SURGICAL PEARLS

Exploring the Suprachoroidal Space
(Part 2 of 2 in a series)

A trip to the previously “unknown”…

BY FLAVIO REZENDE, MD, PHD

Extensive advances in retina imaging technology using spectral-domain OCT with enhanced-depth imaging and swept-source OCT have led to an improved understanding of choroidal changes associated with many posterior segment diseases. Similarly, in the surgical arena, many creative surgeons are beginning to use the suprachoroidal “virtual” space as a new pathway to treat medical and surgical conditions. While the clinical utility of this approach remains to be proven, some techniques, such as the microcatheter infusion of anti-VEGF or triamcinolone for the treatment of large pigment epithelium detachments or recalcitrant DME, are becoming more popular due to their simplicity and encouraging early results.

SUPRACHOROIDAL BUCKLING

In 2013, El Rayes and Oshima¹ described a technique of a long-lasting hyaluronic acid injection into the suprachoroidal space (20 mg/ml – Restylane Perlane; Q-Med) through a 450 μm catheter (MedOne Surgical — not commercially available yet). Current microincision vitrectomy and wide-angle viewing technologies were used to improve a technique initially described by Poole and Sudarsky² in 1986. This concept evolved from the Lincoff’s balloon buckle for the treatment of retinal detachment, which allowed temporary indentation until the laser scar formed, thus “sealing” the retinal breaks. More recently, El Rayes introduced an alternative way of injecting the viscoelastic using a curved cannula with an olive-shaped tip for the treatment of peripheral retinal breaks (not yet commercially available).

Any new surgical technique is evaluated based on its reproducibility and ability to duplicate excellent outcomes in the hands of multiple surgeons. At our center, we performed a series of 10 cases using the above technique for the treatment of retinal detachment associated with atrophic holes or inferior retinal tears in young myopic patients. All breaks were adjacent within 2 clock hours. In a minimal incision valve surgery (MIVS) era, my indications for scleral buckling alone have mostly been limited to this group of patients.

We slightly modified the technique instrumentation by using Healon GV (14 mg/ml, AMO) and the microcatheter for visco canaloplasty (i-TRACK 250, Ellex i-Science Inc.).

PEARLS

›› To gain access to the suprachoroidal space, a 3 mm pars plana sclerotomy is made with a crescent blade 4 mm posterior to the limbus. Care should be taken to provide excellent choroid exposure to avoid difficulties with catheter introduction through any remaining scleral fibers (Figure 1)

Figure 1. Suprachoroidal buckling: A. Sclerotomy at 4 mm from limbus. Note the left side of the wound showing proper choroid exposure, while the right side shows remaining scleral fibers (arrow). B. Healon use to create the plane between the sclera and the choroid. C. Microcatheter being held by non-toothed curved forceps. D. Microcatheter being inserted perpendicular to the sclerotomy plane. Note the red light at the tip (arrow). E. Flashing red light at the tip of the microcatheter placed just posterior to the tear (arrow). F. Red light seen with microscope light off. G. Choroidal indentation and retinal reattachment after Healon GV injection (arrows).

›› Before introducing the micro-catheter, Healon GV (injected via supplied healon cannula) is used to create a small pocket and cleavage plane between sclera and choroid.

›› To ease catheter introduction the i-TRACK 250 μm canaloplasty catheter is cut at mid junction, as the proximal half of the catheter is considerably thicker and easier to maneuver.

›› The i-TRACK has a red flashing light at the tip allowing us to monitor the catheter progress into the suprachoroidal space with the wide-angle viewing microscope. It can also be seen through the conjunctiva and sclera under direct external microscope view. For easier advancement, the catheter is placed perpendicular to the sclerotomy site (Figure 1). Don’t be discouraged if the catheter comes out multiple times in the first few cases. It takes time to get used to holding it in place with a curved non-toothed forceps (without directly looking at it because you should only see the intraocular view through the wide-angle viewing system) while your assistant or scrub nurse injects the viscoelastic.

›› For easier and less traumatic progression of the i-TRACK, aim the catheter towards the sclera not the choroid. The scleral rigidity and curvature will guide the microcatheter posteriorly.

›› Consider using the chandelier light for visualization, as it will help avoid the use of the entire vitrectomy pack for the purpose of using the light pipe only. Some companies provide the light pipe separately.

›› After the indentation is created, the red flashing light and the tip of the catheter are difficult to visualize, so we prefer to place it just posterior to the more posterior retinal break to ensure complete indentation.

›› If you can’t locate the tip, turn off the microscope light and you will see only the flashing red light. Turn light back on and you find it again (Figure 1).

›› It’s important to hold the catheter in place using the forceps during viscoelastic injection, as it can migrate out of the sclerotomy.

›› Typically, one to two vials of Healon GV are needed to achieve good indentation.

›› AC paracentesis may be required to achieve adequate IOP and optic disc perfusion.

›› Indirect laser retinopexy can be done intraoperatively or 1 to 2 days post-op.

›› After proper indentation is achieved, the catheter is removed and the sclerotomy is closed with 6-0 Vicryl.

›› We would advise using this technique for the repair of retinal detachments with tears at 3 or 9 o’clock meridians only after achieving comfort with the procedure to minimize potential risk of damage to the ciliary nerve/artery.

Although El Rayes and Oshima report Restylane indentation for more than 6 months, our experience with Healon GV allows indentation of 4 to 6 weeks, which is sufficient for laser scar formation.

Advantages of this technique over established scleral buckling procedures include faster surgery, temporary indentation, no risk of strabismus/diplopia, no post-op pain, and a quieter eye at immediate post-op follow up.

Our complications included: one penetration of the catheter directly through the pars plana into the vitreous cavity and one penetration of the choroid and the retina in the meridian of the primary tear. These did not result in hemorrhage or redetachment due to the thin structure of the catheter. The penetration site was easily treated with laser retinopexy. Another potential complication is choroidal hemorrhage, which is also a risk of the standard buckling procedure.

All our cases of primary retinal detachment for the particular indication mentioned above were successfully treated with this technique. This technique represents a great addition to our surgical toolbox.

REFERENCES

Dr. Rezende is chief of the retina division and an associate professor in the Department of Ophthalmology at the University of Montreal, where he also heads the vitreoretinal fellowship program.