8.3.2 Special Lenses: MF

Hakan Kaymak and Ulrich Mester

Core Messages

ßThe only multifocal IOL that fits through the 1.5 mm incision size is the *Acri.LISA (*Acri.

Tec, Zeiss, Henningsdorf, Germany).

ßAcri.LISA is an acronym of the main optical properties of the lens.

ßVisual acuity for distance vision is very good with Acri.LISA and is comparable with that of

monofocal IOLs, at least under photopic lighting conditions.

ßNear vision is also sufficient despite the unequal light distribution of the *Acri.LISA in

favor of the far distance.

ßPatients with the Acri.LISA have a pseudoaccommodation range of 5.5 diopters.

ßInitial results of the toric version of the Acri. LISA are very promising.

Table 8.4 Characteristics of Acri.LISA

The use of multifocal intraocular lenses (MIOL) has been very limited in the past due to several drawbacks and limitations [1]: Surgical techniques were not as refined and predictable as today and accurate biometry to achieve emmetropia was challenging. Moreover, independence from glasses could not be achieved in all patients, particularly for near vision. Many patients complained of photic phenomena [2, 3], and driving was impaired due to reduced contrast sensitivity under mesopic conditions [4, 5].

Meanwhile, a new generation of MIOLs has been developed and investigated in clinical studies. Several new optical concepts were incorporated in these lenses:

The only multifocal IOL that fits through the 1.5 mm incision size is the *Acri.LISA (*Acri.Tec, Zeiss,

H. Kaymak ( )

Department of Ophthalmology, Knappschafts Hospital, Sulzbach, Germany

e-mail: sek-augen@kksulzbach.de

Henningsdorf, Germany). The characteristics of this MIOL are summarized in Table 8.4. Acri.LISA is the acronym of the main optical properties of the lens (Fig. 8.38).

With the application of a diffractive optic, the visual performance became independent of the pupil size, which was a major drawback of the previous MIOL-generation with refractive optics.

The introduction of an aspheric lens design enhanced contrast vision, which could be demonstrated previously in clinical studies with monofocal IOLs [6–8].

Another new concept is that of unequal light distribution for distance and near vision, based on the consideration that most patients prioritize distance vision. This concept may also lead to a reduction of halos.

To reduce the complaints due to straylight, smooth steps within the diffractive pattern were engineered (Fig. 8.38).

Clinical studies were performed with this MIOL. Thirty patients with bilateral implantation of the

*Acri.LISA were examined 1 year after surgery of the second eye.

main zone

phase zones between

the main zones

main zone

(acc. to Fiala)

front profile of a bifocal LISA lens (‘smooth steps’)

Fig. 8.39 Mean values and standard deviation of distance visual acuity

Monocular and binocular visual acuity (VA) (uncorrected and best corrected) at the 1 year control period are shown in Fig. 8.39. Despite the dominance for far distance of this MIOL, near VA is also very satisfying (uncorrected monocular 0.85, binocular 1.05 under photopic conditions) (Fig. 8.40).

The near uncorrected VA was tested under two lighting conditions demonstrating a luminance depending improvement from 0.8 (80 lux) to 1.0 (350 lux) (Fig. 8.41).

The defocus curve demonstrated the drop of VA at intermediate distance, but not exceeding the critical limit of 0.5 (Fig. 8.42).

The contrast sensitivity was within the normal range under photopic conditions (Fig. 8.43).

With regard to photopic phenomena after 1 year, almost no patient described halos in everyday life.

Overall patients’ satisfaction was 8.3 using a scale from 0 to 10 after 1 year (Fig. 8.44).

8.3.2.1 Discussion

The Acri.LISA offered good efficacy, predictability and satisfying functional outcomes. Our results are in accordance with the findings of Alió et al. [1] and Alfonso et al. [2]. Alió et al. [1] demonstrated very good MTF values of the Acri.LISA for 3 and 6 mm pupil sizes which reflected our clinical outcomes.

8.3.2.2 Conclusion

VA for distance vision is very good with Acri.LISA and comparable with monofocal IOLs, at least under photopic lighting conditions.

Fig. 8.40 Mean values and standard deviation of near visual acuity

Near Visual Acuity Influence of binocularity

Near binocular Visual Acuity (C.A.T.) Influence of luminance

distance corrected

Luminance level

photopic

Near vision is also sufficient despite the unequal light distribution of the *Acri.LISA in favor of the far distance. A better near VA could be achieved with increasing light luminance. Contrast vision is within the normal range.

There is a significant drop of VA at the intermediate distance. This is because of the bifocal optic of the MIOLs. Therefore, it is advisable to speak of bifocal IOLs instead of multifocal lenses to avoid disappointing patients, who might expect to receive IOLs such as progressive glasses. On the other hand, the drop of VA in

Fig. 8.43 Photopic contrast sensitivity with Acri.LISA (red), normal range (green)

the intermediate distance did not exceed 0.5, which was sufficient for daily activities for most of the patients.

With the Acri.LISA, more than 80% of the patients gained complete independence from spectacles. This is an enormous improvement compared to just one third of patients getting freedom from glasses with the first generation of MIOLs [13].

Even with these newly developed MIOLs, photic phenomena, particularly halos, have not been totally

Overall Satisfaction Score with Acri.Lisa

10.00

0.00

Fig. 8.44 Satisfaction score after 1 year with Acri.LISA

eliminated. These effects seem to be inherent in MIOLs as a result of multiple images, of which only one is in focus. In fact, most patients are usually not disturbed by these optical effects and report that they become less noticeable over time [14, 15].

All the results in our studies were achieved without additional refinement of refraction using photoablative procedures. Using these techniques, further improvement is likely.

One crucial point is exact biometry. We therefore use three different formulas to get as close to emmetropia as possible. Residual refractive errors enhance the side effects of bifocal lenses and should therefore be avoided.

8.3.2.3 Outlook

Until some time, we did not recommend MIOLs for patients with more than 1 diopter of astigmatism and did not accept a second procedure for refinement. Now

Table 8.5 Characteristics of Acri.LISA toric

the toric version of Acri.LISA is available (Table 8.5). First results of this MIOL, which were presented at the ASCRS 2008 in Chicago (Table 8.6), are very promising. A multicenter study comparing the Acri.LISA toric with the Acri.LISA combined with a second refractive procedure, in patients with astigmatism of more than 1.5 D, is under way. The results of the first 6 months are expected in 2009.