Expert panel debates preferred strabismus surgery techniques

At the annual American Association for Pediatric Ophthalmology and Strabismus meeting in New Orleans, OSN Pediatrics/Strabismus Section Editor Robert S. Gold, MD, led a round table discussion on surgical approaches to correcting strabismus. Each of the participants had a different approach to correcting esotropia in patients with a large disparity in distance/near vision, some operating on the near angle, some on the distance angle and some with nuanced differences in the amount of correction to perform. Then the panelists took a new look at plication vs. resection for strabismus surgery, an idea that is not new, but one that is getting more consideration as an alternative to resection.

Robert S. Gold, MD: We will start by talking about surgical treatment for accommodative esotropia with a high accommodative convergence/accommodation (AC/A) ratio, that is, a distance/near disparity with a basic component that requires surgery.

The question is, how do you approach this patient? Which muscle and what angle do you operate on?

Scott E. Olitsky, MD: To me, it is fairly straightforward. I operate on the near angle always. I operate on the medials when they have not been operated on, but I do not think that matters. You can normalize the AC/A ratio regardless of which muscle you work on.

Gold: Do you get overcorrections?

Olitsky: I have more undercorrections than overcorrections. I understand people’s concern about exotropia, but I do not think it happens often. Certainly there is no higher risk in my experience than for any other strabismus we treat.

What does not conceptually make sense to me is, if you are worried about exotropia, which I do not think you need to be, why operate on an in-between angle in which you would still potentially get an exotropia and an undercorrection at near? That is not something I have ever really looked at doing.

Image: Cheng KP

Anthony P. Johnson, MD: I typically operate for the distance angle and adjust for the patient with a high AC/A ratio. I probably see that high AC/A ratio in fewer than 10% of the esotropes I see. And I see more overcorrections than Scott does. It is disturbing to get those overcorrections, so I have evolved into being a little bit less aggressive and more willing to accept an undercorrection of the AC/A ratio than converting the patient into an exotrope.

Kenneth P. Cheng, MD: I will take the middle of the road here. Generally I tend to operate more toward the near angle of deviation, but not quite all the way, depending on how large the distance/near disparity is. I have been fortunate not to see too much in the way of overcorrection, but I do have patients whose eyes are straight at distance but need a bifocal to keep their eyes straight at near.

The one thing I do that I think makes a difference is to operate on the medials. If a patient has a fixation preference, as most of these patients do if they have decompensated, I will still operate on the medials on both eyes, but I will do more on the non-fixating eye than on the fixating eye. Even if the patient has had strabismus surgery once before, I will still redo the medials to avoid the laterals on those patients. I cannot say that I have tried it the other way around and whether it makes a real difference, but I am happy with my results.

M. Edward Wilson, MD: I agree somewhat with what Tony said. I have seen overcorrections. They are few in number but memorable. So I do not go all the way to operating on the near angle.

Another reason I do not is because the distance measurement is often consistent because of the distance angle. If the patient changes accommodative effort, it does not change the measurement much, whereas the near measurement can change a lot. It changes based on the attractiveness of the target. It changes based on small distance if the patient pulls it to near. So I have been happy with operating for the distance angle and then fudging up by 1 mm if the near is 10 prism diopters (DD) greater, 1.5 mm if it is 15 DD greater and 2 mm if it is 20 DD or more greater because sometimes the near deviation will go up to 70 DD. So I do not keep adding. I add 2 mm to my formula when the measurement is 20 DD or more. And that seems to have worked pretty well. If you do a relatively larger number than distance, you are going to get them correct most of the time. There are more undercorrections than overcorrections, but I just want to avoid those overcorrections.

When you overcorrect and you reduce the glasses prescription, that usually works only temporarily. In my experience, patients stay exotropic.

Cheng: I agree with that, not just in this scenario, but also in other scenarios of partially accommodative esotropia.

Roberto Warman, MD: I tend to do the calculation for the distance and add 1 mm. I do not add more than 1 mm.

