Single-pass four-throw pupilloplasty evolves for iris, pupil repair

Traumatic iris repair is not uncommon.

Iridodialysis, iris tissue loss and iris prolapse are noted in eye trauma. Lens damage will need phacoemulsification with IOL implantation, and coexisting iris damage should be addressed simultaneously for functional and anatomical outcomes. Recently, single-pass four-throw (SFT) pupilloplasty has been used for various indications of iris-pupil diaphragm repair. In this column, we discuss a few modifications in SFT.

SFT pupilloplasty

The conventional SFT technique has been described in various literature and studies. To brief, the tip of a 9-0 or 10-0 polypropylene suture needle is passed via a corneal side-port incision across the iris leaflet while the other end of the iris leaflet is held with end-opening forceps (Figures 1a and 1b). This needle is then docked into the barrel of the 26-gauge needle that is then eventually pulled out from the anterior chamber, and this facilitates the exit of the needle from the anterior chamber. A Sinskey hook or end-opening forceps is passed from the paracentesis incision, and pulling the suture end from the exit site creates a loop outside. The suture end is passed through the loop four times. Both suture ends are then pulled from either side, and this leads to sliding of the helical loop inside the anterior chamber, thereby approximating the iris defect; the suture ends are then cut with microscissors.

Pinhole pupilloplasty

Pinhole optics enhance visual acuity and quality. The same technique is utilized in pinhole pupilloplasty (PPP), which is a modification of SFT to make the pupil the size of a pinhole. This helps to filter out stray light from the periphery of the cornea in cases with higher-order corneal aberrations, reduces overall optical aberrations, and improves both visual acuity and image quality. In this method, the pupil size is reduced to 1.3 mm to 1.5 mm as decided by the patient from the preoperative template. The optimum pinhole size is planned from examining the pinhole vision in patients using pinhole template sizes from 1 mm to 2 mm in 0.5 mm increments. PPP has shown good functional results (Figures 2a and 2b) in eyes with corneal ectasia, post-traumatic irregular astigmatism, corneal scars and post-refractive surgery irregular corneas.

Reverse SFT pupilloplasty

Reverse SFT helps in burying the Prolene sutures in the leaflets of the iris to prevent the cut ends of the knots from protruding into the anterior chamber. The long cut end of the Prolene knots can induce inflammation in the anterior chamber or rub the endothelium. This is prevented by changing or reversing the position of the iris knot.

Trocar-assisted iris repair

The technique described involves placement of a 25-gauge trocar at the limbus wherein the lumen of the cannula works as a guide to introduce a double-arm polypropylene suture attached to the long arm needle, thereby preventing any accidental entrapment of corneal fibers into the needle (Figure 3). The technique allows iridodialysis repair in technically challenging situations by directing the needle appropriately and preventing any undulating movement inside the anterior chamber. As the needle passes in, it is secured in the cannula, thereby preventing undue endothelial touch and future specular loss. The remaining SFT steps are performed in a similar manner as described earlier in literature.

Twofold iris repair

This is performed in a large iridodialysis with nonappositional iris damage from insertion. The iris tissue is initially repositioned inside the anterior chamber after injection of viscoelastic to form the anterior chamber. A trocar anterior chamber maintainer is useful for anterior chamber maintenance in such scenarios. Once positioned, a 10-0 double-arm suture attached to a long straight needle is passed through the base of the disinserted iris tissue. The 10-0 needle is passed through the scleral wall at approximately 1.5 mm from the limbus. The second arm of the suture is passed through the iris tissue adjacent to the previous pass. The edge of the iris tissue is held with end-opening forceps to facilitate the passage of a 10-0 needle. The knot is then tied, and the iris tissue is apposed to the scleral wall. Another double-arm 10-0 suture attached to the long needle is passed through the adjacent iris tissue, and nonappositional repair is performed. The procedure is performed to reattach all around the iris dialysis clock hours to appose the iris.

Trifold method

In the trifold method, as the name suggests, three steps are involved. This is done for nonappositional iris repair. The first two steps are to reduce the distance between the two disinserted flaps by attaching the ends by trocar-assisted iris repair to the sclera, and the third step is for pupil reformation by SFT (Figures 4a and 4b).

SFT pupilloplasty suture lysis

Postoperatively, if a patient has a small pupil affecting the visual field or causing an illumination defect, the suture can be lysed by YAG laser photocoagulation, and the pupil size can be titrated or enhanced. Augmentation laser lysis can be performed depending upon the visual acuity and the visual quality in follow-up.

SFT pupilloplasty reversibility

Eyes with severe postoperative inflammation due to Prolene suture or that required retinal surgery for diabetic retinopathy or vitreoretinal disorders are the scenarios that may rarely require removal of SFT suture. This can be performed without difficulty during retinal surgery under local anesthesia.

Conclusion

Single-pass four-throw pupilloplasty is an easy technique with a short learning curve. Among many other iris repair methods, SFT has its own modifications for various clinical scenarios. This can be combined with keratoplasty procedures and transscleral-fixated or glued IOLs as well. Thus, SFT has evolved over the years with modifications and adaptations for new clinical situations and has shown good anatomical and functional results.

• References:
• Agarwal A, et al. J Cataract Refract Surg. 2016;doi:10.1016/j.jcrs.2016.01.015.
• Kumar DA, et al. J Cataract Refract Surg. 2024;doi:10.1097/j.jcrs.0000000000001353.
• Kumar DA, et al. Taiwan J Ophthalmol. 2024;doi:10.4103/tjo.TJO-D-23-00172.
• Narang P, et al. Eur J Ophthalmol. 2017;doi:10.5301/ejo.5000922.
• Narang P, et al. Eur J Ophthalmol. 2018;doi:10.1177/1120672117747038.
• Narang P, et al. Eur J Ophthalmol. 2021;doi:10.1177/1120672120948747.
• Narang P, et al. J Cataract Refract Surg. 2018;doi:10.1016/j.jcrs.2018.08.006.
• Narang P, et al. J Cataract Refract Surg. 2019;doi:10.1016/j.jcrs.2018.12.007.
• Narang R, et al. Eur J Ophthalmol. 2023;doi:10.1177/11206721231165452.

• For more information:
• Amar Agarwal, MS, FRCS, FRCOphth, director of Dr. Agarwal’s Eye Hospital and Eye Research Centre, is the author of several books, including Phaco Nightmares: Conquering Cataract Catastrophes, Bimanual Phaco: Mastering the Phakonit/MICS Technique, Dry Eye: A Practical Guide to Ocular Surface Disorders and Stem Cell Surgery and Presbyopia: A Surgical Textbook. He can be reached at aehl19c@gmail.com; website: www.dragarwal.com.

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