Slightly inferior visual acuity seen with immediate vs. delayed bilateral cataract surgery
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A large cohort study based on the IRIS Registry found that immediately sequential bilateral cataract surgery was associated with worse visual outcomes as compared with delayed sequential bilateral cataract surgery.
The differences were small and may not be clinically relevant, but they still deserve consideration, according to the authors.
The Intelligent Research in Sight (IRIS) Registry is a national comprehensive database built by American Academy of Ophthalmology members. Data from 1,824,196 patients undergoing bilateral cataract surgery were analyzed in this study. Out of them, 44,525 underwent immediately sequential bilateral cataract surgery (ISBCS), 897,469 underwent delayed sequential bilateral cataract surgery with an interval of 1 to 14 days between the two operations (DSBCS-14), and 882,202 underwent the delayed procedure with a longer interval, between 15 and 90 days (DSBCS-90). Patients in all groups had similar demographic characteristics, with similar rates of age-related macular degeneration, diabetic retinopathy and glaucoma. Baseline visual acuity by worse-seeing eye was comparable between groups, while the visual acuity by better-seeing eye was slightly higher in the ISBCS group.
After adjusting for age, race, insurance status and comorbidities, ISBCS was associated with worse postoperative uncorrected visual acuity as compared with DSBCS-90, namely 2.79 fewer letters in the first eye and 1.67 fewer letters in the second eye. The DSBCS-14 group had the best outcomes, with 0.41 more letters in the first eye and 0.79 more letters in the second eye than the DSBCS-90 group. It was also the group that showed more improvement in terms of visual acuity gain between the first and the second eye. The proportion of patients who achieved 20/20 visual acuity in the second surgery eye was higher with both DSBCS-90 (21.7%) and DSBCS-14 (24.2%) as compared with ISBCS (21%).
The authors said that the visual acuity differences found in their study simply show an association and not a cause-effect relationship with the timing of the procedures. In addition, they did not exclude that differences might be attributable to confounders not incorporated in the analysis, such as different surgical techniques or the criteria used by individual surgeons to select patients for immediately sequential vs. delayed surgery at shorter or longer intervals.
“However, many of these unmeasured factors likely reflect what practitioners confront in clinics,” they wrote, noting that the aim of this study was “to evaluate whether appreciable outcome differences remain between surgical groups that were selected in the routine clinical setting” rather than in a prospective trial setting.
As the authors highlighted in the paper, delayed surgery is the most common practice in the U.S., and the two eyes are usually operated on at an interval between 1 and 2 weeks. Historically, this approach has been preferred because it allows better planning of the second eye in terms of lens power and avoids incurring the risk for bilateral endophthalmitis. In addition, Medicare provides only 50% of reimbursement for the second eye when surgery is performed sequentially in the same operative sitting. In a 2018 survey by the American Society of Cataract and Refractive Surgery, only 9% of respondents said they performed ISBCS sometimes or often.
However, ISBCS is now gaining popularity among U.S. ophthalmologists and in several other countries due to the faster gain of bilateral vision, reduced follow-up visits, increased efficiency and reduced costs. In consideration of this, the question of whether unexpected refractive outcomes occur more often with ISBCS “is likely an important consideration,” the authors wrote.
“On the basis of data from the clinical practice setting of nearly 2 million bilateral cataract surgery patients, this study found that ISBCS was associated with worse visual outcomes when compared with DSBCS-90 or DSBCS-14, although the difference may not be clinically relevant,” they wrote.
“Further studies to evaluate other potential confounders are warranted because they may explain the small outcome differences found between the surgery groups,” they wrote.
Perspective
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The take-home message of this study is that in cataract surgery you can learn from the first eye to help hone the results of the second eye. If the first eye ends up with a postop refraction of –0.5 D, then we can use that result to improve IOL calculations and adjust the power for the second eye to achieve a result closer to plano. With premium IOLs, such as extended depth of focus (EDOF) or multifocal/trifocal lenses, we can adjust the second eye to extend the range. If the first eye with an EDOF lens gives great distance vision but not enough computer range vision, we can add 0.5 D or 1 D to the IOL power of the second eye to hit that goal of good computer range vision.
Refractive cataract surgery aims at delivering an accurate postop refractive outcome. While our current IOL calculation methods are good, with the Barrett formula giving about 80% accuracy and the Ladas Super formula AI 2.0 giving about 90% accuracy, there are still outliers. Therefore, I believe that ISBCS may be suitable only for routine cataract surgery in which the patient is not paying for a specific refractive outcome or a premium IOL and will be prepared to wear glasses for any residual refraction. For patients who are paying out of pocket for customized refractive cataract surgery, waiting a week or so between cataract surgeries is a small price to pay to have more accurate refractive outcomes.
I rarely do same-day bilateral cataract surgery. In addition to the above considerations, there are reimbursement issues that make this approach not reasonable in the United States. With current Medicare fees for cataract surgery, we struggle to break even. At half the price for the second eye and no additional facility fee, we would certainly be in the red for the second eye done on the same day.
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