•Not induce corneal endothelial decompensation

•Be compatible with other materials, e.g., silicon oil

•Improve optical quality of the operated eye

The design of the optics, the index of the refraction and the deformability factor all determine the incision size. The optic of the lens is difficult to fold, compress and shift inside the cartridge. Higher-order aberrations can decrease the quality of vision as much as lower-order aberrations and cannot be corrected by spectacle lenses after the cataract surgery. However, aspheric IOLs can be used to correct most of the optical problems after surgery; moreover, the IOL asphericity is the way to reduce the lens width [1]. The high refractive index and proper Abbey factor of the IOL material is the key to reduce the thickness of the lenses. New intraocular lenses will have the high refractive index and the elasticity of silicone or of new hybrid polymers which allow them to be provided through small corneal incision. Reducing the lens width and lens optic diameter is also one way to diminish the incision size. Haptics must keep proper position of the lens after unfolding and stabilize the lens. Modern lenses should have lower inflammation levels and improved biocompatibility gradient. The material and the shape of the lens should diminish the PCO rate and the anterior capsular fibrosis. Most of the MICS lances are one-piece lenses. These types of lenses are well verified in MICS [2, 3]. Only a few lenses comply with the conditions above. Table 8.1 shows the list of these lenses [25].

Table 8.1 List of commercially available MICS lenses

8.1.2 Lenses

8.1.2.1Zeiss – Acri.Tec MICS IOLs

(Zeiss – Acri.Tec Berlin, Germany)

This is a group of IOLs that cover all aspects of modern IOL technology in which all of them are implanted through a sub-2 mm incision. They are all one-piece, foldable, hydrophilic, acrylate lenses, containing 25% of water and they have a square edged optic and haptic with UV-absorber. The total diameter of the all lenses is 11 mm. They differ in diameter and type of the optics. The haptic angulation is 00.

Acri.Smart 46S: This is a lens with a 6 mm optic diameter and has an equiconvex optic design. The range of diopters is from +16.0 to +27.0 D.

Acri.Smart 36A: This lens has an optic diameter of 6 mm. The optic is equiconvex and aspheric. Acri. Smart 36A is available from 0.0 to +32.0 D.

Acri.Smart 46LC: This lens has a 6 mm optic diameter. The range of diopters is from 0.0 to +32.0 D. Refractive index for this lens is 1.51 dry and 1.46 after hydration.

Acri.Smart 48S: The optic diameter is 5.5 mm. The optic design is equiconvex. Available diopters are from +10.0 to +30.0 D.

Acri.Comfort 646 TLC: The optic diameter for this lens is 6.0 mm. It has a square edged optic and haptic lens. The optic design is bitoric, biconvex and aspheric. The range of available spherical diopters is from −10.0 to +32.0 D. The range of cylinder diopters is from +1.0 to +12.0 D.

Acri.Lisa Toric 466TD: The optic diameter is 6 mm. The total diameter of the lens is 11 mm. The optic design has a toric anterior surface and its posterior surface is bifocal with aberration-free technology and smooth micro phase technology. Optical addition of this lens is +3.75 D. The material is a foldable acrylate with 25% water content with a hydrophobic surface. Spherical diopters range is: −10.0 to +32.0 D and the cylinder diopters range is: +1.0 to +12.0 D (Fig. 8.1).

Acri.Lisa 366D: The optic diameter of this lens is 6 mm. The optic design is bifocal, biconvex, optimized aspheric, and corrects optical system SMP. This lens combines diffractive and refractive optics. Illuminance refractive distance focus is 65% and the illuminance diffractive near focus 35%. The lens has +3.75 D power in addition to the near focus. This lens helps to

Fig. 8.1 Acri.Lisa Toric 466TD lens

achieve good near and far vision in different lighting conditions and in different pupil sizes. The range of diopters is from 0.0 to +40.0 D.

Acri.Shooter A2-2000 and Acri.Smart Cartridge injector system is recommended for these lenses. This injector enables the lens to pass through the incision size of about 1.7 mm (Table 8.2).

There is no statistical difference in retinal image quality between conventional IOL AcrySof MA60BM and MICS IOL: Acri.Smart 48S and UltraChoice 1.0. The 0.5 modulation transfer function (MTF) statistical difference for these lenses was not significant. AcrySof and UltraChoice 1.0 (U = 38; p = 0.825) or for the AcrySof and Acri.Smart 48S (U = 20; p = 0.070). Also, the 0.1 MTF values were not statistically significant for AcrySof and UltraChoice (U = 40; p = 0.965) or AcrySof and Acri.Smart (U = 21, p = 0.085). Thin optics, lens injection, lens folding and unfolding under the injector pressure can damage optics. In this study, MICS lenses show excellent MTF performance which

are presented after the implantation in the eye through 1.5 mm incision [3].

