Applications of a cannulated extrusion needle during vitreoretinal microsurgery

A specially designed cannulated extrusion needle facilitates the internal drainage of subretinal fluid during vitreoretinal microsurgery. Case histories demonstrate the use of this instrument in the management of complex retinal detachments including eyes with preretinal and subretinal hemorrhage, proliferative vitreoretinopathy with open peripheral retinal breaks, retinal detachment with giant retinal tear, and combined traction-rhegmatogenous detachments due to diabetic retinopathy. This method of internal drainage appears to have specific advantages over standard techniques by allowing the removal of subretinal hemorrhage, the utilization of pre-existing peripheral breaks for internal drainage, and the complete reattachment of shallow posterior pole retinal detachments to allow laser endophotocoagulation.     

Subretinal bevacizumab detection after intravitreous injection in rabbits

PURPOSE: To evaluate subretinal detection of bevacizumab 2 hours after intravitreous injection of 1.25 mg in rabbit eyes. METHODS: Anterior chamber paracentesis using a 30-gauge needle was performed in nine female Dutch-belted rabbits by removal of 0.05 mL of aqueous humor. Transscleral retinal detachment was performed with a modified 25-gauge infusion cannula connected to a bottle of physiologic saline solution (PSS). The animals were divided into experimental group 1, with intravitreous injection of 0.05 mL of (1.25 mg) with a 30-gauge needle (n = 6) and the control group 2, with intravitreous injection of 0.05 mL of PSS with a 30-gauge needle (n = 3). Two hours after the intravitreous bevacizumab or PSS injection, subretinal fluid was aspirated and immunoassayed to measure the level of bevacizumab. The rabbits were killed by intravenous pentobarbital injection. The eyes were enucleated and fixed in 10% formaldehyde. The pars plana site at which the transscleral cannula was introduced was analyzed by light microscopy, to exclude iatrogenic retinal tears. Eyes with accidental retinal tears were excluded. RESULTS: Subretinal bevacizumab molecules were detected in the six eyes that received an intravitreous bevacizumab injection. No subretinal bevacizumab was detected in the control eyes. Light microscopy showed no evidence of retinal tears or holes in any rabbits used for the bevacizumab detection and control group. CONCLUSIONS: Bevacizumab molecules were detected in the subretinal space after intravitreous injection of 1.25 mg of bevacizumab, possibly as the result of diffusion through the retina in a rabbit model.     

Management of subretinal foreign bodies with a cannulated extrusion needle

We treated two patients who had nonmagnetic subretinal foreign bodies (metallic pellet and lens nucleus fragment) in the presence of a retinal detachment and a distant retinal break. After the pars plana vitrectomy, the soft, flexible tip of the cannulated extrusion needle was used to push the foreign object gently away from the posterior pole toward the retinal break where it was grasped and removed from the eye. This technique for subretinal foreign body removal is preferable to creating a large posterior retinotomy overlying the foreign body because of the potential risks of further macular trauma, hemorrhage, or proliferation of periretinal membranes from the retinotomy site.     

A bent infusion cannula for vitreous surgery

PURPOSE: To modify an infusion cannula for vitreous surgery and decrease cannula-related complications. DESIGN: New surgical instrument. METHODS: A conventional 20-gauge infusion cannula was modified by forming a 135-degree angle at the joint of the flange between the cannula adapter and the needle. The sloped plane of the needle tip was opposite the bent adapter. The cannula was routinely fastened with a 7-0 absorbable suture after insertion into the eye. RESULTS: We used the modified infusion cannula in 50 consecutive phakic eyes (48 patients). Intraoperatively, the cannula remained attached to the globe surface; it did not tilt anteriorly and damage the lens when touched inadvertently. No suprachoroidal or subretinal infusion was observed. Neither the lens nor the retina was damaged. There were no cannula-related retinal detachments or breaks during follow-up. CONCLUSIONS: The modified infusion cannula is more effective and safer during pars plana vitrectomy in phakic eyes compared with a conventional cannula.     

