Viscostretch: A Novel Surgical Technique for Refractory Macular Holes

Abstract

Purpose:

We present a novel technique of subretinal viscodissection for addressing refractory macular holes (MHs).

Methods:

A case report and surgical technique description are provided.

Results:

In this technique, standard pars plana vitrectomy with internal limiting membrane peeling (unless previously peeled) is performed. A cohesive ophthalmic viscosurgical device (OVD) is injected through the MH, focally detaching the parafoveal retinal tissue around the hole. The OVD is removed at the conclusion of the air-fluid exchange. We provide an example of a recurrent 833-µm MH that was successfully closed despite failing initial surgery. There was no retention of subretinal OVD, and anatomic closure was achieved in this patient with a refractory MH.

Conclusions:

In refractory holes with adhesions at the MH base, this technique mobilizes the adjacent retinal tissue and uses the air’s surface tension to facilitate closure. Surgeons can consider using this technique as part of their MH arsenal.

Introduction

Vitrectomy with internal limiting membrane (ILM) peeling and gas tamponade has excellent outcomes for idiopathic macular holes (MHs), with closure rates reported around 90% to 95% depending on the study. ^{1 -3} However, closure rates for large (> 400-µm minimum diameter), chronic, or recurrent MHs can be highly variable. ⁴ Recently, techniques using an ILM flap have been advocated for primary repair with good reported outcomes. ⁵ However, in patients who have already undergone primary surgical repair with ILM peeling, harvesting an autologous ILM flap and transplanting it into the hole can be prohibitively challenging. Alternative surgical approaches range from placement of amniotic membranes, lens capsule transplantation, use of autologous serum, autologous retinal transplantation, and subretinal hydrodissection, to identify a few. ^{6 -10} It is unclear that any single technique is more efficacious across the board for all complex MHs.

In our opinion there are 3 fundamental pathologic forces to be addressed in MH surgery: (a) anterior-posterior traction from pathologic vitreofoveal adhesions (particularly in early-stage MHs), (b) tangential traction from epiretinal membranes and potential intraretinal stiffness or contraction, and (c) retina–retinal pigment epithelium (RPE) adhesions around the base of the hole, particularly in chronic holes. Conventional vitrectomy with ILM peeling addresses some or all of these issues for a given eye. However, in chronic holes that fail primary repair we feel it is critical to address potential adhesions between the retina and underlying RPE as well as intraretinal stiffness or contraction (possibly in part due to atrophy) to maximize chances for successful closure. Indeed, in chronic holes that fail primary repair it is probable that contraction of the surrounding retina results in insufficient tissue laxity to permit closure. There is even some suggestion that there is loss of tissue caused by the operculum contributing to this tissue shortening in more advanced holes. ¹¹ As such, in addition to severing the retina-RPE adhesions, we also advocate subretinal dissection to mobilize the retinal tissue adjacent to the hole to allow it to be drawn together during the air-fluid exchange and tamponade.

Prior reports of subretinal hydrodissection, by either refluxing saline directly through the MH or creating adjacent subretinal saline blebs with a subretinal cannula, ^9,10 begin to address these issues. However, they do not maximize the surface tension force of the air tamponade during air-fluid exchange because of the use of saline for subretinal dissection. Likewise, there have been reports about arcuate retinotomies and relaxing radial retinal incisions aimed to move tissue to close refractory holes, although obviously these involve retinal incisions and associated risks. ^12,13 We advocate use of a cohesive sodium hyaluronate ophthalmic viscosurgical device (OVD, Healon, Abbott Medical Optics Inc) to not only lyse retina-RPE adhesions but also maintain the potential subretinal space, stretching the adjacent retinal tissue until the conclusion of the air-fluid exchange.

Once an MH has been identified as high-risk for repair failure, typically after failing primary surgical repair, we recommend considering an alternative approach to closure. Our Viscostretch technique is typically best used in patients who have failed a primary repair with ILM removal and thus are not candidates for conventional ILM flap techniques.

Methods

In this technique, a standard pars plana vitrectomy (PPV) is performed (gauge at surgeon’s discretion). If the patient has not undergone a prior vitrectomy then a posterior vitreous detachment is induced, if not already present, with thorough peripheral vitrectomy performed. ILM peeling should be performed if not done so previously, or alternatively staining should be performed to confirm the absence of ILM. We typically use a 3-mm ILM peel, but for this technique would wish to ensure that the ILM is peeled to at least 2 to 3 times the radius of the MH itself.

Next, a syringe of cohesive OVD is outfitted with a silicone soft-tip extrusion needle. Before performing the injection, the surgeon can use the silicone soft tip to gently tease at the margins of the MH to help release any significant adhesions that might be present. This is performed manually because the needle is connected to the OVD syringe, not the vitrectomy machine. The OVD is then manually injected as a single globule through the extrusion needle while hovering over the MH (Figure 1).

Figure 1.

