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Medium-add multifocal addresses the most likely source of dissatisfaction with contemporary multifocal IOLs: Intermediate vision
The goal with presbyopic implant surgery is to achieve high levels of patient satisfaction and spectacle independence. In general, this means providing excellent distance, intermediate and near vision (in both dim and bright light), with an acceptable level of light phenomenon while driving at night. The challenge for cataract surgeons is that, in addition to surgical skills, we must also have the communication skills to determine patients’ visual needs and enough knowledge about IOL technology to understand the strengths and weaknesses of each lens.
Over the years I have implanted nearly 6,000 presbyopia-correcting IOLs. We have developed a multivariate regression analysis model to evaluate how presbyopic lenses fare when implanted bilaterally or in various combinations. The model now includes more than 40 independent variables, including a wide range of objective clinical metrics and subjective patient responses related to performance of common visual tasks.
Tecnis Multifocal +4.00 vs. Tecnis Multifocal +3.25
Most recently, I used this model to determine predictors of overall patient satisfaction in cohorts of patients implanted bilaterally with either ZMB00 (Tecnis Multifocal +4.00, Johnson & Johnson Vision) or ZLB00 (Tecnis Multifocal +3.25, Johnson & Johnson Vision) IOLs. Both cohorts were comprised of “best case” patients: They were all at least six months postoperative so that any neuroadaptation had already occurred; all necessary Nd:YAG procedures had been completed; residual refractive error, if any, had been treated; and the ocular surface was well managed. The same regression analysis methodology was applied to both cohorts.
In both cohorts, satisfaction levels were high: 100% of subjects rated themselves either “satisfied” or “very satisfied” overall. If one were to evaluate a cohort that included patients with dry eye or uncorrected astigmatism, the spread of results would be greater (i.e., greater variance), but it would also be impossible to know whether their responses were related to the IOL.
There was a statistically significant increase in the rate of “very satisfied” patients in the bilateral +3.25 cohort (82%) vs. the bilateral +4.00 (64%) cohort (Fig 1). Satisfaction with intermediate vision improved significantly in the +3.25 cohort compared to the +4.00 cohort, while satisfaction scores for distance and near vision were equivalent between the two (Table 1).
Predictors of success
Regression analysis revealed that three variables related to intermediate vision were statistically significant predictors of overall patient satisfaction in the ZMB00/+4.00 cohort: Ability to “read a newspaper” without glasses ( p<0.005); ability to “work at a computer” without glasses (p<0.005); and “intermediate visual acuity at the patient’s preferred focal distance.” (p=0.05). Next, I made “intermediate visual acuity at the preferred focal distance” an independent variable to see if any of the regression factors would predict who would achieve better intermediate vision. Smaller “mesopic pupils” (p<0.005) and better “IOL centration” (p=0.02) were statistically significant predictors of superior intermediate vision. This observation was beyond the pinhole effect because better distance and near vision were not correlated with decreasing mesopic pupils.
A unique design feature of the Tecnis family of multifocal IOLs helps to explain the regression findings related to smaller mesopic pupils. These lenses have a central 1.0-mm button with half the add power of the total near add (Table 2). As the mesopic pupil decreases, the percentage of light being processed through the central intermediate button increases, thereby enhancing intermediate vision. Results from the FDA clinical trial for the ZMB00 model demonstrate this same effect: Subjects with smaller pupils also achieved better intermediate vision in that study (Fig 2).
In the +3.25 cohort, the data strongly suggests that the improved intermediate vision is responsible for the increased percentage of patients responding at the “very satisfied” level (82%/+3.25 vs. 64%/+4.00). Table 1 shows the raw scores for ranking intermediate vision were significantly higher without any difference in the raw scores for distance or near vision. The increased focal length of the +3.25 IOL (17 inches vs. 14 inches for the +4.00) is likely responsible for the improved intermediate vision.
Impact on clinical decision making
Regression revealed that preop mesopic pupil size is a reliable predictor of post op intermediate vision. This information is powerful for preop planning. For example, if you were initially planning to implant two +3.25 IOLs, but preop testing revealed large mesopic pupils, which may result in less than optimal intermediate vision, you should consider changing your surgical plan. This patient would likely achieve greater overall patient satisfaction if one of the +3.25 lenses was replaced with a Symfony or Symfony Toric IOL which would enhance the overall bilateral intermediate function. If the patient had small mesopic pupils you should stick with the bilateral +3.25 lenses which would maximize the near vision while achieving excellent intermediate vision in both eyes because of the small pupils.
We are currently applying the regression evaluation method to our +3.25/Symfony cohort which appears to be achieving very high levels of patient satisfaction.
In summary, this study revealed:
Finally, high levels of success with presbyopia-correcting IOLs are dependent on
Frank A. Bucci, Jr., MD
P: 570/ 825-5949 E: Buccivision@aol.com
Dr. Bucci is the founder of Bucci Laser Vision Institute in Wilkes-Barre, PA. He is a consultant to Johnson & Johnson Vision, although the studies described herein were independent and not funded by industry.
Bucci FA. Regression analysis of patient satisfaction in patients receiving bilateral +3.25 vs. bilateral +4.00 multifocal IOLs. Poster presented at: The Meeting of the American Academy of Ophthalmology, Chicago, 2018.