Set-up for traditional 3-port vitrectomy includes the use of 1 port for attachment of the infusion line and the other 2 ports for insertion of surgical instruments. One of these ports is typically used for an active instrument, such as a vitreous cutter, scissors, or forceps, and the other is used for a passive illumination source. Thus, in standard vitreoretinal surgery, though both hands are being used, one hand largely remains inactive, yielding “unimanual” surgery.

Bimanual vitrectomy refers to active use of both hands to manipulate tissue during vitreoretinal surgery. In bimanual vitrectomy, surgical instruments other than a light pipe are used in both hands to perform various surgical maneuvers. Visualization in the absence of a light pipe is achieved either with use of a chandelier illumination source or a lighted instrument.

ILLUMINATION SOURCES

There are a variety of chandelier systems currently available, including the following:

• Alcon 23- and 25-gauge chandelier, which fits into standard 23- and 25-gauge cannulas respectively (Figure 1).
• Bausch + Lomb 27-gauge and 29-gauge dual-chandelier fibers, which are inserted through separate sclerotomies without cannulas.
• Bausch + Lomb 25- and 27-gauge single-fiber chandelier, which is inserted through a separate sclerotomy without a cannula.
• Bausch + Lomb 23- and 25-gauge single-fiber chandelier, which is inserted through a cannula.
• Bausch + Lomb high-flow infusing chandelier, which acts as both an illumination source and infusion line.
• 25- and 27-gauge Eckardt TwinLight chandelier fibers.
• DORC 23- and 25-gauge chandelier which fits into standard 23- and 25-gauge cannulas respectively (Figure 2).
• DORC 27-gauge dual-fiber chandelier, which is inserted through a separate sclerotomy without a cannula.^1-4

Chandeliers are inserted perpendicularly to the sclera, without an oblique tunnel, to allow for the light source to be directed toward the posterior pole. The dual-fiber chandelier systems tend to provide more homogenous and diffuse illumination than the single-fiber systems. Additionally, the larger gauge single-fiber systems provide better illumination than the smaller gauge single-fiber systems.

Whether the chandelier is inserted with or without the use of a cannula, it is designed to be self-retaining, thus freeing up a hand to allow for bimanual surgery. The down side to chandelier illumination is that while it can often provide adequate diffuse illumination, it may provide insufficient illumination in a specific area of interest.

CLINICAL INDICATIONS FOR BIMANUAL VITRECTOMY

While bimanual vitrectomy is most commonly used during repair of complex retinal detachments, there are a variety of surgical maneuvers than can be performed with greater ease using a bimanual technique.

Posterior Vitreous Detachment Induction

In cases of challenging posterior vitreous detachment (PVD) induction, such as in pediatric vitrectomy, bimanual surgery can be of significant help. Using a soft-tip cannula or vitreous cutter with one hand, the vitreous is engaged over the optic nerve. Using a lighted pick or Maxgrip forceps (Alcon) under chandelier illumination in the other hand, the posterior hyaloid is then dissected from the nerve (Figure 3).

Intraocular Lens Dislocation

Bimanual surgery can be extremely helpful in cases of intraocular lens (IOL) dislocation. Following vitrectomy, an IOL that has dropped into the vitreous cavity can be engaged with a soft-tip cannula under chandelier illumination and then transferred to intraocular forceps in the mid-vitreous cavity. The soft-tip cannula can then be exchanged for a Sinskey hook, which can be inserted through a paracentesis to prolapse the IOL into the anterior chamber.

In the absence of chandelier illumination, the transfer of the IOL from the soft-tip cannula to intraocular forceps needs to be done closer to the iris plane under microscope illumination. This is often more challenging and associated with a higher chance of dropping the IOL.

Intrascleral Intraocular Lens Placement

The technique reported by Yamane et al of sutureless 30-gauge needle-guided intrascleral IOL fixation has gained much popularity recently.⁵ In this technique, a thin-walled 30-gauge needle is used to create 2 scleral tunnels, 180 degrees apart, before entering the eye. The haptics of a posterior chamber IOL are then docked into these needles and externalized. The challenge of this technique is with docking the trailing haptic in the limited space of the anterior segment.

Bonnell et al described a modification of this technique wherein the leading haptic is docked, externalized and secured and then the trailing haptic is placed into the vitreous cavity.⁶ Next, under chandelier illumination, the trailing haptic is docked into the 30-gauge needle in the mid-vitreous cavity. This modification, in our experience, allows for much easier externalization of the trailing haptic with less deformation of the eye.

Removal of Intraocular Foreign Bodies

Intraocular foreign body (IOFB) removal can be complicated by the irregular shape of the IOFB, which can make grasping it challenging. When removing IOFBs, we prefer to not attempt to grasp the foreign body with forceps directly off the retinal surface, because this may traumatize the retina. Instead, we prefer to engage the IOFB with a soft-tip cannula and then transfer the IOFB to diamond-dusted IOFB forceps in the mid-vitreous cavity under chandelier illumination.

