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To receive news and publication updates for Associatd of Ophthalmology, enter your email address in the box below. This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. To evaluate comparative aspiration flow performance and also vitrectomy operating time efficiency using a double-cutting open port vitreous cutting system incorporated in a two-dimensional cutting TDC, DORC International vitrectome design versus standard vitreous cutter.
In vitro investigations compared aspiration flow rates in artificial vitreous humor at varying cutter speeds and vacuum levels using a TDC vitrectome and a standard vitrectome across different aspiration pump systems. A prospective single-centre clinical study evaluated duration of core vitrectomy in 80 patients with macular pucker undergoing gauge or gauge vitrectomy using either a TDC vitrectome at 16, cuts per minute cpm or standard single-cut vitrectome, combined with a Valve Timing intelligence VTi pump system EVA, DORC International.
Aspiration flow rates remained constant independent of TDC vitrectome cut rate, while flow rates decreased linearly at higher cutter speeds using a classic single-blade vitrectome. Vitrectomy surgery performed using a TDC vitrectome was faster than core vitrectomy utilizing a standard single-action vitrectome at similar cut speeds. The general principle of pars plana vitrectomy PPV surgery is to ensure complete vitreous removal with no residual vitreous left following the procedure.
A principal goal in PPV is to minimize vitreous traction by removing only the target ocular tissue, without inadvertently drawing unwanted tissue into the vitrectomy probe port or creating distant traction that might cause iatrogenic retinal tears or other complications. The degree of retinal traction created by vitrectomy cutters is influenced by the effect of time of aspiration, distance from the retina, and cutting rate.
Retinal traction increases with increasing aspiration vacuum and proximity to the retina and decreases with higher cut rates [ 1 ]. Evolution of Vitrectomy Cutter Technology. Developments in vitrectomy probe technology have accelerated in recent years, designed to improve intraoperative surgical control and allow quick core vitrectomy bulk vitreous removal and tractionless controlled vitreous shaving.
Alterations in geometrical design and size of vitrectomy probe, together with duty cycle, which is the proportion of time the cutter port is open rather than closed relative to a complete opening and closing surgical cutting cycle, and cutting speed provide additional performance capabilities for more efficient and safer surgery. This necessitates higher infusion and aspiration pressures to remove vitreous when using smaller-gauge vitrectomes. However, enlarging the port diameter of a vitreous cutter to increase flow becomes less effective as the port becomes larger [ 2 ].
The concept of a double-cutting instrument for use in ophthalmic surgery was first patented in [ 4 ]. When vitreous enters the inner aperture, it is cut first in a forward motion and then again during the backward motion.
Nearly two decades on, it was suggested that a dual port vitreous cutter system might allow surgeons to perform bulk vitrectomy more efficiently [ 5 ]. The idea involved inclusion of an opening in the internal guillotine pipe or inner vitrectome sleeve. Investigators found that, using modified gauge vitrectomy probes, the time of aspiration remained almost constant irrespective of cutting speed, indicating almost no reduction of flow but, more importantly, that aspiration time was significantly reduced compared with a standard single port cutter.
The concept of a double-action surgical cutting probe has only recently been developed and incorporated into modern vitrectomy instrumentation probes that feature 2 cutter openings in the guillotine shaft, thereby performing a vitreous cutting action on both forward and backward stroke of the probe device.
The principal advantages of this novel guillotine sleeve design included a doubling of cut rate, increased flow, and potentially decreased retinal traction or force exerted by the probe. In the author in cooperation with DORC International developed a newer vitrectome design, introducing a modified vitreous cutter technology called two-dimensional cutting TDC vitrectome system, launched in conjunction with the EVA ophthalmic surgical platform, a new aspiration system designed to provide both flow and vacuum control mode vitrectomy for enhanced intraoperative fluidics stability.
The TDC vitrectome comprises a tubular outer part and an axially movable tubular inner part arranged in the outer part [ 7 ].
The outer part has a closed distal end and the inner part an open distal end. Both parts have an opening in the tube, allowing continuous aspiration of tissue during a complete cutter cycle movement. The inner tube has been designed with a rectangular aperture for increased and continuous flow functionality.
