|Year : 2010 | Volume
| Issue : 2 | Page : 177-182
Advances in intraocular lenses for cataract surgery: A review
Rajesh Sinha, Ritika Sachdev, Namrata Sharma, Jeewan S Titiyal
S-7, R. P. Centre, Ansari Nagar, All India Institute of Medical Sciences, New Delhi, India
|Date of Web Publication||26-Feb-2010|
S-7, R. P. Centre, Ansari Nagar, All India Institute of Medical Sciences, New Delhi
|How to cite this article:|
Sinha R, Sachdev R, Sharma N, Titiyal JS. Advances in intraocular lenses for cataract surgery: A review. Indian J Ophthalmol 2010;58:177-82
|How to cite this URL:|
Sinha R, Sachdev R, Sharma N, Titiyal JS. Advances in intraocular lenses for cataract surgery: A review. Indian J Ophthalmol [serial online] 2010 [cited 2013 May 24];58:177-82. Available from: http://www.ijo.in/text.asp?2010/58/2/177/60066
Improvement in medical technology and surgical techniques along with patients' increasing expectations have fuelled the quest for superior vision. This has led to a rapid evolution in the field of intraocular lens (IOL) manufacture. This article discusses new technology that has been applied to modern IOL optics, including multifocal, toric, blue-blocker and aspheric IOLs; lenses designed to be inserted through sub-2-mm incisions and accommodative IOLs.
Aspheric Intraocular Lenses
Dick (Curr Opin Ophthalmol. 2009;20(1):25-32) in his review commented that aspheric IOLs were designed to improve functional vision on the assumption that reducing ocular spherical aberration (SA) would lead to improvements in contrast sensitivity (CS). Although this has largely been confirmed by many studies, several recent studies have reported no difference in CS or in patient preference.
Tzelikis et al. (Am J Ophthalmol. 2008;145(5):827-33) in an intra-individual randomized prospective study (n = 25) reported that TecnisZ9001 IOL (Abbott Medical Optics [AMO] **) with modified anterior aspheric surface induced significantly lesser higher-order aberration (HOA) and SA under photopic and mesopic conditions compared to ClariFlex** IOL.
Kohnen et al. (Ophthalmology 2009;116(9):1697-706) performed a study in which one eye was implanted with a spherical IOL SN60AT (Alcon Laboratories, Fort Worth, TX, USA*) and the contralateral eye with an aspheric (SN60WF*) IOL. Coma and trefoil root mean square and SA were significantly lower in the aspheric group resulting in higher mesopic high-contrast visual acuity (VA), and photopic CS.
Trueb et al. (Ophthalmology 2009; 116(5):890-5) in a randomized prospective study of 464 eyes reported that eyes implanted with the aspheric AcrySof IQ IOL* showed better photopic and mesopic CS at medium and high spatial frequencies than eyes implanted with the spherical AcrySof SN60AT IOL*. High-contrast photopic best corrected visual acuity (BCVA) was similar.
Caporossi et al. (J Refract Surg. 2009;25(7):578-90) reported statistically significant differences in CS under photopic and mesopic conditions between aspheric and spherical IOLs (P<0.5). In addition, aspheric IOLs had significant reductions in total SA at all follow-up examinations (P<.01).
Luo et al. (Zhonghua Yan Ke Za Zhi. 2009;45(3):239-42) reported significantly better CS at higher and middle spatial frequencies with the aspheric AcrySof IQ* as compared to the AcrySof Natural* in a prospective, randomized, double-masked study (n = 260). Patients with AcrySof IQ* had a reduction in total HOA and SA. There was no difference in coma between the two groups.
Awwad et al. (J Refract Surg. 2008;24(6):619-25) reported that compared to a spheric optic, the aspheric design of the AcrySof IQ SN60WF* reduces SA, especially under larger pupil sizes, and improves mesopic CS at higher frequencies with and without glare.
Denoyer et al. (J Cataract Refract Surg. 2009;35(3):496-503) compared the quality of vision with an aspheric IOL with no aberration: SofPort Advanced Optics (Bausch and Lomb, Inc., Rochester, New York, USA^) and an IOL with negative spherical aberration (Tecnis Z9000**). They reported that bilateral implantation of an IOL with no aberration resulted in better quality of near vision. A negative SA IOL provided better night-driving vision and improvements in mesopic CS.