The surgical management of giant retinal tears with the cannulated extrusion needle

In 18 eyes of 17 patients, we treated retinal detachment caused by a giant retinal tear by unfolding and repositioning the retina with a cannulated extrusion needle. After pars plana vitrectomy, a fluid-gas exchange was performed with the patient in the supine position. Using the cannulated extrusion needle to drain subretinal fluid posterior to the giant retinal tear, the retinal flap was manipulated into the correct anatomic position. With this technique, 18 of 18 eyes with retinal detachment caused by a giant retinal tear were successfully reattached intraoperatively. Although eight of these eyes subsequently redetached and required additional surgical procedures, 16 of 18 eyes remain attached with a mean follow-up of 11 months.     

Controlled drainage of subretinal and choroidal fluid

Controlled drainage of subretinal fluid is achieved using a 25-gauge needle, passed obliquely through the sclera. This reduces the risk of choroidal hemorrhage and retinal incarceration.     

Two Cases of Accidental Dislocation of the Silicone Sleeve of an Extrusion Cannula into the Vitreous Cavity

Background

Fluid-air exchange during vitreoretinal surgery is often used as a tool for subretinal fluid endodrainage. Soft-tipped flexible extrusion cannulas are commonly used to aspirate the posterior subretinal fluid.

Methods

This is an observational two-case series describing two patients who underwent 20-G pars plana vitrectomy complicated by the accidental fall of the silicone sleeve of a soft-tipped extrusion cannula into the vitreous cavity. In the first case, the cannula had inadvertently been subjected to sterilization process.

Results

While withdrawing the soft-tipped extrusion cannula from the eye, following internal drainage of transvitreal and subretinal fluid, the loose silicone sleeve probably got entangled at the inner lip of the sclerotomy and finally fell on the retinal surface. In both cases, the silicone sleeve was held and removed with an intraocular forceps.

Conclusions

This rare complication has been reported in the literature only once previously. Sterilization of disposable subretinal fluid cannulas is not advisable because of the risk of dislocation of the silicone sleeve into the eye. Besides this, it is important to check the integrity of the silicone sleeve before and after surgery.Key words: Silicone sleeve, Intraocular foreign body, Extrusion cannula, Vitrectomy     

Modified technique to create retinal detachment during macular translocation surgery

PURPOSE: To report a modified technique for creating total retinal detachment during macular translocation surgery with a 360-degree retinotomy. DESIGN: Interventional case series. METHODS: After vitrectomy, BSS Plus (Alcon, Fort Worth, TX, USA) was injected into the subretinal space with a 39-gauge needle to create a small retinal detachment. The tip of a 20-gauge silicone-tipped needle was then placed in the hole created by the needle, and BSS Plus was injected subretinally at a high flow rate. RESULTS: In 10 eyes (10 patients), we created one iatrogenic retinal hole in seven eyes and two holes in three eyes. The time needed to create total retinal detachment was decreased. CONCLUSIONS: Our technique seems to make creation of a total retinal detachment easier compared with the previous standard procedure and may reduce postoperative complications following macular translocation surgery with a 360-degree retinotomy.     

Modified external needle drainage procedure for rhegmatogenous retinal detachment

PURPOSE: To describe the results of a modified external needle subretinal fluid drainage technique to treat eyes with a rhegmatogenous retinal detachment. METHODS: One hundred eighty-seven consecutive patients with a rhegmatogenous retinal detachment who underwent scleral buckle and modified external needle drainage at Duke Eye Center or Vistar Eye Associates were included in this study. Subretinal fluid was drained by a technique whereby the intraocular pressure was raised to a supranormal level by tightening an encircling scleral buckle and then the subretinal space was entered by a needle introduced externally while the retina was directly viewed with an indirect ophthalmoscope. Subretinal fluid drainage success rate, one-operation reattachment rate, final retinal reattachment rate, intraoperative and postoperative complication rates, and final visual acuity were the main outcome measures. RESULTS: Subretinal fluid was successfully drained in all eyes. The one-operation reattachment rate was 91%, and the final reattachment rate was 98%. Intraoperatively, 15% of eyes required corneal debridement to obtain an adequate view for safe subretinal fluid drainage. Subretinal hemorrhage of no more than one clock hour occurred in 4.2% of eyes. A total of 2.6% of eyes developed an epiretinal membrane postoperatively that required a vitrectomy to improve the visual acuity. The postoperative visual acuity, 0.54 by logMAR (20/69 by Snellen), was significantly better than the preoperative visual acuity, 1.1 logMAR (20/250 by Snellen) (P < 0.0001). CONCLUSIONS: The modified external needle drainage technique is a flexible, effective method to drain subretinal fluid in eyes with a rhegmatogenous retinal detachment. The retinal reattachment rate and complication rate compare favorably to alternative subretinal fluid drainage techniques.     

