First‐in‐human study of the safety, effectiveness and ease of use of the intra‐ocular diathermy forceps during vitrectomy

Editor,

There have been no significant advances in intra‐ocular diathermy design since the 1980s (Parel et al. 1983). The design has disadvantages, which become apparent during attempted closure of hemangioblastoma feeder vessels before tumour excision, which carries considerable risk of haemorrhage (Van Overdam et al. 2017a).

Disadvantages of conventional point‐shaped diathermy probe:

• Coagulation and pressure on blood vessel from one side only, requiring higher energy levels and causing more collateral damage.

• Lack of view of coagulated tissue, unless probe is removed.

• Delay between removal of instrument involved in haemorrhagic episode and introduction of diathermy probe.

Intra‐ocular diathermy forceps address these weaknesses. Its advantages were demonstrated in an ex vivo study (Van Overdam et al. 2017b). We report the findings of a first‐in‐human study.

The study was granted ethics committee approval and complied with the tenets of the Declaration of Helsinki. Patients provided informed consent. We prospectively recruited five patients scheduled for vitrectomy for diabetic tractional retinal detachment at the Academic Hospital Paramaribo. All patients received intravitreal injection of 0.05 ml (1.25 mg) bevacizumab (Avastin, Roche Diagnostics GmbH, Germany) 2–8 days prior to vitrectomy.

The diathermy forceps were developed by modifying available single‐use 23‐gauge ILM‐peeling forceps (Vitreq, the Netherlands). The emitting electrode was connected to one‐half of the core and the return electrode to the other half, with one jaw of the forceps attached to each half of the core and both halves electronically isolated from each other and from the shaft that enclosed them. The diathermy forceps were connected to the vitrectomy device (Millennium, Bausch & Lomb, USA) using the standard cord of the diathermy probe. Coagulation was set to 10% of maximum (7.5 watts) output. Power was controlled linearly by foot pedal. The conventional diathermy probe was available in case haemorrhage could not be controlled with the diathermy forceps and ocular hyperpressure.

The surgeries were performed by 3 of the 4 authors (JP, DJ and SM). Use of the intra‐ocular diathermy forceps can be seen in the Video. All instances of haemorrhage could be controlled with the diathermy forceps. The conventional diathermy probe did not need to be used. There was no postoperative vitreous cavity haemorrhage or vitreous haze on day 1, week 1 or month 1 after surgery. Coagulation energy applied was not measured; however, the effectiveness with which haemorrhage was stopped and the minimal coagulation reaction to collateral tissues indicate that low levels of energy were used.

Advantages of intra‐ocular diathermy forceps:

• Diathermy function: Coagulation and closure of blood vessels by compression and diathermy between the forceps jaws. Also successful coagulation without complete jaw closure, preventing tissue sticking to the forceps and allowing better visualization between the forceps jaws and control of coagulation.

• Peeling function: Peeling membranes and bimanual manipulation of tissues with coagulation available instantly inside the eye to treat any occurring haemorrhage without the need to exchange instruments.

• Novel function: Weakening or dividing strong vascularized adherence points by coagulation between the forceps jaws, allowing peeling of adherent membranes that otherwise would require segmentation (Fig. 1).

  Figure 1.

  

  Video still images showing the novel function of the intra‐ocular diathermy forceps in patient 1. A fibrovascular membrane is identified (A), and it is grasped with the diathermy forceps (B). Peeling of the fibrovascular membrane is not possible because of a strong vascularized adherence point (arrow). Weakening of the vascularized adherence point, by applying coagulation with the diathermy forceps (D), enables peeling of the adherent membrane that would otherwise require segmentation (E). The retinal surface underlying the peeled membrane is intact, without traction and without haemorrhage (F).

The intra‐ocular diathermy forceps are not commercially available, they were made for the purposes of this study. Possible design improvements include thinner electric cord or cordless and 25‐ or 27‐gauge design.

Our findings suggest that intra‐ocular diathermy forceps are not only useful during vitrectomy for diabetic tractional detachment, but also during any other surgery in which coagulation is needed and/or where peeling of membranes or manipulation of tissues is performed. The diathermy forceps appear to be effective and safe for intra‐ocular use in humans. A larger study with quantitative end‐points such as energy used, and number of instrument exchanges is warranted to confirm these findings.

Supporting information

Video S1. Use of the intra‐ocular diathermy forceps during vitrectomy for diabetic tractional retinal detachment in five patients (five eyes). The intra‐ocular diathermy forceps showed its dual function (peeling and coagulation), safety, effectiveness, ease of use, as well as a novel function (peeling after weakening by coagulation of strong vascularized adherence points).