal DME. Ischemic DRP had higher VEGF levels than non-ischemic DRP. All measured cytokines were significantly higher in central retinal vein occlusion (CRVO) than in branch retinal vein occlusion (BRVO). CONCLUSIONS Differences in intravitreal cytokine levels in DRP, RVO and ARMD could be demonstrated. The knowledge of depicted specific characteristic dysregulation of cytokines could allow more targeted future therapies.