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I-Ring expands pupil, enhances surgical field of view
The device is flexible and easy to insert into the eye through a small incision.
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Pupil expansion devices are an essential element of cataract surgery in cases of non-dilating pupils. An adequately sized capsulorrhexis with an adequate and appropriate exposure of the surgical space ensures the ease of surgery. Without the use of a proper pupil expansion device, a small pupil may cause complications such as sphincter tears, intraoperative bleeding, zonular dialysis and, in extreme cases with prolonged struggle, possibly even posterior capsular rent or nucleus drop. Prolonged surgical time and increased maneuvering may result in postoperative complications such as striate keratopathy, uveitis, secondary glaucoma, floppy iris, torn iris, atrophic iris, irregular pupil, endophthalmitis or cystoid macular edema, all resulting in a suboptimal surgical outcome and an unhappy patient.
Currently available devices are designed to be placed either totally intraocularly (rings) or partially externally with the intraocular extension of the device holding back the pupil retracting the iris tissue (iris hooks, Assia pupil expander). The I-Ring is a new pupil expansion device from Beaver-Visitec that is designed to safely expand the iris tissue and enhance the surgeon’s field of view.
Device
The device is made of resilient polyurethane material that is gentle on intraocular tissue. Insertion and placement of the device ensure a complete 360° engagement with the iris, providing a consistent pupil expansion without distortion. The uniform field of view is 6.3 mm, with an aperture shape that helps guide the capsulorrhexis. The device has safe positioning holes that are used to engage the Sinskey hook in such a way that the hook does not contact the iris tissue.
The hinges on the ring provide flexibility to the device during the process of insertion and removal. The hinges also facilitate smooth grasping of the ring with the inserter. The channels on the device help to engage the iris tissue without pinching or distorting it and also provide stability to the iris diaphragm by holding it firmly.
Images: Agarwal A, Narang P
Technique
Each I-Ring pupil expander pack consists of a pupil expansion ring, an inserter and a nest that holds both the ring and the inserter. The inserter comes docked to the nest, and the surgeon does not retract the slider on the handle of the inserter until it is ready to be used.
For a phacoemulsification procedure, make a corneal tunnel incision and inject viscoelastic into the anterior chamber and under the iris to facilitate engagement of the iris. Hold the nest in one hand and the inserter handle in the other. Slowly retract the slider to the rear position, withdrawing the ring from the nest into the cannula of the inserter. When the ring is fully retracted into the inserter, remove the inserter from the nest and discard the nest.
Introducing ring into anterior chamber
Introduce the inserter through the primary incision (Figure 1a) and position the tip of the inserter centrally above the lens. Inject the ring into the anterior chamber by gradually moving the slider forward while simultaneously withdrawing the inserter to allow the ring to be introduced centrally (Figures 1b and 1c). Retract the prongs into the inserter by moving the slider back before withdrawing the inserter from the primary incision.
Maneuvering ring to iris
Use a Sinskey hook to engage and manipulate the ring in the anterior chamber. The four channels secure the ring to the iris to facilitate temporary expansion of the pupil. Initially secure the distal channel to the iris (Figure 1d), then the proximal channel (Figure 1e), followed by the two lateral channels (Figure 1f).
The phacoemulsification procedure ensues as usual after making a capsulorrhexis (Figure 2a) followed by hydrodissection (Figure 2b) and phacoemulsification (Figure 2c). Irrigation and aspiration (Figure 2d) is then performed, and the entire cortical matter is removed.
Disengaging ring from eye
Use a Sinskey hook to disengage the distal channel followed by disengagement of the proximal channel followed by the two lateral channels.
Introduce the inserter through the primary incision (Figure 3a). Gradually extend the prongs by moving the slider forward completely before positioning the cannula platform under the hinge (Figure 3b). Retract the slider to capture the hinge between the prongs and draw the ring into the inserter (Figures 3c and 3d). Gently withdraw the inserter from the primary incision.
A foldable IOL can then be inserted in the bag (Figure 3e), or it can be injected with the I-Ring in place after the cortical wash is complete. Stromal hydration is then done, and all the corneal incisions are sealed (Figure 3f).
The advantage with this device is that it is flexible and easy to insert into the eye through a small incision. It does not hamper entry, exit and maneuvering of additional instruments through the incisions. It also adds to the time and cost of surgery. The ring is easy to position and also to remove.
- For more information:
- Amar Agarwal, MS, FRCS, FRCOphth, is director of Dr. Agarwal’s Eye Hospital and Eye Research Centre. Agarwal is the author of several books published by SLACK Incorporated, publisher of Ocular Surgery News, 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 19 Cathedral Road, Chennai 600 086, India; email: dragarwal@vsnl.com; website: www.dragarwal.com.
- Priya Narang, MS, is the director of Narang Eye Care & Laser Centre, Ahmedabad, India. She can be reached at email: narangpriya19@gmail.com.
Disclosure: Agarwal reports he is a consultant to Beaver-Visitec. Narang reports no relevant financial disclosures.