My approach also depends on the age of the child, to a certain degree, and the amount of plus. If their plus is a lot, they will not outgrow that plus in adolescence, and those cases will go exotropic later if you overcorrect them. If their plus is not that much and they are at an age where they may still outgrow it, then I feel more comfortable that if I have to decrease the plus, eventually nothing will happen. So I fudge. I do not think I have a cookbook answer, but usually I operate more for distance and not the full near.

Olitsky: I agree. I think we remember those overcorrections quite well. We are accepting of the undercorrections, and we do not worry about them too much because they are better. The overcorrections, obviously, look worse.

Gold: In my experience, I sort of hedge. I do not do the near angle. I do not necessarily do the distance angle. I hedge my numbers, as we have talked about. I am also worried about those overcorrections, particularly at distance. I have not had that happen because I hedge my numbers more toward the near angle, again using the disparity to make my final determination.

Wilson: As a teaching comment, I tell our fellows that the dose-response curve in strabismus aligns itself better with how much you have. You tend to get more dose per millimeter when you have more strabismus. With decompensated accommodative esotropia with a high AC/A, the dose-response curve is different. You have to do more surgery. How much more you do may not matter because you get more when there is more, typically. In strabismus, the dose-response curve is more related to the amount of deviation than anything else, in my experience.

Cheng: I would say one thing. I think as a person increases their numbers and gets more aggressive about the near angle, you do have to be a little bit careful about getting gaze incompetence and not having full adduction of that eye because you have recessed the medial 6 mm or 6.5 mm, especially as the patient gets older.

Johnson: Hearing all these different methods from experienced folks reminds me that what we are trying to do is to re-establish fusion. We do not know exactly on a cellular level what stimulates the fusional center, but if we can somehow approach that from whichever method, that is what we are trying to do.

Plication vs. resection

Gold: Subject No. 2. There have been some recent discussions, papers and videos on whether to do a resection or a plication for strabismus, and I wanted to poll this group on whether you have added plication to your armamentarium and, if you have, what issues you have encountered.

Wilson: I have switched completely to plications, and I have been happy with it. We have about a year’s worth of data. I was convinced from listening and talking to Joseph L. Demer, MD, PhD, whose published work compares the dose-response curves of these two approaches. We have been pleased with plications being faster and easier than resections. The lump under the conjunctiva goes away relatively quickly. We started off doing some plications and some resections and trying to compare them, but now I do plications in all cases that I previously would have done resections.

Gold: Is the inflammatory reaction better, worse, no change?

Wilson: I think it is better because the surgical trauma is less. We take single-arm sutures and take just the 2 mm on the ends of the tendon at the measured amount, and then I sew it to the sclera just in front of the muscle. It is quick and it is less surgical trauma, so I think there is less inflammation. There is a lump on the sclera, but that goes away. It has not been objectionable.

Gold: How long does that bump usually last in your patients?

Wilson: A few months, but it is pretty flat, especially in smaller resections. You can do it through a standard fornix incision, or we have also done it through a minimally invasive incision, that is, two small slit incisions, one on each side of the muscle, so that you just engage that part of the tendon and pull it up. That has also induced less trauma.

Warman: Do you modify the amount of millimeters that you use to resect vs. plicate, or do they stay about the same?

Wilson: I was worried about that. Joe Demer looked at that, comparing the dose-response, and came to the conclusion that you could use your resection table for plication. That made us feel more comfortable. We are still looking at our results, but so far it appears that the doses do correlate. If anything, the plication is a little more powerful. Probably it is just related to where you place the needle. If you place the needle in front of the tendon, you might be tightening it a little more than you realize. So we are trying to be careful to actually plicate the amount that we wish and not pull it in front of the original insertion.

Warman: Mexican strabismologists have been talking about plications for decades. This is not necessarily a new thing.

Wilson: No, it has been done for a long, long, long time. Decades.

Warman: We may have to look into it again.

