Surgical removal of subfoveal perfluorocarbon liquid using combined flute needle and vacuum aspiration in silicone oil-filled eyes: A novel technique to remove subfoveal PFCL.

We report a procedure using a pressure-controllable flute needle to remove subfoveal retention of perfluorocarbon liquid (PFCL) under silicone oil. With a two-port pars plana approach, we used a 27-gauge dental injection needle to create a retinotomy at the farthest edge of the PFCL bubble from the fovea. A 27-gauge flute needle was then inserted into the edge of the subfoveal PFCL to aspirate it with vacuum pressure. Three patients with subfoveal retained PFCL were treated by this procedure within silicone oil tamponade 1 month after the first operation. They promptly underwent successful removal of the PFCL with postoperative retinal reattachment and good visual outcome. This procedure allows safe and early treatment for subfoveal retained PFCL. Many medical institutions around the world could implement this procedure using common dental injection needles and flute needles.

Subfoveal perfluorocarbon liquid (PFCL) migration is a stubborn complication following vitreoretinal surgery with the use of PFCL. Authors used various microcannulas to perform a retinotomy near the macula to aspirate the retained PFCL bubbles in 3 months, when the silicone oil was extracted.[1234] The PFCL droplets could prevent macular reattachment and are toxic to the retina, which could lead to a vision-threatening outcome. Therefore, it should be removed as early as possible once found.

To decrease exposure time, we report a procedure using a general flute needle combined with vacuum aspiration to remove the subfoveal retained PFCL in silico ne-oiled eyes.

Surgical Technique

A 53-year-old man was referred to the Eye Hospital of Wenzhou Medical University. His best corrected visual acuity (BCVA) was limited to hand motion at 3 feet in his right eye for 1 week, secondary to ocular trauma. Fundus examination revealed a large retinal detachment superiorly extending clockwise from the 9- to 3-o’clock position, as well as an irregular tear at the 1-o’clock peripheral position. The patient underwent 23-gauge vitrectomy followed by PFCL injection, endolaser retinopexy, fluid-air exchange, and silicone-oil tamponade. We did not observe subretinal retention of PFCL at the conclusion of the procedure. The patient was instructed to place their head in the prone position for 2 weeks after operation. The retinal detachment was noted to be fully repaired 2 days later. One week postoperatively, the BCVA was 20/400 in his right eye. Subfoveal retained PFCL was found by optical coherence tomography (OCT) [Fig. 1a] and wide-field fundus examination [Fig. 1c].

Figure 1

Pre- and postoperative OCT and fundus examination. Preoperative fundus imaging (a) and OCT (c) present PFCL droplets underneath the fovea in the right eye. Six-month postoperative fundus examination (b and d) reveals a reattached foveal profile and the absence of the submacular PFCL

One month after surgery, we attempted to remove the subfoveal PFCL under silicone oil. Featuring an inner 27-gauge flat silicone tip and a 25-gauge annular shaft, the flute needle (Rumex Inc, Florida, USA) was attached to a 1-ml syringe. A Luer slip needle-free connector (NIPRO Inc, Osaka, Japan) interfaced the syringe with the extrusion tubing of a conventional vitrectomy machine [Fig. 2a]. Active aspiration was controlled by a foot pedal of the vitrectomy machine to be below 30 mmHg. We used the bent-tip of a 27-gauge dental injection needle (NIPRO Inc, Osaka, Japan) to make the retinotomy through a 2-port pars plana route [Fig. 2b]. The retinotomy was at the farthest edge of the subfoveal PFCL bubble from fovea. Under intraocular illumination, we inserted the flat silicone tip subretinally on the parafoveal facing to aspirate PFCL (see video clip, http://v.youku.com/v_show/id_XMzU5MDY4NDI4OA==.html). The patient's intraocular pressure was monitored during surgery. Silicone oil was injected through one of the ports if intraoperative hypotony was noticed at the end of the procedure.

