Vitreous Collagen Research Articles

CLINICOPATHOLOGIC CHANGES OF VITREOMACULAR INTERFACE IN IDIOPATHIC EPIRETINAL MEMBRANE WITH DISORGANIZATION OF RETINAL INNER LAYERS.

To compare the pathological characteristics of the vitreomacular interface of the idiopathic epiretinal membrane with and without disorganization of retinal inner layers (DRIL) and to correlate with clinical data. In this clinicopathologic study, the samples of epiretinal membrane and internal limiting membrane were extracted from DRIL(+) (19 eyes) and DRIL(-) (22 eyes) idiopathic epiretinal membrane eyes. Ultrathin series sectioning for transmission electron microscopy was observed and correlated with surgery status and prognosis. All idiopathic epiretinal membrane eyes presented fibrocellular membranes accompanied by vitreous collagen, glial cells, and myofibroblasts, regardless of association with DRIL. A robust signal indicative of Collagen Type VI was observed in eyes DRIL(-), whereas Collagen Type I was discovered in DRIL eyes. Cell debris and microvascular basement membrane were seen on the retinal side of DRIL eyes and a larger cell count on the vitreous side. These have more intraoperative complications and less surgery benefit. Although internal limiting membrane peeling seems important, the histopathologic findings underscore the potential for retinal injury in DRIL(+) idiopathic epiretinal membrane eyes. This suggests that further research is needed to investigate individual preoperative assessment and to modify surgical procedures.

In vitro three-dimensional volumetric printing of vitreous body models using decellularized extracellular matrix bioink

Hyalocytes, which are considered to originate from the monocyte/macrophage lineage, play active roles in vitreous collagen and hyaluronic acid synthesis. Obtaining a hyalocyte-compatible bioink during the 3D bioprinting of eye models is challenging. In this study, we investigated the suitability of a cartilage-decellularized extracellular matrix (dECM)-based bioink for printing a vitreous body model. Given that achieving a 3D structure and environment identical to those of the vitreous body necessitates good printability and biocompatibility, we examined the mechanical and biological properties of the developed dECM-based bioink. Furthermore, we proposed a 3D bioprinting strategy for volumetric vitreous body fabrication that supports cell viability, transparency, and self-sustainability. The construction of a 3D structure composed of bioink microfibers resulted in improved transparency and hyalocyte-like macrophage activity in volumetric vitreous mimetics, mimicking real vitreous bodies. The results indicate that our 3D structure could serve as a platform for drug testing in disease models and demonstrate that the proposed printing technology, utilizing a dECM-based bioink and volumetric vitreous body, has the potential to facilitate the development of advanced eye models for future studies on floater formation and visual disorders.

Ultrastructural Details of Epiretinal Membrane Foveoschisis

Introduction: The aim of this study was to describe differences in the vitreomacular interface (VMI) in idiopathic epiretinal membrane (ERM) foveoschisis compared to macular pseudohole (MPH) and lamellar macular hole (LMH). Methods: We analysed surgically excised epiretinal material and internal limiting membrane (ILM) specimens obtained from 16 eyes of 16 patients with ERM foveoschisis (6 eyes), MPH (5 eyes), and LMH (5 eyes) during standard pars plana vitrectomy (PPV) with membrane peeling. The three entities were classified according to the newly introduced optical coherence tomography (OCT) terminology. Transmission electron microscopy (TEM) was used to describe the ultrastructural features. Results: We found fibrocellular epiretinal tissues in all samples analysed. However, the cell and collagen composition of the VMI differed between groups. Eyes with ERM foveoschisis were characterized by a higher number of cells, multilayered membranes, and thick strands of vitreous collagen embedding the major cell types of myofibroblasts compared to MPH. Eyes with MPH also showed a predominance of myofibroblasts, but these were located directly on the ILM with no collagen between the cells and the ILM. Eyes with LMH showed a thick, multilayered epiretinal proliferation consisting mainly of non-tractional glial cells, corresponding to hypodense epiretinal proliferation on OCT. Eyes with ERM foveoschisis and MPH were more likely to have incomplete PVD compared to LMH in terms of posterior hyaloid status. Discussion/Conclusion: Tractional ERMs in eyes with ERM foveoschisis and MPH differ in their ultrastructure. The main difference is in the amount and topographical distribution of vitreous collagen. However, the epiretinal cell types are predominantly myofibroblasts in both entities. This highlights the importance of distinguishing ERM foveoschisis from both MPH and LMH in terms of pathogenesis and surgical peeling procedures.

