A careful slit-lamp microscope examination of the eye during the pre-operative consultation can pick up most cases of compromised zonular support. The most common signs would be those related to pseudo-exfoliation syndrome such as deposition of fibrillar material on the lens capsule and iris. Traumatic zonulopathy may show as an excessively deep anterior chamber, phacodonesis, or a gap between the iris and the anterior lens capsule. In this case, however, the pre-operative examination appeared completely normal.
The first indication of zonulopathy was wrinkling of the anterior lens capsule upon attempted capsulorhexis creation (figure below). The zonular support was so weak that it was difficult to puncture the lens capsule initially. Once the capsulorhexis was completed, it was evident that the nucleus exhibited too much mobility to make intra-capsular surgery safe. Care was taken to hydro-dissect and then hydro-delineate the lens nucleus and bring it up out of the capsular bag. The nucleus was removed without trouble but when it came time to aspirate the epi-nuclear shell, the surgeon was surprised to see a crescent-shaped bright red reflex in one quadrant (figure above).
This area of bright red reflex indicated the absence of zonular support for that quadrant, instead of the global zonular laxity that was expected. Using extra viscoelastic, the remaining lens epi-nucleus and cortex was separated from the capsular bag and then gently aspirated using the irrigation/aspiration probe. The flow settings were decreased to 20 cc/minute in order to avoid washing away the protective viscoelastic. Once most of the lens cortex was removed, the capsular bag was inflated with a cohesive viscoelastic and a capsular tension ring was placed into the capsular bag to provide equatorial support. This helps to bolster the area of the capsular bag that is missing zonular attachments, but it can trap cortex in the bag and make cortical clean-up more challenging.
If this patient was scheduled for a monofocal non-toric IOL, then a three-piece design may provide the most options for placement. It could be placed entirely within the capsular bag, entirely within the sulcus, or optic captured with the haptics in the sulcus and the optic behind the capsulorhexis. In our case, however, the patient needed a toric IOL to address two diopters of pre-existing corneal astigmatism and he also elected for an extended depth of focus design. This IOL type is only available in a single-piece acrylic platform which must be placed within the capsular bag. Additionally, the toric axis of the IOL must be accurately aligned with the steep corneal astigmatic axis and the central EDOF beam-shaping element must be placed in the patient’s visual and pupillary axis.
Care was taken to carefully load and then inject this IOL into the capsular bag. It was then dialed into position using the chopper without placing stress on the capsular bag. Finally, it was appropriately aligned and centered at the end of the case and it remained that way in the post-op period (figures below). The patient recovered excellent vision and was so pleased that he requested the same surgery for his second eye.
We cannot always predict the challenges that we will face during the cataract surgery even if we do an extensive and detailed pre-operative examination. Sometimes the only way to detect zonulopathy is to start the surgery and touch the tissues. By picking up on the subtle clue of capsular wrinkling during capsulorhexis creation, we were on the lookout for zonular issues. Then when the crescent-shaped red reflex presented, we realized that a quadrant of zonular support was missing and that a different technique and a capsular tension ring would be needed. Surgeons don’t like surprises, but using a step-wise approach we are able to handle the challenges that each case brings.
click to learn how I recovered from this surprise zonular loss and successfully completed the case: