February 2019

INTERNATIONAL

Presentation spotlight
Advantages of a split bifocal IOL


by Stefanie Petrou Binder, MD, EyeWorld Contributing Writer

Split bifocal IOLs offer some advantages for near and far visual acuity without any reduction in contrast sensitivity

The 2018 World Ophthalmology Congress addressed topics of interest to refractive surgeons, taking special note of promising new IOL designs. Speaking on split bifocals in lens surgery, Leonidas Mavroudis, MD, Thessaloniki, Greece, discussed the unique rewards offered by the Lentis Mplus (Oculentis, Berlin, Germany) split bifocal technology.

Lentis Mplus

The newest split bifocal in the Lentis IOL series, the Lentis Mplus X, is a one-piece, non-rotational, plate haptic, bifocal IOL with two refractive segments, including a large aspherical zone for distance and a smaller near zone with a 3 D add. The distance zone acts as a monofocal IOL, while the near zone is the only area of the optic that directs light to the near focal point.
“The larger upper part is for distance vision and the smaller part is for close distances, and in the new IOL model, there is a blend zone between the two that is not as sharp as in the previous one, which is important to reduce dysphotopsias,” Dr. Mavroudis said. “This lens has great visual results from different studies, however, it has its own advantages and disadvantages.”
According to the outcomes of a large, retrospective, private clinic study that investigated the Lentis Mplus for efficacy, patient satisfaction, and complication rate in 9,366 eyes (4,683 patients), excellent distance and near visual acuity were achieved. Ninety-five percent of the patients achieved a binocular UDVA of 6/7.5 (0.1 logMAR) or better 3 months postoperatively. Severe dysphotopsia requiring an IOL exchange occurred in 55 eyes. Overall patient satisfaction was high, with 97.5% of patients willing to recommend the procedure.1
Another Lentis Mplus study was directed at a more demanding group: presbyopic patients. The investigation included 220 emmetropic, presbyopic patients, without cataract, who received the Lentis, revealing 99.7% of eyes within 1 D of emmetropia, 3 months postoperatively, with a mean binocular UNVA of 0.10±0.12 logMAR. Patients said the refractive procedure improved their lives in 91.9% of cases, and 93.5% were willing to recommend it to friends and family. Three patients requested IOL exchange because of severe night vision phenomena or unsatisfactory quality of vision.2

Coma

Coma is a potential issue with some multifocal IOLs. A comparison between monofocal and the Lentis Mplus IOLs revealed that the Lentis, with rotational asymmetry, restored distance, intermediate, and near visual function following cataract surgery in 52 eyes of 29 patients. The Lentis group had significantly better UNVA and DCNVA, and defocus curves demonstrated significantly better visual acuities in the Lentis group at several levels of defocus. The Lentis group also caused significantly higher amounts of primary coma especially in eyes with significant IOL tilt.3
The reduction of postoperative aberrations caused by multifocal IOLs contributes to patient satisfaction and improves outcomes. According to the results of another study undertaken in 90 eyes of 53 patients, refractive predictability and intermediate visual outcomes improved significantly with the use of capsular tension rings. Intraocular aberrometry, however, did not differ significantly between eyes with and without CTRs.4
Split bifocal IOLs cause significant coma compared to diffractive IOLs, according to an in vitro comparison of different presbyopia correcting IOL types. The Lentis Mplus showed the highest HOAs at three tested pupil sizes, especially at apertures of 4.0 and 4.7 mm.5 Independent ray tracing analysis (true wavefront) on the Lentis Mplus allows decoupling of the IOL power pupillary distribution from the true higher order aberrations of the eye, therefore providing the appropriate phase map to accurately evaluate optical quality.6
The question is whether coma is bad in every situation. Dr. Mavroudis argued, “Corneal coma aberrations are associated with increased pseudoaccommodation after cataract surgery. In the normal young lens, there is a significant decrease of the spherical aberration and increase in vertical coma with increasing accommodation. Some coma is good for near vision, as we know from many studies.”
The difference between ideal and real accommodation responses is mainly attributed to parameters associated with the accommodation process, such as the near visual acuity, depth of defocus, pupil diameter, and wavefront aberrations. “Wavefront aberrations are dependent on pupil size. In the normal crystalline lens, there is an early response to accommodation with coma inductions. The spherical aberration decreases as the stimulus vergence increases,” Dr. Mavroudis said.

Why choose this technology?

“Compared to diffractive IOLs, which are associated with a contrast sensitivity loss, washout effect, and halos at night, the Lentis does much better,” Dr. Mavroudis explained. “In fact, the asymmetric, split bifocal Lentis Mplus IOL offers unique advantages over diffractive lenses. Contrast sensitivity is almost as good as with monofocal lenses, and we have limited halos at night, in the lower half of the lens. Snellen visual acuity is equal to that achieved with monofocal lenses as well. The Lentis is less tear film quality-dependent, unlike diffractive lenses. However, asymmetric lenses have their own challenges, including careful patient selection, like with all MFIOLs, the need for near perfect surgery due to late IOL tilt or decentration, the possibility of coma postoperatively, and the possibility of late lens rotation, which may not always be possible or give a satisfactory outcome. Also, intermediate and in some instances near visual acuity outcomes may not always meet the patient’s expectations.”
Data from different studies suggest moderate but not severe night vision problems among patients implanted with the Lentis bifocal IOL. Addressing the issue of reducing photopic phenomena, Dr. Mavroudis suggested placing the near IOL zone at the top or along the side of the IOL. Positioning should be based on Purkinje reflex, keeping the near add further away. He cautioned against excessive rotation intraoperatively to protect the zonules, especially with the plate haptic model, the C-loop model being more zonule-friendly.
Dr. Mavroudis implanted the L312MF version in 33 patients and experienced no washout vision in any of his patients. Six of the patients required spectacles for some tasks and some complained of night vision structures resembling “small children,” which he reduced through lens rotation performed 180 days postop in two patients. In his experience the position of the add did not matter as long as the lens was centered on the visual axis and the cornea was not asymmetrical.

References

1. Venter JA, et al. Visual outcomes and patient satisfaction in 9366 eyes using a refractive segmented multifocal intraocular lens. J Cataract Refract Surg. 2013;39:1477–84.
2. Venter JA, et al. Visual outcomes and patient satisfaction with a rotational asymmetric refractive intraocular lens for emmetropic presbyopia. J Cataract Refract Surg. 2015;41:585–93.
3. Alio JL, et al. Visual outcomes and optical performance of a monofocal intraocular lens and a new-generation multifocal intraocular lens. J Cataract Refract Surg. 2011;37:241–50.
4. Alio JL, et al. Rotationally asymmetric multifocal IOL implantation with and without capsular tension ring: refractive and visual outcomes and intraocular optical performance. J Refract Surg. 2012;28:253–8.
5. Camps VJ, et al. In vitro aberrometric assessment of a multifocal intraocular lens and two extended depth of focus IOLs. J Ophthalmol. 2017;2017:7095734.
6. Akondi V, et al. Evaluation of the true wavefront aberrations in eyes implanted with a rotationally asymmetric multifocal intraocular lens. J Refract Surg. 2017;33:257–265.

Editors’ note: Dr. Mavroudis has no financial interests related to his comments.

Contact information

Mavroudis: ftopouzis@otenet.gr

Advantages of a split bifocal IOL Advantages of a split bifocal IOL
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