Peeling internal limiting membrane (ILM) and/or epiretinal membrane (ERM) from the retinal surface (“membrane peeling”) is the primary goal of surgery to address a variety of vitreoretinal pathologies and is one of the more technically challenging ophthalmic surgical techniques. Membrane peeling is a critical component of surgery to address macular hole (MH), ERM, macular edema, diabetic retinopathy, and proliferative vitreoretinopathy.
Although there is considerable variation in technique, membrane peeling is typically performed using vitreoretinal forceps, with four steps common to most membrane-peeling procedures, listed as follows: 1) Identify or create a membrane edge or flap; 2) Secure the membrane flap with forceps; 3) Peel membrane from the retina with forceps; and 4) Remove forceps from the eye while grasping and removing the peeled membrane.
Membranes are relatively weak structures and may tear as they are peeled. Therefore, membrane peeling often involves repeating one or more of the four steps. For example, a surgeon may peel a portion of ILM, remove the forceps and ILM from the eye, wipe the ILM from the forceps, reinsert the forceps (typically requiring adjustments in viewing system illumination and focus), create and grasp a new ILM flap, and repeat steps as necessary. Instrument exchanges are time-consuming and may increase the risk of retinal breaks due to vitreoretinal traction as forceps push through peripheral vitreous. Valved cannulas can strip pieces of membrane from the forceps as they are removed from the eye, trapping them within the lumen of the cannula, where they can be pushed back into the vitreous cavity as forceps are reinserted. If not identified, located, and removed at the time of surgery, these residual pieces of membrane can become visually distracting floaters following surgery.
Many techniques and devices have been described to address the four steps of membrane peeling.1 Membrane edges or flaps can be created with a barbed blade or needle, a pick, an abrasive tip, or by pinching the ILM or ERM with forceps. Dozens of forceps with different tip geometries are commercially available. Removing membranes using a vitrectomy cutter, a well-known technique for diabetic epiretinal proliferations, has been described for ILM and ERM removal.2 However, the smooth tip of a vitrectomy probe is not designed to create a membrane edge, nor is the port ideally sized or located to easily engage ILM or ERM with vacuum.
We have developed a device, which we refer to as a micro-vacuum-pick (MVP), and method that allows membrane peeling without forceps (Figure 1). The current manifestation of the device consists of a handle with a tubing connector at its proximal end, to be connected to the active vacuum line of a typical vitrectomy machine. The handle has a lumen continuous with that of a 23-, 25-, or 27-gauge stainless steel tube that is the length of a typical vitreoretinal forceps shaft and tip. At the distal end of the tube is a smooth-edged spatula. On each side of the spatula is a small burr or point that we refer to as a “micropick.” Immediately proximal to the spatula is a vacuum port that opens into the lumen of the stainless-steel tube. The port is small enough to be occluded by relatively small amounts of membrane, but large enough to allow active aspiration of membrane pieces.
The micro-vacuum-pick (MVP). The magnified view shows the distal tip of the device, consisting of a smooth spatula, two micropicks (indicated by arrows), and a vacuum port (curved arrow). The inset shows the MVP attached to an active vacuum extrusion line.
The MVP can be used to perform each of the four steps of membrane peeling. After positioning the tip so that one of the micropicks faces the retina, the surgeon can use the micropick to create an edge or flap in the ILM or ERM (Figure 2). The micropick is designed to incise ILM or ERM but is shorter than the thickness of normal retina to reduce the likelihood of creating an iatrogenic retinal defect. Once a membrane flap has been created or identified, the surgeon slides the smooth spatula beneath the membrane edge. The spatula is used to elevate the membrane while guiding the membrane to the vacuum port. The surgeon applies foot-pedal controlled vacuum via the vitrectomy machine to pull the membrane into the vacuum port (Figure 3). Relatively low levels of vacuum (50 mm Hg to 200 mm Hg) will draw membranes into the port. The spatula shields the underlying retina from vacuum forces. Once the port is occluded, significantly more vacuum holding force (200 mm Hg to 600 mm Hg) can be used to strip the membrane from the retinal surface (Figure 4). The smooth edge of the spatula minimizes unwanted shearing of the retina during membrane peeling. After a portion of membrane is separated from the retina, it can be removed from the eye by vacuum extraction through the lumen of the MVP. In this method, ILM and ERM can be peeled with a single device (See video below).
The micropick is used to create an internal limiting membrane flap in an eye with an idiopathic macular hole.
The spatula and vacuum port are used to secure and peel the internal limiting membrane from the macula.
The peeled internal limiting membrane is removed from the eye via the vacuum port.
One surgeon (CCA) has used the MVP in its current manifestation to perform 24 consecutive surgeries for macular epiretinal membrane and/or MH. Twenty-two cases were with a 25-gauge version of the device; one with a 27-gauge version and one with a 23-gauge version. In each case, the membrane peel was completed using only the MVP, without any use of forceps. In two 25-gauge cases, a piece of thick ERM clogged the vacuum port and an instrument exchange was necessary to remove the MVP from the eye, wipe the membrane from the port, and reinsert the MVP to peel remaining membrane. In all other cases, no instrument exchanges were necessary. In MH cases, the MVP was also used to perform the fluid-air exchange, eliminating the need for an extrusion cannula. The vacuum level necessary to initially engage membranes was typically less than 100 mm Hg. Once the port was occluded, vacuum was increased to between 200 mm Hg to 600 mm Hg to peel the membrane and to remove membrane through the device lumen.
Creating a membrane flap with forceps is technically challenging and has been associated with complications including retinal abrasion, bleeding, and full-thickness macular defects.3 Because membrane peeling with the MVP eliminates the hand movements needed to open and close forceps tips, the risk of unintentional retinal contact and associated complications might be decreased compared to forceps. Ergonomic studies demonstrate that unintentional movements with vitreoretinal forceps are directly associated with instrument activation.4 Our subjective impression is that surgery with the MVP is less fatiguing for the surgeon's hand than with conventional forceps.
We have not used the MVP in eyes containing silicone oil, in eyes with rhegmatogenous or tractional retinal detachment, or in eyes in which preservation or manipulation of an ILM flap is necessary. Our initial experience with the MVP method and device has been positive and suggests that the MVP will prove to be an effective alternative to forceps for membrane peeling during vitreoretinal surgery.
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- Villegas VM, Gold AS, Murray TG. Vitrectomy With Cutter-only ILM Peel During Full-thickness Macular Hole Surgery. Retina Today. 2017;(SeptemberSupplement):4–5.
- Yeh S, Bourgeois KA, Benz MS. Full-thickness eccentric macular hole following vitrectomy with internal limiting membrane peeling. Ophthalmic Surg Lasers Imaging. 2007;38(1):59–60. doi:10.3928/15428877-20070101-09 [CrossRef] PMID:17278538
- Dogramaci M, Steel DH. Unintentional movements during the use of vitreoretinal forceps. Transl Vis Sci Technol. 2018;7(6):28. doi:10.1167/tvst.7.6.28 [CrossRef] PMID: 30619648