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Accommodation in pseudophakic eyes
Taiwan Journal of Ophthalmology 2 (2012) 117e121
Contents lists available at SciVerse ScienceDirect
Taiwan Journal of Ophthalmology journal homepage: www.e-tjo.com
Review article
Accommodation in pseudophakic eyes Ming Chen a, b, * a b
University of Teesside, UK University of Hawaii, Honolulu, HI, USA
a r t i c l e i n f o
a b s t r a c t
Article history: Received 8 March 2012 Received in revised form 4 April 2012 Accepted 4 May 2012 Available online 11 July 2012
Purpose: Today, many patients who have undergone cataract surgery want to enjoy good non-spectacle corrected distant vision and nonspectacle corrected near vision with glasses independence. According to the literature, the implantation of an accommodative intraocular lens (AIOLs) can achieve the level of vision after cataract surgery. However, there is a debate regarding the true accommodative capability of the AIOLs (i.e., whether the IOLs can move forward when attempting to accommodate like the natural crystalline lens of a phakic eye). This review aims to answer the following questions: (1) Can pseudophakic eye accommodate? (2) If pseudophakic eyes can accommodate, how long does this accommodation last? (3) Is there pseudoaccommodation? Methods: This is a systematic review of randomized and nonrandomized controlled trials that have compared different IOLs in accommodation using subjective and objective methods of testing accommodation. All peer reviewed randomized and nonrandomized controlled trials that compared different IOLs in accommodation were included. Results: There was evidence of pseudophakic accommodation up to 12 months postoperatively for AIOLs (mostly 1CU): subjective accommodation [95% confidence interval (CI), 0.36e0.98], objective optic shift (95% CI, 0.12e0.76). However, accommodation decreased at 12 months postoperatively (95% CI, 0.55e1.00). In addition, several papers have reported evidence of pseudoaccommodation. Conclusion: There is pseudophakic accommodation up to 1 year post cataract surgery, mostly 1CU AIOL. Pseudoaccommodation may coexist. Copyright Ó 2012, The Ophthalmologic Society of Taiwan. Published by Elsevier Taiwan LLC. All rights reserved.
Keywords: accommodation cataract surgery intraocular lens implant intraocular lens optic shift pseudoaccommodation
1. Introduction The ability of accommodation in accommodative intraocular lens (AIOLs) has been demonstrated in multiple studies by objective and subjective methods.1 Accommodation involves three mechanisms: contraction of the ciliary muscle, convergence of the eye, and constriction of the pupil.2 Accommodation is a necessary physiological mechanism that enables the human eye to see things up close. Pseudophakic accommodation refers to the accommodation of an eye when its crystal lens has been replaced by an intraocular lens (IOL) during cataract surgery. This change in the power of the eye may be accomplished by a forward movement the intraocular lens upon contraction of the ciliary muscle; at that point, convergence of the eye, and constriction of the pupil are actively occurring.
* 55 South Kukui Street, Honolulu, HI, USA. E-mail address: [email protected].
Some eyes that were corrected for distant vision with a monofocal IOL (nonaccommodative) also achieved a high level of near visual acuity with distance correction after cataract surgery.3 This raises the question, “Is there a pseudoaccommodative effect?” Pseudoaccommodation is not a true accommodation of pseudophakic eyes; rather, it is the ability of the eyes to allow near vision, possibly due to various aberrations in the optical system of the eyes. These optical aberrations are independent of the ciliary muscle’s contraction.4e9 The factors that allow for pseudoaccommodation include the depth of field, which may be affected by pupil size, ptotic eyelids, and squinting.10 Pseudoaccommodation may also involve residual myopic astigmatism and polychromatic and monochromatic higher-order aberrations of the eye (e.g., spherical aberration and coma).10 Therefore, subjective tests alone cannot easily distinguish the accommodative and pseudoaccommodative components that together allow near vision. In the control trials analyzed in this review, the following methods were used to measure accommodation: objective techniques (PlusOptix PowerRefractor videorefractometry, streak
2211-5056/$ e see front matter Copyright Ó 2012, The Ophthalmologic Society of Taiwan. Published by Elsevier Taiwan LLC. All rights reserved. http://dx.doi.org/10.1016/j.tjo.2012.05.002
118
M. Chen / Taiwan Journal of Ophthalmology 2 (2012) 117e121
retinoscopy) and subjective techniques [subjective near point (push-up test, accommodometer), defocusing]; static with pharmacologic stimulation after Pilocarpine 2% eye drops directly (conventional refractometry); indirectly (change in the anterior chamber depth with Zeiss IOLMaster).11e15 Objective measurements of accommodation are necessary to evaluate commercially available AIOLs in a scientific manner. The objective parameters include measurements of changes in the anterior chamber depth as well as measurements of autorefraction.