The axial position of the distal cutting edge of the inner part as a function of the circumferential direction initially proceeds towards the proximal end and then back to the distal end again. Figure 1 illustrates core design elements of a TDC vitrectome and a classic single-cut vitrectome. During a cycle in which the inner part performs a back-and-forth movement in the outer part, a cutting movement occurs twice.
A first cutting movement occurs by cooperation of the distal end of the inner part with the distal cutting edge of the outer part. The second cutting movement is realized through cooperation of the distal cutting edge of the inner part with the proximal cutting edge of the outer part. The port diameter of this new TDC vitrectome is larger than previous vitrectome designs for the gauge TDC vitrectome, e.
Owing to the increased cutting and snipping capacity, the surgical intervention can be shortened and, moreover, the traction exerted on the ocular tissue drawn in during the aspiration phase decreases while the suction flow increases. We report below the methodologies and findings from in vitro comparisons of aspiration flow dynamics utilizing TDC and standard vitrectomes connected to different surgical platforms, together with methods and results of a prospective surgical case series study evaluating duration of core vitrectomy procedures and therefore comparative flow efficiency performance, using a TDC vitrectome system versus standard vitreous cutter system.
In vitro evaluations were undertaken to assess volumetric aspiration flow rates the main outcome measure of a two-dimensional cutting vitrectome compared with a standard vitrectome of the same gauge. A standard blade vitrectome of both gauges was also evaluated for aspiration flow rate at varying cut rates when connected to an Associate machine.
A cut rate and a vacuum level were set on a EVA machine according to the following range of tested settings: Before each test, a priming procedure was performed to ensure that the aspiration tubing of the cutter was completely filled with water and that the cutter was positioned with its tip into a cup filled with fluid.
The cup was placed on a high precision balance 0. After activation of the vitreous cutter, a small time was allowed for attainment of a constant vacuum level in the aspiration tubing. When the vacuum level was constant, the weight reduction of the fluid in the cup was measured and the aspiration flow calculated by dividing the weight reduction by the time elapsed.
Initially, these tests were performed with water. The same tests were then performed using artificial vitreous humor as aspirating fluid. The artificial vitreous, consisting of a mixture of deionized water, agar, and hyaluronic acid sodium salt, was produced according to a protocol published by Kummer et al.
For all tests performed, a density of 1. Per gauge size and type at least 2 vitreous cutters were tested. The average aspiration flow was calculated by averaging the measurement results of the different trials and the different vitreous cutters of the same type and gauge. We evaluated overall vitrectomy cutting time in seconds required to remove core vitreous in 80 patients diagnosed with macular pucker as part of a comparative evaluation of flow and operating duration using a TDC vitrectome and former standard single-cut vitrectome design gauge and gauge systems, DORC during core vitrectomy procedures.
Inclusion criteria were chosen to ensure adherence to a similarity principle, with similar vitreous liquefaction, similar case duration and difficulty, similar vitreous volume, and similar overall ocular conditions having had no prior ocular surgical intervention. Patients with a diagnosis at baseline of glaucoma, asteroid hyalosis, acute or chronic uveitis, or trauma were excluded.
A total of 80 patients were enrolled, with equal numbers, or 20 eyes, randomly allocated to one of four surgical treatment groups: All vitrectomized subjects were adequately informed prior to surgery about standard PPV for epiretinal membrane and core vitrectomy measurements and signed a consent form. Time measurement of core vitrectomy duration was made by a secondary person without a need to change standard vitrectomy procedures of PPV for epiretinal membrane removal.
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The study adhered to the tenets of the Declaration of Helsinki, and local regulatory requirements were fulfilled. Time and flow data were analyzed using linear least squares regression analyses and two-tailed -tests. Performance of the new generation gauge and gauge TDC vitrectomes was analyzed relative to the current generation or standard gauge and gauge cutter.
Statistical significance value of comparison between PPV durations performed using standard and TDC vitreous cutters was set at 0.
When the classic gauge vitrectome was connected to the Associate system, aspiration flow rate decreased from 1. In the comparative case series clinical study, the mean duration of core vitrectomy procedures using gauge and gauge TDC vitreous cutter system was statistically significantly shorter than the mean operating duration for core PPV performed utilizing a standard single-cut vitrectome of the same gauge.
