Eyeworld

18 February 2019 EW NEWS & OPINION by Maxine Lipner EyeWorld Senior Contributing Writer hit the sides of the iris instead of entering the eye. While any pupilloplasty tech- nique will work, Dr. Agarwal uses what he terms a single-pass four- throw pupilloplasty. With the tech- nique, the practitioner first catches the iris with forceps before passing a straight needle with 10-0 or 9-0 Prolene through it. Then, from the other end, the physician enters the iris through a clear corneal incision and passes a 26-gauge or 30-gauge needle. Using a railroad technique, the suture is passed out and a loop created. Through this loop the surgeon passes four throws, which results in one thread on one end and the other piece on the side of the clear corneal incision. These can be pulled simultaneously as if tighten- ing a shoelace, cinching this part of the iris so that it covers more of the pupil. Then the practitioner can do the same on the other side, resulting in a small pupil, Dr. Agarwal said. The procedure can be repeated until one gets a 1.5 mm pupil. A vitrector can also be used to help achieve this. Dr. Agarwal has created a 1.5 mm pinhole marker to ensure that the pupil is the correct size. This is placed on the cornea around the pinhole to see that the pupil is exactly 1.5 mm. To make sure the pupil is centered, the practitioner can look for the reflection of the light of the Lumera microscope (Carl Zeiss Meditec, Jena, Germany) to show exactly where the pupil is, Dr. Agarwal explained. This is the Pur- kinje image. One can make the pupil surrounding the Purkinje images and that would give a 1.5 mm pupil. "Alternately, with the pinhole mark- er, you can mark on the cornea the center, so you can have a centered pupil," he said. "The whole pinhole pupil- loplasty procedure doesn't take more than 10 minutes. The cost is only the amount of one suture," Dr. Agarwal said. This is something that can be done by any practitioner, he stressed. Visual boon With this technique, he reported, patients start instantly seeing better. Those who are well-suited to this tend to have high irregular astigma- tism, for instance someone who may have a scar on the cornea, under- went corneal transplantation, or has New technique for improving acuity in high astigmatism I magine being able to treat pa- tients with high irregular astig- matism using a simple, low-cost procedure and offer them excel- lent vision in turn. This is the promise of pinhole pupilloplasty, according to Amar Agarwal, MD, chairman and medical director, Dr. Agarwal's Group of Eye Hospitals, Chennai, India, who pioneered the unique procedure. Dr. Agarwal drew inspiration from a sea creature known as a nau- tilus, a mollusk with no lens in its eye. "What makes the mollusk see Performing single-pass four-throw pinhole pupilloplasty Preop vision 6/60 after penetrating keratoplasty with more than 20 D of astigmatism Postop day 1 after pinhole pupilloplasty; vision improved to 6/12 is that nature has given it a pinhole eye," he said. Dr. Agarwal started thinking about whether it might be possible to use the same phenom- enon to improve vision in humans with vexing issues such as high astigmatism. The theory behind how this pinhole effect could improve vision is a byproduct of what's known as the Stiles-Crawford effect. The idea is that a ray of light coming straight into the eye offers maximum stimulation of cones, Dr. Agarwal explained, adding that there actu- ally are no rods in the center of the fovea. Meanwhile, if light was com- ing in from the side, the response of the cones would be less. Dr. Claudio Trindade had initially developed a piggyback pinhole IOL that was a dark lens with a 1.5 mm opening in the center, creating a pinhole effect in an eye that usually had a 5 mm opening. "Those lenses are very good, but the problem is they do not have FDA approval," Dr. Agarwal said. The problems with the pinhole IOLs are the cost, availability, and FDA approval. Unique four-throw technique Dr. Agarwal decided to create the effect in the eye using a technique called single-pass pinhole pupil- loplasty, relying on the iris to keep a portion of the light out. "We tried making the pupil small by making it fixed at 1.5 mm," he said, adding that any light beyond this range will Pinhole pupilloplasty preop and postop; preop vision 6/60, postop 6/12; patient with 8 D of astigmatism Source: Amar Agarwal, MD

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