A new instrument for drainage or injection of fluid within subretinal space

PURPOSE: To describe a new instrument, the subretinal aspiration and injection device (SR-AID), designed to facilitate the controlled external drainage or injection of fluid in the subretinal space. METHODS: The SR-AID is formed by an assembly of a probe, handle body, and a driving unit. The curved conduit within the probe segment forms a curved tunnel and acts as a guide along which a needle moves back and forth. The feasibility of fluid injection beneath the attached retina was tested in animal eyes. The efficacy of subretinal fluid drainage with the SR-AID were assessed in six cases of clinical retinal detachment. RESULTS: External approach to the subretinal space under ophthalmoscopic monitoring can be achieved by oblique angle penetration of the scleral wall with a needle from the SR-AID. Fluid was injected successfully into the subretinal space in three of six rabbit eyes and in two of two pig eyes. The mean duration required for the drainage of subretinal fluid with the SR-AID was 127 seconds. There was no incidence of significant subretinal hemorrhage or retinal perforation in the animal experiments and in human cases. CONCLUSION: Our case series suggests that the SR-AID provides an efficient and safe means of access to the subretinal space.     

Modified needle drainage. A safe and efficient technique of subretinal fluid drainage in scleral buckling procedure

PURPOSE: To compare modified needle drainage (MND) with conventional drainage (CD) of subretinal fluid (SRF) as described by Schepens in surgery for primary rhegmatogenous retinal detachment. METHODS: Prospective randomised clinical trial of 80 patients undergoing scleral buckling with subretinal fluid drainage for primary rhegmatogenous retinal detachment. In 40 patients modified needle drainage of subretinal fluid (SRF) was done using a perpendicular trans-scleral entry with a 26-gauge needle and the appearance of SRF in the hub of needle as end point. In 40 patients conventional drainage was done as described by Schepens using a diathermy needle. Adequacy of SRF drainage, intraoperative complications, anatomical and functional outcome were noted. RESULTS: 100% adequate drainage was achieved in all cases. The complication rate was 32.5% (n=13) in the CD group and 15% (n=6) in the MND group. In the CD group, 17.5% (n=7) patients had subretinal haemorrhage and in 2 eyes it was clinically significant. In the MND group 15% (n=6) of cases had subretinal haemorrhage and in one patient it was clinically significant. In the CD group, more serious SRF drainage complications were observed; these were absent in the MND group. CONCLUSION: Modified needle drainage is a safe and effective procedure for SRF drainage. In comparison with CD, MND is technically easy, less cumbersome and requires no special equipment.     

Suprachoroidal hemorrhage caused by breakage of a 25-gauge cannula

A 72-year-old woman had vitreous surgery for epiretinal membrane using the 25-gauge vitrectomy system. During the removal of the cannula at the end of the surgery, half of its tip was noted to be missing. The following day, a severe choroidal detachment associated with a hypotony was found. A second surgery was performed, including drainage of suprachoroidal hemorrhage and choroidal fluid and the removal of the tip of the 25-gauge cannula stuck inside the sclerotomy. The retained cannula tip might have acted as a channel allowing vitreous fluid into the suprachoroidal space, resulting in choroidal detachment, hemorrhage, and hypotony.     

Limitation of 25-gauge vitrectomy instrumentation in highly myopic eyes.

In highly myopic eyes, a 25-gauge soft-tip needle is unable to remove fluid completely during air-fluid exchange because the needle is too short to reach the back of the elongated globe. In the simulated example, we found that the standard soft-tip cannulated needle is unsuitable for use in eyes with axial lengths greater than 31 mm. Other 25-gauge instruments are similarly unable to reach the back of a long eye.     

New infusion cannula for prevention of retinal damage by infusion air during vitrectomy

PURPOSE: Postoperative visual field defects are sometimes found after macular hole surgery. We have previously shown that damage to the retina by air infusion from an infusion cannula is a causative factor. To minimize such damage, we modified the infusion cannula and examined its effects experimentally. METHODS: An infusion cannula with a closed tip and openings on four sides was created. Experimentally, a vitrectomy was performed in rabbit eyes using this new infusion cannula or a conventional cannula. After fluid-air exchange at an air pressure of 40 mmHg, eyes were removed and processed for histologic examination. The areas of the retinal damage caused by air infusion were evaluated. RESULTS: The area of retinal damage created by the new cannula was reduced significantly when compared with damage from conventional cannula use. CONCLUSION: This new cannula, designed for the purpose of scattering the air infusion, can reduce retinal damage, which leads to less frequent postoperative visual field defects.     

The effect of intraoperative retinal manipulation on the underlying retinal pigment epithelium: an experimental study

PURPOSE: Retinal pigment epithelial changes described after vitreoretinal surgery may result from localized compression injury caused by intentional or inadvertent contact with vitreoretinal instruments. The authors evaluated these changes resulting from manipulation of the retina without frank retinal injury. METHODS: One eye each of six pigmented rabbits underwent surgery during which the inner retinal surface was touched at several points with a 20-gauge silicone-tipped subretinal fluid cannula without causing a retinal break or subretinal hemorrhage. The rabbits were followed-up with indirect ophthalmoscopy, fundus photography, and fluorescein angiography, and were killed at 1 hour, 1 week, or 2 weeks. Light microscopy was used for histopathologic evaluation. RESULTS: On fluorescein angiography, diffuse leakage noted at the injury sites significantly decreased by the fourth day and almost completely disappeared by the second week. Disruption of photoreceptor outer segments and retinal pigment epithelium in the early specimens, and irregular pigmentation, proliferation, and migration of the retinal pigment epithelium at 1 and 2 weeks were the prominent features on histopathologic examination. CONCLUSIONS: Intraoperative manipulation of the attached retina may cause significant pigment epithelium displacement and proliferation and varying degrees of disorganization of normal retinal architecture in the absence of clinically evident retinal breaks and subretinal hemorrhages.     

Removal of retained subfoveal perfluoro-n-octane liquid

PURPOSE: To report a novel technique to remove retained submacular perfluorocarbon liquid. DESIGN: Retrospective cases series. METHODS: Two patients with retained subfoveal perfluorocarbon liquid were treated with this technique. With a three-port pars plana approach, a 39-gauge flexible cannula was used to perform a retinotomy adjacent to the subfoveal perfluorocarbon bubble. The tip of the cannula was inserted into the bubble, which was removed with active suction. RESULTS: Both patients underwent successful removal of the perfluorocarbon liquid without complications. In one patient, visual acuity improved from 20/70 to 20/30, with resolution of his preoperative central scotoma. The second patient required removal of subfoveal perfluorocarbon liquid at the time of silicone oil removal. The preoperative vision of finger counting improved to 20/60. CONCLUSIONS: Subretinal perfluorocarbon can be removed using a flexible 39-gauge cannula without inducing retinal detachment or making a large retinotomy. This technique may benefit patients with retained subfoveal perfluorocarbon liquid.     

改良穿刺放液在外路法视网膜脱离复位术中的应用

目的 探讨外路法视网膜脱离复位手术中改良穿刺放视网膜下液的临床有效性及安全性.设计回顾性病例系列.研究对象2006年1月至2009年9月收住南京医科大学第一附属医院眼科的329例孔源性视网膜脱离的患者.方法 手术显微镜下予巩膜环扎和（或）巩膜外加压术,术中均联合改良穿刺法放出视网膜下液,即穿刺点选在角巩膜缘后11 mm的直肌两侧,避开涡状静脉和视网膜裂孔,采用25 G 5/8-in针头（1ml BD针头,新加坡Becton Dickinson Medical（S）Pte Ltd.）垂直巩膜穿刺放出视网膜下液,穿刺深度不超过针头斜面.收集术前、术后及手术数据并进行分析.主要指标改良穿刺放液的成功率及并发症的发生率.结果 329例外路法视网膜脱离复位手术,327例（99.4%）引流出视网膜下液,2例未引流出视网膜下液.改良穿刺放液的并发症有视网膜下出血2例（0.6%）,出血范围小于2PD,穿刺点正对视网膜裂孔处1例（0.3%）,导致玻璃体自巩膜穿刺口脱出.结论 改良穿刺放液法是外路法视网膜脱离复位术中引流视网膜下液的一种安全、有效的方法.     

