BLOG: Even cataract surgery can be humbling
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Many of us cite the statistic that cataract surgery is over 95% successful, meaning that most patients will have better vision. However, that statistic alone doesn’t describe the unexpected journey some will have to join the 95%.
This case is one that preoperatively had no warnings of what was to follow. And while the outcome was eventually good, looking back, there were several lessons that were reminders to remain humble and cautious even while working with such a successful surgery.
Case report
A 56-year-old woman was referred for consideration of cataract surgery, complaining of profound decreased vision, the right eye much worse than the left. Other than cataracts, her ocular history was unremarkable. She took medication for depression and hypothyroidism but otherwise was healthy.
Her best corrected visual acuity was 20/200 OD with a refraction of –4.00 DS. The left eye acuity measured 20/20 without correction and refracted at plano-0.25 D x 171. The significant finding on the ocular exam was a 2+ white nuclear sclerotic cataract in the right eye, a type that characteristically causes a more profound myopic shift and loss of acuity than typical nuclear sclerosis. The left lens showed 2+ cortical spoking.
Her preoperative keratometry showed with-the-rule toricity of a little over 1.00 D toricity in the right eye and a little under 1.00 D OS. After a discussion of IOL types and refractive targets, she opted to have the right eye corrected for emmetropia with a Tecnis (Johnson & Johnson Vision) single focus IOL. She elected to have surgery on the left eye with the same plan as the right.
The right eye surgery was performed with a superior mini scleral tunnel incision. On the morning of post-op day 1, her uncorrected acuity measured 20/40. A refraction of +0.70 D -0.75 D x 123 corrected her to 20/20. She was pleased with the outcome and opted to have surgery on her left eye that day, again performed with a superior mini scleral tunnel incision.
At post-op day 1 she reported blurry vision and pain in her left eye. Her uncorrected vision was 20/200. A refraction of +1.50 D -1.75 D x 023 resulted in 20/80 acuity. Her exam showed an intact scleral tunnel incision with subconjunctival hemorrhage. There was no corneal edema, and her exam otherwise was within what is expected on day 1. The IOL was well-placed in the capsule without appreciable tilt.
She returned 1 week later complaining of poor vision in the left eye. The uncorrected vision in her right eye was 20/25, while the left was 20/200. The refraction of her left eye was +1.25 D -1.75 D x 027, which gave 20/20 acuity. Pentacam (Oculus) measurements of the left cornea revealed 2.00 D of front surface with-the-rule toricity, over double from what was present preoperatively.
So, what happened?
A scleral tunnel wound isn’t expected to change corneal toricity. In the rare case that it does, the incision should relax and flatten the meridian at which it is placed, in this case 90 degrees, resulting in less with-the-rule astigmatism, not more. What could possibly cause tightening of the steeper meridian?
One possible culprit to consider is corneal incision contracture (CIC), or so-called phaco burn. The phaco probe generates heat that can burn the tissue surrounding the wound. However, in this case, the phaco time was short, the settings proper for an average cataract. The surgeon was exceptionally well-experienced. There was no whitening of the cornea near the wound that is characteristic of CIC. Further, the wound was scleral and not a clear corneal incision.
A review of the video of the surgery revealed the likely cause. Diathermy cautery is typically used on the sclera to control bleeding of the wound. In this patient’s case, the cautery time and settings were normal. Still, this patient most likely had an idiosyncratic tightening of the collagen at the site of cautery, resulting in increased with-the-rule toricity and refractive astigmatism.
The good news is that unlike phaco burn, diathermy-induced astigmatism will usually fade to preoperative amounts with time. The frustration is that this can take up to 6 months.
Lessons learned
Even a procedure as successful as cataract surgery is sometimes humbling. And in retrospect, there were several things that warranted caution in proceeding with the second eye.
We all have patients who have good Snellen acuity yet complain that they are unable to drive safely or comfortably at night because of moderate cataracts, usually of the cortical type. Performing any surgery on an eye with uncorrected vision of 20/20 should never be taken lightly, even when, as in the case of this patient, glare acuity drops significantly. It’s one thing to have someone with a moderate cortical cataract with a preoperative refraction of +3.00 D. It’s quite another when they have never had to wear glasses to see distance clearly.
This case was a reminder to approach those latter patients carefully, perhaps discouraging consideration of surgery altogether until he or she and the doctor together are sure it is the proper time.
Finally, while the safety and success of modern surgery means we can offer patients surgery schedules that are convenient for them and result in little time taken from work, next day surgery for the second eye isn’t appropriate for everyone. In hindsight, this patient would have had a more satisfying outcome had the second eye been scheduled at least a month after the first, if scheduled at all. It’s possible she would have elected to never have had surgery in the second eye. We’ll never know.
Outcome
Four months after surgery, the patient’s left eye measured 20/30 uncorrected. Her refraction was plano -0.25 D x 031 and 20/20 vision. Her left eye keratometry had returned to its preoperative measurement of just under 1 D with-the-rule astigmatism.
While she is satisfied now, she’ll likely never be happy that she had surgery in the left eye. The frustration and fear of having in her mind poor vision after surgery for several months will probably be what she remembers.
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