Multifocal IOLs developed after the 1990s are rotationally symmetric and based on the principles of diffraction, refraction, or a combination of diffraction and refraction. These IOLs distribute incoming light rays to two principal focal points (near and distance vision focus) or to several foci. The Lentis Mplus multifocal IOL (manufactured by Oculentis GmbH, Berlin, Germany; distributed in Europe by Topcon, Rotterdam, Netherlands) features a completely new approach in multifocal lens technology: An aspheric, asymmetric distance-vision zone is combined with a 3.00 D sector-shaped, near-vision zone, allowing seamless transition between the zones (Figure 1).

The Mplus combines two spherical surfaces with different radii; one main surface and an embedded surface create two defined focal points (Figure 2). The design of the surface-embedded segment makes this multifocal IOL independent of pupil size and ensures optimum adjustment of near and distance vision acuity. Another feature of the lens is that light hitting the transition area of the embedded sector is reflected away from the optical axis to prevent superposition of interference or diffraction. Although there is a resultant minor loss of light intensity, contrast sensitivity is significantly improved, and glare and halo effects are reduced.

POSITIONING OF THE OPTICAL AXIS
The optical axis of the Lentis Mplus must be positioned in the line of sight, with the sector-shaped reading zone in an inferior position, to guarantee the best possible effect. The acrylic material, HydroSmart (Oculentis), provides excellent biocompatibility, and the successful Lentis design ensures stability in the capsular bag. Another important feature of the Lentis Mplus is its 360° continuous square optic and haptic edge, which reduces the risk of posterior capsular opacification.

The IOL is currently under clinical evaluation in a European multicenter study (Heidelberg, Germany; Pardubice, Czech Republic; and Poznan, Poland). A total of 79 patients, 54 binocular and 25 monocular, mean age 68 ±12 years, were implanted with the Lentis Mplus. The average IOL power was 20.90 ±2.10 D. Patients returned for follow-up at 1 and 3 months; visual acuity, contrast perception, postoperative use of spectacles, refraction, patient satisfaction, patient positioning and handling, complications, side effects including glare and halos, and postoperative visual acuity were determined at each visit.

RESULTS
Three months after surgery, postoperative results are excellent, with a mean distance BCVA of 0.01 logMAR and near UCVA of 0.08 logMAR (Table 1). The average spherical equivalent is -0.11 ±0.60 D (n=110 eyes). Figure 3 shows the average results of the defocus examination. Note the two peaks at 0.00 D and approximately -2.50 D, which are explained by the IOL's two foci. In the intermediary area of -1.00 D, good visual results are obtained. On average, the range of 0.75 to -3.00 D achieves a visual acuity value of more than 0.3 logMAR (ie, more than 0.5 decimal Snellen visual acuity).

Contrast perception with the Lentis Mplus is equivalent to that of a 20-year-old with healthy eyes. At 3- month follow-up, patients answered a questionnaire to determine overall satisfaction. Ten percent of patients reported halos, and 3% reported glare. Ninty percent said they would choose the Lentis Mplus lens again; five percent said they would not choose the lens again, and another 5% were undecided. The fact that this level of satisfaction was reported at 3 months suggests that the IOL requires a short adaptation period, with most patients experiencing spontaneous toleration. Futhermore, results from the 6-month follow-up confirm these excellent clinical outcomes.

SUMMARY
The current multicenter clinical trial has shown good results for the Lentis Mplus. This lens is well centered and stable in the capsular bag. As early as 3 months postoperatively, near and distance visual acuity and contrast sensitivity are excellent; halo and glare effects are rarely reported. These promising findings led to Conformité Européene (CE) approval in March 2009.

Gerd U. Auffarth, MD, is the Acting Chairman, Department of Ophthalmology, University of Heidelberg, Germany. Professor Auffarth is a member of the CRST Europe Editorial Board. He states that he has no financial interest in the products or companies mentioned. He may be reached at tel: +49 6221 566624; fax: +49 6221 568229; e-mail: ga@uni-hd.de.