1485: how I know zonular support is weak

Weak zonular support makes cataract surgery far more challenging and increases the potential risks such as vitreous prolapse, retained lens material, dislocation of the IOL, and the need for more surgery. With some cases of traumatic zonular damage, we can see phacodonesis during the pre-operative exam with the entire cataractous lens moving as the patient changes gaze. However, if the zonular damage is primarily in one quadrant, there may not be any signs of zonular weakness until the time of surgery. In the case presented here, I did not realize the extent of zonular weakness until the surgery started.

The anterior lens capsule should be taut and as it is punctured to start the capsulorhexis, it should not move. In this case the anterior capsule wrinkled as the surgeon attempted the capsulorhexis and the entire cataract shifted enough so that the capsular bag equator was briefly visible. The capsulorhexis was completed and the nucleus was carefully removed using the phaco probe and a chop technique which placed minimal stress on the capsular bag.

During cortex removal the capsular bag was not as deep as expected since some of the infusion fluid went through the area of zonular loss and collected in the anterior hyaloid space. In addition when the cortex from the sub-incisional area was engaged, the capsular bag equator was visualized since that quadrant had an absence of zonular support. At this point cortex removal was stopped and the capsular bag and anterior chamber were filled with viscoelastic.

With one quadrant of zonular weakness, about 90 degrees, placing a capsular tension ring will be sufficient to provide good long term support and stability. With larger degress of zonular loss other techniques such as suture fixation of a CTR or capsular support segment may be required. To insert the CTR, the capsular bag is completely filled with viscoelastic and then a hook is used to guide the leading eyelet into the capsular bag. Once the entire CTR is in the capsular bag, both eyelets are released and the CTR exerts its force at the equator.

With the capsular bag full of viscoelastic the IOL can be implanted even before removing the residual cortical lens material. With the capsule stabilized, using a single-piece IOL in the bag is a great choice. Other options including using a three-piece IOL in the bag or with the haptics in the sulcus and the optic captured behind the capsulorhexis.

Once the IOL is securely positioned within the capsular bag, the bimanual irrigation/aspiration handpieces are used to remove the remaining lens cortex. Since the CTR may be holding the cortex against the capsular bag equator, pulling in a tangential direction is preferred instead of going radially. The same bimanual set is used to remove the viscoelastic and the case can be completed.

To ensure that there is no prolapse of vitreous strands in the anterior chamber, a small aliquot of preservative-free triamcinolone acetonide is injected. If there is vitreous present these small white particles will stick to it, making identification easier.

Because our patient is not expected to sustain further trauma, this type of case is ideal for a CTR because the zonular weakness is not progressive. Contrast this to a case of severe pseudo-exfoliation where the zonular weakness tends to be global, for a full 360 degrees, and then progressive, worsening with each year of life. Using just a CTR in cases of progressive zonulopathy may not be sufficient for long-term stability.

After the surgery the patient was asked about a prior history of trauma and then he recalled that decades ago he was in a severe auto accident where the steering wheel hit his face so hard that is displaced his nasal bones and caused multiple fractures. Fortunately, he recovered from that trauma and we were able to deliver a great outcome to this eye with traumatic zonular damage. The post-op course was uneventful and the IOL has excellent centration and stability.

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