What is the reoperation rate for strabismus surgery in patients with thyroid eye disease?

Short answer: Approximately 25%

I’d like to share a paper I’ve been working on recently that was just published by the American Journal of Ophthalmology!

I had the opportunity to observe numerous strabismus surgeries during my ophthalmology rotation this summer. This included several operations for patients with thyroid eye disease (aka Graves’ disease), one of which was a reoperation. Working with my mentor, Dr. Lambert, I developed a project using insurance databases to examine risk factors for reoperation after strabismus surgeries among patients with thyroid eye disease. I’d previously worked on some projects investigating the cost of various treatments for non-infectious uveitis using insurance databases, making this project much easier.

Bette Davis Eyes - Wikipedia
Two-time Best Actress winner Bette Davis (1908 – 1989). Source.

As some background, Graves’ disease is an autoimmune disease in which the body produces an antibody that overstimulates the thyroid. This can cause symptoms including swelling in the neck, diarrhea, heat intolerance, irregular heartbeat, fatigue, and insomnia. In a minority of patients, Graves’ disease also leads to scarring of the muscles of the eye and expansion of the tissue behind the eye (retro-orbital tissue). Scarring of the muscles of the eye leads to misalignment of the eyes (strabismus or squint) and double vision (diplopia). Expansion of the tissue behind the eyes can lead to the eyes bulging forward (proptosis). Famously, the actress Bette Davis was suspected to suffer from thyroid eye disease.

Thyroid Eye Disease In Your Exam Lane
Strabismus and proptosis in thyroid eye disease. Source.

In some cases of strabismus that leads to double vision, surgery may be required. Some previous studies have examined the rate of strabismus surgery reoperation – however, our study is the largest reported in the literature thus far. More specifically, our study examined patients in a large commercial insurance claims database between 2003 and 2019 with thyroid eye disease who underwent at least one strabismus operation. We extract information about patient characteristics (age at diagnosis, sex, race), primary surgery characteristics (number of muscles operated on, which muscles were operated on, use of adjustable sutures), and timing of reoperations. We then used this information to examine associations between time to reoperation and patient/surgery characteristics.

The headline findings are that 111/448 patients in our study (24.8%) underwent a reoperation. The number of muscles operated on initially was the only independent predictor for undergoing a reoperation. Similarly, the number of muscles operated on initially was associated with a shorter time to the first reoperation. Other factors such as age at diagnosis of thyroid eye disease, the time between diagnosis of thyroid eye disease and surgery, gender, race, and other characteristics of the primary surgery were not associated with a time to reoperation.

Strabismus Surgery - American Association for Pediatric Ophthalmology and  Strabismus
Recession of an extraocular muscle (type of strabismus surgery). Source: AAPOS

Overall, I think our work contributes to the literature by providing an unbiased look at the rates of strabismus reoperation in thyroid eye disease. It also confirms that disease severity (which dictates the number of muscles operated on initially) likely drives the rate of reoperation. Finally, adjustable sutures did not reduce the rate of reoperations in patients with thyroid eye disease, which is consistent with previous work. Hopefully, this work will help with patient education and surgical decision-making!

I wish I could discuss the paper in more detail, but it’s still an “Article in Press” and only the abstract is available for non-subscribers to the American Journal of Opthalmology. If you have institutional access and have an interest in strabismus surgery, I encourage you to check out the paper!

Jezebel (1938) - IMDb
Bette Davis and George Brent in a 1938 movie in which Davis won Best Picture. Source: IMDB

Bonus quiz:

  1. For which movies did Bette Davis win Best Actress?
  2. Who sang “Bette Davis Eyes” (1981)?
  3. Which new treatment for thyroid eye disease was FDA approved in 2020?

