Iridodialysis can occur after blunt trauma to the globe1 or surgical manipulation, such as removal of a closed-loop anterior chamber intraocular lens (IOL).2 To our knowledge, there has been no report of severe iridodialysis during phacoemulsification. We report a new form of iridodialysis and discuss its underlying causes.
An 83-year-old woman had phacoemulsification in the left eye. The mydriasis was slightly insufficient, with a maximum pupillary diameter of approximately 7.5 mm. After a 3.0 mm temporal clear corneal incision was created, continuous curvilinear capsulorhexis and hydrodissection were performed. Using the phaco chop technique, the nucleus was cracked and phacoemulsification initiated by aspirating the central epinucleus. During removal of the first quadrant, the nasal iridial margin was sucked into the phacoemulsification tip. The iris was quickly released from the tip upon termination of the aspiration. The setting parameters of the Prestige phacoemulsifier (Allergan Medical Optics) were as follows: vacuum level 300 mm Hg, flow rate 28 mL/min, ultrasound power 60%, and bottle height 70 cm. These parameters were not modifed after the first suction of the iris.
During removal of another quadrant, the second and major suction of the iris into the phacoemulsification tip occurred, causing severe iridodialysis extending from 7 to 11 o'clock (Figures 1 and 2). Using a second hand hook, the iris was liberated from the phacoemulsification tip. The vacuum level was decreased to 180 mm Hg and the flow rate lowered to 22 mL/min. The nuclear fragments and cortical material were removed by pressing and holding the dehisced iris with a hook. An acrylic foldable IOL (Alcon MA60BM) was then implanted in the capsular bag.
Significant pupillary deformation was not seen when the anterior chamber was filled with viscoelastic material. However, once the viscoelastic material was washed out and replaced with balanced salt solution, pupillary decentration became remarkable. The authors repaired the iridodialysis using a double-armed 10-0 polypropylene McCannell suture with a long curved needle (PC-9, Alcon Laboratories Inc.). The suturing method was similar to those reported previously.3,4 Peritomy was placed at 3 o'clock. Along with viscoelastic material infusion into the anterior chamber, the first needle entered the anterior chamber through the temporal corneal incision, penetrated the base of the iris, and exited through the chamber angle and sclera (Figures 3 and 4). The second needle entered the anterior chamber through the same entry site, went over the iris, and exited through the sclera. Both sutures were tied episclerally, and the knot was rotated and buried in the sclera. The conjunctiva was reapproximated in the usual fashion. Postoperatively, the patient has maintained good iris position without complications (Figure 5).
Because of tissue fraying and flaccidity, additional damage is difficult to avoid once the iris has been sucked into the phacoemulsification tip. In the current case, machine settings should have been changed after the first incident. In particular, the flow rate should have been lowered to reduce the risk of another suction. The high vacuum level setting was also partly responsible for the iris tearing while caught in the tip. When this complication occurs, the flow rate influences the aspiration of the iris into the tip, while the vacuum level determines the holding and tearing force exerted on the iris after suction.5 The fragility of this patient's iris, confirmed when surgery was performed on the fellow eye 1 week later, may also have contributed to the current episode.
Increasingly, cataract surgery is performed by phacoemulsification, and surgical techniques using high vacuum and flow rate settings are becoming popular. Surgeons should be aware that severe iridodialysis can occur from inappropriate parameter settings, inadequate surgical manipulation, and patients' background conditions.
1. Nunziata BR. Repair of iridodialysis using a 17-millimeter straight needle. Ophthalmic Surg 1993; 24:627-629
2. Kervick GN, Johnston SS. Repair of inferior iridodialysis using a partial-thickness scleral flap. Ophthalmic Surg 1991; 22:354-355
3. Wachler BB, Krueger RR. Double-armed McCannell suture for repair of traumatic iridodialysis. Am J Ophthalmol 1996; 122:109-110
4. Kaufman SC, Insler MS. Surgical repair of a traumatic iridodialysis. Ophthalmic Surg Lasers 1996; 27:963-966
5. Neuhann TF, Steinert RF. Instrumentation. In: Steinert RF, ed, Cataract Surgery: Technique, Complications, & Management. Philadelphia, PA, WB Saunders, 1995; 57-67