Publication Exclusive: Cataract surgery can be complicated by presence of loose zonules

Loose zonules complicate cataract surgery because their laxity makes removal of the nucleus and cortex challenging and limits stability of the IOL. In some patients we are able to detect zonular laxity during the preoperative consultation. Severe laxity may result in subluxation of the cataract or marked phacodonesis, in which the cataract is seen to move or shake in response to ocular movement. Patients with visible pseudoexfoliative material on the anterior lens capsule are also at higher risk for loose zonules. Other signs may be more subtle, such as a shallow anterior chamber in the presence of a normal axial length. This may occur because the loose zonules allow the entire lens-iris diaphragm to push forward and compress the anterior chamber. A more difficult situation is to detect the presence of zonular laxity once the cataract surgery has already begun.

Beginning the procedure

Normal zonular tension allows the crystalline lens to be firmly in position with the anterior capsule held taut like the head of a drum. If we are using a sharp instrument such as a cystotome or needle to puncture the anterior capsule in preparation for the capsulorrhexis, it may be difficult to judge its tautness. When using the tips of the capsulorrhexis forceps to make the initial puncture, it is easier to detect the presence of loose zonules. Upon attempted puncture, the anterior capsule wrinkles, becomes focally depressed and resists penetration — much like an underinflated balloon. This is the first sign that the zonules are weak and that the case will be technically difficult.

Creating the capsulorrhexis

At this point, the goal is to create a capsulorrhexis, safely remove the nucleus and cortex, and figure out a plan for stable placement of the IOL. In the case here, a sharp cystotome was used to puncture the anterior capsule and start the capsulorrhexis. When the forceps are used to continue the curvilinear tear, the capsule continues to wrinkle on both sides of the capsulorrhexis. Care should be taken to create a round, well-centered continuous capsulorrhexis in order to maximize the options for IOL placement. The benefit to a sufficiently large capsulorrhexis of about 5 mm to 5.5 mm in diameter is the ability to bring the nucleus out of the capsule to avoid further damaging the zonules during phaco.

Click here to read the full publication exclusive, Back to Basics, published in Ocular Surgery News U.S. Edition, July 25, 2015.