Sandoval et al. (Eye 2008; 22(12):1469-75) reported an improved quality of vision with aspheric acrylic IOL (AcrysofIQ*) as a result of the reduction of total HOA and SA.
Rekas et al. (J Cataract Refract Surg. 2009;35(2):297-302) reported that SA and coma were similar in eyes with an aspheric IOL and younger phakic eyes, although HOA was higher in pseudophakic eyes. There were no differences between pseudophakic eyes and older phakic eyes in coma and HOA, although pseudophakic eyes had lower SA.
Nabh et al. (J Cataract Refract Surg. 2009;35(2):347-53) compared BCVA, CS, visual function score, and patient satisfaction with the Tecnis Z900** IOL (43 eyes), AcrySof SN60WF* IOL (41 eyes) and Akreos Adapt AO^ IOL, (46 eyes). With 4.0 mm, 5.0 mm, and 6.0 mm pupil diameters, the mean SA was found to be significantly less with AcrySof SN60WF* and Akreos Adapt AO^ IOLs than with the Tecnis Z9003** IOL. There were no significant differences in total higher-order root-mean-square (RMS) values between IOLs. Visual performance scores with all the three IOLs were comparable.
Teichman and Ahmed (Curr Opin Ophthalmol. 2009 Dec 25. [Epub ahead of print]) observed that decreased CS seen in glaucoma may be enhanced by use of aspheric IOLs.
Cadarso et al. (J Refract Surg. 2008;24(8):811-6) reported that significant reduction in ocular SA was noted after AcrySof IQ* IOL implantation, at all pupil diameters compared to the spherical IOL, although photopic BCVA between groups remained similar.
Su and Hu (J Refract Surg. 2009;25(3):265-72) reported significantly reduced total ocular and SA with Tecnis Z9000** aspheric IOL as compared with the conventional spherical IOL (AcrySof single-piece SA60AT*), but this was not seen to result in better functional vision under mesopic or photopic conditions. Small pupil size may be a factor, which limits the beneficial effect of aspheric IOLs on visual performance.
Posterior Capsular Opacification
Biber et al. (J Cataract Refract Surg. 2009;35(7):1234-8) reported that IOL configuration may contribute to the difference in the posterior capsular opacification (PCO) rate between spherical and aspheric IOL. Based on the Nd:YAG rate as an indicator for visual significance, PCO may be less visually significant in eyes with the aspheric IOL than in eyes with the spherical IOL.
Reduced depth of focus, degradation of distance-corrected near vision
Nanavaty et al. (J Cataract Refract Surg. 2009;35(4):663-71) in a prospective randomized controlled study comprising patients with bilateral cataract who received an aspheric AcrySof SN60WF* IOL or a spherical AcrySof SN60AT* IOL in the first eye and the other IOL in the second eye reported significantly better mesopic CS; reduced total and internal spherical aberrations with the aspheric IOL but no significant difference in BCVA or photopic CS. The aspheric IOL group had 0.46 diopter less depth of focus than the spherical IOL group at six months (P<.05). Distance-corrected near acuity was significantly better with the spherical IOL. They concluded that reduction of aberrations may reduce depth of focus with aspheric IOLs. This may be disadvantageous for near vision and reading ability.
Rocha et al. (Ophthalmology 2007;114:2050-4) reported that reduction of total SA with aspheric IOL (AcrysofIQ*) may degrade distance-corrected near and intermediate VA.
Effect of tilt and decentration
Eppig et al. (J Cataract Refract Surg. 2009;35(6):1091-100) reported that aberration-correcting IOLs were very sensitive to decentration and tilt.
Baumeister et al. (J Cataract Refract Surg. 2009;35(6):1006-12) reported that the amounts of tilt and decentration of both aspheric and spherical IOLs were not large enough to cause deterioration of optical quality. The mean optic tilt was 2.89±1.46° (SD) for the spherical IOL and 2.85±1.36° for the aspheric IOL. The mean optic decentration was 0.19±0.12 mm and 0.27±0.16 mm, respectively. No significant intergroup differences in IOL tilt or decentration were found.
