Fig. 8.8 AcriFlex MICS 46CSE IOL

Fig. 8.9 Hoya Y-60H MICS

IOL

8.1.2.10Miniflex IOL (Mediphacos Ltda., Minas Gerais, Brasil)

This is also a new MICS lens and can be implanted through 1.8 mm incision. The material is Flexacryl® Hybrid Acrylic which brings together hydrophobic and hydrophilic monomers. The optics is aberration neutral. The lens can be implanted through 1.8 mm incision using a docking technique. The lens was presented on ESCRS 2008 in Berlin by Carlos Verges (Fig. 8.10).

Fig. 8.10 Miniflex IOL

8.1.3 Optical Quality of MICS IOLs

As an important parameter for adequate IOL performance, we have evaluated objectively the optical quality of MICS IOLs and compared it with that of the conventional ones [3]. The optical quality was studied by the MTF for monochromatic light using the optical quality analysis system (OQAS, Visiometrics S.L.) at a spatial frequency of 0.5 and 0.1 MTF of the different IOLs.

Two MICS IOLs (UltraChoice 1.0, ThinOptX, and Acri.Smart 48S, Acri.Tec) were evaluated and compared with one conventional small-incision IOL (AcrySof MA60BM, Alcon Laboratories). The results showed that MICS IOLs have excellent MTF performance when implanted after cataract surgery, equal to that of conventional IOLs (Fig. 8.11).

For the Acri.Smart 48S IOL, the point-spread function (PSF) was evaluated before and after pushing the lens through the Acri.Glide cartridge (Acri.Tec GmbH). After 120 min., no difference between the untreated and treated Acri.Smart could be detected (Fig. 8.12).

Also, in the ThinOptX UltraChoice 1.0 IOL through its tandem fashion of working, each stepped ring provides the same optical information to the same focal point on the retina and MTF and visual acuity are therefore excellent (Fig. 8.13) [23].

We also evaluated the intraocular optical quality of a new MICS IOL Akreos MI60 (Bausch & Lomb) by using our model of intraocular optical quality analysis [24]. With regard to the Strehl ratio, it was 0.26 ± 0.03. The mean value of 0.5 MTF was 3.0 ± 0.5 cycles per degree (cpd) and the mean of MTF cut-off value was 22.3 ± 7.9 cpd (Fig. 8.14).

In order to show the intraocular optical performance of the IOL, intraocular aberrations for a typical eye implanted with Akreos MI60 are shown in (Fig. 8.15) for a 6 mm pupil.

12.000

0.5 MTF

0.1 MTF

10.000

2.000

0.000 Ultrachoice Acri.Smart AcrySof

IOL

Fig. 8.11 Spatial frequency (cpd) for 0.5 and 0.1 MTF values of Acri.Smart, ThinOptX and AcrySof IOLs [3]

a

b

Fig. 8.12 Acri.Smart lens (a) Acri. Smart lens. (b) Optical quality analysis system (OQAS) image as detected following implantation of the lens [23]

These results showed that MI60 IOL fulfills all the requirements for the modern trend in cataract surgery and MICS, with excellent intraocular optical performance once implanted inside the eye [26].

8.1.4 Conclusion

The number of lenses available for MICS is increasing. Now we have some microincisional lenses which can be injected through sub-2 mm incisions, with clinical data which confirm their perfect characteristics. The decrease of the incision and excellent quality of vision following the surgery, jointly with multifocal capacity to correct refractive errors with precision, makes cataract surgery a part of the refractive surgery. Now we know that MICS lenses have an optical quality equal to or superior to conventional lenses for standard cataract surgery. MICS lenses have excellent capsular bag stability and PCO rate. With the result of postoperative vision after MICS technique and MICS IOLs, we can expect an improvement in the refractive result and optical quality of the eye. In the future an

MTF 1.00

Frequency at 0.5 height (c/d): 3.527

0.83

0.67

0.50

0.33

0.17

c/d

INTRAOCULAR ABERRATIONS

Fig. 8.15 Wavefront intraocular aberrations after surgery of the MI60 IOL

explosive development of MICS IOLs is expected to follow the demand of progress in cataract surgery.

Take Home Pearls

ßTen types of lenses are available today to be used in MICS sub-2 mm

ßMICS lenses fulfill all the demands of modern cataract lenses

ßModern IOL design, higher index of refraction and improved Abbey factor are the ways to

improve MICS IOLs

References

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3.Alió JL, Schimchak P, Montés-Micó R, Galal A. Retinal image quality after microincision intraocular lens implantation. J Cataract Refract Surg 2005; 31:1557–1560

4.Elkady B, Alió JL, Ortiz D, Montalbán R. Corneal aberrations after microincision cataract surgery. J Cataract Refract Surg. 2008; 34:40–45

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13.Pandey SK, Werner L, Agarwal A, Agarwal A, Lal V, Patel N, Hoyos JE, Callahan JS, Callahan JD. Phakonit cataract removal through a sub-1.0 mm incision and implantation of the ThinOptX rollable intraocular lens. J Cataract Refract Surg 2002; 28:1710–1713

14.Kaya V, Oztürker ZK, Oztürker C, Yasar O, Sivrikaya H, Ağca A, Yilmaz OF. ThinOptX vs AcrySof: comparison of visual and refractive results, contrast sensitivity, and the

incidence of posterior capsule opacification. Eur J Ophthalmol 2007; 17:307–314

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8.2 Implantation Techniques

T. Amzallag

Core Messages

ßTo inject an intraocular lens (IOL) through a sub-2 mm corneal incision a wound-assisted

visco-injection technique is generally required.

ßIt is mandatory to understand the IOL characteristics (material, design) and to know how to

handle the dedicated injectors.

ßThe wound-assisted injection technique is the most used as it enables the smallest incision

size, to date.

ßAt every step, the surgeon should keep in mind the exact incision plane in order to follow it

closely when injecting.

ßThe precise loading of the IOL in the cartridge, the loading of the cartridge in the injector and

the injection itself should fulfill very precise rules in order to lead to reliable and reproducible results.

Implantation of an intraocular lens through a microincision requires a new technological as well as technical approach, especially as the incision size is decreasing.

A new technological approach is necessary as both the implants and the injectors need to have the expected efficiency.

In spite of the reduction in the volume of the implant, it should have mechanical strength and, after being injected, should maintain the standards of optical quality and postoperative intra-saccular behavior, similar to the best products available.

The injectors and cartridges should be microincisioncompatible. Today, it is indeed the internal diameter of the cartridge that determines the incision size. In practice, the internal diameter of the cartridge should be less than 1.4mm while using the wound-assisted technique