Surgeons master pupilloplasty to restore visual form, function

Pupilloplasty is performed to alter or change the shape of a pupil that does not conform to normal pupillary dimensions, and there are several techniques surgeons can use to improve outcomes for patients.

Pupil repair is one of the most rewarding procedures in ophthalmology, OSN Glaucoma Board Member Ike K. Ahmed, MD, FRCSC, said. Pupil repair combines visual, functional and cosmetic rehabilitation into one surgical procedure.

“It’s triple rehabilitation for these patients that we’re able to manage with pupilloplasties. We do these procedures when we have irides that are defective or pupils that are dilated from whatever causes. Those are the primary indications. They can be divided into congenital iris abnormalities, trauma, post-surgical complications, and we also see certain degenerative conditions and disease states that can necessitate a pupilloplasty,” Ahmed said.

The classic pupilloplasty

Indications for pupilloplasty can be debilitating for patients, Ahmed said. Typical indications include visual symptoms, such as light sensitivity or glare, which can be alleviated with a classic pupilloplasty procedure.

Image: Narang P

“The single suture is the most classic and common closure technique, and it works well for a localized defect. Often there are multiple sutures that need to be placed, so that often requires two, three or four sutures to do that. I will sometimes use mattress suture closures for a larger defect, but I do find that there is often more tissue bunching with that so I would prefer not to do that, but it is an option,” Ahmed said.

However, Ahmed said his favorite pupilloplasty technique is a pupillary cerclage, in which a surgeon performs a “running, baseball style, purse string suture knot around the pupil” to bring it down from a dilated state.

“Probably the bigger question, when it comes to iris suturing, is choosing the right suture material. We use 10-0 Prolene, and then we decide on the right needle. For most of our sutures we like to use a long, curved needle, the Ethicon CIF-4 needle,” he said.

Every surgeon needs a technique

Every anterior segment surgeon should master a pupilloplasty technique, OSN Cataract Surgery Section Editor John A. Hovanesian, MD, FACS, said. In general, anterior segment surgeons try to avoid the iris during their most common surgeries because it can make the surgery much more difficult and dangerous.

“You try to avoid it, but at the same time it is a structure we have to deal with because it’s an essential part of the optics to the eye. However, there are two or three categories where you run into an abnormal pupil and have to deal with it. One is congenital, two is trauma prior to our intervention, and three is iris damage that we cause through our surgery. All of these are equally common, with the third scenario possibly the most common form of iris abnormality. In some cataract cases it is impossible to avoid the iris,” Hovanesian said.

Siepser sliding knot technique

A simple pupilloplasty can be performed with the Siepser sliding knot technique, in which a surgeon makes several paracentesis incisions and then passes a needle through the first paracentesis and the iris, and captures the parts of the pupil to be brought together, he said.

A surgeon can then capture the needle, docking it into a 25-gauge needle coming into the eye from the other paracentesis, Hovanesian said.

“You then bring the needle out, and it can be re-externalized through the first incision to do a three-one-one-one knot type configuration. You then tie a secured knot and bring the pupil together. That’s the classic pupilloplasty. Sometimes, you need to have two or three sutures like that in order to close a larger iris defect,” he said.

Tying the suture knot

One of the big debates with pupilloplasty concerns the most beneficial way a surgeon can tie the suture knot, Ahmed said.

The classic McCannel suture technique requires the knot to be brought out of the wound to tie it. Most surgeons now tie the knot by leaving it in the eye using the Siepser sliding knot technique, he said.

Ahmed said he usually uses a technique he developed himself to tie suture knots.

“I developed a technique a few years ago using intraocular tying forceps, ‘tyres,’ and you use them to tie the suture and bring the suture knot into the eye. We can do that with the use of a micro-tyre, and that’s essentially the technique that we use to do that. There are some variations, but people have called it the Ahmed suture technique. It’s important for surgeons to be comfortable with their approach,” he said.

With any pupilloplasty, the biggest challenge for a surgeon is access, Ahmed noted.

“You’re working in a small space. You’re not directly suturing the tissue. You’re basically going through incisions, and that requires you to position them accurately and position them well. It requires the use of a closed system technique, using the incisions as a fulcrum, avoiding torsion and traction on the cornea, and using very gentle techniques to allow the sutures to be passed without torquing the eye,” he said.

