For pupil expansion during cataract surgery, various devices have been formulated and used to help maintain the pupil in a dilated state. Rings are excellent devices that have been used by various surgeons for more than a decade in cases of miotic pupils. Rings basically work on the principle of gently holding the pupillary edge in a dilated state and then allowing the pupil to come back to its natural shape and size after surgery.
The I-Ring (Beaver-Visitec) is a newly devised pupil expansion ring that helps to achieve adequate pupillary dilation for eyes with miotic pupils that do not respond to pharmacological dilation.
The video demonstrates the use of the I-Ring in a case of a small pupil. Initially, the I-Ring is loaded onto the inserter and introduced inside the eye. The device comprises positioning holes, flanges and hinges. The hinges provide flexibility to the ring so that it can be easily introduced and removed from the corneal tunnel incision with the help of the inserter. Once the ring is placed in the anterior chamber, a Sinskey hook is placed in the most distal positioning hole and the edge of the ring is placed at the pupil margin so that the flange engages the iris tissue. Subsequently, the proximal flange is positioned, followed by the lateral flanges. The phacoemulsification procedure is performed as usual, and the IOL is implanted in the capsular bag. The I-Ring is then disengaged from the pupil margin by again placing the Sinskey hook in one of the positioning holes and pulling the device along the center of the pupil. Similarly, all the flanges are disengaged, and the inserter is introduced into the eye from the main corneal tunnel incision. The prongs of the inserter engage the I-Ring, and the slider on the inserter is pulled back. This withdraws the device into the inserter that is then removed from the eye. Stromal hydration and sealing of all the corneal incisions are then performed.
Care should be taken while using rings in cases of shallow anterior chamber. Profuse use of viscoelastic is advocated to coat the endothelium and prevent any damage to the eye. Secondly, after the surgery when the ring is disengaged, care should be taken when the prongs of the inserter are engaging the ring. At this juncture, there is a possibility that the iris tissue might also get engaged along with the ring and any inadvertent pull may cause iridodialysis. To prevent this, the portion of the ring that is to be engaged first should be placed away from the iris tissue or preferably in the center of the pupil over the IOL. This obviates any chance of accidental engagement of iris tissue into the prongs of the inserter.