Faster recovery and less discomfort with refined MISS technique

A new minimally invasive strabismus surgery (MISS) technique for rectus and oblique muscle displacement offers a safe and effective means of performing muscle surgery through a smaller conjunctival incision than was possible with previously reported MISS techniques, according to Daniel S Mojon MD, FEBO, EMHSA, Airport Medical Center Eye Clinic, Zürich, Switzerland.
“The minimally invasive transconjunctival suturing technique (TRASU) allows for the suturing of the muscle at its original insertion and the reattaching of a muscle far behind the original insertion without the need to prolong the cut more anteriorly and posteriorly. The surgery is conducted through an opening that is about two-thirds the size of traditional MISS conjunctival incisions,” he said.
The refined suturing technique, which can be used for recessions, resections, plications, advancements and transpositions, offers several advantages over existing methods, Dr Mojon told EuroTimes. 
“This technique has several advantages including faster surgery because we are dealing with a smaller opening that can be closed very quickly. There is also significantly less discomfort for the patient and quicker postoperative rehabilitation. It also results in less scarring, which is particularly important in the event of repeat surgery. In fact, with this technique sometimes even repeat surgery is less visible than primary surgery – that is how minimally invasive it is,” he said.

Radial cuts
Explaining the technique for recessing a horizontal muscle in more detail, Dr Mojon said that muscle exposure is performed, as usual for MISS, through two radial cuts, one along the superior and the other along the inferior margin of the horizontal muscles. After muscle separation from surrounding tissue and hooking, the suture is passed between sclera and muscle for 2mm and then passed through the muscle and the conjunctiva. Now, the suture is retrieved in the space between the conjunctiva and the muscle before tying the suture. Then, again using TRASU, the scleral reinsertion is prepared. Postoperatively, openings resulting after TRASU remain totally covered by the lids apart from during upgaze and excessive lateral gaze, he said.
To assess the new technique, Dr Mojon carried out a prospective study at Kantonsspital, St Gallen, Switzerland, in which the first 20 consecutive patients treated with TRASU MISS were matched with a non-concurrent, retrospective comparison group of 20 patients with a traditional MISS opening. 
While the long-term results did not differ in the two groups, the MISS technique delivered better visual acuity and less lid swelling in the immediate postoperative period. 
“With the transconjunctival suture I am able to position the suture very anteriorally without opening the conjunctiva and without any bleeding,” said Dr Mojon. “Some of the patients are completely amazed afterwards at just how clear their operated eyes are after surgery. There is occasionally some swelling of the eyelids with repeat surgeries but very little discomfort,” he added.
While MISS may be performed with the same instruments used for standard, open surgery, it does require using an operating microscope which can take some adjustment for surgeons used to working with loupes.
Nevertheless, once the learning curve has been negotiated, one of the big advantages of MISS compared to the widely used Parks fornix approach is that it can be used for all types of patient, said Dr Mojon.
“The Parks fornix technique for rectus muscle access is very popular in the United States and while it is an excellent technique that works well, its use is difficult in older patients with inelastic conjunctiva, in young patients with prominent Tenon’s tissue and in cases with significant pre-existing scarring,” he said.
Dr Mojon said that in his hands, only about one patient in every 1,000 is not suitable for the MISS technique.
“This is a big plus because it allows me to be consistent and avoid switching from one technique to another and having to change instruments. This ultimately results in faster surgery which is generally better news for the patient as well,” he concluded.

Daniel S Mojon: daniel.mojon@gmail.com