Points were deducted if The method of randomization was described but was inappropriate. The method of blinding was described but was inappropriate.
2.5. Data extraction Data were collected for the following outcome measures:
2. Methods The meta-analysis was not considered because the trials were not all homogeneous. In order to draw some conclusion for a relative merit of this topic, a systematic review of the best-quality data is necessary. Peer-reviewed randomized and nonrandomized control trials were selected because of their validity and the objective outcomes. 2.1. Inclusion criteria 2.1.1. Types of studies All peer-reviewed randomized and nonrandomized controlled trials that compared different IOLs in the context of accommodation were included. 2.1.2. Types of participants The participants were individuals aged 19 years or older who had undergone cataract surgery and received intraocular lens implants. 2.2. Exclusion criteria Congenital cataract patients were excluded from the study due to potential differences in the treatment plans. 2.3. Search methods: electronic search The Cochrane Central Register of Controlled Trials (Central) on the Cochrane Library, MEDILINE, Journal of Cataract and Refractive Surgery, and PubMed from 1966 to 2010 were searched. Seventeen papers were identified as meeting the inclusion criteria for this review. These included 13 randomized control studies and four nonrandomized control studies. A total of 1111 eyes were included in the 17 trials. 2.4. Assessment of study validity and quality Trial quality was assessed according to the methods described in Section 6 of The Cochrane Handbook for Systematic Reviews of Interventions.16 A score ranging from 0 to 5 was allocated according to the method of Jadad et al.17 Each question required either a “yes” or “no” answer. Each “yes” answers would score a single point and each “no” answers scored zero points. The questions were as follows: 1. Was the study described as randomized? 2. Was the study described as double blind? 3. Was there a description of withdrawals and dropouts? Additional points were given if The method of randomization was described in the paper, and the method was appropriate. The method of blinding was described and it was appropriate.
(1) More accommodative power in accommodative IOLs compared to controls (2) More optic shift in accommodative IOLs compared to controls (3) Postoperative time at time of study
2.6. Data synthesis Data syntheses were performed by creating a table listing all 17 papers with the comparison among accommodative IOLs and standard IOL in terms of accommodation, optic shift, and the postoperative time. This study has been approved by the institutional review board of the University of Teesside for ethical issues and complied with the Declaration of Helsinki. 3. Results 3.1. Search results The initial electronic searches found a total of 332 papers: PubMed 33, Cochrane 11, Medline 109, Journal of Cataract Refractive Surgery 168, and Reference & Manufacturer 11. A total of 164 titles and abstracts were selected for review, as shown in Table 1.18,19,25e27,30e41 After reading the full text as a second selective procedure, 17 papers were identified as meeting the inclusion criteria for this review (PubMed 2, Cochrane 2, Medline 7, JCRS 6). There were 13 randomized control studies and four nonrandomized control studies. A total of 1111 eyes were included from the 17 trials as shown in Table 2. 3.2. Quality of the included studies (1) The Jadad scores for the 17 trials included were as follows: 76.4% had a score of 2 or higher, 23.6% had a score of 0, 42.4% had a score of 2, 10% had a score of 3, and 24% had a score of 4 (Fig. 1).