Wilson: I give Kenneth W. Wright, MD, credit for, in the U.S. at least, publishing and trying to popularize plication. What changed my thinking is the minimally invasive movement, if you will — the method of plicating just the ends of the muscle and yet the whole tendon falls forward. That particular type of operation is what sold me, the one done by Daniel S. Mojon, MD, where, using his new incision, he grabs the two ends of the tendon, folds it forward, and the whole tendon comes forward and you just undermine. You do not have to do much else. That sold me.

Olitsky: I have thought about this quite a bit because we have had more people talking about it. One thing that had concerned me was that different surgeons were getting great results but with different amounts of surgery. What I have been hearing and what Ed is saying is that the amounts of reduction or augmentation are compatible with the tables already in use. This is not something I have been doing, but it is something I will definitely be doing after the meeting.

I have one more question for Ed. Have you converted to doing more plications than recessions then? Do you now think about plicating the laterals where you may have recessed the medials before because the procedure, as you described it, seems like it is an easier procedure on both the surgeon and the patient perhaps?

Wilson: That is an interesting thought. We think of recession as being associated with less surgical trauma than a resection, so we try to do recessions whenever possible. Certainly, I would give that some thought. We are doing plications as a first operation for age-related distance esotropia, for instance, which I think is a growing condition and perfect for this plication operation. So that is one example of where I would not do recessions. I would go straight to a plication for an esotropia because it is a distance esotropia that older people get.

Olitsky: But it sounds like it may become the more standard procedure.

Wilson: You may be right.

Cheng: When you think about the effect of a recess/resect procedure, the bulk of the effect and repositioning of the eye comes from the recession, and the resection component of the surgery is more a leashing of the eye in position for a while. That is why I think that the amount of plication is not as critical. In other words, I think that the surgical measurements and how much surgery you are doing are more dependent upon the recession half of the procedure than on the resection or plication part, which might explain why people describe good results with variable amounts of surgery.

I have not started doing plications yet. I have been concerned that if you perform the plication at the middle of the muscle, back another millimeter or who knows how much, then as your suture dissolves, how much does the muscle slide back on itself because you have not touched the capsule? The capsule is still intact and I suspect should not adhere to itself. I would not think that it would scar too much to itself, but not having done these and not having reoperated on these, I cannot say that I speak with any type of authority whatsoever.

Wilson: That was the concern everybody had. I think that is why we are so late in coming to this because we all had those concerns. I reoperated a plication to recess the muscle 6 months after surgery because of an overcorrection. It is the only reoperation I have done. I could not tell that it had been plicated. The muscle had just remodeled, and it looked just the same as a resected muscle. It was tight. It dissected. It looked flat. The sarcomeres must have just adapted. It was done with a Vicryl suture, and I recessed it a small amount 6 months later. That was amazing to me because I had not seen what the muscle looks like later. It looked exactly like you would expect. The middle does not sag. When the tendon rolls forward, if you do it correctly, it is symmetric. The muscle, the tendon, they want to stay together. The interfiber connections want to keep it together. When you pull it forward, it wants to make a nice, symmetric roll. I was impressed that it looked so good on reoperation. It did not look like some unusual operation had been done on it.

Gold: When you did reoperate, you did not take it down? It is basically scarred together?

Wilson: There was nothing to take down. It was completely flat, and it looked like a shortened tendon. So whatever we are doing with the plication during the remodeling period, it just becomes a shortened tendon, which I think is amazing. I would not have predicted that.

Cheng: The key to this is for somebody to conduct a study on a number of rabbits and to see on histopathology whether the muscle capsule folds over on itself, or in fact if in the healing process the muscle gradually slips back, capsule and all, having been held in position long enough for the sarcomeres to remodel and the muscles to effectively shorten.

Wilson: That would be interesting.

Gold: The take-home for us is that, while this may not be a new procedure, it is certainly newer in the U.S. and is being done recently by more and more people.

