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

Pastor‐Idoate, Salvador; Bonshek, Richard; Irion, Luciane; Zambrano, Isaac; Carlin, Paul; Mironov, Aleksandr; Bishop, Paul; McLeod, David; Stanga, Paulo E

doi:10.1371/journal.pone.0173883

Cited by 19 publications

(21 citation statements)

References 33 publications

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“…3 ). This LC location is consistent with previous reports in porcine eyes, 9 , 17 – 19 and corresponded to a region of higher echogenicity within the ONH in the ultrasound images. A division of the ONH into anterior and posterior halves showed the LC present within the anterior half of the ONH in both the ultrasound and histology images.…”

Section: Resultssupporting

confidence: 92%

Regional Deformation of the Optic Nerve Head and Peripapillary Sclera During IOP Elevation

Pavlatos

Clayson

et al. 2018

Invest. Ophthalmol. Vis. Sci.

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PurposeTo measure the deformation of the porcine optic nerve head (ONH) and peripapillary sclera (PPS) in response to intraocular pressure (IOP) elevation.MethodsHigh-frequency ultrasound was used to image the ONH and PPS of 12 porcine eyes during ex vivo inflation testing from 5 to 30 mm Hg. A speckle tracking algorithm was used to compute tissue displacements in the anterior-posterior direction and expansion of the scleral canal. Through-thickness, in-plane, and shear strains were calculated within the ONH. Regional displacements and strains were analyzed and compared.ResultsThe ONH and PPS showed overall posterior displacement in response to IOP elevation. Posterior displacement of the ONH was larger than and strongly correlated with the posterior displacement of the PPS throughout inflation testing. Scleral canal expansion was much smaller and leveled off quicker than ONH posterior displacement as IOP increased. Through-thickness compression was concentrated in the anterior ONH, which also experienced larger in-plane and shear strains than the posterior ONH. Within the anterior ONH, all three strains were significantly higher in the periphery compared with the center, with the shear strain exhibiting the greatest difference between the two regions.ConclusionsHigh-resolution ultrasound speckle tracking revealed the full-thickness mechanical response of the posterior eye to IOP elevation. A mismatch in posterior displacement was found between the ONH and PPS, and regional analyses showed a concentration of strains within the periphery of the anterior porcine ONH. These deformation patterns may help in understanding IOP-associated optic nerve damage and glaucoma susceptibility.

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Section: Resultssupporting

confidence: 92%

Regional Deformation of the Optic Nerve Head and Peripapillary Sclera During IOP Elevation

Pavlatos

Clayson

et al. 2018

Invest. Ophthalmol. Vis. Sci.

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“…This study is the follow up to the ultrastructural and histopathological findings after pars plana vitrectomy (PPV) in cadaveric porcine and human eyes and non-delay live porcine eyes. In our previous study, light microscopy and electron microscopy showed similar morphological changes in the retina, vitreous and crystalline lens after PPV [ 2 ]. The HV have also produced consistent water and vitreous flow rates across the range of stroke length and aspiration levels [ 3 ].…”

Section: Introductionmentioning

confidence: 72%

“…The described US tissue damage includes global biomechanical properties alteration, histo-morphological changes, protein denaturation and tissue necrosis [ 10 – 14 ]. In our previous work, comparison between the control eyes, porcine and human cadaveric eyes that had PPV with GV or HV had histopathological findings primarily at the inner retinal layers, with some degree of vacuolization and fragmentation in the NFL and GCL, as well as internal limiting membrane (ILM) separation [ 2 ]. These changes are similar in this study 30 days following PPV with either the HV or GV.…”

Section: Discussionmentioning

confidence: 99%

“…Although we have addressed most of the limitations from our previous study [ 2 ], one of the main limitations in this study is that we have not performed electro-diagnostic tests such as electroretinography or visual evoked potentials to assess the functionality of the retina or optic nerve head cells following the HV. As most of the changes are limited to the inner retinal layers rather than the RPE layers, we can only assume that most of the functionality of the retina layers are intact without performing the electrodiagnostic tests.…”