Blue-Filtering Intraocular Lenses: Role in Age-Related Maculopathy
Algvere et al. (Acta Ophthalmol Scand. 2006;84(1):4-15) in their review commented that short-wavelength radiation (rhodopsin spectrum), and the blue light hazard (excitation peak 440 nanometer) have a major impact on photoreceptor and RPE function, inducing photochemical damage and apoptotic cell death. Following cataract surgery, there is a dramatic change in ocular transmittance. Epidemiological data indicate a significantly increased five-year incidence of late age-related maculopathy (ARM) in non-phakic eyes compared with phakic eyes. The authors suggested that the implantation of 'yellow' IOLs that absorb high-energy blue radiation might be helpful in preventing ARM.
Yanagi et al. (J Cataract Refract Surg. 2006;32(9):1540-4) noted that in cases without an IOL, the white-light exposure decreased cell viability to 28% of the non-irradiated control. Although the UV-absorbing IOL tended to reduce light-induced cell death, the decrease was not significant. The blue-light-filtering IOL was noted to significantly attenuate light-induced cell damage, increasing cell viability to 42%. The presence of the blue-light filtering IOL significantly attenuated the upregulation of VEGF expression compared to upregulation without an IOL. Their study supports the theory that a blue-light-filtering IOL may be more protective against A2E-induced photochemical damage and inhibit more light-induced VEGF production than a conventional UV-absorbing IOL.
The Controversies: Effect on Color Vision, Contrast Sensitivity and Scotopic Vision
Hammond et al. (Am J Ophthalmol. 2009;148(2):272-276) performed a study on 58 subjects: 17 with yellow IOLs (AcrySof Natural*; SN60WF), 20 with clear IOLs, and 21 phakic controls. Subjects with AcrySof Natural* (P < .0001) and clear IOLs (P < .035) were noted to withstand significantly more light than the phakic controls. Subjects with the AcrySof Natural* lens could withstand significantly more light (P < .02) than subjects with clear IOLs. Photostress recovery was noted to be significantly longer for subjects with clear IOLs vs. phakic controls (P < .01), but the AcrySof Natural* lens was not different from phakic controls (P < .09). This study concluded that the AcrySof Natural* lens is related to reduced glare disability relative to a clear IOL or phakic controls.
Wirtitsch et al. (Ophthalmology 2009;116(1):39-45) in their study randomly assigned and implanted a blue-light-filtering Hoya AF-1 (UY) YA-60BB IOL (Hoya Medical Europe, Frankfurt/Main, Germany) in one eye and a UV-filtering Hoya AF-1 (UV) VA-60BB IOL (Hoya Medical Europe, Frankfurt/Main, Germany) in the contralateral eye. They reported that the blue-light-filtering IOLs had worse contrast acuity (P = 0.0004) and foveal threshold (P = 0.008) compared with the UV-filtering IOLs. Color vision tests and high-contrast visual acuity did not show any statistically significant difference. They recommended bilateral implantation of the same IOL type and avoidance of a mixed implantation of a blue-light-filtering IOL in one and a non-blue-light-filtering IOL in the contralateral eye.
Schmidinger et al. (J Cataract Refract Surg. 2008;34(5):769-73) noted no clinically significant difference in CS with blue-light-filtering IOLs.
Greenstein et al. (J Cataract Refract Surg. 2007;33(4):667-72) reported no significant effect on scotopic sensitivity and hue discrimination with yellow-tinted IOL.
Muftuoglu et al. (J Cataract Refract Surg. 2007;33(4):658-66) implanted AcrySof SN60AT Natural* IOL and eyes with a conventional AcrySof SA60AT* IOL and found no statistically significant difference in photopic CS, scotopic CS with and without glare, or disability glare between the two groups.
Hayashi K and Hayashi H (Br J Ophthalmol. 2006;90(8):1019-23) reported no significant differences between the yellow tinted (HOYA YA60BB, Tokyo, Japan) and non-tinted (VA60BB) IOL groups in mean VA or in photopic or higher luminance mesopic contrast VA with and without glare source at either two weeks or three months after surgery. The incidence of patients who noticed cyanopsia was significantly less in the yellow tinted IOL group than in the non-tinted IOL group at two weeks after surgery (P = 0.0234), but no patients reported cyanopsia at three months.
