SURGICAL UPDATES: Transscleral Surgery

Seeing the sclera as a gateway rather than an obstacle.

By John W. Kitchens, MD
 

Inever thought much about the sclera during my residency.To me, it was just an obstacle between me andthe anterior or posterior chambers. It was only duringmy fellowship, when I was introduced to the conceptof scleral tunnels as an alternative to sutures for holding ascleral buckle in place, that I began to value the sclera.Since that time, I have practiced and learned a number oftechniques that use the sclera as a gateway, rather than anobstacle, to the subretinal and suprachoroidal spaces.

SCLERAL TUNNELS
Scleral tunnel creation is not a new technique. Scleraltunnels have been around in some form since the adventof buckling itself. I learned the technique during fellowshipat Bascom Palmer Eye Institute, where a number offaculty members used tunnels. It was a fun, effective, andfast way to place a buckle.

The key to creating a scleral tunnel is having the properinstrumentation and selecting the right buckle to place.First, it is essential to have a Castroviejo scleral dissector(E2990; Bausch + Lomb/Storz, St. Louis, MO). This instrumentis shaped like a miniature crescent blade, but thedifference is that the tip of the blade is sharp and thesides are somewhat dull. This allows the surgeon to wigglethe blade side-to-side without transecting the scleraltunnel anteriorly or posteriorly. Second, proper buckleselection is essential. Only moderately sized buckles canbe placed in this fashion. A type 240 band is easily placedthrough a smaller tunnel. I typically use a type 41 band,which gives a broader buckle and allows the placementof a segmental element (such as a biconvex tire type287WG [WG for wide groove]) that can be held in placeby a single 5-0 nylon suture per quadrant. Although atype 42 band can be used, the tunnel must be a fairamount larger to accommodate it.

The advantages of using tunnels are that there is lesshardware on the eye and no suture spaghetti and thatbuckle placement is faster. The disadvantage is the risk ofperforating the eye wall. Keys to lessening this riskinclude avoiding the placement of tunnels in areas ofectatic sclera and creating tunnels that are less than 70%of scleral thickness.

It takes practice, and the novice should not be surprised surprisedif the first few attempts result in transected tunnels,thin tunnels, or tunnels that break when the buckleis placed. The learning curve is about 10 to 15 tunnels,and one should err on the side of making the tunnels tooshallow at first.

Following are the steps to create a scleral tunnel:
1. Use a No. 64 blade to create two parallel anteriorposteriorpartial thickness (50% to 70% thickness) incisionsof the sclera, 3 mm from each other and 2.5 to4 mm in length (2.5 mm for a type 240 band, 4 mm for atype 41 band).

2. Use a Castroviejo scleral dissector to engage the scleraat the edge of one incision with the tip angled slightlytoward the eye. The tip is then wiggled gently back andforth to advance the blade 1 mm into the sclera. At thispoint, with the sclera engaged and the tunnel started, thetip is angled slightly away from the eye and the wigglemotion is continued until the full tunnel has been created.

3. Make sure the buckle has been cut with a bevelededge, as this will assist with sliding the buckle throughthe tunnel. Direct the leading edge of the buckle towardthe eye until the edge of the tunnel is engaged, then redirectthe buckle more parallel to the eye wall. When theedge of the band appears on the other side of the tunnel,grasp it with a second set of nontoothed forceps (NugentUtility Forceps, Bausch + Lomb/Storz) and pull the bucklethrough the tunnel. Pulling it through works muchbetter than pushing it through.

GUARDED NEEDLE DRAINAGE
Needle drainage of subretinal fluid, first described bySteve Charles,1 is a rewarding way to drain fluid in a controlledmanner under direct visualization.

I was fortunate to train under some great scleral bucklesurgeons during my residency, fellowship, and earlyyears with Retina Associates of Kentucky. Few proceduresare more satisfying than reattaching a patient’s retina completely with the use of a buckle. It makes one feel likean old-world craftsman who could fashion a beautifulpiece of furniture from a tree stump found in the woods.But one thing that did not appeal to me during bucklingprocedures in these early years was drainage of subretinalfluid using a traditional scleral cutdown. Perhaps this wasbecause, in a few cases, the eye bled with the perforationof the choroid or because I could not see what was goingon inside the eye during the drain. For whatever reason, Idid not like this aspect of buckling until I discovered needledrainage of subretinal fluid.

One downside of the needle drainage technique is itslearning curve. It takes time to become familiar with visualizingthe needle in the subretinal space. In fact, evenafter 30 cases, there were still instances when I wouldthink I had visualized the needle in the proper position,only to find that it was elsewhere. Another downside isthat it requires an attentive assistant to help with thedrainage. Finally, it is hard to teach this technique to fellowsin training. I have tried trimming the needle to ashorter length, but this invariably dulls the needle edgeand is not effective.