Other investigations proved that there were no statistical changes in corneal aberrations after MICS with Acri.Smart 48S lens. They demonstrated that the total RMS can slightly decrease from 2.15μm ± 2.51 (SD) preoperative to 1.96 ± 2.01 μm postoperatively and the corneal astigmatism also decreases from preoperative −0.80 ± 0.76 D to postoperatively −0.63 ± 0.62 D after this type of surgery. The use of Acri.Smart lens and cataract surgery through incisions smaller than 1.5 mm do not affect the cornea and they can improve optical quality of the eye [4].

Wehner et al. presented and evaluated the position of the Acri.Smart 46S lens after 1½ years of implantation in 43 eyes in 37 patients. The lenses were implanted through a 1.4-mm microincision. The results indicated that there was no lens decentration during this period and the position of those lenses remained stable. First multi center study of the Acri.Smart 48S lens was carried out by Wehner. He injected these lenses by a 1.7– 2.0 mm tunnel. He did not observe decentration or dislocation and none of the lens surfaces were damaged. The PCO was observed in two eyes out of 100 [5].

Lubinski et al. did MICS with Acri.Smart 48S lens. The mean incision size was 1.56 ± 0.07mm. One month after surgery, the preoperative UCVA was 0.49 ± 0.33; and postoperative UCVA was 0.97 ± 0.11. The change was statistically significant p < 0.001. BCVA was also changed. Preoperative was 0.68 ± 0.3 and postoperatively 1.0 (p < 0.001). BCVA for near vision was improved from preoperative 5.27 ± 3.30 to postoperatively 2.91 ± 1.48 (p = 0.002). Authors argue that MICS with Acri.Smart 48S lens implantation is a safe and effective procedure [6].

Mencuccietal.evaluatedAcri.SmartandUltraChoice 1.0 lenses in the electron microscopy. In this study the authors did not find any lens damage after unfolding, which could be connected to the mechanical injury during injection process. They also did not notice post injector surface modification. They confirmed good system injection and excellent material quality of the lenses. They demonstrated only the OVD sediment on the surface of the lens. The conclusion of this investigation demonstrates that MICS lenses have a very good structure and acceptable surface properties after injecting through MICS incision [7].

Synder et al. evaluated Acri.Smart lenses after MICS. They did the mean incision size about 1.7 mm. They concluded that MICS is a safe method allowing for minimization of corneal incision. The IOLs were very well centered in all cases [8].

We evaluated implantation of the Acri.Smart 48S lens in 45 eyes. The mean corneal incision size was 1.46 ± 0.19 mm. The UCDVA before surgery was 0.2

± 0.2 and 0.7 ± 0.3 after surgery. This difference was statistically significant 6 months after surgery. The BCDVA before surgery was 0.4 ± 0.2 and 0.9 ± 0.2 after surgery. The difference was statistically significant 6 months after surgery. The UCNVA was 0.6 in 60% of the patients and the BCNVA was 0.8 in 90% of the cases 6 months after surgery. The residual sphere was ±1.25D in 81.1% of eyes and residual cylinder was −1.25D in 62.2% of eyes. The spherical equivalent in 42.8% of the eyes was within ±1.25D of the desired correction, and in 30.5% cases it was between −1.25 and −2.0 D. Mean addition for near vision was +1.5D or less in 70% of cases. The IOL position did not change in any of the cases during 6 months [9].

Cavallini et al. evaluated Acri.Smart 46S IOL in aspect of the use in vitreoretinal surgery. In all cases, the fundus of the eye was excellent, even when up to the extreme periphery, without glare or reflections. This lens allows the surgeon to comfortably perform vitrectomy of the vitreous base and laser retinopexy up to extreme periphery without complications [10].

Kurz et al. investigated the possibility to compensate the positive spherical aberration of the cornea. The Acri.Smart 46S IOL and Acri.Smart 36A IOL 8 weeks after surgery did not differ in baseline characteristics. Implantation of both IOL types resulted in a negative spherical aberration Z40, which was significantly different between two groups. The postoperative visual acuity and pupil size were not statistically

different. The contrast sensitivity also was the same in both groups [11].

8.1.2.2ThinOptX MICS IOLs (ThinOptX, Abingdon, VA)

This company has only one MICS IOL: the UltraChoice 1.0 is an 18% hydrophilic, acrylic, rollable IOL with plate-haptic. The length of the lens is 11 mm and the length of the spherical optic is 5.5-mm. This lens is very thin, central optical zone is only 350 μm thick and the haptic is 50 μm thick. This lens can be rolled and inserted through an incision less than 1.5 mm. The optic has a refractive–diffractive design. The central optical zone has five concentric diffractive segments of the posterior surface. The rings can create single focused images, because they are independent optical units. However, when they act together they may create focused image (Fig. 8.2).