Rodríguez-Galietero et al. (J Cataract Refract Surg. 2005;31(11):2088-92) reported a better CS with the AcrySof Natural* IOL than AcrySof SA60AT* in diabetic patients.
Yuan et al. (Am J Ophthalmol. 2004;138(1):138-40) reported that the yellow UV IOLs showed statistically significantly higher spatial CS than ordinary UV IOLs in the low and middle frequencies. There was no significant difference in color vision but the incidences of photophobia and cyanopsia were less in patients who received the yellow UV IOLs.
Cionni and Tsai (J Cataract Refract Surg. 2006;32(2):236-42) reported that the Farnsworth-Munsell 100-hue testing showed no difference in color perception between subjects with AcrySof Natural* IOLs and those in an age-matched phakic control group or in those with a UV-only filtering AcrySof* IOL.
Mainster and Turner (Surv Ophthalmol. 2009 Oct 31) in their review of blue-blocking IOLs commented that restriction of violet and blue light adversely affects pseudophakic photopic luminance contrast, photopic S-cone foveal threshold, mesopic contrast acuity, scotopic short-wavelength sensitivity and circadian photoreception.
Implications in Ophthalmic Investigations and Procedures
Shiraya et al. (Acta Ophthalmol. 2009 Sep 11) studied the influence of a yellow-tinted IOL on laser beam transmittance. They found no apparent differences in transmittance values between the tinted and clear IOLs when the 521, 568 and 647 nm wavelengths were used. In contrast, the transmittance ratio decreased for the tinted IOL when the short wavelengths - 488 nm and 514 nm - were used, especially when an IOL of a higher dioptric power was used. This ratio was found to be 91.9% for a +10 D, 86.7% for a +20 D and 82.2% for a +30 D lens when a 488 to 514 nm wavelength beam was used. They suggested that when treating patients using photocoagulation, one must bear in mind the decreased transmittance ratio of short-wavelength laser beams when passed through tinted IOLs and increase the setting power of the beam accordingly.
Visualization in vitreoretinal surgeries
Falkner-Radler et al. (Am J Ophthalmol. 2008;145(3):499-503) reported that the blue light-filter IOLs did not reduce visualization during vitreoretinal surgery.
Retinal Nerve Fibre Layer (RNFL) photography
Vuori and Mantyjarvi (Acta Ophthalmol Scand. 2006;84(1):92-4) reported that the Acrysof Natural* blue-filtering IOL did not interfere with RNFL photography and can also be used in patients with glaucoma.
Frequency Doubling Technology (FDT) Perimetry
Ueda et al. (Am J Ophthalmol. 2006;142(5):856-8) evaluated the effect of IOL color on FDT and reported no effect during interpretation of the results of FDT perimetry.
Short-wavelength Automated Perimetry (SWAP)
Kara-Junior et al. (J Cataract Refract Surg. 2006;32(8):1328-30) reported no interference of yellow filter of AcrySof Natural* IOL in blue-yellow perception in SWAP.
Auffarth and Dick (Ophthalmologe 2001;98(2):127-37) in their review opined that earlier multifocal IOLs were associated with decentration, surgically-induced astigmatism, reduced CS and increased glare. The newer multizonal, progressive refractive IOLs combined with improved surgical techniques have overcome those problems.
Jacobi et al. (Ophthalmology 2001;108(8):1375-80) separately reported that multifocal IOL is a viable alternative to monofocal IOL in pediatric patients in the age group two to 14 years and in eyes with traumatic cataract (Ophthalmology 2003;110(3):531-8).
Petermeier et al. (Br J Ophthalmol. 2009;93(10):1296-301) reported that patients with anisometropic amblyopia may benefit from implantation of an AcrySof ReSTOR*.
Souza et al. (J Refract Surg. 2006;22(3):303-5) reported that in young patients with unilateral cataract, multifocal IOL implantation provides satisfactory visual acuity.
Jacobi et al. (Ophthalmology 2002;109(12):2315-24) reported that secondary scleral-fixated multifocal IOL implantation was as successful as monofocal IOL implantation in achieving BCVA comparable with preoperative BCVA. Moreover, stereopsis, uncorrected and distance-corrected near visual acuities were better in the multifocal patients than in the monofocal eyes making multifocal IOL a viable alternative in children and young patients with contact lens-intolerant aphakia.
