Pupil Expansion Devices for Small-Pupil Cataract Surgery
Journal of Cataract and Refractive Surgery
Tian et al. compared the degree of postoperative iris distortion produced by the diamond-shaped Malyugin ring and a newer device, the circular Visitec I-Ring, in a single patient who had poorly dilating pupils. They found that the I-Ring produced less postoperative distortion than the Malyugin ring.
In this case study, routine phacoemulsification was performed in the right eye of a 79-year-old woman with the assistance of a Malyugin ring for iris dilation. One month later, the patient had phacoemulsification in the left eye, this time with the I-Ring.
Anterior chamber slit-lamp photographs were taken of both eyes—the right eye at 3 months postoperatively, and the left eye at 2 months postop. The authors calculated the degree of distortion in the postoperative pupils using the ratio of the pupil area to the area of the circle of best fit.
They found that the I-Ring resulted in an 11% distortion and a rounder shape compared with the Malyugin ring, which produced distortion of 49% and a more rhomboid shape. They attributed these differences to the softer material of the I-Ring and the difference in shape of the devices: The diamond configuration of the Malyugin ring has 4 points of contact with the iris, while the round I-Ring produces equal pressure circumferentially.
The authors acknowledged that their study described only a single case. Further, the comparison was limited to aesthetics; the patient achieved 20/20 vision in both eyes.
The original article can be found here.