Pupil Expansion Rings Have Clear Advantages in Cataract Surgery

Sumit (Sam) Garg, MD


July 18, 2019

Small pupils not only can lead to increased surgical times and difficulty in removing the cataract but also are associated with a higher complication rate, including posterior capsular rupture. Every surgeon has their own definition of what constitutes a small pupil and what technique (eg, pharmacologic, stretching) and/or device (eg, overfill with ophthalmic viscosurgical devices, iris hooks, various iris ring expanders) they favor depending on the situation/patient.

In a recent retrospective case series,[1] Nderitu and Ursell compared outcomes with two of the most common device-based approaches to addressing the small pupil: iris expansion rings and iris hooks. They examined case time and complication rate during cataract removal, performed by both attending-level consultant surgeons and trainees using these separate devices.

As would be expected, they found that iris rings were faster than iris hooks for both consultants and trainees. The additional time required to use hooks in both groups was significant when compared with the use of rings for standard cases. Intraoperative complication rates did not increase in cases using either pupil expander, and final visual outcomes were comparable.

Nderitu and Ursell did find that iris rings were associated with significantly higher rates of postoperative anterior uveitis and corneal edema. This is not unexpected, as any manipulation of the iris can lead to increased postoperative inflammation. In addition, as rings are of a fixed diameter, one cannot titrate the amount of stress on the iris, which could contribute to greater amounts of inflammation. Certainly, iris rings and hooks both have a learning curve, and iris stress can be minimized as one gains experience. The study did not specify whether cases of uveitis and inflammation were more common in the resident group than in the consultant group.

In my experience, iris rings are faster to use and produce excellent outcomes. Once you master the initial learning curve, the use of iris rings has several benefits: faster cases (translating to less corneal damage and complication risk), predictable iris expansion, ease of implantation and removal, and minimal iris damage, among others. Despite this, many surgeons remain hesitant to try iris rings for various reasons, including comfort with hooks, increased cost of rings (single use, no reusable option), and perhaps less stress on the iris.

Overall, I am a fan of iris expansion devices, which have helped me tremendously when operating on patients with the small pupil or those with intraoperative floppy iris syndrome. I breathe a little easier knowing that I have them in my toolbelt when approaching these complex cases.

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