Modified McCannel technique

A modified McCannel technique is also effective for challenging pupilloplasty cases, Priya Narang, MS, of Narang Eye Care and Laser Centre in Ahmedabad, India, said.

The McCannel technique, according to the American Academy of Ophthalmology, is typically used for large iris lacerations. A limbal paracentesis can be made over the iris, and a Drews needle with 10-0 polypropylene can be passed through the peripheral cornea, the edges of the iris and the opposite side of the peripheral cornea. Surgeons introduce a Sinskey hook through the paracentesis, draw it back out through the paracentesis and securely tie the suture to finish the technique.

Single-pass four-throw technique

However, Narang said she exclusively uses a single-pass four-throw (SFT) technique for all of her pupilloplasty cases.

According to a study co-authored by Narang in the European Journal of Ophthalmology, SFT is conducted by passing a needle through the edges of the iris defect along the pupillary margin. A suture is passed through the loop with four throws, which creates a helical configuration that is self-locking and self-retaining.

“I use the SFT technique, and currently it’s the most common technique that is employed in almost all the cases that need a pupilloplasty procedure. There are many advantages with this technique, the first being that it is very easy to perform and the needle is to be passed just once through the anterior chamber. So, obviously, there is less intraocular manipulation with less dispersion of the iris pigments and inflammation,” she said.

Additionally, in SFT, only approximation loops are taken, and there is no second securing loop, she said. A typical knot is not formed, and it does not add to the bulk of the tissue.

This is advantageous in endothelial keratoplasty procedures that pose a chance of the knot rubbing against the endothelial graft, she noted.

“I also perform this in cases where patients undergo secondary intraocular lens placement with a glued technique, along with a pre-Descemet’s endothelial keratoplasty. In these cases, it is essential to narrow down the pupil size to prevent the escape of an air bubble into the vitreous cavity so that graft adherence is facilitated,” Narang said.

Narang said she also chooses to perform SFT as a primary procedure in cases that undergo glued IOL fixation in eyes with larger white-to-white diameter. This is necessary to prevent optic capture that can be due to the anterior shift in the plane of the IOL to maximize the length of haptic externalization.

Improving SFT outcomes

There are several ways surgeons can increase the odds of SFT producing positive clinical outcomes, Narang said.

“The specific pearls that I would like to share for SFT are that after the loop is formed, only four throws be taken. When SFT is performed with three throws, the approximation loop can open up. When performed with five throws, although the loop does not open yet, it may add to the bulk of the suture inside the eye. Four throws work optimally well, and the loops are secured due to creation of a helical pattern,” Narang said.

The SFT technique has challenges that are common to all pupilloplasty procedures. The procedure’s success depends on the engagement of the iris tissue into the long arm of the needle and then being able to pass the needle through both leaflets of the iris tissue without dragging the iris tissue, Narang said.

“This entire procedure needs to be done without dragging the iris tissue or else the tissue can get cut through and the procedure needs to be repeated again. The second challenge is being in a position to not accidentally engage the suture into the corneal lip, or else when the suture ends are pulled the loop refuses to slide inside the eye due to entrapment of the corneal tissue. The suture then needs to be cut, and the procedure needs to be performed again,” she said.

Hovanesian described SFT as “an elegant technique” that can repair a pupil that is fixed or dilated and needs to be smaller for optical reasons. Surgeons should be cautioned that the technique is not effective for an iris that “is rigid and will tear.”

“No technique is going to take an iris that is made of papier mâché or tissue paper and cause it to adequately stretch. We don’t have a way to do that,” he said.

Argon laser iridoplasty

Another technique that works well for an eye with a relatively decentered pupil is argon laser iridoplasty, which is performed by placing several argon laser spots in the direction that the surgeon wants to pull the pupil, OSN Cornea/External Disease Board Member Eric D. Donnenfeld, MD, said.

Surgeons performing argon laser iridoplasty can move the pupil “up to a millimeter or a millimeter-and-a-half in the correct direction.” It is often helpful for patients who have dysphotopsia from multifocal IOLs with glare and halo, he said.

In a 2012 study published in the Journal of Refractive Surgery, Donnenfeld and colleagues concluded argon laser iridoplasty can significantly improve visual function and should be considered to correct visual problems associated with decentered multifocal IOLs.

More indications for pupilloplasty

The procedure is effective for patients who have multifocal IOLs with halos in which the lens is not centered on the pupil, or when a pupil may be updrawn and needs to be centered on the eye for surgeons to perform a refractive procedure, Donnenfeld said.

