The LENTIS Mplus multifocal intraocular lens (Oculentis GmbH, Germany) is currently being evaluated in a multi-centre clinical trial (Heidelberg, Pardubice, Poznan). So far, the lens has been implanted in 119 eyes of 72 patients. The mean age of the study participants was 67 ± 12 years. The power of the implanted MIOLs was on average 21.00 +/- 2.01 D. The study parameters, followed up after one and three months, included visual acuity, contrast perception, glare and halos, postoperative use of spectacles, refraction, patient satisfaction, positioning and handling, complications.

Table 1: Best corrected distance and uncorrected near visual acuity (one month and three months after surgery).

Three months after surgery, the postoperative results have a mean best corrected distance visual acuity of 0.01 logMAR and a mean uncorrected near visual acuity of 0.08 logMAR (Table 1). With regard to contrast perception, the results obtained with LENTIS Mplus were very good and are equivalent to those of a 20-year-old person with healthy eyes. Patient satisfaction was analysed with a questionnaire. Only 10% of the patients reported halos and 3% mentioned glare effects. Ninety percent of the patients said they would choose a LENTIS Mplus lens again, 5% were undecided and another 5% decided against the lens. Interestingly, this high patient satisfaction with the novel MIOL was observed very early after surgery already (3 months postoperatively). This indicates a very short adaption period and a spontaneous tolerability of the LENTIS Mplus lens.

How does it work?

Figure 1: LENTIS Mplus IOL

Multifocal intraocular lenses (MIOL), developed since the 1990s, are rotationally symmetric and are either based on the principles of diffraction and/or refraction of the light or on a combination of these two principles. They distribute the incoming light rays to two principal focal points, a near and a distance vision focus or to several foci. The LENTIS Mplus features a new approach in multifocal lens technology: an aspheric, asymmetric distance-vision zone is combined with a sector shaped near-vision zone of + 3.0 D allowing for seamless transition between the zones (Figure 1).

Figure 2: Light propagates along the Z-axis in direction of the reference planes P1, P2, P3 thus forming two focal points allowing for clear near and distance visual acuity with smooth transition.

The lens combines two spherical surfaces with different radii: one main surface with a radius R1 and an embedded surface with a radius R2 creating two defined focal points (Figure 2). The design principle of the surface-embedded sector segment makes the MIOL independent of the pupil size. This embedded sector segment ensures optimum adjustment of near and distance vision acuity. Another distinctive feature of the lens is that the light - when it hits the transition area to the embedded sector element - will be reflected away from the optical axis. This prevents any superposition of interference/diffraction normally caused by curvature variations on optical surfaces. On the one hand, it will result in a minor loss of light intensity; on the other hand, however, in significantly improved contrast sensitivity as well as less glare and/or halo effects. A prerequisite for the best possible effect of the LENTIS Mplus lens is positioning of its optical axis on the line of sight of the eye as well as inferior positioning of the sector-shaped reading zone. The HydroSmart acrylic material used since 1996 already guarantees biocompatibility. The design ensures high stability in the capsular bag. Another important feature is the 360-degree continuous square optic and haptic edge to reduce the risk of posterior capsule opacification.

What do we think?

The multi-centre clinical trial has shown very good results for this new lens. It can be centred stably in the capsular bag. As early on as three months postoperative, near and distance visual acuity as well as contrast sensitivity were excellent; halo and glare effects were rarely reported combined with a very high rate of patient satisfaction. These promising findings certainly helped lead to its CE mark approval in March 2009.