Applications of a cannulated extrusion needle during vitreoretinal microsurgery

Surgical Results for Proliferative Vitreoretinopathy

We reviewed 88 consecutive eyes that underwent vitrectomy for retinal detachment with proliferative vitreoretinopathy (PVR) and were followed a minimum of six months. A primary goal of the surgery was the meticulous trimming of the vitreous base in hopes of decreasing the incidence of post-operative reproliferation and anterior PVR. Those eyes with anterior PVR had aggressive release of vitreous base contraction (anteroposterior and circumferential) with intraocular scissors. All posterior tractional membranes were removed. All eyes received long-acting gas for postoperative retinal tamponade. Macular reattachment was achieved in 78 (88.6%) eyes. Forty-six (52.3%) obtained at least 5/200 vision. Seventeen (19%) eyes were re-operated at least once. We compared the importance of initial lens status (pseudophakic, aphakic, phakic), need for relaxing retinotomy, presence of anterior PVR, and history of previous vitrectomy on the anatomic and visual results. No single factor was responsible for a statistically significant effect on either vision or anatomic success, except for the need for a relaxing retinotomy, which carried with it a decreased chance of an eye obtaining 5/200 vision (Fisher's exact test, p = 0.03).

Scleral rupture during retinal detachment surgery: risk factors, management options, and outcomes

OBJECTIVE

To evaluate the potential risk factors, management strategies, and outcomes of scleral rupture during retinal detachment (RD) surgery.

DESIGN

Case-control study.

PARTICIPANTS AND CONTROLS

Fourteen consecutive patients with scleral rupture during RD surgery (cases) and 65 consecutive patients who underwent RD surgery without scleral rupture (controls).

INTERVENTION

Demographic and clinical data were abstracted from patients' medical records.

OUTCOME MEASURES

Visual acuity and retinal attachment status at the last examination.

RESULTS

Significant risk factors for scleral rupture during RD surgery were reoperation after failed RD surgery (71 % vs. 32%), and pre-existing scleral pathologic condition (29% vs. none). The site of rupture was in the bed of a previously placed scleral buckle in all patients with a previous buckling surgery. Repair of the rupture included scleral sutures in eight (57%), scleral patch graft in four (29%), and placement of a scleral buckle over the site in two (14%) eyes. Eleven (79%) underwent vitrectomy with retinal tamponade by gas (n = 4) or silicone oil (n = 7). Complications observed postoperatively included vitreoretinal incarceration (n = 3), vitreous hemorrhage (n = 2), suprachoroidal hemorrhage (n = 2) and subretinal hemorrhage (n = 3). In the 14 eyes with scleral rupture, the final visual acuity was > or =20/40 in 1 (7%), 20/50 to 20/200 in 5 (36%), and <20/200 in 8 (57%). Ten (71 %) had proliferative vitreoretinopathy develop. The retina was attached in 7 (50%), 6 (43%) had localized peripheral detachment, and 1 had a total retinal detachment. The vision improved in 4 (29%), was unchanged in 5 (36%), and was worse than before surgery in 5 (36%). In the 65 controls, the visual acuity at the time of the last examination was > or =20/40 in 26 (40%), 20/50 to 20/200 in 21 (32%), and <20/200 in 18 (28%). Sixty three (97%) patients had complete retinal reattachment, 1 (2%) had a localized peripheral RD, and 1 (2%) had an RD involving the posterior pole. After surgery, the vision improved in 45 (69%), was unchanged in 15 (23%), and was worse in 5 (8%) of the control eyes. The visual and anatomic outcomes of the eyes with scleral rupture were significantly worse than in the control group (P = 0.002 and P < 0.001, respectively).

CONCLUSIONS

Risk factors associated with intraoperative scleral rupture include reoperation for failed RD surgery and pre-existing scleral pathology. Although this complication may be compatible with a good visual outcome in some patients, a high incidence of persistent or recurrent RD with proliferative vitreoretinopathy worsens the visual outcome for most patients with this complication.