I struggled to find a safer way to do needle drainage.While doing a case with one of our talented fellows, itstruck me to limit the advancement of the needle by usinga guard—a guarded needle drainage technique. It did nottake long to find the perfect guard, as it was right on thetable in front of us: the buckle sleeve. By placing the sleeveover the needle, we could control the amount of penetrationof the needle into the eye (Figures 1 and 2). Thisguarded needle technique has the additional advantagethat it can allow the surgeon to depress the eye wall duringdrainage with the sleeve to encourage egress of subretinalfluid.

Following are the steps for performing the guardedneedle drainage technique:
1. Place and tighten the buckle.
2. Place a tractional 2-0 silk suture 180° away from thedrainage site around the buckle. The assistant will pull on this suture later in the procedure to increase the intraocularpressure (IOP) and encourage the drainage of subretinalfluid.
3. Attach a 26-, 27-, or 30-gauge needle (3/8 or 5/8 in)to a 1 or 3 cc syringe with the plunger removed.
4. Slide a type 270 sleeve over the needle. (Precutsleeves do not work, as they are too short.) Trim thesleeve so that approximately 3 to 4 mm of the needle tipis visible.
5. Place the needle tip with the bevel away from the retinaon the anterior edge of the buckle. Avoid areas of vortexveins and stay 1 to 2 clock hours away from retinal breaks.
6. Use the indirect ophthalmoscope to visualize theneedle prior to insertion into the subretinal space by gentlydepressing the needle against the eye wall.
7. Slide the needle into the subretinal space, directingit posteriorly to avoid inadvertent penetration of the retina.If the retina is engaged, the potential break should fallon the buckle due to the placement of the needle on theanterior edge of the buckle.
8. Have the assistant gently pull on the tractionalsuture to increase the IOP and encourage the fluid todrain through the open-ended syringe.

25-GAUGE DRAINAGE OFHEMORRHAGIC CHOROIDALS
This technique was developed out of necessity in thecare of a monocular patient who had developed hemorrhagicchoroidal detachments 1 week after trabeculectomysurgery. We attempted to manage the patient conservativelywith oral prednisone, but after about a monthhis visual acuity remained light perception with appositionalchoroidals despite an IOP in the high teens. Theglaucoma surgeon was concerned about his filtering bleb,which was not working well.

We decided to use a 25-gauge cannula (AlconLaboratories, Inc., Fort Worth, TX) in a novel way to assistwith drainage of the liquefied hemorrhage. This turned outto be a very effective technique that reduced operativetime and prevented compromise to the conjunctiva. (Thetechnique earned a Rhett Buckler video award at the 2008meeting of the American Society of Retina Specialists.)

The technique was aided by several factors. First, thechoroidals had adequate time to liquefy. Second, theolder generation of Alcon cannulas were made ofpolyamide, not metal, and could be trimmed to 2 mmlength in an attempt to prevent iatrogenic damage to theretinal pigment epithelium (RPE) and retina as thedetachments settled. Third, there was space to placeboth infusion and a chandelier light through the parsplana, although more anterior than normal. Finally, surgeonand patient were both very lucky.

Many choroidals, even hemorrhagic choroidals, willimprove given time. Do not attempt this technique forpatients who are demonstrating improvement in their conditionor in patients with shallow or minimal choroidals.

Following is the technique for drainage of choroidalhemorrhages using modified 25-gauge instrumentation:
1. Place infusion either in the anterior chamber orpreferably in the posterior chamber if space allows. Besure to visualize the infusion to ensure it is not in thesuprachoroidal space. Consider placing a chandelier orusing an illuminated infusion line, as this can help visualizethe drainage of the choroidal.
2. Remove the polyamide cannula and trim it to 2mm. Replace it onto the trocar. Do not try this with thenewer metal cannulas, as they cannot be cut easily.
3. Again visualize the infusion line to ensure it is in theproper position. Turn on the infusion.
4. Measure 8 mm to 10 mm posterior to the limbus inthe area of highest choroidal detachment and away fromthe filtering bleb if one is present.
5. Advance the cannula-trocar using a very shallowentry angle parallel to the limbus.
6. Say a short prayer, and then remove the trocar.
7. Watch for the return of the red reflex. If the hemorrhageis very liquefied or the choroidal is serous in nature, itwill drain rapidly, so be ready to remove the cannula.
8. Remove the cannula. It is not uncommon the get asurge of suprachoroidal blood when pulling out thecannula.