Confocal reflectance microscopy for mapping collagen fiber organization in the vitreous gel of the eye.

Vitreous collagen structure plays an important role in ocular mechanics. However, capturing this structure with existing vitreous imaging methods is hindered by the loss of sample position and orientation, low resolution, or a small field of view. The objective of this study was to evaluate confocal reflectance microscopy as a solution to these limitations. Intrinsic reflectance avoids staining, and optical sectioning eliminates the requirement for thin sectioning, minimizing processing for optimal preservation of the natural structure. We developed a sample preparation and imaging strategy using ex vivo grossly sectioned porcine eyes. Imaging revealed a network of uniform diameter crossing fibers (1.1 ± 0.3 µm for a typical image) with generally poor alignment (alignment coefficient = 0.40 ± 0.21 for a typical image). To test the utility of our approach for detecting differences in fiber spatial distribution, we imaged eyes every 1 mm along an anterior-posterior axis originating at the limbus and quantified the number of fibers in each image. Fiber density was higher anteriorly near the vitreous base, regardless of the imaging plane. These data demonstrate that confocal reflectance microscopy addresses the previously unmet need for a robust, micron-scale technique to map features of collagen networks in situ across the vitreous.

IMAGING THE VITREOUS WITH A NOVEL BOOSTED OPTICAL COHERENCE TOMOGRAPHY TECHNIQUE

To evaluate the degenerative findings including cistern formation in the premacular vitreous using optical coherence tomography. A novel enhanced vitreous imaging method by which four A-scans at each position were averaged before the Fourier transform increased the image quality per frame so that subsequent image registration for averaging could occur. Analysis of B-scans and volume-rendered images of eyes in subjects of various ages was performed. There were 43 eyes of 23 subjects ranging in age from 23 to 68 years. The texture in the vitreous images suggests specific orientations of the vitreous fibers in the macular region; there were fibers circumferential to the retina immediately anterior to the premacular bursa. The pattern of the vitreous fibers seemed less well-defined internal to the zone of circumferential fibers. In younger eyes, there were striations oriented in a roughly inferior to superior direction in this zone. In older eyes, there were striations in the same orientation but actually were alternating zones of vitreous synchysis and syneresis. In these same eyes, numerous cisterns appeared at various levels in the vitreous gel. With extensive vitreous condensation and synchysis, definition of the premacular bursa was lost. With this novel method of enhanced vitreous imaging, the vitreous seemed to have stereotypic patterns of degeneration. The formation of vitreous syneresis and synchysis may be related to organization architecture of the vitreous, including the pattern of vitreous collagen deposition, and the effects of eye motion through decades of time.

Human Vitreous Collagen Fragments Dimension As a Function of Vitrectomy Cut Rate.

PurposeTo study the dimensions and distribution of human vitreous collagen type II fragments collected after vitrectomy performed at varying cut rates and to evaluate if increasing the cut rate produces smaller collagen fragments, thus reducing retinal traction and/or viscosity.MethodsFluid was collected during core vitrectomies performed for macular surgery at cut rates from 1000 to 16,000 cuts per minute (CPM) and immediately refrigerated. Protein fractions were separated by molecular weight (MW; >100 kDa, 50–100 kDa, 50–30 kDa, 30–10 kDa, and <10 kDa) through centrifugal filters. The Human Collagen II ELISA Kit colorimetric assay was then used to measure the COL2A1 in unfiltered and filtered samples.ResultsVitreous samples collected after vitrectomy performed at 16,000 CPM contained a higher concentration of protein with MW over 100 kDa than at any other cutting frequency (P < 0.01). No significant differences were found in fractions collected with a MW between 50 and 100 kDa. Collagen type II fragments over 100 kDa were significantly more represented than smaller fragments at each cut rate. The proportion of smaller (50–100 kDa) collagen fragments compared with those over 100 kDa was higher at 2000 CPM than at higher cut rates.ConclusionsVitreous samples collected at different cut rates do not contain a significantly different proportion of collagen type II fragments of the tested MW. The extreme variability of vitreous flow through the cutter port may explain the uncertain predictability of collagen fragment MWs.Translational RelevanceIncreasing the cut rate does not produce vitreous fragments of proportionally smaller dimension. It is necessary to achieve an invariant instantaneous flow through the cutter port in order to decrease retinal traction during vitrectomy.