Table 1 Search results. Number discarded due to irrelevance
Number duplicated from another database
Number reviewed by title and abstract
Database or method
Number of articles found
PubMed Medline Cochrane JCRS Reference & Manufacturer Total
33 109 11 168 11
23 54 8 79 4
2 3 1 12 0
10 55 3 89 7
332
168
18
164
M. Chen / Taiwan Journal of Ophthalmology 2 (2012) 117e121
(2) The Critical Appraisal Skills Program (CASP) was used to evaluate randomized control trials. Most trials complied with the requirements for validity (Fig. 2). Table 2 Results after reading the full text of articles from the first selection. Database or method
PubMed Medline Cochrane JCRS Reference & Manufacturer Total
Number reviewed by title and abstract (first selection)
Number selected after reading the full text (second selection)
10 55 3 889 7
2 7 2 6 0
164
17
119
Power: Did the study have enough participants? One trial Results: What were the main results, and how were the results presented? All 17 trials Precise: Were the results precise? All 17 trials Apply: Could the outcome be applied to other populations? Sixteen trials (Tables 3 and 4). Table 3 List of standard monofocal posterior chamber IOLs compared in this review. Material PMMA MA30AC MA60BM AcrysoftIQ SN60AT Akeros
Polymethylmethacrylate Hydrophobic acrylic Hydrophobic acrylic Hydrophobic acrylic Hydrophobic acrylic Hydrophobic acrylic
Manufacturers
Design
Various companies Alcon Alcon Alcon Alcon Bausch-Lomb
Multi-piece Multi-piece Multi-piece Single-piece Single-piece Single-piece
Table 4 List of accommodative IOLs (AIOLs) compared in this review. Material ICU Tetraflex Crystalens BioComfold
Hydrophobic acrylic Hydrophobic acrylic Silicone elastomer Silicone
Manufacturers
Design
HumanOptics AG Lenstec, Inc. Eyeonics, Inc. Morcher
Single-piece Single-piece Single-piece Single-piece
3.3. Results of data synthesis Results of data synthesis are shown in Table 5. Table 5 A list of control trials that demonstrated the presence or absence of “more accommodation” and “more optic shift” in AIOLs compared to standard IOLs.
Fig. 1. Pie distribution of Jadad’s scores for the17 trials: 76.4% had scores of 2 and above.
Vamosi et al18 Chen19 Rocha et al25 Shentu et al26 Altan-Yaycioglu et al27 Marchini et al30 31
Schneider Li et al32 Hancox et al33 Harman et al34 Wolffsohn et al35 Dogru et al36 Sauder et al37 Legeais et al38 Fig. 2. Summary of the appraisal of 17 trials with CASP (Critical Appraisal Skills Program). RCT (Randomized control Trials).
The following criteria were assessed for the (CASP) program: Question: Was there a clearly focused question? All 17 trials RCT: Was this a randomized controlled trial? Thirteen trials (76%) Allocation: Were participants appropriately allocated to the intervention and control groups? All 17 trials Blind: Were the participants, staff, and study personnel “blind” to the participants’ study groups? Four trials Drop out: Did any of the participants who entered the study subsequently leave? One trial Data collection: Were data collected in the same way for all the groups? All 17 trials
Mastropasqua et al39 Findl and Leydolt40 Heatley et al41
IOL
More More optic accommodation shift
Post op
Akeros vs. MA60BM AcrysoftIQ vs. MA30AC AcrysoftIQ vs. SN60AT AcrysoftIQ vs. SN60AT Acrysoft vs. PMMA
Positive Positive
Yes N/A
N/A
No
12 mo 71/ 2 mo N/A
Positive
No
N/A
N/A
No
N/A
1CU & Crystalens vs. mono 1CU vs. PMMA Tetraflex vs. Acrysoft 1CU vs. MA30AC 1CU vs. monofocal Tetraflex vs. Softec 1CU vs. Acrysoft 1CU vs. foldable IOL BioComfold vs. foldable 1CU vs. IFP6.0
Positive
Yes
2 mo
Negative Positive Positive Negative Positive Positive Positive Negative
No N/A Yes N/A N/A N/A Yes Yes
3 mo 6 mo N/A 18 mo 6 mo 6 mo 8 mo N/A
Positive
N/A
6 mo
1CU vs. MA30AC
Positive
Yes
3 mo
1CU vs. MA30AC
Positive
N/A
6 mo/ 1y
Five studies in this list were the comparison between standard IOLs. N/A ¼ not available; Post-op ¼ postoperative time at time of study.
3.4. Summary of the results Of the 17 trials, 12 investigated AIOLs (71%) and nine trials investigated 1CU AIOLs (75%). Two trials investigated Tetraflex AIOLs, one studied the Crystalens AIOLs, and one studied the BioComfold AIOLs.