References:

  1. Hwang B, Heo H, Lambert S. Risk Factors for Reoperation after Strabismus Surgery among Patients with Thryoid Eye Disease. American Journal of Opthalmology. November 2021. https://doi.org/10.1016/j.ajo.2021.11.022
  2. https://eyewiki.aao.org/Thyroid_Eye_Disease
  3. https://www.smartvisionlabs.com/blog/bette-davis-eyes/#:~:text=Those%20’Bette%20Davis%20eyes’%20could,eyes%20which%20makes%20them%20swell.
  4. https://www.reviewofoptometry.com/article/thyroid-eye-disease-in-your-exam-lane
  5. https://aapos.org/glossary/strabismus-surgery
  6. Zhang MS, Hutchinson AK, Drack AV, Cleveland J, Lambert SR. Improved ocular alignment with adjustable sutures in adults undergoing strabismus surgery. Ophthalmology. 2012;119(2):396-402. doi:10.1016/j.ophtha.2011.07.044

Quiz Answers

  1. Dangerous (1935) and Jezebel (1938). A scene from Jezebel is pictured above.
  2. Kim Carnes
  3. Tepezza (teprotumumab-trbw). IT’s an IGF-1R antagonist.

Do students perceive they learn more by lectures or active learning?

Short answer: Students perceive they learn more by lectures. However, students actually learn more by active learning!

I recently came across a PNAS paper comparing active to passive learning for college students taking an introductory physics course at Havard (Deslauriers et al. PNAS 2019) [1]. In short, active learning has long been known to be superior to passive learning (e.g. lectures); however, STEM instructors generally choose traditional teaching methods. To investigate this discrepancy, the researchers randomly assigned students (total n = 157) to active learning (group problem-solving session) and passive learning groups (lectures). Students tended to prefer passive learning and felt like they were learning more from lectures (higher perception of learning). However, students in the active learning group actually performed better on tests. The researchers hypothesize that the increased cognitive load of active learning may have led to decreased perception of learning.

Figure 1 reproduced from Deslauriers et al. Comparing test scores and survey questions assessing the feeling of learning in active and passive learning groups.

Personally, this research was quite concerning. Most of my learning is passive – especially from lecturers who excel at addressing misconceptions (thus depriving me of the chance to actively clear up misunderstandings or construct my own opinions). This phenomenon may also explain why medical students tend to better remember diseases that they have seen in an actual patient, rather than only read about in a textbook. This gap between the perception of learning and actual learning is not only a problem for aspiring physicists and medical students, but also for patients.

It is not uncommon to hear a patient say, “He didn’t tell me anything,” when describing an encounter with their physician. So either the specialist did not explain things well, or the patient did not hold onto the details. Patients typically do a good job of following what is being said while it is being explained. However, they may not be able to recall the details of the discussion later.

Rishi Gupta, Reflections of a Pupil, Page 157.

This quote comes from Dr. Rishi Gupta’s book, Reflections of a Pupil, a compilation of life lessons from a vitreoretinal surgeon in Halifax. At first, the book may seem to only contain platitudes and obvious advice (treat patients like how you would treat a family member, constantly strive for self-improvement or you’ll be left behind, never operate on the wrong eye). Nonetheless, the book grew on me for the following reasons:

  1. There is great value in reviewing life lessons through the lens of a more experienced surgeon’s perspective
  2. The book helps one understanding implicit values held by senior physicians.
  3. Obviously, I haven’t had the opportunity to reinforce each pearl in the book through real life examples – and while the specifics might differ for every trainee – these “missed” lessons are precisely the most important to pick up on! For example, I will never say “oops “again in the operating room…

If you don’t believe the perspective of a medical student, Dr. Uday Devgan of CataractCoach fame gives a glowing review of the book below.

Anyways, Dr. Gupta continues the quote above with an especially apt analogy: “I liken this to being driven through an unfamiliar area of town. We all follow the left or right turns as they are happening. However, when asked to drive that same route again on our own, many of us would have a tough time.” A few suggestions (from Dr. Gupta and other research) to combat this discrepancy between perceived and actual learning in patients:

  1. Summarize every encounter with a few bullet points and a brief plan so patients don’t lose sight of the bigger picture.
  2. Provide handouts that patients can slowly digest at home with the help of their friends/family/the internet.
  3. Encourage patients to teach back what they have understood (this can be time consuming though!).
  4. Reinforce the same concept multiple times. Don’t be afraid to bring patients back for a second visit.
    1. People tend to remember the gestalt of a visit (how they felt) more than the specific information given. Ensuring patients feel like their concerns are being heard at the initial visit 1) more likely they will return 2) less likely to file a malpractice claim

For those interested in other suggestions for promoting active learning for students in general, this Edutopia article provides suggestions such as:

  1. highlighting the benefits of active learning to students
  2. encouraging students to see the struggle of learning as productive
  3. helping students develop metacognitive skills to more accurately gauge their own level of understanding.