Fibrinolysis of experimental subretinal haemorrhage without removal using tissue plasminogen activator

AIMS/BACKGROUND

Human recombinant tissue plasminogen activator (rt-PA) fibrinolysis of subretinal haemorrhage with concomitant removal has been shown to reverse the natural history of photoreceptor degeneration in experimental subretinal haemorrhages if evacuated within 7 days. The aim of the study was to determine whether fibrinolysis of subretinal haemorrhage without concomitant removal would offer a simpler approach with similar photoreceptor sparing.

METHODS

A neodymium YAG laser was used to create experimental subretinal haemorrhages beneath the holangiotic retina of the cat. Tissue plasminogen activator (10 micrograms/ml) was injected into 4 day old subretinal haemorrhages to evaluate its effect on altering the natural history of retinal degeneration. Light and electron microscopy were used to study the histopathological effect.

RESULTS

The injection of rt-PA into large 4 day old subretinal haemorrhages without concomitant removal did not alter the natural history of retinal degeneration. In fact, a second focus of retinal degeneration occurred at a gravity dependent inferior site where the subretinal haemorrhages had migrated.

CONCLUSIONS

There was no therapeutic benefit from the injection of rt-PA into subretinal haemorrhages without con-comitant removal in this cat model.

Treatment of massive subretinal hemorrhage from complications of scleral buckling procedures

Vitrectomy techniques permit removal of subretinal hemorrhage, but the prognosis varies and depends principally on the cause of the hemorrhage. Nine consecutive patients undergoing pars plana vitrectomy with internal drainage of massive subretinal hemorrhage from complications of scleral buckling procedures were studied, to evaluate the long-term results. In all eyes, the final visual acuity was improved, compared with preoperative visual acuity, and was 20/80 or better in seven of nine cases. Recurrent retinal detachment secondary to proliferative vitreoretinopathy developed in two patients, but complete retinal reattachment was achieved after further procedures were performed. Patients with massive subretinal hemorrhage from complications of scleral buckling procedures comprise a subgroup of patients with subretinal hemorrhage in which internal drainage via pars plana vitrectomy is an acceptable alternative to observation only and may result in improved visual acuity outcomes.

Tissue plasminogen activator thrombolysis during surgical evacuation of experimental subretinal hemorrhage

To assess the role for intraoperative thrombolysis during surgical evacuation of massive subretinal hemorrhage, the authors studied the ability of tissue plasminogen activator (tPA) to facilitate removal of an experimental subretinal blood clot through a small drainage retinotomy. In rabbit eyes, a single subretinal injection of tissue plasminogen activator in concentrations of up to 250 micrograms/ml failed to produce significant (greater than 50%) clot dissolution during a 3-hour period. However, repetitive subretinal lavage and aspiration with tPA (50 micrograms/ml) resulted in progressive intraoperative clot dissolution in rabbits and allowed complete evacuation of blood through a small drainage retinotomy in 6 (100%) of 6 cat eyes. Repetitive vigorous subretinal irrigation with saline solution had no discernible effect on clot size in rabbit eyes. Histopathologic examination of cat eyes following tPA-assisted surgical evacuation of subretinal blood showed preservation of the outer retina in 2 eyes and severe atrophy of the outer retina in 4 eyes.

Recognition and removal of the posterior cortical vitreous during vitreoretinal surgery for impending macular hole

Vitreoretinal surgery for impending macular hole includes recognition and removal of the posterior cortical vitreous. Previously described surgical techniques for removal of cortical vitreous used either rigid instruments (a tapered extrusion needle or a barbed microvitreoretinal blade) or a short fenestrated soft-tipped suction needle. We used a technique with the cannulated extrusion needle that detects the presence of the posterior cortical vitreous and facilitates safe removal of this layer from the retina. Although this technique is most useful when performing vitrectomy for impending macular hole, it may also be used during vitrectomy for other conditions with uncertain detachment of the posterior cortical vitreous.