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Six out of the nine 1CU trials (67%) showed more accommodation in diopters compared to the standard IOL [95% confidence interval (CI), 0.36e0.98] when measurements were obtained from 2 months to 1 year postoperatively. Four out of the nine 1CU AIOLs (44%) trials demonstrated an optic shift (95% CI, 0.12e0.76). There were two Tetraflex accommodative IOL trials. Both demonstrated an increase in accommodation but no optic shift compared to the control IOL at up to 6 months postoperatively. Some nonaccommodative IOLs (NAIOLs) such as the Akeros and the AcrysoftIQ had more accommodation compared to the other NAIOLs. Akeros IOL (Hydrophilic Acrylic, Bausch-Lomb) showed more accommodation and optic shift compared to MA60BM (Alcon, multipiece Acrysof) at up to 1 year.18 Overall, 75% of the trials found more accommodation in AIOLs compared to standard IOLs. However, seven out of the nine trials (78%) that reported more accommodation in accommodative IOLs showed a decrease in accommodation as the postoperation time increased to 12 months (95% CI, 0.55e1.00). The remaining accommodation could not be differentiated from pseudoaccommodation. 4. Discussion This review included 17 trials that measured and compared pseudophakic accommodation among AIOL and NAIOLs. Trial quality was rigorously evaluated using the Jadad score and the CASP. Most trials complied with the requirements for validity. However, some showed weakness in blinding, power, or description of dropouts. Most of the trials investigated 1CU AIOLs, indicating that the results were mostly pertinent to 1CU AIOLs. According the result, patients who received AIOLs after cataract surgery enjoyed more accommodation compared to those patients who received NAIOLs up to 1 year. There was one trial that demonstrated more accommodation from the Akeros IOL (Hydrophilic Acrylic, Bausch-Lomb NAIOL) compared to another NAIOL MA60BM (Alcon, multipiece Hydrophobic Acrysof) at up to 1 year. Therefore, the design and the material of AIOLs or NAIOLs may be the contributing reason to those patients to have short-term ability of accommodation. There was a lack of valid studies on other AIOLs such as the Crystalens. In this review, the characteristics of pseudoaccommodation were studied and described to explain the ability of pseudophakic participants in these studies to read without accommodation. Pseudoaccommodation and monovision may contribute to the success of AIOLs despite a decrease in accommodation over time. For clinical and practical reason, in the attempt to allow patients to use a standard NAIOL without reading glasses, the following features of pseudoaccommodation can be considered. (1) Achieving less negative accommodation (back shift of the IOL).19 (2) Incorporating the formula of for mini-monovision in the IOL power calculation.20e22 (3) Leaving 1e2 diopters of myopic astigmatism and virtually no sphere in the nondominant eye.23 (4) Leaving the eyes with larger vertical coma aberrations that can achieve a larger range of accommodation.24 (5) Maintaining total spherical aberration without aspheric IOL implantation, which may enhance distance-corrected near and intermediate vision.25,26 (6) The posterior position of the IOL in the eye (closer to the nodal point). (7) The presence of a small pupil (Increased depth perception). (8) An uncomplicated small-incision phacoemulsification surgery with a continuous curvilinear capsulorhexis and an in-the-bag implanted soft lens.27
(9) The improvement of distance-corrected near vision is better with a larger continuous curvilinear capsulorhexis and with less overlapping of the optic.28 (10) Good patient selection and preoperative consultation.29 Future studies should focus on how to further develop new generation of accommodative IOLs such as the Synchrony (dualoptic design) or NuLens. 5. Conclusion This review showed evidence of pseudophakic accommodation in AIOLs and NAIOLs up to 12 months postoperatively (mainly in 1CU AIOLs). However, most of the IOLs showed a decrease in accommodation as the postoperative time increased to 12 months. Pseudoaccommodation may play a role in the ability to attain distant corrected near vision. References 1. Cumming JS, Colvard M, Dell S. Clinical evaluation of the Crystalens AT-45 accommodating intraocular lens: results of the U.S. Food and Drug Administration clinical trial. J Cataract Refract Surg 2006;32:812e25. 2. Coleman DJ, Fish SK. Presbyopia, accommodation, and the mature catenary. Ophthalmology 2001;108:1544e51. 