Erianin Controls Collagen-Mediated Retinal Angiogenesis via the RhoA/ROCK1 Signaling Pathway Induced by the alpha2/beta1 Integrin-Collagen Interaction.

PurposeErianin has been reported to inhibit tumor activity by suppressing the expression of integrins. It is hypothesized that erianin can inhibit retinal neovascularization in collagen by suppressing the expression of integrins. With an aim to test this hypothesis, the regulation of erianin on collagen-mediated retinal angiogenesis via the Ras homolog gene family member A (RhoA)/Rho-associated coiled-coil containing protein kinase 1 (ROCK1) signaling pathway induced by α2 and β1 integrin-collagen interactions was investigated.MethodsThe effects of erianin on human retinal vascular endothelial cells (HRVECs) were assessed in vitro using a hypoxia model in a three-dimensional cell culture induced by cobalt (II) chloride (CoCl2). A hypoxia-induced retinopathy model in adult zebrafish and zebrafish embryos was established to assess the antiangiogenic effect of erianin with and without vitreous collagen in vivo. The expression of α2 and β1 integrin and RhoA/ROCK1 pathway in HRVECs and zebrafish retinas were analyzed.ResultsIn vitro, collagen improved the angiogenic potential of HRVECs, including migration, adhesion, and tube formation, in a three-dimensional cell culture model. Erianin suppressed the angiogenic processes of the CoCl2-induced hypoxia HRVEC model in a concentration-dependent manner. In vivo, erianin reduced retinal angiogenesis in the hypoxia-induced retinopathy model in adult and embryo zebrafish. Erianin inhibited the expression of α2 and β1 integrin and RhoA/ROCK1 in a hypoxia-induced model in vitro in three-dimensional cell culture and in vivo in adult zebrafish.ConclusionsCollagen-mediated retinal angiogenesis may be regulated by erianin via the RhoA/ROCK1 signaling pathway induced by α2 and β1 integrin-collagen interactions. These findings suggest that erianin has the therapeutic potential on intraocular collagen-mediated retinal angiogenesis.

Lamellar Hole-associated Epiretinal Proliferation in choroideremia: a case report

BackgroundTo report a clinical case of a patient affected with choroideremia (CHM) who underwent macular surgery for a macular hole (MH) with Lamellar Hole-associated Epiretinal Proliferation (LHEP).Case presentationWe have described a 48-year-old male patient affected with CHM who developed MH with LHEP over a 7-year follow-up. The patient was referred to the Regional Center for Hereditary Retinal Degenerations of the Eye Clinic in Florence (Italy) in April 2012. The patient underwent vitrectomy and Inner Limiting Membrane (ILM) and LHEP peeling with fluid-air exchange. Ultra-structural examination of the excised epiretinal proliferation, carried out using electron microscopy, showed dense amorphous material, mainly composed of abundant clusters of fibrous collagens resembling compact fibrous long spacing collagen (FLSC), embedded in native vitreous collagen (NVC) and type IV collagen. No cells were detected in any of the specimens collected. At the 3rd-week postoperative follow-up the macular hole was closed.ConclusionMacular hole with LHEP can be detected in CHM patients; in our patient the macular hole showed tractional and degenerative features, with good anatomical results after macular surgery.

Vitreous collagen cross-linking and maturation and interactions with internal limiting membrane (ILM) collagen may have a potential role in modulating postnatal growth of the eyeball

At birth, the eye is moderately hypermetropic but achieves emmetropia by the age of 5–6 years in a large majority (Chakraborty et al., 2020; Gwiazda et al., 1993). The process of emmetropization is attributed to changes in several components of the eye structure, predominantly cornea, crystalline lens and axial length. Emmetropization is possible only when there is a fine balance between the optical power of the eye and its focal length. The former is determined by the combined dioptric power of the cornea and crystalline lens and the latter by the axial length of the eyeball. Increase in axial length has been shown to be the most important factor for reaching emmetropia. The main determinant of this increase is reported to be expansion of the vitreous chamber (Mutti et al., 2005; Larsen, 1971). Growth of the vitreous body during postnatal development is well established. However, what initiates vitreous chamber expansion and what brings about its precise arrest at the point of emmetropization are aspects that have not been explored and remain an enigma. It is hypothesized herein that vitreous chamber expansion and resultant early increase in axial length that precisely stops at the point of emmetropia, occurs secondary to postnatal structural and conformational changes within the vitreous collagen and internal limiting membrane (ILM) collagen and molecular interactions between these two structures.

