Coding Corner


In the last RETINA Roundup post, we provided an overview of various creative ways to approach complex macular holes. One of the techniques is to detach the macula with BSS injected through subretinal cannulas. Mark Walsh.png We were able to reach Mark Walsh MD PhD from Retina Associates in Tucson, AZ, for a phone interview. He was a co-investigator in a paper published in RETINA (Szigiato et al. 2016) that describes their macular detachment technique for recurrent or persistent macular holes. YY: Hi Mark, thanks for your time today. You and colleagues from Toronto published and frequently talk about the macular detachment technique for difficult macular holes. Before getting into details, how do you approach macular hole surgery in general? MW: For most macular holes I peel ILM and use gas. If it's high-risk, I usually make an inverted ILM flap these days. But the ballooning of the macula is awesome for recurrent or persistent macular holes where the ILM has been peeled already. YY: What's the rational and how does this promote hole closure? MW: In these tough cases, the macula tends to be stiff and stuck down to the RPE. By ballooning up the macula, it releases it from the RPE, and stretches out the stiff macula. On post-op day 1, the subretinal fluid is all gone, and the macular hole is usually closed already. YY: Let's get down to the nitty-gritty of the technique. What instruments do you use and what are your exact steps? MW: I use a 23G/41G subretinal cannula from DORC. I connect it to the viscous fluid injector, and titrate the pressure outside the eye. When the injection pressure allows the fluid to go from a drip to a stream, that's the setting that I like. I retract the 41G needle, enter the eye, and then expose the 41G needle. The key is to floor the pedal before going through the retina. If you step on the pedal after penetrating the retina, there's a high risk for hitting the RPE. But by stepping on the pedal right before, the macula will start ballooning up soon after you make contact with the macular surface. I've never had any RPE markings by using this technique. MH Detachment 1 BSS being injected through a 41G cannula into the subretinal space, creating a blister to lift the macula off of the RPE. MH Detachment 2 Several injections are usually required to balloon the entire macula, and air fluid exchange is performed followed by gas exchange. YY: That's a really nice pearl. I think the cannula also goes through retina very easily where ILM is previously peeled. Sometimes the ILM can be very stiff and can require more force than you would like. Do you make one blister, or do you need more? MW: Since the fluid will come out of the macular hole, you usually need to make several blisters within the arcades to elevate the macula. It's very easy and quick, and we've had great success using this technique. YY: Thanks for all the pearls! Yoshihiro Yonekawa, M.D.