Diffractive Multifocal IOLs
Hayashi et al. (J Cataract Refract Surg. 2009;35(12):2070-6) reported that the diffractive multifocal IOL with a low add power (ReSTOR SN6AD1* IOL with a +3.0 D add) provided significantly better intermediate and near visual acuity than the monofocal (AcrySof IQ* SN60WF) IOL. Contrast sensitivity with and without glare was reduced with multifocal IOL, and all-distance VA was independent of pupil diameter.
Castillo-Gomez et al. (J Cataract Refract Surg. 2009;35(7):1244-50) compared visual quality after bilateral implantation of Acri.LISA 366D, Carl Zeiss Meditec, Jena, Germany( # ) (Group A) or Tecnis ZM900** (Group B) multifocal IOLs. They reported that both diffractive multifocal IOLs improved functional visual capacity at distance and near and were comparable.
Alfonso et al. (Eur J Ophthalmol. 2009 Sep 30 [Epub ahead of print]) implanted multifocal IOL (AcrySof ReSTOR Natural SN60D3*) and reported good VA and CS for both distance and near, with and without distance correction in eyes with high and low myopia. Better results were seen in low myopic eyes compared to high levels of myopia.
Alfonso et al. (Eur J Ophthalmol. 2009;19(5):748-53) further reported a better VA and CS for both distance and near, with and without distance correction in eyes with low hyperopia compared to high levels of hyperopia after implantation of the same IOL.
Cionni et al. (J Cataract Refract Surg. 2009;35(6):1033-9) reported that although unilateral implantation of apodized diffractive (Acrysof ReSTOR*) multifocal IOL provided patients with high levels of spectacle freedom and good CS, overall clinical results favored bilateral implantation for stereopsis, uncorrected near VA, and BCVA for near and intermediate distance.
Refractive Multifocal IOLs
Kawamorita et al. (J Refract Surg.2009;25(5):467-9) reported that ReZoom** refractive multifocal IOL gave better image quality than the Array** refractive multifocal IOL, particularly at distant focus. For good near vision, the desired pupil size should be at least 3.45 mm.
Fernandez-Vega et al. (Am J Ophthalmol. 2009;148(2):214-220) reported that bilateral implantation of the Acri.LISA 366D IOL # provided a satisfactory full range of vision in patients with high hyperopia (IOL power 25 to 36D) comparable with that obtained in patients with low to moderate hyperopia.
Hayashi et al. (Ophthalmology 2009;116(3):401-8) observed that the refractive multifocal IOL (Hoya SFX MV1 Hoya Medical Europe, Frankfurt/Main, Germany) with minimal added power provided significantly better intermediate and near VA than a monofocal IOL.
Diffractive and Refractive Multifocal IOLs: Mix 'n' Match
Hutz et al. (Eur J Ophthalmol. 2009; Dec 12 [Epub ahead of print]) reported that the combination of a far dominant refractive (ReZoom**) multifocal IOL (with better distance performance) with a near dominant diffractive (Tecnis ZM900**) multifocal IOL (with better near vision) proved to be very suitable to help meet cataract patients' visual needs.
Chen et al. (Acta Ophthalmol. 2009 Oct 30. [Epub ahead of print]) reported that the combined implantation of refractive and diffractive multifocal (ReZoom** and Tecnis** MF) IOLs improved reading ability and near stereoacuity with a good visual quality.
Goes (J Cataract Refract Surg. 2008;34(5):755-62) implanted a refractive multifocal IOL (ReZoom**) in their dominant eye and a diffractive multifocal IOL (Tecnis**) in their non-dominant eye and reported good visual outcomes with this "mix and match" approach.
Gierek-Ciaciura et al. (Graefes Arch Clin Exp Ophthalmol. 2009 Sep 8 [Epub ahead of print]) compared the patients' visual results after bilateral implantation of three groups of multifocal intraocular lenses: ReZoom** NXG1, Acrysof ReSTOR* SA60D3 and Tecnis MF ZM900**. The results were comparable with regard to BCVA, glare and halo.