Analysis of opticin binding to collagen fibrils identifies a single binding site in the gap region and a high specificity towards thin heterotypic fibrils containing collagens II, and XI or V/XI.

Opticin is a class III member of the extracellular matrix small leucine-rich repeat protein/proteoglycan (SLRP) family found in vitreous humour and cartilage. It was first identified associated with the surface of vitreous collagen fibrils and several other SLRPs are also known to bind collagen fibrils and it some cases alter fibril morphology. The purpose of this study was to investigate the binding of opticin to the collagen II-containing fibrils found in vitreous and cartilage. Electron microscopic studies using gold labelling demonstrated that opticin binds vitreous and thin cartilage collagen fibrils specifically at a single site in the gap region of the collagen D-period corresponding to the e2 stain band; this is the first demonstration of the binding site of a class III SLRP on collagen fibrils. Opticin did not bind thick cartilage collagen fibrils from cartilage or tactoids formed in vitro from collagen II, but shows high specificity for thin, heterotypic collagen fibrils containing collagens II, and XI or V/XI. Vitreous collagen fibrils from opticin null and wild-type mice were compared and no difference in fibril morphology or diameter was observed. Similarly, in vitro fibrillogenesis experiments showed that opticin did not affect fibril formation. We propose that when opticin is bound to collagen fibrils, rather than influencing their morphology it instead hinders the binding of other molecules to the fibril surfaces and/or act as an intermediary bridge linking the collagen fibrils to other non-collagenous molecules.

Intravitreal Pharmacokinetic Study of the Antiangiogenic Glycoprotein Opticin

Opticin is an endogenous vitreous glycoprotein that may have therapeutic potential as it has been shown that supranormal concentrations suppress preretinal neovascularization. Herein we investigated the pharmacokinetics of opticin following intravitreal injection in rabbits. To measure simultaneously concentrations of human and rabbit opticin, a selected reaction monitoring mass spectrometry assay was developed. The mean concentration of endogenous rabbit opticin in 7 uninjected eyes was measured and found to be 19.2 nM or 0.62 μg/mL. When the vitreous was separated by centrifugation into a supernatant and collagen-containing pellet, 94% of the rabbit opticin was in the supernatant. Intravitreal injection of human opticin (40 μg) into both eyes of rabbits was followed by enucleation at 5, 24, and 72 h and 7, 14, and 28 days postinjection (n = 6 at each time point) and measurement of vitreous human and rabbit opticin concentrations in the supernatant and collagen-containing pellet following centrifugation. The volume of distribution of human opticin was calculated to be 3.31 mL, and the vitreous half-life was 4.2 days. Assuming that rabbit and human opticin are cleared from rabbit vitreous at the same rate, opticin is secreted into the vitreous at a rate of 0.14 μg/day. We conclude that intravitreally injected opticin has a vitreous half-life that is similar to currently available antiangiogenic therapeutics. While opticin was first identified bound to vitreous collagen fibrils, here we demonstrate that >90% of endogenous opticin is not bound to collagen. Endogenous opticin is secreted by the nonpigmented ciliary epithelium into the rabbit vitreous at a remarkably high rate, and the turnover in vitreous is approximately 15% per day.

Induction of posterior vitreous detachment (PVD) by non-enzymatic reagents targeting vitreous collagen liquefaction as well as vitreoretinal adhesion