Figure 2

Structure of this combined instrument. The flute needle (④) consists of an outer 25-gauge annular shaft to maintain stability of the retina and an inner 27-gauge silicone tip for atraumatic extrafoveal suction, and a Luer lock (②) interface a 1-ml syringe (③) with active aspiration tubing (①) connected to vitrectomy machine (a). Dental injection needle (⑤) has a 27-gauge beveled tip for retinotomy (b)

Two months after the procedure, the patient underwent surgical silicone removal. Half a year postoperatively, the subfoveal PFCL was not visible on dilated fundus examination [Fig. 1b] and OCT [Fig. 1d] confirmed a reattached macula within the intact retinal profile. BCVA improved to 20/32 in the right eye. After this attempt, we have successfully performed this procedure on two other similar patients with obvious improvement in BCVA.

Discussion

Two factors are found to retain PFCL subretinally: large peripheral retinotomies greater than 120°; and insufficient saline rinse at the conclusion of fluid-air exchange.[5] Long-term exposure to PFCL can lead to localized photoreceptor damage, retinal pigment epithelial atrophy, or an overlying retinal hole. These changes in the periphery may not affect the vision, but subfoveal retention requires surgical removal sooner rather than later. To decrease exposure time of PFCL with a possibly better outcome, we promptly planned a surgical removal as soon as subfoveal PFCL was noted postoperatively under silicone oil.

Uncontrolled surgical aspiration of subretinal PFCL can result in several complications of visual loss. Complications include retinal pigment epithelium (RPE) or nerve fiber layer damage, macular hole, submacular hemorrhage, proliferation, or fibrosis, as well as expansion of the extrafoveal retinotomy.[2] To minimize these potential iatrogenic injuries, temporary therapeutic retinal detachment has been attempted, including displacement of PFCL to peripheral retinal location,[6] and drainage of PFCL with saline rinse through a retinotomy outside the macula.[7] Large volume of PFCL droplets within the fluid adjacent to giant retinal holes could resist the adhesive force between attached RPE and photoreceptor.[2] Thinned retina overlying the PFCL bubble could potentially rupture secondary to unstable pressure injection, which would form a macular hole.[6] Therefore, whether displacing the PFCL peripherally or flushing it through a juxtofoveal retinotomy, both need controlled and visible injection of balanced salt solution with a syringe pump.

For these problems, we used a combined flute needle to extract submacular PFCL within silicone oil tamponade. The flute needle consisted of a 25-gauge inner flat silicone tip and 27-gauge outer annulus. The inner flat silicone tip could aspirate PFCL atraumatically. The outer annulus, 600 μm shorter than inner tip, was used to stabilize the retinomy.[8] Larger macular hole could take shorter times to aspirate PFCL with a prescribed suction because of considerably decreased resistance. With subfoveal PFCL, minimizing damage to the macular area should be the most important objective.[9] Thus, a finer gauge cannula and a lower vacuum level would be optimal for subfoveal removal under silicone oil. Compared with Joondeph's design,[8] we added a 1-ml syringe as a grip to make the instrument convenient for operation. A Luer slip interfaced the syringe with the extrusion tubing. Negative aspiration was regulated by a footboard control of the extrusion tubing on a traditional vitrectomy machine. A juxtofoveal retinotomy was performed under silicone oil similar to that performed under preretinal PFCL.[10] However, the former will not cause further intraocular retention of PFCL after subfoveal retention removal. No complication associated with the cannula or aspiration procedure was noted in our patients. Cannulas or pipettes above 30-gauge are not registered in many countries like China. Consequently, they have not yet been distributed with Chinese hospitals. On the other hand, the instrument assembled by common needles is much cheaper than microcannulas larger than 30-gauge.

This approach will help shorten residual time of PFCL, preventing further visual impairment due to its sustained toxicity on macula. Many medical institutions around the world could implement this procedure using common dental injection needles and flute needles. Using 30-gauge or larger needles may also be compatible with this method.

Supporting cases

Two other patients were managed with this procedure and got good visual outcomes.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.