Wilson: For those in our readership who do strabismus surgery, perhaps on adults and maybe not every single week, this procedure allows you to tighten a muscle. It eliminates the risk of a lost muscle.

Cheng: You are talking about this being easier, but I do not think a resection is difficult. And lost muscle does not happen with any realistic frequency. So, for the pediatric ophthalmologist, this is analogous to the cataract surgeon taking an extra 4 seconds or 30 seconds or a minute off of their cataract surgery time.

Gold: We hear about all of these minimally invasive procedures in ophthalmology and in anything else, and this is being touted as not necessarily minimally invasive but less invasive.

Cheng: That is the same thing as taking 30 seconds off the cataract operation. Regarding minimally invasive, now you have two incisions instead of one in the cul-de-sac, and you put in a suture or not. I do not close my cul-de-sac incisions, and it all works out fine. I wonder whether this is everything that it is touted to be? I certainly do not disagree with you. I think it is a good thing that we are looking at this and trying to improve things, but let’s be realistically and practically objective when we look at what we are talking about.

Johnson: With the minimally invasive approach, like I have seen on video, it seems like the tinier incision would, for me, make it harder.

And does it preserve the blood supply like it theoretically suggests?

Wilson: I am not sure it preserves blood supply, but it certainly may. You still may interrupt some of the blood supply, but I would think that it has less risk of anterior segment ischemia. We do not see anterior segment ischemia often anyway, but I would think it would.

I do not recommend that people do this through a smaller incision when they start. I think you should do the operation through whatever incision you like to do. But after becoming comfortable with plication, making incisions smaller and learning to dissect underneath the conjunctiva and learning to stretch the conjunctiva less is advantageous in the adult population, especially the older adults, in whom the conjunctiva tears and rips. But it is more difficult.

• References:
• Chauhuri Z, et al. JAMA Ophthalmol. 2014;doi:10.1001/jamaophthalmol.2013.8188.
• Mojon DS. Eye (Lond). 2015;doi:10.1038/eye.2014.281.
• Wright KW, et al. Color Atlas of Strabismus Surgery: Strategies and Techniques. 4th ed. New York: Springer; 2014.

• For more information:
• Kenneth P. Cheng, MD, can be reached at 100 Bradford Road, Suite 320, Wexford, PA 15090; email: kpchengmd@me.com.
• Robert S. Gold, MD, can be reached at 790 Concourse Parkway South, Suite 200, Maitland, FL 32751; email: rsgeye@gmail.com.
• Anthony P. Johnson, MD, can be reached at Jervey Eye Group, 601 Halton Road, Greenville, SC 29607; email: apj@jervey.com.
• Scott E. Olitsky, MD, can be reached at Children’s Mercy Hospitals and Clinics, 2401 Gillham Road, Kansas City, MO 64108; email: seolitsky@cmh.edu.
• Roberto Warman, MD, can be reached at Miami Children’s Hospital, 3200 SW 60th Court, Suite 103, Miami, FL 33155; email: rwarman@eyes4kids.com.
• M. Edward Wilson, MD, can be reached at Albert Florens Storm Eye Institute, 167 Ashley Ave., Charleston, SC 29425; email: wilsonme@musc.edu.

Disclosure: The round table participants report no relevant financial disclosures.

Is it worthwhile to incorporate minimally invasive strabismus surgery into your strabismus surgery practice?

Minimally invasive strabismus surgery allows surgical options not previously available

With minimally invasive surgery, we can do strabismus surgery with topical anesthesia and correct small, even micro, deviations without adjustable sutures. The use of the grooved hook rather than the standard hook facilitates strabismus surgery with topical anesthesia and allows safe surgery through small incisions. The Wright grooved hook self-retracts the conjunctiva, allowing excellent insertion exposure even with small incision surgery. It is also very helpful for suturing tight muscles.