Induction of posterior vitreous detachment (PVD) by pharmacologic vitreolysis has been largely attempted through the use of enzymatic reagents. Ocriplasmin has been the only FDA-approved clinical reagent so far. Several adverse effects of ocriplasmin have emerged, however, and the search for alternative PVD-inducing reagents continues. Since i) collagen forms an important structural component of the vitreous, and ii) strong vitreo-retinal adhesions exist between the cortical vitreous and the internal limiting membrane (ILM) of the retina, an effective PVD-inducing reagent would require both, vitreous liquefaction, and concurrent dehiscence of vitreoretinal adhesion, without being toxic to retinal cells. We designed a combination of two reagents to achieve these two objectives; a triple helix-destabilizing collagen binding domain (CBD), and a fusion of RGD (integrin-binding) tripeptide with CBD (RCBD) to facilitate separation of posterior cortical vitreous from retinal surface. Based on in vitro, ex-vivo, and in vivo experiments, we show that a combination of CBD and RCBD displays potential for safe pharmacologic vitreolysis. Our findings assume significance in light of the fact that synthetic RGD-containing peptides have already been used for inhibition of tumor cell invasion. Proteins such as variants of collagen binding domains could have extended therapeutic uses in the future.

Comparison of Vitreomacular Interface Changes in Myopic Foveoschisis and Idiopathic Epiretinal Membrane Foveoschisis

To compare characteristics of the vitreomacular interface (VMI) in myopic foveoschisis (mFS) and idiopathic epiretinal membrane foveoschisis (iERM-FS), and to correlate with optical coherence tomography and clinical data. Clinicopathologic study. Epiretinal membrane and internal limiting membrane (ILM) specimens were removed from eyes with mFS (5 eyes) and iERM-FS (5 eyes). Harvested tissue was processed for immunocytochemistry and prepared by ultrathin series sectioning for transmission electron microscopy. Cell and collagen compositions were compared and correlated with clinical data. All eyes presented fibrocellular membranes irrespective if associated with mFS or iERM-FS. Cell and collagen types and distribution on the vitreal side of the ILM were similar in both groups, consistent with presence of tractional membranes on optical coherence tomography images. Immunostaining of all specimens were positive for glial cells, microglia, and hyalocytes. Electron microscopy revealed evidence of epiretinal cell multilayers with masses of vitreous collagen and signs of vitreous remodeling in both groups. Three eyes with mFS but none of the eyes with iERM-FS showed massive thinning of the ILM with prominent retinal undulations and presence of retinal nerve fiber layer fragments. Whereas fibrocellular components of premacular tissue in mFS are similar to iERM-FS, pathologic abnormalities of the ILM were exclusively present in high myopia. Although peeling of the ILM appears important to completely remove tractional components of the VMI, histopathologic findings emphasize the risk for retinal damage in these highly myopic eyes, indicating that individual preoperative assessment and modification of surgical techniques require further investigation.

The image characteristics of optical coherence tomography of the posterior cortical anterior vitreous capsular bag in human eyes

Objective To observe the OCT image characteristics of the posterior cortical anterior vitreous capsular bag (PPVP) in human eyes. Methods A retrospective clinical study. From May 2012 to February 2017, 107 PPVP patients (173 eyes) diagnosed by OCT in Ophthalmology Department of The Third People's Hospital of Chengdu were included in the study. One hundred and three eyes underwent examination of frequency-domain OCT (SD-OCT) and 70 eyes underwent examination of frequency-scanning light source OCT (SS-OCT), respectively. SD-OCT the German Heidelberg Spectralis OCT instrument. SS-OCT was performed by the vitreous enhancement scan mode of Japan's Topcon DRI OCT instrument. The differences of different types of PPVP OCT imaging and image characteristics were observed. Results SD-OCT and SS-OCT showed that the PPVP structure was clear and manifested as macular weakly reflective in the shape of a boat-shaped cavity, the front boundary was vitreous collagen, and the rear boundary was vitreous cortex. There was a weakly reflective Martegiani area on the nasal side of PPVP, and there was a connection channels between them. The two examinations showed a similar pattern, but SS-OCT with the clearer imaging of PPVP. Conclusions The OCT image of PPVP in the human eye is characterized by an anterior weakly reflecting boat-shaped cavity in the macula, with anterior border of vitreous collagen and posterior border of vitreous cortex. Martegiani area is located on the nasal side. Key words: Tomography, optical coherence; Posterior precortical vitreous pockets