Thin-Roller Injector is a single-use injector. It consists of a loading chamber and a tip with an injector. This lens can be injected also by the Geuder Cartridge (Geuder Instruments, Germany) [12].

In a clinical study in which we evaluated different MICS IOLs, we demonstrated that there were no statistical differences in retinal image quality between conventional IOL AcrySof MA60BM and MICS IOL: Acri.Smart 48S and UltraChoice 1.0. This study shows excellent optic attribute of this MICS lenses after injecting and unfolding [3].

Fig. 8.2 ThinOptX MICS IOLs

Mencucci at al. analyzed electron microscopic scans of this lens and did not notice post injector surface damage [7]. Many authors confirm that UltraChoice 1.0 lens has the perfect characteristics. This lens can be easily inserted through incisions smaller than 1.5 mm. The perfect flexibility and ability to retain the original memory indicate that the lens can easily adapt to capsule [13].

Dogru et al. published visual results 6 months after the implantation of ThinOptix OIL. They compared this lens with AcrySof IOL (MA60BM). They did not notice any post operated statistical significant difference between these lenses in visual acuity, IOP, endothelial cell density and opacification changes. They found a significant change in intermediate and low-contrast charts. The mean contrast visual acuity scores were higher in the intermediate and low-con- trast charts in the ThinOptiX group than in the AcrySof group [12].

Kaya et al. compared 1 year follow-up of UltraChoice 1.0 and Acrysof lenses (MA30AC). They noticed statistically significant lower visual acuity and higher PCO scores in the ThinOptix OILs group. The contrast sensitivity was also lower in the ThinOptix IOLs group [14].

Cinhuseyinoglu at al. evaluated ThinOptiX lens with MICS in a large group of 85 patients. They found that 92.22% of the patients had BSCVA equal to or better than 0.8 when evaluated 6 months after surgery. They concluded that MICS and the ThinOptiX rollable IOL implantation could be the future of cataract refractive surgical procedures [15].

Prakash et al. inserted ThinOptiX lens through a clear corneal 1.7 mm incision. They confirmed good visual acuity after surgery in their patients. However, they noticed a higher rate of POC in some cases of this lens implantation. The PCO rate was 16.12% at 15 months after surgery [16].

During the live surgery session at Alicante Refractiva Internacional (ARI 2006 Alicante, Spain), it was also demonstrated that the UltraChoice 1.0 IOL is implantable through incisions of 1.1 mm.

8.1.2.3Akreos MI60 AO Micro Incision IOL (Bausch & Lomb, Rochester, NY)

This is a single-piece lens consisting of central optic and four flexible haptics. This biconvex, aspheric lens is made of 26% hydrophilic acrylic material with

Fig. 8.3 Akreos MI60 AO

Micro Incision IOL

UV-absorber. Its lens has a 6 mm optic diameter and the angulation is 100. The lens has the posterior ridge to prevent PCO. The lens is available in three diameters – 10.5, 10.7 and 11.0 mm. The power of the lens ranges from +10.0 to +30.0D. This lens can be implanted through incisions less than 1.8 mm. Akreos MI60 can be injected with LP604350 single-use injector Viscoject™ Injector and 1.8 Viscoglide cartridge (Medicel, Widnau, Switzerland) (Fig. 8.3).

Amzallag presented results of 20 patients who received Akreos AO MI60 Micro Incision lenses. The mean size of the microincision group was 1.86 mm. The excellent stability of the lens was confirmed by minimal decentration (0.11 mm) and small PCO rate. In his published data the stretch of the incision was about 0.09 mm. This indicates that this lens can be easily and safely inserted through incisions less than 2.0 mm [17, 18].

Luciano et al. presented 20 cases of patients with Akreos AO MI60 Micro Incision lens implantation through 1.8 mm incision on 87 Congresso Nazionale SOI 2007. The results of this work are very promising. The mean UCVA was 0.89 and BCVA was 1.0. The lens had very good stability in the capsular sac.

We reported during the World Ophthalmology Congress in Hong Kong (2008), results of the optical quality and visual outcomes of MI60 lens in MICS surgery up to 12 months. Preoperative spherical equivalent was −0.53 ± 2.93 D (−9.0 to +8.4 D). The postoperative spherical equivalent was −0.50 ± 0.60 D (−1.75 to +1.0). The mean LogMAR BCVA improved from 0.54

± 0.23 to 0.11 ± 0.21. At 12 months, LogMAR UCVA was 0.32 ± 0.23. The mean Strehl ratio for the IOL once implanted inside the eye was: 0.26 ± 0.03. Final corneal incision size was sub-1.9 mm in all cases. This demonstrates that this new IOL showed excellent intraocular optical performance with excellent visual and refractive outcomes.