Table 2 tabulates the mean duration of core vitrectomy procedures for each surgical intervention group assessed. In vitro tests demonstrate that a more predictable and consistent flow of vitreous around the instrument probe is achieved using a TDC vitrectome compared with a regular vitrectome system.
A TDC vitrectome delivered good overall stability in aspiration flow rate that is independent of cut speed. Moreover, the continuous open port of the TDC vitreous cutter permits greater tissue removal efficiency that is unaffected by cutter velocities, showing the potential of TDC vitrectome technology for faster, less turbulent, and potentially safer smaller-gauge vitrectomy. The reported comparative evaluation of core vitrectomy duration in 80 patients undergoing 0600 for macular pucker epiretinal membranes dlrc that surgical case time using TDC vitrectome PPV is less than vitrectomy operating 600 performed using a standard single port cutter of the same gauge.
Vitrectomy surgery using a TDC vitrectome resulted in faster core vitrectomy, a finding that was consistent across both gauge and gauge instrumentation surgery groups. Fluidic stability and control during vitrectomy is essential. Retinal surgeons choose high vitreous cutter rates so as to maximize fluidic stability and reduce unwanted force or traction. Higher cutting rates using a TDC vitrectome in combination with continuous uninterrupted aspiration flow as a result of 2 open cutting ports help to ensure faster complete vitreous removal.
If the higher double-cutting rate minimizes unwanted vitreous traction and reduces the risk of iatrogenic retinal damage is object of a safety designed ongoing study. Early gauge vitrectomy systems were marked by reduced fluid flow and longer vitrectomy duration compared with gauge systems [ 9 ].
Journal of Ophthalmology
However, the design of new generation dual-opening vitreous cutters effectively overcomes these associste limitations by providing for consistent flow irrespective of the cut rate used during vitrectomy surgery.
Findings from this small comparative case series assessment are supportive assockate the efficiency of TDC dotc technology and of assoclate cut speeds for vitrectomy surgery. Results suggest significantly decreased operating time for core vitrectomy. Evaluations reported herein are nonetheless limited by small research scale and by the fact that the same surgeon performed all vitrectomies in this single-centre clinical assessment.
There is undoubtedly a surgical learning curve involved in mastering the technique of using small-gauge vitrectomy instruments, typically involving the first 20 or so cases. Future follow-up studies might usefully evaluate postoperative visual, anatomic, and safety outcomes. Survey trends illustrate growing utilization of sutureless microincision vitrectomy in everyday retina practice [ 10 ]. Advocates of microincisional vitrectomy instrumentation highlight surgical advantages compared with conventional gauge surgery in addition to sutureless vitrectomy capability, namely, reduced operating time, greater precision in performing delicate maneuvers, less associaye manipulation, and reduced postoperative inflammation and rapid visual recovery [ 1112 ].
A report by the American Academy of Ophthalmology in noted that, compared assiciate gauge vitrectomy, small-gauge vitrectomy is associated with significantly dor levels of patient discomfort and ocular inflammation, with faster improvement in visual acuity, and an acceptably low incidence of adverse events comparable to those observed for gauge vitrectomy [ 13 ]. Overall, vitrectomy case duration using a TDC vitrectome in combination with the EVA surgical machine was shorter than vitrectomy operating time using a standard or classic single-cut vitrectome in patients undergoing vitrectomy for epiretinal membranes.
Faster operating times offer the potential of reduced costs as well quicker postoperative rehabilitation [ 14 ]. Reported findings suggest that a TDC vitrectomy probe provides greater operating efficiency than conventional vitreous cutter instrumentation during sutureless small-gauge vitrectomy. Experimental assessments show maintenance of constant high aspiration flow independent of cutter speed using a two-dimensional cutting TDC vitrectome for vitreous removal.
A prospective single-centre clinical study assessed duration of core vitrectomy procedure using a TDC vitrectome versus a standard single-cut guillotine vitrectome; the results reveal shorter operating times using a double-cutting TDC vitrectomy probe. Indexed in Science Associzte Index Expanded. Assiciate to Table of Contents Alerts. Table of Contents Alerts. Introduction The general principle of pars plana vitrectomy PPV surgery is to ensure complete vitreous removal with no residual vitreous left following the procedure.
Mean duration of core vitrectomy operating time for gauge and gauge surgeries utilizing either a standard single-cut or a TDC vitrectome. View at Google Scholar F.