Zelichowska et al. (J Cataract Refract Surg. 2008;34(12):2036-42) implanted refractive (ReZoom**) or apodized diffractive multifocal IOLs (AcrySof ReSTOR*) and noted that both IOLs provided good visual performance at distance and near under photopic conditions. The HOA, in particular coma and SA, and photopic CS were significantly higher in the ReZoom** group (all P<.001).
Alfonso et al. (J Cataract Refract Surg. 2008;34(11):1848-54) reported that diffractive multifocal IOLs provided good and comparable VA at distance and near when implanted in patients with previous myopic laser in-situ keratomileusis. However, the aspheric Acri.LISA IOL # gave better intermediate VA than the spherical AcrySof ReSTOR* IOL.
Cillino et al. (Ophthalmology 2008;115(9):1508-16) performed a randomized prospective clinical trial comparing visual performance after bilateral implantation of the multifocal refractive Array SA40N**, multifocal refractive ReZoom** multifocal diffractive pupil-independent Tecnis ZM900** and monofocal IOLs. The monofocal IOL group exhibited a lower uncorrected and best distance-corrected near VA than the multifocal IOL groups (P<0.0005). New-generation, diffractive, pupil-independent multifocal IOLs provided better near vision, equivalent intermediate vision with less unwanted photic phenomena, and greater spectacle independence than either monofocal or refractive multifocal IOLs.
Ortiz et al. (J Cataract Refract Surg. 2008;34(5):755-62) reported that multifocal refractive IOLs resulted in higher intraocular aberrations. The hybrid refractive-diffractive IOL was least affected by pupil diameter in terms of intraocular aberrations.
Martínez Palmer et al. (J Refract Surg. 2008;24(3):257-64) evaluated the visual function of three types of multifocal IOLs: symmetric diffractive multifocal Tecnis ZM900**; zonal refractive multifocal ReZoom**; and asymmetric diffractive multifocal TwinSet (Acri.Tec # ) IOLs with Tecnis** monofocal IOL as the control group in a prospective, randomized, controlled clinical study of 114 patients. They reported that the monofocal IOL showed better visual function and lesser photic phenomena than multifocal IOLs but patients were spectacle-dependent. ReZoom** provided better distance BCVA than the TwinSet # diffractive model. Patients with Tecnis** and TwinSet # diffractive multifocal IOLs were more spectacle independent than patients with ReZoom**. Patients with TwinSet # had less favorable CS scores. Patients with Tecnis** diffractive ZM900 IOL reported more photic phenomena.
Palomino Bautista et al. (Eur J Ophthalmol. 2009;19(5):762-8) in their study with multifocal Tecnis** IOL in 250 eyes observed that most patients required a neuroadaptation period of nearly six months to experience full visual benefits of the lens.
Kaymak et al. (J Refract Surg. 2008;24(3):287-93) investigated the efficacy of a special visual training program on the postoperative visual performance with ReSTOR* and Technis** IOLs and reported an accelerated visual performance by a specific two-week training program. This effect was sustained over a six-month period.
Woodward et al. (J Cataract Refract Surg. 2009;35(6):992-7) analyzed the reasons for patient dissatisfaction after multifocal IOL implantation. Thirty-two patients (43 eyes) reported unwanted visual symptoms after multifocal IOL implantation, that included 28 eyes (65%) with an AcrySof ReSTOR* IOL and 15 (35%) with a ReZoom** IOL. Thirty patients (41 eyes) reported blurred vision, 15 (18 eyes) reported photic phenomena, and 13 (16 eyes) reported both. Causes of blurred vision included ametropia (12 eyes, 29%), dry eye syndrome (six eyes, 15%), posterior capsule opacification (PCO) (22 eyes, 54%), and unexplained etiology (one eye, 2%). Causes of photic phenomena included IOL decentration (two eyes, 12%), retained lens fragment (one eye, 6%), PCO (12 eyes, 66%), dry eye syndrome (one eye, 2%), and unexplained etiology (two eyes, 11%). Three eyes (7%) required IOL exchange. The authors recommended that Neodymium:YAG capsulotomy should be delayed until it has been determined that IOL exchange will not be necessary.
Leyland and Zinicola (Ophthalmology 2003;110(9):1789-98) reported reduced CS and subjective experience of halos around lights with these IOLs.