Complex Retinal Detachment Repair

Bimanual vitrectomy is especially helpful in cases of complex retinal detachment. In cases of diabetic tractional retinal detachment, tightly adherent fibrovascular membranes can be gently grasped, stabilized, and reflected with the forceps in one hand, while adhesions between the membrane and underlying retina are severed using a vitreous cutter or intraocular scissors with the other hand (Figure 4).⁷ Using this technique, the surgeon can better appreciate the surgical plane in which the dissection should be carried out, thus avoiding the creation of an iatrogenic break.

Tightly adherent preretinal membranes in cases of proliferative vitreoretinopathy can be more efficiently removed from detached retina by grasping the membranes with forceps in one hand and then bluntly dissecting the membranes off the retina with the tip of closed forceps in the other hand. Additionally, the shaft of the second pair of forceps can be used as a fulcrum over which a broader sheet of preretinal membrane can be peeled off the retina.

Bimanual surgery can also aid in efficient removal of elastic subretinal membranes. In this technique, the subretinal membranes are delivered through a retinal break using a hand-over-hand technique wherein the subretinal band is delivered tangentially with forceps in one hand and then transferred to forceps in the other hand back and forth until the entire subretinal band has been removed. The second pair of forceps is also used to stabilize the retina and provide countertraction while the subretinal membranes are being delivered.

Bimanual surgery also allows for more careful shaving of peripheral vitreous and anterior membrane dissection in the absence of a skilled assistant. In such situations, the surgeon can use one hand to perform scleral depression while manipulating intraocular tissue with the other hand.

Removal of tightly adherent membranes can also be achieved with use of a lighted instrument. In such situations, the membrane is stabilized and reflected with one hand and visualized and dissected with use of a lighted pick. Lighted endolasers can also be used to treat the anterior retina without a skilled assistant. In this scenario, the surgeon can perform scleral depression with one hand to visualize the anterior retina and then apply laser without the need for a chandelier.

Direct Perfluorocarbon–Silicone Oil Exchange

In certain situations, such as management of a giant retinal tear, cases of relaxing retinectomy creation or autologous retinal transplantation, the surgeon may need to perform a direct perfluorocarbon–silicone oil (PFC–SO) exchange. In this technique, the eye is filled with PFC and then exchanged for SO without first going to air.

To perform this technique, the surgeon needs to hold the viscous fluid injection cannula in one hand to place silicone oil and the soft-tip cannula in the other hand to passively aspirate PFC. This is most easily performed under chandelier illumination. Alternately, the infusion cannula can be removed and a skilled assistant can insert and hold the light pipe to provide illumination.

Simultaneous Drying and Treatment of a Retinal Break

On occasion, it may be challenging to adequately dry a retinal break to subsequently achieve laser uptake. This is most often because a small amount of subretinal fluid accumulates in the time during which the soft-tip cannula is exchanged for the endolaser. In this situation, a bimanual technique can be very helpful, wherein a soft-tip cannula is used in one hand and an endolaser under chandelier illumination, or lighted endolaser, is held in the other hand (Figure 5). The retinal break is then dried and simultaneously surrounded with laser.

Applying Diathermy to Leaking Blood Vessels

Diabetic vitrectomy can be complicated by oozing from neovascular pegs. The fibrin-rich clot that forms may be difficult to remove and can obscure surgical maneuvers. Application of diathermy to the causative vessel can be hindered by rapid accumulation of blood. If the case is being performed using a bimanual technique, a soft-tip cannula can be used in one hand to aspirate blood over the leaking blood vessel and the other hand can immediately apply diathermy.

Bimanual Tacking of Epiretinal Prosthesis

One of the more challenging steps of placement of the Argus II implant is placement of the retinal tack to secure the epiretinal prosthesis. This is because the tacking instrument needs to simultaneously stabilize the prosthesis in the X and Y axes while applying a tacking motion along the Z axis. With use of chandelier illumination, the prosthesis can be stabilized with forceps in one hand while tacking the prosthesis with the other hand (Figure 6).⁸

Pediatric Epiretinal Membranes

These membranes are often tightly and broadly adherent to the macula and require bimanual approach to grasp and reflect membrane with forceps, while adhesions are dissected and severed with intraocular scissors.

CONCLUSION

Bimanual vitrectomy can allow for a range of surgical techniques that are not easily performed with a unimanual approach. With continued development of new lighted instruments and chandelier systems, bimanual vitrectomy continues to gain popularity. Surgeons who familiarize themselves with bimanual surgical techniques may be able to perform challenging cases more safely and efficiently. RP

REFERENCES

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