References

  1. Deslauriers L, McCarty L, Miller K, Callaghan K, Kestin G. Measuring actual learning versus feeling of learning in response to being actively engaged in the classroom. Proceedings of the National Academy of Sciences. Sep 2019, 116 (39) 19251-19257; DOI: 10.1073/pnas.1821936116
  2. Gupta, Rishi. Reflections of a Pupil. Pages 155-158.
  3. Huntington B, Kuhn N. Communication gaffes: a root cause of malpractice claims. Proc (Bayl Univ Med Cent). 2003;16(2):157-161. doi:10.1080/08998280.2003.11927898
  4. https://www.edutopia.org/article/students-think-lectures-are-best-research-suggests-theyre-wrong

Note: I feel like my introduction to the Deslauriers et al. paper may have come from some popular STEM Youtuber, IFL Science, or just something random on Twitter. Apologies I’m unable to remember the exact source, but I won’t pretend I remember this paper from a careful perusal of the primary literature about learning.

Note 2: The research of Deslauriers et al. is similar, but not entirely the same as the illusion of explanatory depth (which is more just a metacognitive deficit/ bias).

Spiral of Tillaux

Spiral of Tillaux | Optometry, Optician, Spiral
Spiral of Tillaux. Measurements are given in millimeters. From aao.org.

Paul Jules Tillaux was a French surgeon that is the namesake of the spiral of Tillaux, an imaginary curve through the insertions of the eye’s rectus muscles.

There are six extraocular muscles that control the movement of the eye (the legendary 7th extraocular muscle, the levator palpebrae, controls eyelid elevation). These are:

  1. Medial rectus
  2. Lateral rectus
  3. Superior rectus
  4. Inferior rectus
  5. Superior oblique
  6. Inferior oblique

The 4 rectus muscles originate in the back of orbit at the annulus of Zinn and insert anteriorly on the globe near the limbus. Starting from the superior rectus and going to the lateral rectus, inferior rectus, and medial rectus, the muscle insertions lie progressively closer to the limbus (border between the cornea and sclera). This forms the aforementioned spiral of Tillaux.

As seen in the image above, for the average adult, the medial rectus inserts 5.5mm from the limbus, the inferior rectus 6.5mm, the lateral rectus 6.9mm, and the superior rectus 7.7mm. For the time-crunched resident reviewing for OKAPs, Dr. Pouw and Dr. Young on Eyes for Ears remind us that these values may be more easily remembered as 5.5, 6.6, 7.7, and 7.0.

The spiral of Tillaux has some importance when performing ophthalmic surgery. As the superior rectus insertion is quite posterior, a scleral pass that is too deep may perforate the retina (it doesn’t help that the sclera is the thinnest [a mere 0.3mm] directly posterior to the rectus muscle insertions). In cases when there is a remote history of strabismus surgery but the amount of advancement or recession is unknown, measurements of muscle insertions from the limbus may allow the surgeon to estimate the extent of previous surgeries.

Muscles of the right orbit from Gray’s Anatomy.

Other Eponyms

Like many other surgeons of yesteryear, Dr. Tillaux is honored with eponyms across a variety of fields. He is best known to orthopedic surgeons for the Tillaux-Chaput fracture, an unusual fracture of the anterolateral tibial epiphysis. This Salter-Harris III fracture is most commonly seen in adolescents after forced lateral rotation of the foot.

The Tillaux maneuver is a physical exam technique to demonstrate adherence of a breast tumor to the pectoralis major.

There is also a Tillaux apparatus that maintains femoral diaphysis fractures in constant, steady adduction; Tillaux’s sign, an indication of a mesenteric tumor; and a Tillaux painful crepitus sign tenosynovitis of the adductor and short extensor of the thumb.

References

  1. https://eyesforears.net/episodes/2019/12/26/episode-34-strabismus-fundamentals-part-i
  2. American Academy of Ophthalmology,. (2021). 2021-2022 Basic and Clinical Science Course, Section 02: Fundamentals and Principles of Ophthalmology. Page 18-20.
  3. https://www.orthobullets.com/pediatrics/4028/tillaux-fractures
  4. https://litfl.com/paul-jules-tillaux-eponym/