Ito and Shimizu (J Cataract Refract Surg. 2009;35(9):1501-4) reported that the reading ability after bilateral cataract surgery was better in patients who had pseudophakic monovision than patients who had refractive multifocal IOL implantation.
Hofmann et al. (J Refract Surg. 2009;25(6):485-92) reported that patients with diffractive IOL had significantly more glare for all light conditions, especially at night.
Negishi et al. (Jpn J Ophthalmol. 2005;49(4):281-6) reported that up to 1.0 mm of decentration of a monofocal and multifocal IOL would not greatly affect the retinal image quality.
Elgohary et al. (J Cataract Refract Surg. 2007;33(2):342-7) reported opacification of two silicone multifocal IOLs.
Inoue et al. (J Cataract Refract Surg. 2009;35(7):1239-43) reported aberrations with diffractive multifocal IOLs and attributed it to the optical design of the IOLs.
Toric Intraocular Lenses: A step towards postoperative emmetropia
Statham et al. (Clin Experiment Ophthalmol. 2009;37(8):775-9) reported that the AcrySof Toric* IOL was noted to provide a significant improvement in postoperative astigmatism and uncorrected visual acuity (UCVA) when compared statistically with its spherical counterpart for patients with low degrees of corneal astigmatism.
Lane et al. (J Refract Surg. 2009;25(10):899-901) reported that patients with bilateral AcrySof Toric* IOLs achieved superior spectacle freedom, residual refractive cylinder, and distance UCVA compared to patients with bilateral spherical control IOLs.
Mendicute et al. (J Cataract Refract Surg. 2009 Mar;35(3):451-8) compared toric IOL implantation with paired opposite clear corneal incisions (OCCIs) for correction of preexisting corneal astigmatism of more than 1.00 diopters in patients undergoing cataract extraction. The authors concluded that toric IOL implantation achieved a slight enhanced effect over OCCIs in treating preexisting astigmatism.
Bauer (J Cataract Refract Surg. 2008;34(9):1483-8) reported that implantation of the AcrySof Toric* IOL proved to be an effective, safe, and predictable method of managing corneal astigmatism in cataract patients.
Mendicute et al. (J Cataract Refract Surg. 2008;34(4):601-7) also performed a similar study and reported that phacoemulsification and posterior chamber AcrySof Toric* IOL implantation is an effective option to correct preexisting astigmatism in cataract surgery.
Tehrani et al. (J Cataract Refract Surg. 2003;29(12):2444-7) reported implantation of an IOL with a torus of 30.0 diopters (D) in the capsular bag in an eye after penetrating keratoplasty. Additionally, a spherical IOL of -15.0D sphere was implanted in the ciliary sulcus. Six months after implantation, the IOLs were noted to be well centered and the UCVA was 20/60.
Navas and Suarez (J Cataract Refract Surg. 2009 Nov;35(11):2024-7) reported two cases of toric IOL implantation for keratoconus with stable refraction for at least five years.
Rotational Stability: A concern
Pereira et al. (Eye. 2009 Jun 26. [Epub ahead of print]) evaluated the rotational stability of the Acrysof Toric* IOL after experimental eye trauma in human cadaver eyes. The IOL rotated 5.8° and 41.0° in the absence and presence of leakage from the incision respectively.
Chang (J Cataract Refract Surg. 2008;34(11):1842-7) compared the rotational stability of single-piece open-loop acrylic (AcrySof SN60T Toric*) and plate-haptic silicone toric (AA4203 Toric) IOLs and concluded that both toric IOLs had good rotational stability; former being statistically better, with good reduction in preexisting corneal astigmatism.
Rollable IOLs: Evolving IOL technology for microincision cataract surgery (MICS)
Kaufmann et al. (J Cataract Refract Surg. 2009;35(9):1555-62) reported that biaxial MICS with insertion of an UltraChoice 1.0 Rollable Thinlens (ThinOptx, Abingdon, VA ## ) through a temporal incision of 2.0 mm offers prospects of astigmatic neutrality in cataract surgery.
Ouchi and Kinoshita (Eye.2009;23(3):703-7) reported that as the ThinOptX rollable lens ## is designed for negative SA, they encountered smaller whole SA and higher CS with the ThinOptix # # lens than with the Acrysof* lens.