CONTROLLED DRAINAGE OFSEROUS CHOROIDALS
This technique, controlled drainage of serous choroidals using active aspiration and a guarded needle(CDSCUAAGN for short!) was born from the secondand third techniques described above. It seemed thatthe use of a 25-gauge cannula was less than ideal forserous choroidals, as the drainage occurred too rapidlyand in an uncontrolled manner. A transscleral needletechnique would provide more resistance to outflowand allow the use of a smaller incision. The downside tousing an unguarded needle would be the risk of overpenetrationand iatrogenic damage to the RPE and retinaas the detachments settled. The innovation of theguarded needle technique solved this problem. In anattempt to create a more controlled environment fordrainage, the needle was attached to aspiration to allowtotal control of the drainage (Figure 3).

The first patient in which this technique was usedhad undergone placement of an ExPress shunt (AlconLaboratories, Inc.) with associated overfiltration. Whenthe patient presented he had appositional serouschoroidals that had been present for a couple of weeks.In surgery we first addressed the overfiltering flap withadditional sutures. After this we used a guarded needle(a 26-gauge 3/8 inch needle with a type 270 sleeveguard) attached to the aspiration of the Accurusmachine (Alcon Laboratories, Inc.). We placed an infusionline carefully through the anterior pars plana.

The control allowed by this method was impressive.We could start and stop the drainage at any point. Inthe associated video (see sidebar for EyeTube link) onecan see that the drainage is stopped and the BIOM(Oculus, Lynnwood, WA) is then refocused to allow abetter view before resuming the drain.

The patient did well with no recurrence of thechoroidals and a return to his baseline vision.
The technique is performed as follows:
1. Set up the guarded needle as described previously.Attach the needle to the aspiration tubing.
2. Place an infusion line and ensure that it is in theproper location. Chandelier illumination is also helpfulfor this technique.
3. Turn on the infusion.
4. Advance the guarded needle 8 to 10 mm posteriorto the limbus in the area of the highest choroidaldetachment. Make a shallow entry parallel to the irisplane.
5. Move your posterior viewing system (BIOM, etc.)into position.
6. Engage aspiration slowly and watch the choroidalsdrain.

CONCLUSION
It is hoped that these techniques will allow you tobetter care for patients with challenging problems(choroidal detachments, hemorrhagic choroidaldetachments) or to expand your buckling repertoire abit further. In addition, I hope these help you enjoyengaging with the sclera more and finding it to be agateway rather than an obstacle.

WATCH IT ON NOW ON THE RETINA SURGERYCHANNEL AT WWW.EYETUBE.NET
Transscleral Surgery
By John W. Kitchens, MD
direct link to video: http://eyetube.net/?v=gobos

John W. Kitchens, MD, is a Partner with RetinaAssociates of Kentucky in Lexington and is amember of the Vit-Buckle Society. Dr. Kitchensstates that he has no financial relationshipsregarding products or companies mentioned inthis article. He can be reached at jkitchens@gmail.com.

Rohit Ross Lakhanpal, MD, FACS, is ManagingPartner at Eye Consultants of Maryland and aClinical Assistant Professor of Ophthalmology atThe University of Maryland School of Medicine. Heis also a Principal of the Timonium Surgery CenterLLC. He is a contributor to more than 50 articles, bookchapters, and presentations. He reports no financial or proprietaryinterest in any of the products or techniques mentionedin this article. He is a proud member of The American Collegeof Surgeons, The American Society of Retina Specialists, andThe Retina Society. He has been a consultant in the past forboth Bausch + Lomb and Alcon Surgical. He is currently theVice-President of the Vit-Buckle Society (VBS). Dr. Lakhanpal isCo-Section Editor of the VBS page in Retina Today andEYETUBE.NET. He can be reached at retinaross@yahoo.comor at his primary office number 410-581-2020.

Thomas Albini, MD, is an Assistant Professor ofClinical Ophthalmology at the Bascom Palmer EyeInstitute in Miami, FL. He specializes in vitreoretinaldiseases and surgery and uveitis. He has served asa speaker for Bausch + Lomb and Alcon Surgical and asa consultant for Alcon Surgical. He is the Membership Chairof the VBS. Dr. Albini is Section Co-Editor of the VBS page inRetina Today and on EYETUBE.NET. He can be reached at+1 305 482 5006 or via e-mail at talbini@med.miami.edu.

 

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Retina Today is a publication that delivers the latest research and clinical developments from areas such as medical retina, retinal surgery, vitreous, diabetes, retinal imaging, posterior segment oncology and ocular trauma. Each issue provides insight from well-respected specialists on cutting-edge therapies and surgical techniques that are currently in use and on the horizon.