The SOS Advanced Strabismus eye has a conjunctiva, Tenons and an inferior oblique muscle as well as 4 rectus muscles. This video demonstrates how to simulate a left inferior oblique recession, emphasing the correct positioning of the fornical incision, identifying and then hooking the inferior oblique under direct vision and then suturing it to the scleral in the appropriate position.
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Once trainees have mastered rectus muscle surgery, we move on to inferior oblique procedures. The eye is set up in exactly the same way as the advanced eye for rectus muscle surgery. Here we can see the inferior oblique tendon emerging on the contralateral eye. So irrespective of what technique you normally perform for inferior oblique weakening procedures, it can be realistically simulated using these eyes. Here we can see the conjunctiva and Tenon’s capsule being opened up via fornix-based incision, just adjacent to the inferior and lateral rectus. The conj and Tenon’s is then reflected, and you can just start to see the pinkish hue of the inferior oblique covered with its capsule, coming into view. Just to improve visualization here, we’ll just open up the conjunctival incision a little bit more, so the camera can see the tendon itself. Probably the most important thing to teach the trainees is to hook the inferior oblique muscle under direct visualization, and not perform any form of blind hooking. And here we can see the inferior oblique being hooked with a squint hook, passed underneath the tendon, and then bringing it anteriorly into the conjunctival opening. Another squint hook is placed adjacent to the first. The assistant just helps hold the squint hook, so the tips are brought into view. To enhance the realism of the procedure, we have added an extra layer of capsule-type material over the inferior oblique tendon, which now has to be cleaned off, to reveal the tendon itself, before suturing can be carried out. This can either be done with Moorfields forceps, or in this case, more successfully with Westcott scissors. Rather satisfyingly, once it’s dissected, we can see the entire tendon. The next maneuver we teach the trainees is to look for the posterior fibers of the inferior oblique, to make sure they’ve all been hooked. Which, of course, they will be with this model eye, because it isn’t made from material which can be split. But nevertheless, an important maneuver to teach. This muscle has a very similar feel to the pass of a spatulated needle, as the tendon does in real life. Here is 6-0 vicryl suture being used to secure the tendon. As well as recession procedures, myectomies can be carried out, using the model eye, as can anteriorization. As the inferior oblique is cut, traction is placed on the tendon to produce that realistic separation of the tendon, once it has been completely disinserted. The sclera is marked at the appropriate recession point. And the scleral suture is passed. The squint hook is just holding the inferior rectus. And as I said earlier, recession can be carried out at any point, and even anteriorizations can be performed. The tendon doesn’t deform as a real tendon would, so it’s difficult to snug it down securely to the sclera. But it’s still possible to accurately place the inferior oblique in the desired recession point.