Mencucci et al. (J Cataract Refract Surg. 2006;32(2):318-23) analyzed the surface quality before and after folding of two IOL models designed for MICS: UltraChoice 1.0 Rollable ThinLens## and AcriSmart#. After folding, the IOLs showed no sign of surface alteration, probably because of high water content, which makes them soft and flexible.
Kaya et al. (Eur J Ophthalmol. 2007;17(3):307-14) observed an increased rate of PCO with ThinOptX IOL## on long-term evaluation.
The Future: Conquering Presbyopia-the final frontier
Accommodative IOLs: Finally, a cure for Presbyopia?
Patel et al. (J Refract Surg. 2008;24(3):294-9) compared the visual outcomes of two IOLs (AcriSmart # [multifocal] and AT-45 [accommodative]) for correction of distance and near VA with laser in situ keratomileusis (LASIK) procedure for presbyopia (presbyLASIK) and a control group fitted with a standard distance-correcting monofocal IOL (Acrysof*). The distance and near acuities improved with presbyLASIK and AcriSmart IOLs # when compared with controls. In those patients treated with the AT-45 IOL, average visual acuity improved for distance but not for near.
Harman et al. (Ophthalmology 2008;115(6):993-1001) reported a better near vision with 1CU accommodating IOL (Human Optics, Erlangen, GermanyΩ ) compared to a monofocal IOL, but with photopic phenomena.
Pepose et al. (Am J Ophthalmol. 2007;144(3):347-357) compared the visual performance of patients with bilateral vs. combination Crystalens^, ReZoom**, and ReSTOR* IOLs. Monocular testing showed that eyes with Crystalens^ accommodating IOL had statistically better best spectacle-corrected distance, uncorrected and distance-corrected intermediate, and best-corrected near vision. Eyes with the ReSTOR* multifocal IOL had better uncorrected near vision, required the lowest reading add, and had the lowest uncorrected and distance-corrected intermediate vision. Monocular mesopic CS with and without glare was better with the Crystalens^ IOL vs. either multifocal IOL at specific spatial frequencies. Any combination of Crystalens^ in one or both eyes was better for intermediate vision. Any combination of ReSTOR* in one or both eyes was better for near vision. The Crystalens^ and ReSTOR* combination had better mean intermediate and near vision. A multifocal IOL in one or both eyes was associated with lower CS and more photic phenomena. The accommodating and multifocal IOL combinations elicited less night glare symptoms than in patients with either bilateral multifocal IOL, but more than with bilateral Crystalens^ implantation. The binocular subjective quality of vision and quality of life questionnaires were favorable for the bilateral Crystalens^ group.
Mesci et al. (Eur J Ophthalmol. 2010;20(1):90-100) in a comparative study found that the diffractive multifocal IOL resulted in more favorable visual acuities and higher CS values than accommodative and refractive multifocal IOL.
Limitations of the Present Technology
Wolffsohn et al. (Br J Ophthalmol. 2006;90(6):693-6) reported that the accommodative ability of the lens appears to decrease by six months post-surgery.
Mastropasqua et al. (Acta Ophthalmol Scand. 2007;85(4):409-14) reported that patients implanted with 1CUΩ IOLs lost their accommodation capacities with time because of the high incidence and degree of anterior and posterior capsule opacification.
Sandstedt et al. (Trans Am Ophthalmol Soc. 2006;104:29-39) assessed the feasibility of creating customized multifocal and aspheric patterns onto a light-adjustable lens (LAL) using a digital light delivery (DLD) system. Silicone LALs were placed in a wet cell and irradiated in vitro using the DLD. Spatial intensity patterns were designed and generated to (1) create a multifocal optic with customized power and diameter and (2) simultaneously correct defocus and spherical aberration. In addition, the LALs were adjusted in vivo for defocus and spherical aberration using a rabbit model. In vitro creation of multifocal patterns demonstrated ability to reproducibly customize zone diameter and power. Both bull's-eye bifocal and annular patterns were successfully created on LAL. Spherical aberration was reduced simultaneously with correction of hyperopia and myopia, both in vitro and in vivo. Additionally, these customized spatial intensity profiles can be written onto an LAL that is first adjusted to emmotropia. The ability to readjust the LAL was demonstrated.