Macular interface pathophysiology

AbstractThe vitreous body occupies nearly 80% of the total ocular volume. It constitutes a dynamic structure that normally changes composition and formation through time. Vitreous characteristics can also change owing trauma, metabolic or oxidative factors. Physiologically, the process of gradual vitreous liquefaction (synchysis) comes along with the progressive vitreous collagen fibrils packing and aggregation (syneresis). Both synchysis and syneresis can lead to posterior vitreous detachment (PVD) after normal cortex dehiscence from the underlying retina tissue (vitreoretinal interface).In contrast, when the dehiscence process is abnormal (anomalous, incomplete or partial), various pathological conditions can be created on the retina. The pathologies formed specifically on the macular region from the above conditions are named vitreomacular interface diseases (VMID). In this presentation, we will analyse the pathophysiological mechanisms of different VMID like a macular hole (MH), vitreomacular traction syndrome (VTS) and epiretinal membrane (ERM). Moreover, we will present different molecular and cellular components mentioned in the literature and implicated in VMID formation, and we will try to highlight potential future treatment options for the diseases.

A Case Series of Resolving Vitreous Haemorrhage in the Setting of Diabetic Retinopathy

This case series presents 2 patients (67 and 58 year old females) with resolving vitreous hemorrhage in the setting of diabetic retinopathy. Both patients had around 50% of the retina still visible and the hemorrhage was confined at the posterior vitreous cavity near the retina, hence, a partial pan retinal photocoagulation (PRP) was feasibly applied. On B-scan, both cases showed a liquified vitreous with posterior vitreous detachment (PVD). For both patients, vitreous hemorrhage resolution occurred at less than 4 months from onset and consequently PRP was completed. Vitreous hemorrhage differs with bleeding in other tissues due to the presence of vitreous collagen matrix which promotes rapid clotting and hinders resolution of hemorrhage by preventing passive diffusion and delay in inflammatory cellular response. The prognosis for clearing hemorrhage was better when the fundus reflex was brighter and the retina adjacent to the ora serrata was visible. Clearing occurred sooner when hemorrhage was retrohyaloid rather than in the vitreous gel. In diabetic eye, the vitreous undergoes metabolic derangements resulting in premature liquefaction and abnormal vitreoretinal adhesion leading to traction and membrane formation. Partial PVD has also been associated with higher rate of diabetic retinopathy progression since it serves as scaffold for growth of neovascular tufts.

Photoablation of Human Vitreous Opacities by Light-Induced Vapor Nanobubbles.

Myopia, diabetes, and aging are the main causes of progressive vitreous collagen aggregation, resulting in vitreous opacities, which can significantly disturb vision. As vitreous opacities, which induce the visual phenomenon of "floaters", are accessible with nanomaterials and light, we propose a nanotechnology-based approach to locally ablate them with highly reduced light energy compared to the more traditional YAG laser therapy. Our strategy relies on the plasmon properties of gold nanoparticles that generate vapor nanobubbles upon pulsed-laser illumination whose mechanical force can ablate vitreous opacities. We designed gold nanoparticles coated with hyaluronic acid (HA), which have excellent diffusional mobility in human vitreous, an essential requirement to reach the vitreous opacities. In addition, we found that HA-coated gold nanoparticles can accumulate extensively on human vitreous opacities that were obtained by vitrectomy from patients with vision-degrading myodesopsia. When subsequently applying nanosecond laser pulses, the collagen aggregates were efficiently destroyed with ∼1000 times less light energy than typically used in YAG laser therapy. This low-energy "floater-specific destruction", which is due to the accumulation of the small gold nanoparticles on the opacities, is attractive, as it may be safer to the surrounding ocular tissues while at the same time being easier and faster to apply compared to YAG laser therapy, where the opacities need to be ablated piece by piece by a tightly focused laser beam. Gold nanoparticle-assisted photoablation may therefore provide a safer, faster, and more reliable destruction of vitreous opacities in the treatment of ophthalmologic diseases.

Premacular Cell Proliferation Profiles in Tangential Traction Vitreo-Maculopathies Suggest a Key Role for Hyalocytes

