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Cover Focus | May/June '19

Sneaky Weak Zonules

Most cataract cases proceed routinely. Occasionally, however, they can go sideways, requiring quick recognition, decisive decision-making, and careful execution to avert disaster. The case shown in the video below provides a close look at zonulopathy and the warning signs interwoven throughout the procedure. Additionally, this article includes pearls for identifying and tackling eyes with zonulopathy and minimizing further zonular trauma.


In any patient with a small or medium-sized pupil, the surgeon should suspect zonular disease. If the pupil does not respond to intracameral epinephrine, the patient may have weak zonules, not intraoperative floppy iris syndrome.


When puncturing the capsule to initiate the capsulorhexis causes capsular striae, this is a telltale sign of zonular weakness. I prefer to use forceps for this step rather than a cystotome for a variety of reasons. In this case, this approach was particularly advantageous because I was able to see capsular striae when trying to puncture the capsule with forceps, confirming the presence of weak zonules.

The zonules are like the springs of a trampoline. They are supposed to apply outward centrifugal forces to keep the central mesh taut. If the springs are weak, the mesh sags and cannot resist an external force. Similarly, weak zonules cannot resist the force of the capsulorhexis forceps. As the forceps push down on the anterior capsule, it is difficult to puncture the capsule, and striae may result.


Capsular striae at the edge of the capsulorhexis flap are signs of zonular weakness. It is difficult to pull the flap due to poor counter-force from the weak zonules.


Difficulty spinning the lens after hydrodissection may also be a sign of zonular weakness. When an attempt is made to spin the lens, there are persistent adhesions between the lens and the capsular bag. Normally, the zonules are strong enough to hold the bag in place while the lens is spun with torsional force. But, when the zonules are weak, the adjacent capsular bag tends to stick to the lens, making it difficult to spin.


When we encounter weak zonules, it is prudent to use a cataract disassembly technique that causes minimal zonular trauma. Mechanical fracturing techniques such as the double chop1 and the cross chop2 can be used to disassemble the lens without spinning it, and this can help minimize zonular stress.


In an eye with weak zonules, do not try to grab the lens pieces with the phaco tip. The phaco tip uses vacuum to grab and hold the lens pieces, and this can be dangerous in the setting of weak zonules. In trying to grab a lens piece, you could grab the capsular bag instead and rip more zonules or cause a capsular rupture. It is far better and safer to use the chopper to pull the lens pieces out of the capsular bag and into the central safe zone.


Stubborn cortical remnants within the capsular fornix are best liberated by flushing the fornix with pulses of balanced saline solution on a syringe. This frees the cortical material efficiently and atraumatically. Care must also be taken to flush within the bag, as flushing outside of the bag can cause focal loss of iris pigment.


When you inject a capsular tension ring, use a Sinskey hook to capture the leading eyelet. As the capsular tension ring is advanced, the Sinskey hook minimizes rotational stress on the zonules.


It is my strong opinion that all surgeons should utilize these peals not only in eyes with weak zonules but in all cataract cases. Employing these techniques will ensure minimal stress on the zonules and will help prepare the surgeon for any potential zonular complication.

1. Kim DB. Cross chop: modified rotationless horizonal chop technique for weak zonules. J Cataract Refract Surg. 2009;35:1335-1337.

2. Kim DB. Double-chop: modified-chop technique eliminating ultrasonic energy and vacuum for lens fragmentation. J Cataract Refract Surg. 2016;42:1402-1407.

D. Brian Kim, MD