Patients with small pupils are always challenging for the cataract surgeon. Poor pupil dilation may be observed in cases complicated by pseudoexfoliation (PXF) syndrome, uveitis, posterior synechiae, trauma, or previous intraocular surgery. It may also be associated with local and systemic medications. Inadequate pupil dilation can decrease visualization during all stages of phacoemulsification, compromising surgery and increasing the risk of complications.

Most surgeons decide to mechanically dilate the pupil at the time of surgery if pharmacological agents fail. Unfortunately, there is no general recommendation or universal solution for the problems that small pupils present to cataract surgery; strategies for enlargement greatly depend upon surgical skill, preference, and the individual intraoperative situation.

Several iris retraction devices have been introduced into clinical practice, including the Graether Pupil Expander (Eagle Vision, Memphis, Tennessee), Perfect Pupil Injectable (PPI; Milvella Ltd., Sydney, Australia), and the Morcher Pupil Dilator (Morcher GmbH, Stuttgart, Germany). The main disadvantages of such technologies include their bulkiness and rigidity, making them difficult to insert, remove, and manipulate through a small incision. All of these rings are difficult to position if the anterior chamber is shallow or the pupil is less than 4 mm wide.

Using flexible iris hooks to retract tissue is relatively simple and has therefore been adopted by many surgeons. Multiple incisions for hook insertion are necessary, however, which is the main disadvangate of this technique. If the hooks overstretch the pupil size to more than a 6-mm square, irregular atonic pupils will likely appear postoperatively.

Several years ago, I introduced a new device into clinical practice that facilitates phacoemulsification in eyes with small pupils. This rectangular device, made of 5-0 polypropylene, uses the scroll principle to catch the pupillary margin. It is stretches the pupil to 6 mm wide. The main advantages of this device include gentle and less traumatic fixation of the iris margin and controlled stretching of the pupil. I previously described my surgical technique in the April 2007 issue of CRST Europe (The IQ-Ring, pages 25-28).

I performed the first implantations of the ring 7 years ago at the S. Fyodorov Eye Microsurgery Complex in Moscow. Since then, the device has undergone several design modifications. Recently, MicroSurgical Technology (Redmond, Washington) has become involved in further developing the device and marketing it in other countries. The current version of this single-use device, the Malyugin Ring System, consists of a holder and inserter packaged together with each ring. The inserter is used to withdraw the ring from the holder. It also introduces the ring into the anterior chamber and removes the ring from the eye. I have found that the inserter works very well, and ring implantation and removal is much easier and less traumatic for anterior chamber tissue.

SURGICAL TECHNIQUE
Herein, I present a description and still-video presentation of one cataract patient whose surgery was complicated by a small pupil, previously inoperated glaucoma, and PXF syndrome (Figure 1A).

The ring is loaded into the inserter (Figure 1B). Then, it is inserted through an unenlarged 2.2-mm clear corneal incision at the beginning of phacoemulsification. The tip of the inserter is positioned at the center of the anterior chamber. While pushing on the thumb button, the ring is released from the tip until the distal scroll is engaged with the distal iris (Figures 1C and D). Both lateral scrolls will then start to emerge from the tube of the inserter and simultaneously catch the iris margins (Figure 1E). The proximal scroll is expelled from the cannula/inserter, and the injector is moved proximally until the inserter hook is no longer holding the ring. In this position, the proximal scroll is lying on top of the iris. The inserter is withdrawn from the eye, and an iris hook is used to push the proximal scroll into the pupillary space. The proximal region of the iris margin is engaged (Figures 1F and G).

Once the ring is in position, cataract surgery is performed as usual, including continuous curvilinear capsulorrhexis, hydrodissection, emulsification, cortex removal, and IOL implantation (Figures 1H through M). The Malyugin Ring is then removed from the eye in the reverse order (Figures 1N through P).

I have used the Malyugin Ring System in more than 50 procedures. Clinical trials have shown that it performs as well as if not better than conventional pupil hooks in terms of both safety and efficacy. Additionally, intra- and postoperative complications with the Malyugin Ring were either reduced or comparable to those conventional hooks. Our clinical study demonstrated superior endothelial cell protection and a decrease of hyphemas, fibrinoid reactions, and early postoperative ocular hypertension in the Malyugin Ring group as compared with a group for which iris hooks were used.

CONCLUSION
Adequate transpupillary access to the lens is essential for the success of phaco procedures. We believe that our iris retraction technique with the Malyugin Ring System has many advantages:

• The ring is as effective as conventional iris hooks; however, compared with other commonly used iris retractors, it is friendlier to the eye due to its well- distributed stretching, gentle holding of delicate iris tissue, and the easier and less traumatic implantation. It has no sharp or pointed ends that can damage the eye;
• Equidistant positioning of the loops holds the iris tissue, ensuring correct position of the iris and preventing the effects of an overstretched pupil that are often observed when iris hooks are incorrectly placed;
• The device applies pressure to the iris sphincter over an area, which is wider than iris hooks. It is particularly useful in patients in whom cutting or tearing of the iris tissue should be avoided, especially in the presence of rubeosis, chronic anterior uveitis, or systemic coagulopathy. The iris rim is safely fixed in the ring's loops, and there is no risk of iris aspiration during phacoemulsification;
• Additional incisions are not required. This instrument is inserted through the main incision, thus reducing surgical trauma and minimizing the risk of contamination and postoperative inflammatory reaction. When a square pupil is formed by a conventional iris retractors, the iris can prolapse through the wound. This is particularly true in patients with relatively wide paracenteses or atonic and atrophic irises that seem particularly floppy;
• Sufficient room is available for nucleus fragmentation and removal. The device configuration allows the surgeon to work in the deep lens layers below the iris plane and the square-shaped pupil formed by the ring. This provides enough space for grooving and cutting the nucleus and increases peripheral visualization during the chopping phase; and
• The ring is inserted and removed from the eye with help of an inserter, reducing the risks of contamination and disturbance of the incision architecture and wound integrity.

SUMMARY
Different techniques of nucleus disassembly in small-incision cataract surgery require a wide and unobstructed view of the anterior portion of the lens and the instruments inserted into the anterior chamber. Sufficient manipulability of the instruments is also crucial for the successful completion of surgery. A pupil that fails to dilate makes cataract removal more difficult. The Malyugin Ring System adequately dilates the pupil and prevents iris sphincter damage. The easy-to-insert-and-remove device expands the pupil to 6 mm, protects the iris sphincter during surgery, and allows the pupil to return to its normal shape, size, and function after the operation.

The Malyugin Ring is an important tool in phacoemulsification surgery. Careful intraoperative manipulation and insertion of the ring with liberal use of an ophthalmic viscoelastic device can help prevent complications. After surgery, most of our patients' pupils were almost indistinguishable from their appearance before surgery, and functional activity was preserved.

I consider this new device among the most effective methods to increase the size of even very rigid small pupils during phacoemulsification surgery. The use of this method is highly recommended, as it is likely to reduce postoperative abnormalities in pupil size and function.

Boris Malyugin, MD, PhD, is the Chief of the Department of Cataract and Implant Surgery and Deputy Director General at the S. Fyodorov Eye Microsurgery Complex, Moscow, Russia. Dr. Malyugin states that he is a patent owner of the Malyugin Ring. Dr. Maylugin is a member of the CRST Europe Editorial Board. He may be reached at tel: +7 495 488-8511; fax: +7 495 905-8051; boris.malyugin@gmail.com.