Another indication for pupilloplasty is when a patient has an iridectomy that is visually significant, he said.

“Sometimes if it’s placed in the wrong spot, patients can have significant glare or halo. For those patients, I’ll use a suture to close the pupil, a 10-0 Prolene suture or a 10-0 nylon on an older patient. I like to use it on a ski needle, if I have a larger incision, such as when I’m removing an anterior lens. I’ll just pass it through and bring out the sutures through the incision I’ve made,” Donnenfeld said.

If the procedure is on an intact eye with a smaller incision, Donnenfeld said he will make stab incisions on either side of the iridectomy and then pass a ski needle through the iris on one side and out the other side. Then, he will capture it on a Healon cannula or a 23-gauge needle. Donnenfeld noted he brings the cannula out of the eye, making sure not to touch the cornea or the wound, and sweeps the suture out from one side to the other side and finishes with a slip knot technique.

The third indication for pupilloplasty is when a patient has an enlarged, dilated pupil and the pupil is fixed, which can cause significant glare and halo, he said.

“You want to do a cerclage and bring the pupil down. The traditional way of doing that is just passing a suture through the iris at the pupil margin, pass it six to seven times in a circular fashion, and then tie it and pull the pupil down in the desired way. A new technique, the four-spot pupilloplasty, which is an easier way to do it, is when you just tie off all four corners. Rather than going completely in a circle, you just tie off the four corners and constrict the pupil in that fashion,” he said.

Additionally, if presented with iridodialysis, Donnenfeld said he will create a pocket in the sclera and use a double-armed ski needle, pass the needle through the opposite side of the eye through the iris on one side of the dialysis, and then pass it through the other side of the dialysis and pull it out through the pocket.

“I then sew the iris back into the angle to improve the function of the iris. Then, I’ll generally go back, grab the iris and pull it through softly so I don’t end up creating an irregular iris. I’ll put three throws, not lock the nylon to the pocket, then go with forceps into the eye and pull the iris into the position I want it to be in. Then I will suture it down in that position so the pupil stays nice and round,” he said.

Visualize the outcome

With any technique a surgeon chooses, it is important to visualize the desired outcome, Ahmed said. This means being creative during the procedure and visualizing what the iris and pupil will look like after the final suture is placed.

“It’s very important for our patients to maintain a round, circular pupil, avoiding ovalization of the pupil and avoiding distortion of the pupil. One thing I’ve found, before passing the needle, it often helps to take two microforceps and approximate the tissue of where you want the sutures to be passed. You get an idea of what it will look like before you pass the suture. You grab both ends, bring them together, see where they meet nicely and picture in your mind of where you want to pass the knot. It gives you an idea of what to expect,” Ahmed said.

Pupilloplasty is a rewarding procedure to master and important to learn gradually, he said. Start with a simple repair of a small defect that can be closed with one or two sutures and learn from that point. – by Robert Linnehan

• References:
• Narang P, et al. Eur J Ophthalmol. 2016;doi:10.5301/ejo.5000922.
• Repair of iridodialysis. American Academy of Ophthalmology. https://www.aao.org/image/repair-of-iridodialysis.
• Solomon R, et al. J Refract Surg. 2012;doi:10.3928/1081597X-20120209-01.

• For more information:
• Ike K. Ahmed, MD, FRCSC, can be reached at Prism Eye Institute, 3200 Erin Mills Parkway, Unit 1, Millway Plaza, Mississauga, Ontario L5L 1W8, Canada; email: ikeahmed@mac.com.
• Eric D. Donnenfeld, MD, can be reached at Ophthalmic Consultants of Long Island, 711 Stewart Ave., Suite 160, Garden City, NY 11530; email: ericdonnenfeld@gmail.com.
• John A. Hovanesian, MD, FACS, can be reached at Harvard Eye Associates, 24401 Calle De La Louisa, Suite 300, Laguna Hills, CA 92653; email: drhovanesian@harvardeye.com.
• Priya Narang, MS, can be reached at Narang Eye Care and Laser Centre, 2nd Floor, AEON Complex, Vijay Cross Roads, Ahmedabad, 9. Gujarat, India; email: narangpriya19@gmail.com.

Disclosures: Ahmed, Donnenfeld and Narang report no relevant financial disclosures. Hovanesian reports he is the medical director for Katana Surgical.

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