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Bifocal diffractive IOL with +3.25 D near addition maintains near, distance visual acuity
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An aspheric, bifocal, diffractive multifocal IOL with a +3.25 D near addition yielded monocular corrected distance and near visual acuity of 20/25 or better in all eyes, according to a study.
The authors described results obtained with the diffractive bifocal Tecnis ZLB00 multifocal IOL (Abbott Medical Optics) with a near addition of +3.25 D on the IOL plane.
“The basic idea of this kind of lens is that this is low near addition,” Gerd Auffarth, MD, PhD, FEBO, the corresponding author, told Ocular Surgery News. “The traditional Tecnis multifocal is +4 D, and this is +3.25 D.”
In general, IOL manufacturers reduce near addition for two reasons, Auffarth said.
Gerd Auffarth
“One reason is to enhance intermediate vision without losing near acuity. The second reason is to reduce side effects. Especially with diffractive lenses, you have the problem of glare and halo and things like that,” he said.
The prospective, non-randomized multicenter clinical study, published in the Journal of Refractive Surgery, included 44 eyes of 44 patients who underwent cataract extraction and implantation of the Tecnis ZLB00 multifocal IOL in the capsular bag.
Investigators evaluated changes in logMAR uncorrected and corrected near, intermediate and distance visual acuity and manifest refraction 3 months after surgery. Patients were asked to rate photic phenomena, spectacle dependence and overall satisfaction.
Mean preoperative axial length was 23.35 mm, and mean anterior chamber depth was 3.03 mm. Mean power of implanted IOLs was 22.61 D.
No severe intraoperative or postoperative complications occurred.
Visual acuity, refraction
Postoperative monocular logMAR uncorrected distance, near and intermediate visual acuities were 0.10 or better in 82.5%, 86.5% and 68.8% of eyes, respectively.
Monocular corrected distance and near visual acuity of 0.10 was achieved in all eyes. Monocular corrected distance visual acuity improved significantly (P = .001).
“The best outcome in individual patients was 20/20 at all three distances,” Auffarth said. “In some individual patients, you can actually get a logMAR of –0.0, which is a little bit higher than 20/20.”
Mean monocular intermediate visual acuity was 0.09, and mean binocular intermediate visual acuity was 0.06. This finding confirmed the attainment of functional intermediate visual acuity with the Tecnis ZLB00, the authors said.
Postoperative spherical equivalent was within 0.5 D of emmetropia in 91.2% of eyes and within 1 D in 100% of eyes.
Manifest sphere and cylinder decreased significantly after surgery (P = .030 and P = .021, respectively).
Patient satisfaction
All patients were at least moderately satisfied with surgical outcomes; 39.1% of patients were very satisfied, 43.5% were satisfied and 17.4% were moderately satisfied.
Six patients (13.6%) required spectacles for some daily activities. Eight patients (18.2%) reported mild halos.
“There are a lot of activities where good intermediate vision is appreciated by patients, not only pure reading ability in a short distance,” Auffarth said. “So, we have much less chair time and complaints from patients with multifocal lenses when we have lower-add lenses. And this applies to this lens even better because it’s not a real low add, but it’s a lower add than we had in previous models from this company.”
Auffarth said that the defocus curve for intermediate vision stabilized at 0.01 to 0.2 logMAR over a range of at least 3.5 D.
“It’s not the classic older bifocal diffractive lenses, where [intermediate vision] goes down in this valley to below 20/40 or something,” Auffarth said. “You always keep it even better than 20/40. I have individual patients with defocus curves where they maintain 20/25 over the entire defocus curve. They go down after –3 D or –4 D. So, it’s really a difference from the conventional older models.” – by Matt Hasson
- Reference:
- Kretz FT, et al. J Refract Surg. 2015;doi:10.3928/1081597X-20150423-02.
- For more information:
- Gerd Auffarth, MD, PhD, FEBO, can be reached at International Vision Correction and Research Centre & David J. Apple International Laboratory on Ocular Pathology, Department of Ophthalmology, University of Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany; email: gerd.auffarth@med.uni-heidelberg.de.
Disclosure: Auffarth reports he received research grants and lecture fees from Alcon, Abbott Medical Optics, Bausch + Lomb Technolas Perfect Vision, Carl Zeiss Meditec and Rayner.
Perspective
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Jorge L. Alió, MD, PhD
The authors report the outcomes of a well-known lens, the Tecnis, in which instead of the previous 4 D, only 3.25 D has been used as near vision add. The lens has the same optical characteristics as the former one, and it is targeting improvements in intermediate vision. The authors confirm in this report good outcomes for intermediate but not so good for near. Subjective symptoms, photic phenomena and patient dissatisfaction are not found significant in this series of 44 patients.
In this study, the authors do not report characteristics such as the pupil dependence of the lens and the intermediate far light distribution depending on the pupil size. It is important to know that both pupil size and light distribution are important for the clinical use of this lens model as pupil dependence (or independence as in the previous model of this same lens) are critical for the choice of the lens in patients with systemic medications that could affect the pupil behavior or because of senility. The model had a pupil independence profile, which made it very interesting for these doubtful cases. The defocus curve is not shown in the study even though they report all the data. Most probably this lens behaves as an intermediate dominant lens, with near vision capabilities. In order to know whether this lens is better (or not) in terms of subjective symptoms to the previous Tecnis with 4 D, the authors should perform a comparison with previous studies on such a lens in a similar population.
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