Surgical still images demonstrating instillation of an ophthalmic viscosurgical device (OVD) through the macular hole (MH) to dissect the parafoveal tissue. (A) Using a silicone-tipped cannula on a cohesive OVD, the margins of the hole can be gently teased to sever any adhesions. (B) The OVD is injected while hovering above the center of MH. (B, then larger in C) The OVD propagates subretinally, visible as a surrounding rim of elevated retinal tissue. (C) The OVD maintains the surrounding bleb even when the injection is terminated. Indocyanine green stain had been performed before the Viscostretch technique to confirm absence of adjacent internal limiting membrane around the MH. There is a small area of hemorrhage at the superior (bottom in surgeon’s view) margin of the hole from manual manipulation before injection.

We maintain an intraocular pressure of 25 mm Hg during the injection. The cannula is maintained close to the hole but does not require the tip of the cannula to be physically introduced into the subretinal space. The cohesive nature and high molecular weight of the OVD create a vector force during the injection that runs tangentially under the retina. OVD is injected until a sizeable subretinal bleb has been created in a ring around the MH, in general with a radius at least 2 to 3 times that of the MH itself to ensure enough tissue has been mobilized for closure. We would also consider the use of the viscous fluid control (VFC system on Constellation Vision Systems, Alcon) with a silicone-tip extrusion to allow fine control of the injection force with the vitrectomy foot pedal, although we have not yet performed this and determined the ideal pounds per square inch for injection.

An air-fluid exchange is then performed, draining all fluid from over the optic nerve. During this step the cohesive OVD remains a subretinal bleb while all fluid is removed from the eye. Once a complete drainage has been performed, the OVD is removed through the MH (Figure 2). By waiting until the end of the exchange, the air surface tension applies downward force on the mobilized retina around the MH to compress the elevated flaps of the hole margins, much like hinged doors swinging shut. During the OVD removal, one can also gently aspirate the margins of the MH with the silicone cannula to draw the retinal tissue together and manually aid hole closure. Gas exchange is then performed, and the eye is closed in routine fashion.

Figure 2.

Surgical still images of removal of a subretinal ophthalmic viscosurgical device (OVD). First, a complete air-fluid exchange is performed before attention is focused on the macular hole. (A) OVD is aspirated directly through the hole, which at this time still has a large diameter. (B) As the OVD is removed in a single clump, because of its cohesive nature, the hole collapses centrally, the collapse aided by the air bubble’s surface tension. (C) The hole is effectively closed at the conclusion of the air-fluid exchange, with a small area of hemorrhage observed from manual manipulation prior to OVD use.

Results

The following case is representative of our technique. A 62-year-old woman underwent 25-gauge PPV with ILM peeling and 10% C₃F₈ (perfluoropropane) tamponade for a stage IV MH in her left eye. Her preoperative visual acuity (VA) was 20/800, the hole measured 460 µm in minimum diameter, and the patient had noted central vision distortion for about 6 months before the initial surgery, indicating some chronicity. Postoperatively, the hole remained open. Owing to medical comorbidities, the patient did not undergo a second surgery until 7 months later. Before that surgery her VA was 20/125, with a minimum diameter of 833 μm. A second 25-gauge PPV was performed with indocyanine green staining to confirm the absence of ILM. Because of the absence of available ILM, Viscostretch was used as previously described, an air-fluid exchange was performed, and a tamponade of 20% SF₆ (sulfur hexafluoride) gas was used. This time the MH closed postoperatively (Figure 3). The patient noted subjective improvement in her vision, with an initial postoperative VA of 20/100 that improved to 20/70 after cataract extraction.

Figure 3.

Preoperative and postoperative optical coherence tomography B-scans of our first patient for whom the Viscostretch technique was used. (A) Preoperatively the patient had a large macular hole (833-µm minimum diameter) for which she had already undergone pars plana vitrectomy with internal limiting membrane peeling. Preoperative acuity was 20/400. (B) Postoperatively the macular hole has closed, although with loss of subfoveal inner and outer segment junctions. There is no retained subretinal ophthalmic viscosurgical device visible. Postoperative acuity was 20/100, improving to 20/70 after subsequent cataract extraction.

Conclusions

In summary, we present a novel technique for approaching recurrent MHs. In this technique we use a cohesive OVD to perform subretinal viscodissection directly through the MH, releasing retina-RPE adhesions and mobilizing the adjacent retinal tissue to facilitate closure during air-fluid exchange. This technique addresses some of the mechanical challenges of refractory MHs in ways distinct from prior techniques.

In our patient there was no retention of subretinal OVD, likely because of the cohesive nature of Healon. There is little downside to incorporating the technique into routine practice because of the ready availability of cohesive OVD and relative ease of performing the injection, particularly when compared with other advanced hole-management strategies.

However, it must be noted that this represents our experience with a single case and not a prospective trial. Furthermore, in this procedure there is manual manipulation of the hole edge, which helps to mobilize the tissue but has unknown effects on the long-term viability of the retinal tissue. We also do not know the long-term implications of the presence of OVD in the subretinal space. Likewise, the advantages and disadvantages of inducing a macular detachment to secure anatomic macular improvement and possible visual rehabilitation will be known only with time and additional case material, although similar circumstances are encountered in entities other than macular stretching such as repair of macular fold following retinal detachment. We will continue to evaluate our ongoing experience with additional patients and postoperative monitoring of retinal tissue recovery but suggest that surgeons consider adding Viscostretch to their armamentarium for recurrent MHs without adjacent ILM.