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You know it's going to be a challenging cataract case when ...
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A new patient was referred to our practice for evaluation for cataract surgery. Things seemed rather routine: 75-year-old gentleman, best corrected acuity of 20/50 in both eyes, and he was motivated to improve his vision since he just failed his California DMV driving vision test.
When I examined him at the slit-lamp microscope, I noticed a few indicators of a challenging case:
1. Poor dilation — only about 4 mm or so.
2. Pseudoexfoliation material on the anterior lens capsule.
3. Slight phacodonesis.
 Pseudoexfoliation material seen on the anterior lens capsule. |
But the most important sign was from the biometry worksheet: his axial length (AL) was 25.50 mm but his anterior chamber depth (ACD) was just 2.2 mm. I once heard Alan Crandall, MD, speak about pseudoexfoliation, and his pearl was to judge the relationship between the ACD and the AL. In a myopic eye with a longer AL, a short ACD can indicate excessive zonular weakness so that the entire cataract is somewhat mobile.
I explained these issues to the patient, and we scheduled a date for the surgery. I selected a monofocal IOL with zero spherical aberration since they tend to be optically more immune to decentration, and I also ordered a capsular tension ring (CTR) in case I encountered a focal area of zonular loss. There's a debate as to the usefulness of a capsular tension ring in eyes with diffuse, progressive zonular weakness. If the patient had a traumatic cataract with loss of a few clock hours of zonules, then the CTR makes sense to me. But if all of the zonules are lax, then I'm not sure that a CTR is truly beneficial. And if the zonular weakness is progressive, then what about the additional bulk of the CTR in the capsular bag? Will it make dislocation of the entire bag-IOL-CTR complex more likely?
The patient's surgery went well. I made a large capsulorrhexis (about 5.5 mm) in an effort to prevent anterior capsule phimosis, thanks to a pearl I learned from Brad Shingleton, MD (the CTR may help with this as well). The phacoemulsification was relatively routine, with care taken not to stress the capsular bag. And with a little extra planning and a few key pearls from friends, I wasn't too stressed either.