Vitreous prolapse through the scleral wound in 25-gauge transconjunctival vitrectomy

PURPOSE: To examine the effectiveness of excising peripheral vitreous until the cannula tip is exposed to prevent vitreous prolapse through the scleral wound in 25-gauge transconjunctival vitrectomy. METHODS: Twenty-five-gauge vitrectomy was performed in 60 consecutive eyes. Peripheral vitrectomy was conducted until the cannula tip was exposed in 30 eyes and with conservation of the vitreous around the cannula in 30 eyes. Vitreous prolapse through the scleral wound was examined using a suction stick. RESULTS: Vitreous prolapse through the scleral wound was transparent, fine and short, and detectable only with the suction stick. The incidence of vitreous prolapse through the scleral wound was 0% (0 of 30 eyes) when peripheral vitreous was excised until the cannula tip was exposed, and 20% (6 of 30 eyes) when the vitreous around the cannula was conserved, with a significant difference between two groups (p=0.0237). In two of six eyes with vitreous prolapse, the scleral wound was open, but there was no leakage of intraocular fluid and normal ocular pressure was maintained. CONCLUSIONS: If peripheral vitrectomy is performed without excising the vitreous surrounding the cannula, there is a 20% risk of the vitreous prolapsing through the scleral wound. Vitreous prolapse through the scleral wound is difficult to detect because it is transparent, fine and short, and there is no intraocular fluid leakage. Therefore, detecting vitreous prolapse with a suction stick and appropriate intervention are important for preventing endophthalmitis.     

Effects on retinal adhesive force in vivo of metabolically active agents in the subretinal space.

The in vivo effects on the retinal adhesive force of injecting metabolically active agents into the subretinal space of rabbits were studied. Small retinal detachments (blebs) were made in living Dutch rabbit eyes by injecting experimental solutions into the subretinal space with a micropipette. A second micropipette, inserted into the same bleb, measured fluid pressure using a resistance servonulling system. The adhesive force was calculated according to Laplace's law. Blebs containing dibutyryl cyclic adenosine monophosphate, furosemide, and amiloride showed retinal adhesiveness to be decreased to 69%, 86%, and 81% of control values, respectively. Dibutyryl cyclic guanosine monophosphate and acetazolamide had no significant effect. Ouabain increased retinal adhesiveness to 119% of normal. The nonspecific metabolic toxin, dinitrophenol, reduced adhesiveness to an unmeasurable level. For some agents, the rate at which subretinal fluid was absorbed also was measured. Furosemide and amiloride in the subretinal space caused slight slowing of subretinal fluid absorption; acetazolamide had no effect. These data support the concept that metabolic factors contribute to retinal adhesion in vivo.     

Continuous outflow devices for macular translocation with 360-degree retinotomy

PURPOSE: Separation of the retina from retinal pigment epithelium is the most difficult step in macular translocation surgery. To complete this critical step, we have developed two specially designed continuous outflow needles, a rigid needle for creating retinal detachment and a liquid perfluorocarbon injection needle with a soft tip. DESIGN: Experimental study, new instrument development. METHODS: To permit continuous outflow during separation of the retina from the retinal pigment epithelium, the shaft of the continuous outflow needle is smaller than 20 gauge in diameter to allow continuous flow of fluid from the vitreous cavity. RESULTS: These instruments have been used successfully in 54 eyes that underwent macular translocation with 360-degree retinotomy. The rigid needle creates safe retinal detachment by keeping intraocular pressure lower, which is strictly needed for this step. The injection needle facilitates injection of perfluorocarbon liquid while manipulating the retina gently with its soft tip. CONCLUSION: Continuous outflow instruments are useful tools because they facilitate critical steps in the delicate process of macular translocation surgery.