Temporary Scleral Buckle In Retinal Reattachment

This minimally invasive approach offers potential advantages over existing methods.

NIKOLAS J.S. LONDON, MD • PAUL E. TORNAMBE, MD, FACS • JOSEPH ASILIS, MD

On occasion, it is good to revisit the history of our procedures and to examine excellent ideas that have evolved from their original intent over years of refinement. The scleral buckle was initially developed as a temporary procedure.

The first recorded buckle procedure was performed by Jess in 1937, when he inserted a surgical sponge between Tenon’s capsule and the sclera.¹ This device was not sutured and was positioned so that it would be easy to remove. Over the next few decades, this concept evolved into the more recognizable segmental scleral sponge by Custodis² and subsequently into the encircling scleral buckle by Schepens.³

As it exists today, the scleral buckle is a proven method for reattaching the retina. Single operation success rates are high, and the potential for serious side effects, such as endophthalmitis, is low.

THE DOWN SIDE OF SCLERAL BUCKLING

Unfortunately, however, even with modern techniques the scleral buckle has its share of drawbacks and potential side effects that have undoubtedly contributed to its declining popularity. Compared to pars plana vitrectomy, scleral buckling requires a more extensive preoperative evaluation. The procedure itself is not sexy: the surgery has more tugging and pulling, moving muscles out of the way and localizing and suturing the exoplant to the sclera. It is time-consuming, requires an operating room, and may require general anesthesia.

Scleral suturing or belt loop includes the risk of scleral perforation, and the most dangerous step is the draining of subretinal fluid, with the potential for retinal incarceration or subretinal hemorrhage, or both.

A Host of Postoperative Concerns

Scleral buckling also results in permanent refractive changes, as well as potential injury to the extraocular muscles, not to mention the associated staff and other overhead expenses. Following surgery, anxiety that the break will not fall on the crest of the buckle or that the subretinal fluid will not resolve is common.

Other potential postoperative complications include conjunctival extrusion, skin extrusion, pain, extraocular infection, strabismus, erosion and intrusion, endophthalmitis, choroidal effusion, inflammation, macular distortion, subretinal fluid, anterior segment ischemia, injury to the optic nerve, and recurrent detachment.

Overall, complications associated with permanent buckles have occurred in 1.3% to 24.4% of eyes,^4-7 and they may present even decades after surgery. Particularly for certain patients with limited pathology, such as a small phakic detachment associated with atrophic holes, or for young patients with retinal dialysis, our current options may be overkill, placing such patients at unnecessary risk.

An Old Solution?

It is unclear why we as a specialty tolerate these risks. We recognize the issues, yet the scleral buckle has seen very little innovation over the past 50 years. We stand by and watch as surgeons utilize the buckle less every year, mostly for the reasons outlined here. It is not as if these issues are insurmountable. This is, in part, our motivation for revisiting the idea of a temporary, segmental scleral buckle.

We know that the concept can work. While most of the younger generation of retinal surgeons have only heard of his device, Lincoff developed a temporary balloon buckle in 1979 that was quite effective in repairing retinal detachments.⁸

This device was an equally effective alternative to more conventional techniques in the management of selected retinal detachments, with single operation success rates often exceeding 90%.⁹

Despite a high success rate in reattaching the retina, Lincoff’s device never gained widespread popularity, probably due to several factors, including difficulty inserting the device, corneal abrasions and patient discomfort due to its external cannula, occasional leakage of the balloon leading to a less-than-expected indentation, and limited availability, compounded by cessation of production by its US manufacturer.

As far as we can tell, these shortcomings were never addressed. Lincoff’s concept was brilliant, and we believe that we can use it as a platform to develop an equally effective buckle that is also more practical, sophisticated, and tolerable for our patients.

CONSIDER THE MECHANISMS OF ACTION

A temporary buckle, such as the balloon or our device, relies on thinking about retinal detachments differently. We would argue that one way to think of a simple retinal detachment (ie, one not associated with giant tear or large number of tears, PVR, etc.) is a retinal tear associated with subretinal fluid. At least, that is how detachments start.

Clearly, we do not treat retinal tears with scleral buckling or vitrectomy surgery, so if a retinal detachment can be reduced back to a flat tear, then should we treat it any differently than a retinal tear that was never associated with subretinal fluid? A scleral buckle can do exactly this, and it is worth taking a step back to consider how.

Through multiple mechanisms of action, scleral buckles are thought to be capable of independently eliminating subretinal fluid. By indenting the posterior eye wall complex, buckles can relieve vitreous traction and overcome the vector force of vitreous on the retina.

Indentation also pushes the retinal pigment epithelium pump closer to the break, and it may push the break itself into solid vitreous, effectively plugging the defect. Indentation is also thought to alter intraocular fluid currents, dissuading fluid movement into the subretinal space.

These mechanisms act in concert to re-establish contact and adhesion between the retina and RPE at the site of the break. Scleral indentation alone can cure a retinal detachment, but because the vitreoretinal traction is not eliminated, the detachment would likely recur if permanent adhesion were not established.

This adhesion accomplished by several methods, including diathermy (a historical footnote), cryotherapy, and/or laser photocoagulation. A buckle should provide its effects until the chorioretinal adhesion has matured. In general, at least one week is required for laser photocoagulation and two to three weeks for cryotherapy.