There is a growing subgroup of patients who just cannot be treated with standard strabismus surgery and require minimally invasive “smaller” surgery. What do you do with a refractive surgery patient or postoperative cataract patient who now sees 20/20 without correction, but has vertical diplopia due to a small hypertropia of 2 to 4 prism diopters? Standard strabismus surgery does not correct these micro-deviations. A vertical microtropia may not seem like much, but it is quite debilitating to the patient with double vision. These patients are not happy campers after paying out of pocket for refractive surgery or enhanced cataract surgery when they are told they need prism glasses.

Approximately 10 years ago, I developed a minimally invasive procedure for patients with a micro-hypertropia—the Wright central tenotomy—which can be done using topical anesthesia in a fully awake patient and takes less than 1 minute. This no-suture technique is safe and adjustable. I have had no overcorrections and only an occasional undercorrection. The enhancement is only a 2-minute procedure if needed.

Minimally invasive strabismus surgery has expanded our horizons necessary for the increasing expectations of our patients. The ability of these minimally invasive procedures to reliably correct small and even micro deviations greatly has changed the way we approach strabismus. We are no longer dependent on prism glasses, and for the most part, do not need the often aggravating and painful adjustable suture technique. Small incision minimally invasive strabismus surgery has been good for our patients because, in the old days, we would cut and strip the Tenon’s capsule, which resulted in scarring adhesions and the complication of restriction. Except for the unusual difficult reoperation, the days of large incisions and big dissections are gone. I look forward to younger, innovative strabismologists moving minimally invasive surgery even further. One day I would love to see endoscopic strabismus surgery. The Wright Foundation for Pediatric Ophthalmology and Strabismus will explore new approaches to strabismus surgery at a pre-Academy meeting “Strabismus and Pediatric Plastics.”

• Reference:
• Wright KW. Trans Am Ophthalmol Soc. 2009;07:97-103.

Kenneth W. Wright, MD, is the director of Wright Foundation for Pediatric Ophthalmology & Strabismus. He can be reached at wright2020md@aol.com and www.wrighteyecare.com. Disclosure: Wright receives royalties from Titan Surgical and Springer Publishers.

‘Minimally invasive’ means many things

I answer this question “No” with a qualification. The surgery that many of us perform is minimally invasive and should also be classified as “MISS.” The small incision and subconjunctival dissection described by Daniel S. Mojon, MD, requires an operating microscope, which minimizes the surgical field. Many strabismus surgeons find the use of a microscope to be counterproductive. The normally excessive connective tissue surrounding the muscles in young children would make the required dissection of the check ligaments and Tenon’s capsule beneath the conjunctiva difficult and possibly associated with hemorrhage. In fact, Dr. Mojon believes the ideal patient for this procedure should be 14 years of age or older, when the normal physiologic reduction in the connective tissue surrounding the muscles commences.

Some of the proposed advantages of MISS include less postoperative “redness” and discomfort, preservation of perilimbal vasculature, and fewer cases of Dellen formation. All of these advantages are accomplished by using a conjunctival fornix incision. For me, this is MISS with better visualization. Furthermore, in many recessions I prefer minimal dissection of the perimuscular connective tissue and check ligaments and require only a few millimeters of clean insertion in which to pass the sutures to secure the tendon prior to disinsertion.

I haven’t seen a comparison of the “incision to closure” operative time between this new technique and the standard limbal or fornix conjunctival incision. I suspect the procedure described by Dr. Mojon takes longer. Quality surgical efficiency should always be a goal in the operating room.

Could I think of a case where the placement of a few keyhole openings of the conjunctiva would be desirable? Perhaps, if I have excellent visualization through a transparent conjunctiva as occurs in some elderly patients with minimal connective tissue. The term “minimally invasive” when applied to any surgery is appealing to patients. We all need to better describe how the different procedures used to isolate an extraocular muscle are all examples of MISS.

Rudolph S. Wagner, MD, is an OSN Pediatrics/Strabismus Board Member. Disclosure: Wagner reports no relevant financial disclosures.