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.

Factors prognostic of visual outcome in patients with subretinal hemorrhage

We reviewed the charts of 29 patients with large subretinal hemorrhages involving the center of the fovea to evaluate factors that might be prognostic of visual outcome. The average final visual acuity was 20/480 with a mean follow-up of three years. Patients with thick hemorrhages (causing an obvious elevation of the fovea) had worse final visual acuity than patients with thin hemorrhages (P = .02). The diameter of the hemorrhage was not a significant predictor of outcome. Patients with aging macular degeneration had poorer final visual acuity (mean, 20/1,700, P = .002), and patients with choroidal ruptures had better final visual acuity, (mean 20/35, P less than .001) than the remainder of the patients. We found that the presence of aging macular degeneration was a more important predictor of the outcome of legal blindness than the thickness of the hemorrhage (P = .03). Although the prognosis in patients with subfoveal blood is generally poor, some patients have excellent return of vision.

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.

Endoretinal biopsy in immunosuppressed and healthy patients with retinitis. Indications, utility, and techniques

Endoretinal biopsies were taken using pars plana vitrectomy techniques in 13 eyes with inflammatory or infectious retinitis complicated by retinal detachment (RD). The surgical technique has evolved over a 4-year period. The authors review the surgical technique including techniques of removal of the vitreous, appropriate hemostasis, selection of the biopsy site, and atraumatic removal of the tissue from the vitreous cavity. Careful processing of the material for histopathology, immunopathology, and electron microscopy is necessary and has provided useful information in patient diagnosis and management. The authors have used the technique in cases of rhegmatogenous RD complicating presumed viral retinitis. The technique has proven to be useful in confirming the clinical diagnosis and is relatively safe when used in selected cases.

New silicone tipped cannulas for subretinal fluid drainage

Two new disposable cannulas for internal drainage of subretinal fluid are described in this article. We describe a curved and a straight version consisting of plastic hubs, 20 gauge proximal and 25 gauge distal stainless steel hypodermic tubing, and soft and flexible silicone tubing overmounts. Both these cannulas facilitate atraumatic drainage of subretinal fluid through pre-existing retinal holes and tears or through a retinotomy performed during vitreoretinal microsurgery.

Design features and surgical use of a cannulated extrusion needle

A cannulated extrusion needle was designed as a modification of the standard 20-gauge extrusion by including an inner 24-gauge flexible cannula that can be extended up to 18 mm beyond the metal tip. Indications for use of the instrument are reviewed along with selected case histories demonstrating its use. The instrument is used primarily for internal subretinal fluid drainage in eyes with complex retinal detachments caused by proliferative vitreoretinopathy. The flexible cannula is guided into the subretinal space through an open peripheral retinal break and the subretinal fluid is evacuated during a simultaneous fluid/air exchange. The positive pressure of the automated air pump creates a pressure gradient sufficient to achieve passive egress of subretinal fluid through the cannula. Active suction is avoided because of the risk of posterior retinal incarceration into the cannula tip. In addition, the cannula can be used to remove hemorrhage, gas, or silicone oil in the subretinal space.

Complications of endodrainage retinotomies created during vitreous surgery for complicated retinal detachment

The authors report nine cases of endodrainage retinotomy site complications that occurred after vitreous surgery for complicated retinal detachments (RDs). Postoperative subretinal neovascularization developed in four eyes at the retinotomy drainage site. In two eyes, postoperative proliferation at a posteriorly placed endodrainage site created traction macular detachments. Redetachment due to retinotomy opening caused by postoperative drainage site proliferation developed in three eyes. The retinas of all nine eyes were eventually reattached, and vision improved from the preoperative level. These complications are related to retinal pigment epithelium and/or Bruch's membrane damage during internal subretinal fluid drainage and retinotomy endolaser photocoagulation. Careful evaluation of extrusion instruments, drainage techniques, retinotomy placement, and subsequent endolaser treatment is necessary to minimize these complications.