Purpose: To compare immunocytochemical and ultrastructural features of premacular tissue surgically removed from eyes with tangential traction vitreo-maculopathies. Methods: By spectral-domain optical coherence tomography (SD-OCT), premacular tissue was differentiated into premacular proliferation and premacular membrane (PMM). Specimens were harvested during vitrectomy from 10 eyes with macular pucker, lamellar macular hole (LMH) and full-thickness macular hole, and prepared for immunocytochemistry and transmission electron microscopy. Results: All specimens showed positive autofluorescence consistent with the yellow colour of peeled tissue. Glial cells were predominantly positive in premacular proliferation. Hyalocytes were the main cell type in PMM. Electron microscopy revealed densely packed premacular glial cells neighbouring hyalocytes and vitreous collagen strands. Myofibroblasts with features indicative of contractile properties were found in PMM, exclusively. Cell composition of premacular proliferation was free of contractile elements. Conclusion: All three types of vitreo-maculopathy have similar cell constituents in their premacular tissue. Cell population of premacular proliferation is not unique for LMHs. Corresponding to SD-OCT, electron microscopy demonstrates hyalocytes and vitreous collagen in PMMs both directly adjacent to the cellular complex of premacular proliferation. Study results point to the vitreous as one important pathogenic player potentially driving the degenerative cellular process at the vitreoretinal interface in tangential traction vitreo-maculopathies.

VITRECTOMY FOR INTERMEDIATE AGE-RELATED MACULAR DEGENERATION ASSOCIATED WITH TANGENTIAL VITREOMACULAR TRACTION: A CLINICOPATHOLOGIC CORRELATION.

To describe the morphologic characteristics of the vitreomacular interface in intermediate age-related macular degeneration associated with tangential traction due to premacular membrane formation and to correlate with optical coherence tomography (OCT) findings and clinical data. Premacular membrane specimens were removed sequentially with the internal limiting membrane from 27 eyes of 26 patients with intermediate age-related macular degeneration during standard vitrectomy. Specimens were processed for immunocytochemical staining of epiretinal cells and extracellular matrix components. Ultrastructural analysis was performed using transmission electron microscopy. Spectral domain optical coherence tomography images and patient charts were evaluated in retrospect. Immunocytochemistry revealed hyalocytes and myofibroblasts as predominant cell types. Ultrastructural analysis demonstrated evidence of vitreoschisis in all eyes. Myofibroblasts with contractile properties were observed to span between folds of the internal limiting membrane and vitreous cortex collagen. Retinal pigment epithelial cells or inflammatory cells were not detected. Mean visual acuity (Snellen) showed significant improvement from 20/72 ± 20/36 to 20/41 ± 20/32 (P < 0.001) after a mean follow-up period of 19 months (median, 17 months). During this period, none of the eyes required anti-vascular endothelial growth factor therapy. Fibrocellular premacular proliferation in intermediate age-related macular degeneration predominantly consists of vitreous collagen, hyalocytes, and myofibroblasts with contractile properties. Vitreoschisis and vitreous-derived cells appear to play an important role in traction formation of this subgroup of eyes. In patients with intermediate age-related macular degeneration and contractile premacular membrane, release of traction by vitrectomy with internal limiting membrane peeling results in significantly functional and anatomical improvement.

Ultrastructural and histopathologic findings after pars plana vitrectomy with a new hypersonic vitrector system. Qualitative preliminary assessment.

PurposePreliminary assessment of a new prototype ultrasound-based hypersonic vitrector (HV) by qualitatively examining the histopathological changes in the retina and vitreous body after pars plana vitrectomy (PPV) and its ability to fragment vitreous collagen.MethodsFourteen porcine cadaveric eyes, 20 eyes in live swine and six human cadaveric eyes underwent PPV using the HV or a pneumatic guillotine vitrector (GV). An additional 4 porcine crystalline lenses were touched with either the HV or GV for 1 minute. Following PPV, human vitreous was removed and processed for electron microscopy (EM). Eyes and lenses were fixed and sectioned for light microscopy (LM).ResultsThere were no macroscopic retinal or optic nerve defects associated with either HV or GV PPVs. Cadaveric retinal specimens showed separation of the inner limiting membrane (ILM) and vacuolization and fragmentation at the nerve fiber layer (NFL) and the ganglion cell layer (GCL). ILM fragmentation and separation were found after PPV in live swine with both vitrectors. Small disruptions of the posterior capsule or structural lens defects were found after HV touch. The EM analysis revealed more fragmentation of human vitreous collagen fibrils after HV compared to GV PPV.ConclusionsLM and EM analysis of retina, vitreous, and crystalline lens after PPV showed similar morphological changes using the HV or the GV. Vitreous fragmentation appeared more effective with the HV. Overall this study suggests that the HV may be a promising new technology. More work is needed to quantitatively assess its safety and efficacy.