Multiple papers have shown that scleral buckles removed for various complications had a low risk of redetachment, and those that did redetach were rarely due to the original pathology.¹⁰ If we could not create a permanent chorioretinal adhesion, temporary buckles would not be possible — but we can.

OUR DEVICE

Our device (Figure 1) is based on these concepts and is a variation on the Lincoff balloon premise that a permanent scleral buckle is not always needed. Again, the Lincoff balloon was effective, with a success rate exceeding 90% in some studies, but suffered from the shortcomings we describe here.

Figure 1. Photograph of the current design of our device in isolation, as well as positioned around a cadaver globe.

We wondered whether we could improve the device with modern materials and technology. Could we design a device with the benefits of the balloon but without the drawbacks? We believe the answer is yes.

Our device (new, patented design for an exoplant) addresses many of the balloon’s shortcomings. It is easy to insert, with a solid build and no “wet noodle” effect. No cannula extrudes from the eye to irritate the patient. No leakage is possible, giving the device a much more predictable push. Further, the device covers a much larger area, covering more pathology.

The surgeon can insert our exoplant in an office procedure or in a clean room under local anesthesia through a simple conjunctival incision. We expect the entire procedure to be performed in less than 15 minutes. The solid material is designed to provide four clock hours of indentation over the vitreous base. The procedure would likely involve some variation of the following steps:

1. Application of topical anesthesia, followed by subconjunctival anesthesia to cover the surgical site.

2. Cryotherapy in the usual fashion to surround the pathology.

3. Following standard sterile procedures, creating a limbus-based conjunctival incision, followed by undermining of Tenon’s capsule using blunt scissors.

4. Use of a muscle hook to identify the adjacent rectus muscles, with the device then inserted into the sub-Tenon’s space with the arms slipped under the muscles.

5. A single, partial-thickness scleral suture placed to secure the anterior end of the device.

6. Closing of the overlying conjunctiva with a second suture. The device would be left in place for three weeks and then removed in the office.

CURRENT SURGICAL METHODS MAY BE OVERKILL FOR SOME PATIENTS

Take, for example, a young, phakic, myopic woman with a history of refractive surgery, leaving her with uncorrected 20/20 in both eyes. If she were to present with a superotemporal retinal detachment due to atrophic defects in lattice with fluid well away from the macula (Figure 2), what would the repair procedure be? How might the surgeon design an ideal method if starting from scratch?

Figure 2. Schematic of a young myope with a macula-sparing retinal detachment associated with atrophic retinal holes in lattice degeneration.

Despite a high level of success, all current retinal detachment repair options, which include pneumatic retinopexy, Lincoff balloon, permanent scleral buckle, and pars plana vitrectomy, have potential drawbacks (Table).

Pneumatic retinopexy is generally limited to use with superior retinal detachments with a single break or a small group of tears. It can be difficult and less effective in young patients with a formed vitreous.

The Lincoff balloon procedure is not commercially available in the United States, is difficult to insert, and can be uncomfortable for the patient. Permanent scleral buckles require an operating room, and complications can include scleral perforation, postoperative refractive error, and muscle imbalances, among other problems.

Vitrectomy, which is also an OR procedure, requires expensive equipment and single-use packs. It also accelerates cataract development and introduces the risks of intraocular surgery, including endophthalmitis.

A Niche for a Temporary Buckle

While no procedures are perfect, we believe that a niche exists for our device, ie, patients for whom other procedures would have greater drawbacks and worse potential complications.

A few other situations may warrant the use of our device, such as subclinical retinal detachments, retinal dialyses, new inferior breaks in a patient following pars plana vitrectomy or pneumatic retinopexy, young phakic patients, patients with a history of refractive surgery or premium IOLs, or patients with a need to avoid the operating room due to medical conditions or cost considerations.

Pseudophakic patients, who may be an excellent vitrectomy candidate if it were not for inferior pathology that requires an encircling band, might also benefit from the device. A temporary buckle may supplement vitrectomy and avoid a lifetime of glasses.

On a final note, we must consider the cost-efficacy of our procedures. In our era of managed care and economic oversight, minimally invasive and cost-effective methods deserve serious attention.

In the near future, we will likely see a trend toward reimbursement based on the cost-effectiveness of our procedures, in addition to the success of our outcomes.

RESULTS AND CONCLUSION

So far, we have treated six patients using our device, with only one success. This was an older model that was ovoid in shape. In two cases, the device was too small to create the desired push. In another case the device migrated. In two cases, the devices extruded, something also very unlikely with our current design.

In the one successful case, we sutured the conjunctiva to maintain the stability of the exoplant, placed the device circumferentially, and reattached the retina.

Over the past year the device has evolved from the ovoid shape. The current iteration is a radial wedge that contours to the shape of the globe in an anteroposterior direction. At the midpoint is a circumferential cylinder that is meant to rest just posterior to the muscle insertions and provide four hours of scleral indentation.

We have evaluated the device with cadaver eyes but have yet to implant it in a clinical situation. We will do so soon, and as we as the concept continues to evolve, we look forward to keeping you informed of our progress. RP

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