Optimal prevention of phacoemulsification complications depends upon achieving, at the completion of surgery, placement of an intraocular lens within an intact capsular bag that is supported by an intact zonular apparatus. Studies have suggested that the risks of retinal detachment, endophthalmitis, and cystoid macular edema increase when the capsule is not intact. Therefore, techniques that minimize the risk of damage to the capsule offer the best alternatives for preventing phacoemulsification complications. Among preoperative factors that often lead to complications in cataract surgery, the small pupil and compromised zonule lend themselves to effective management options. With prior planning, the surgeon can effectively manage difficult cases and achieve excellent outcomes.
THE SMALL PUPIL
The small pupil creates an increased risk of capsular rupture and vitreous loss and must be managed effectively in order to prevent posterior segment complications of phacoemulsification. There are a variety of techniques for the management of the small pupil, including sector iridectomy, iris hooks, iris rings, and pupillary stretching with or without the use of multiple half-width sphincterotomies.1 The surgeon can use the Beehler Pupil Dilator, No. 19009 (Moria, Doylestown, PA), which is uniformly applicable in the presence of small pupils, and is usually able to stretch the pupil to between 6 and 7 mm, while creating tiny microsphincterotomies circumferentially around the pupil (Figure 1). Using a Lester hook (Katena Products, Inc., Denville, NJ) supplemented with an intraocular miotic, the surgeon can mechanically reduce the pupil at the end of the procedure. Pupils enlarged in this manner maintain a good cosmetic appearance and an ability to react to light, but may require miotic drops for a period of time after cataract surgery to avoid synechiae to the capsulorhexis margin.
COMPROMISED ZONULES
Weak zonules lead to particularly challenging situations during phacoemulsification. It is extremely important not to challenge the integrity of the zonule by overpressurizing the eye. This can occur after peribulbar or retrobulbar injection with digital pressure or a Honan Balloon (Katena Products, Inc.), when the anterior chamber is overexpanded with viscoelastic before capsulotomy, or as a result of an excessively high bottle height during phacoemulsification.
PERFORMING THE CAPSULOTOMY
Due to the lack of zonular integrity, it is often difficult to perforate the capsule to begin a capsulorhexis. A pinch-type forceps such as the Kershner capsulorhexis cystotome forceps (Rhein Medical 05-2320, Tampa, FL) allows the surgeon to grasp the capsule and initiate the tear without exerting downward pressure on the lens. During capsulotomy, special care is required because traction on the capsule can unzip weakened zonular fibers. If there are areas of missing zonular fibers, centripetal traction on the capsular flap may result in further damage. Techniques of two-handed capsulotomy using tangential forces as described by Thomas F. Neuhann, MD,2 are excellent adjunctive techniques in eyes with zonular compromise. After initiating the capsulotomy, the surgeon stabilizes the capsular flap with the forceps through the main incision while introducing a second instrument, such as a bifurcated spatula, through the side port incision. He or she places slight backward traction on the flap with the forceps while using the second instrument to directly advance the torn edge in a tangential manner.
THE CAPSULAR TENSION RING
Another useful modality in the management of the compromised zonule is the Morcher Capsular Tension Ring (Morcher GmbH, Stuttgart, Germany [not currently approved by the US Food and Drug Administration]) (Figure 2).3 This PMMA ring comes in two sizes, 10 mm and 14 mm for high myopia. When the surgeon places the ring in the capsular bag, the ring keeps the bag stretched and provides several advantages. It prevents concentration of forces on individual zonular fibers by distributing all forces to the entire zonular apparatus. The ring also keeps the bag stretched throughout the procedure, allowing for greater safety during all intraocular manipulations. Finally, the continuous pressure of the ring against the capsular fornices bolsters the zonular traction on the capsule and counters the force of constriction after metaplasia and fibrosis of the capsulorhexis.
The surgeon slips the ring into the incision and feeds it under the capsulorhexis with a forceps, while the second hand guides it with a Lester hook. Once the ring is in place, the surgeon performs cortical cleaving hydrodissection followed by hydrodelineation. Although cortical cleaving hydrodissection may have been performed, the endocapsular ring holds much of the cortex pressed up against the capsular fornices, requiring additional force to remove the cortex with irrigation/aspiration. Despite this requirement, the procedure is much safer due to the equal distribution of forces by the ring and the stabilization of the capsular bag.4
PARTING THOUGHTS
Prevention of cataract surgery complications depends on the maintenance of an intact lens capsule and zonular apparatus. Special techniques for the management of small pupils and compromised zonules minimize the risk of damage to the posterior capsule by maximizing control of nuclear disassembly and evacuation. By enlarging a small pupil and stabilizing the capsule with a capsular tension ring, the surgeon can convert an extremely troublesome surgery into a nearly routine phacoemulsification procedure.
Mark Packer, MD, is Clinical Assistant Professor, Casey Eye Institute, Department of Ophthalmology, Oregon Health and Science University, and in private practice in Eugene, Oregon. He does not hold a financial interest in any of the products mentioned herein. Dr. Packer may be reached at (541) 687-2110; mpacker@finemd.com
Richard S. Hoffman, MD, is Clinical Instructor, Casey Eye Institute, Department of Ophthalmology, Oregon Health and Science University, and in private practice in Eugene, Oregon. He does not hold a financial interest in any of the products mentioned herein. Dr. Packer may be reached at (541) 687-2110; mpacker@finemd.com
1. Fine IH: Phacoemulsification in the presence of a small pupil, in Steinert RF (ed): Cataract Surgery: Technique, Complications, & Management. Philadelphia, PA, WB Saunders, 1995, pp 199-208
2. Neuhann TF: Capsulorhexis, in Steinert RF (ed): Cataract Surgery: Technique, Complications, & Management. Philadelphia, PA, WB Saunders, 1995, pp 134-142
3. Cionni RJ, Osher RH: Endocapsular ring approach to the subluxed cataractous lens. J Cataract Refract Surg 16:563-566, 1995
4. Fine IH, Hoffman RS: Phacoemulsification in the presence of pseudoexfoliation: Challenges and options. J Cataract Refract Surg 23:160-165, 1997