Section: Discussionmentioning

confidence: 99%

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Live porcine thirty days delayed recovery surgery: Qualitative findings with the hypersonic vitrectomy

et al. 2018

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IntroductionQualitatively assess the possible delayed structural, macroscopic and microscopic changes in the neuro-retina, retinal vasculature, retinal pigment epithelium (RPE) and optic nerve head (ONH) after pars plana vitrectomy (PPV) surgery using a new hypersonic vitrector (HV).Materials and methodsEight live porcine eyes underwent PPV using either the HV or a conventional pneumatic guillotine vitrector (GV). The un-operated fellow eye from each pig was used as an external control. The pigs were post-operatively kept alive for 30 days before termination and enucleation of the eyes. Prior to enucleation, all eyes underwent examination of the lens and indirect ophthalmoscopy. Enucleated eyes were fixed in formalin, examined macroscopically and processed for histological assessment. Microscopic analysis included assessment of neuro-retina, retinal vasculature, RPE and ONH, as well as observation for any morphological intraocular changes. Comparison was made between: (1) treated and untreated areas of the same eye (internal control) (2) different areas within the same eye operated on using different vitrector settings (3) eyes operated on with the HV and GV (4) eyes receiving surgery and the fellow un-operated eye (external control, same pig).ResultsAll lenses had remained clear at 30 days into the postoperative period. On indirect ophthalmoscopy, the retina had remained attached in all eyes with no visible changes to the neuro-retina, retinal vasculature, RPE or ONH. Two eyes showed localized RPE depigmentation secondary to previously documented intraoperative retinal touch. The Morphological changes in the retinal layers above depigmented RPE were no different from retinal change elsewhere. There were mild and similar microscopic changes observed in the neuro-retina, retinal vasculature, RPE or ONH associated with either the HV or GV PPVs. Preliminary histological findings revealed no significant differences between eyes operated on with the HV and those operated on the GV.DiscussionAt 30 days into the postoperative period, there seemed to be similar morphological changes attributable to the use of HV and GV. Therefore, the HV promises to be a new alternative to the currently commercially available GV for PPV.

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“…5 Recently, hypersonic vitrectomy systems have been introduced in which a handpiece, the hypersonic vitrectomy probe (HVP), produces high-frequency longitudinal vibrations with the aim of inducing vitreous liquefaction close to the tip. 6,7 The potential advantages of HVPs are related to probe design and mechanism of action. With regard to the former, in a GVP the inner needle moves inside the outer one, determining the cyclic port opening and closing, whereas in the HVP there is a single needle and the port is always open.…”

Section: Introductionmentioning

confidence: 99%

Fluid Dynamic Assessment of Hypersonic and Guillotine Vitrectomy Probes in Viscoelastic Vitreous Substitutes

Stocchino

Nepita

Repetto

et al. 2020

Trans. Vis. Sci. Tech.

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To assess the fluidics of 23-gauge (G) large-port (L) and tear drop-port (TD) hypersonic vitrectomy probes (HVPs) compared with guillotine vitrectomy probes (GVPs) of various calibers (23G, 25G, and 27G) and geometries (single and double blades). Also, to identify the working parameters that provide the best balance between acceleration and flow rate, and, for HVPs, to measure temperature variations in the fluid. Methods: We used particle image velocimetry to measure flow fields in balanced salt solution and viscoelastic artificial vitreous. We analyzed acceleration, kinetic energy, and volumetric flux. The parameters considered were vacuum pressure, ultrasound stroke, and cut rate. Temperature measurements were taken using an infrared thermal camera. Results: The flow rate was significantly higher for HVPs than GVPs. With both probes, flow rate and acceleration increased with vacuum pressure. Flow rate depended weakly on the ultrasound stroke or cut rate. In HVPs, the acceleration peaked at a stroke of 30 μm, whereas in GVPs it peaked at a cutting rate of 4000 to 5000 cuts per minute (cpm). The HPV/TD combination generated higher flow rates and lower accelerations than did HPV/L. The increase in temperature was small. Conclusions: Under the present experimental setup and medium, HVPs offered better fluidics compared with GVPs in terms of flow and acceleration; however, the flow structure for HVPs is more complicated and unsteady. The HPV/TD combination produced larger flows than did the HPV/L combination and slightly smaller accelerations. HPVs generated a small temperature increase. Translational Relevance: In the tested artificial vitreous, HVPs were found to be more efficient in terms of generating lower acceleration for a given flow rate. The slight increase in temperature observed with HVPs is unlikely to be clinically significant.

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

Cited by 19 publications

References 33 publications

Regional Deformation of the Optic Nerve Head and Peripapillary Sclera During IOP Elevation

Regional Deformation of the Optic Nerve Head and Peripapillary Sclera During IOP Elevation

Live porcine thirty days delayed recovery surgery: Qualitative findings with the hypersonic vitrectomy

Fluid Dynamic Assessment of Hypersonic and Guillotine Vitrectomy Probes in Viscoelastic Vitreous Substitutes

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