3. Leyland MD, Langan L, Goolfee F. Prospective randomized double-mask trial of bilateral multifocal, bifocal or monofocal intraocular lens. Eye 2002;16:481e90. 4. Huber C. Myopic astigmatism: a substitute for accommodation in pseudophakic. Doc Ophthalmol 1981;52:123e78. 5. Trindade F, Oliveira A, Frasson M. Benefit of against-the-rule astigmatism to uncorrected near acuity. J Cataract Refract Surg 1997;23:82e5. 6. Nakazawa M, Ohtsuki K. Apparent accommodation in pseudophakic eyes after implantation posterior chamber intraocular lenses: optical analysis. Invest Ophthalmol Vis Sci 1984;25:1458e60. 7. Fukuyama M, Oshika T, Amano S, Yoshitomi F. Relationship between apparent accommodation and corneal multifocality in pseudophakic eyes. Ophthalmology 1999;106:1178e81. 8. Oshika T, Mimura T, Tanaka S, Amano S, Fukuyama M, Yoshitomi F. Apparent accommodation and corneal wavefront aberration in pseudophakic eyes. Invest Ophthalmol Vis Sci 2002;43:2882e6. 9. Hardman Lea SJ, Rubinstein MP, Haworth SM. Pseudophakic accommodation? A study of the stability of capsular bag supported one piece, rigid tripod, or soft flexible implants. Br J Ophthalmol 1990;74:22e5. 10. Millodot M. Dictionary of optometry and visual science. 7th ed. Taipei: ButterworthHeinemann; 2009. 11. Langenbucher A, Huber S, Nguyen NX, Seitz B, Gusek-Schneider GC, Kuchle M. Measurement of accommodation after implantation of an accommodating posterior chamber intraocular lens. J Cataract Refract Surg 2003;29:677e85. 12. Rosenfield M, Portello JK, Blustein GH, Jang C. Comparison of clinical techniques to assess the near accommodative response. Optom Vis Sci 1996;73:382e8. 13. Rosenfield M, Cohen AS. Repeatability of clinical measurements of the amplitude of accommodation. Ophthalmic Physiol Opt 1996;16:247e9. 14. Kragha IKOK. Amplitude of accommodation: population and methodological differences. Ophthalmic Physiol Opt 1986;6:75e80. 15. Rutstein RP, Fuhr PD, Swiatocha J. Comparing the amplitude of accommodation determined objectively and subjectively. Optom Vis Sci 1993;70:496e500. 16. Higgins JPT, Green S, editors. Assessing study quality. Cochrane handbook for systematic reviews of interventions 4.2.5 (updated May 2005); Section 6 the Cochrane Library 2005, Issue 3 Chichester, UK: John Wiley & Sons. 17. Jadad A, Moore A, Carroll D, Jenkinson C, Reynold J, Gavaghan D. Assessing the quality of reports of randomized clinical trials: is blinding necessary? Control Clin Trials 1996;17:1e12. 18. Vamosi P, Nemeth G, Berta A. Pseudophakic accommodation with 2 models of foldable intraocular lenses. J Cataract Refract Surg 2006;32:221e6. 19. Chen M. A study to compare single piece IOL (SN60WF) vs. multipiece IOL (MA30AC) in accommodation using cycloplegic auto refraction. J Clin Exp Ophthalmol 2010;1:111. 20. Chen M, Chen M. A study of monofocal intraocular lens (Acrysoft) in minimonovision (MMV) and premium multifocal implantation of ReStor. Clin Optometry 2009;1:1e3. 21. Chen M, Atebara N, Chen T. A comparison of a monofocal Acrysoft IOL using the “Blended Monovision” formula with the multifocal Array IOL to glasses independence after cataract surgery. Ann Ophthalmol 2007;39:237e40. 22. Ito M, Shimizu K, Amano R, Niida T, Totsuka S, Lida Y, et al. Assessment of visual function and satisfaction in pseudophakic monovision. Nippon Ganka Gakkai Zasshi 2008;112:531e8. 23. Bradbury JA, Hillman JS, Cassells-Brown A. Optimal postoperative refraction for good unaided near and distance vision with monofocal intraocular lenses. Br J Ophthalmol 1992;76:300e2.
M. Chen / Taiwan Journal of Ophthalmology 2 (2012) 117e121 24. Nishi T, Nawa Y, Ueda T, Masuda K, Taketani F, Hara Y. Effect of total higherorder aberrations on accommodation in pseudophakic eyes. J Refract Surg 2010;36:380e8. 25. Rocha KM, Soriano ES, Chamon W, Chalita M, Nose’ W. Spherical aberration and depth of focus in eyes implanted with aspheric and spherical intraocular lenses: a prospective randomized study. Ophthalmology 2007;114:2050e4. 26. Shentu X, Tang X, Yao K. Spherical aberration, visual performance and pseudoaccommodation of eyes implanted with different aspheric intraocular lens. Clin Exp Ophthalmol 2008;36:620e4. 27. Altan-Yaycioglu R, Gözüm N, Gücükoglu A. Pseudo-accommodation with intraocular lenses implanted in the bag. J Refract Surg 2002;18:271e5. 28. Vargas LG, Auffarth GU, Becker KA, Rabsilber T, Holzer M. Performance of the 1CU accommodating intraocular lens in relation to capsulorhexis size. J Cataract Refract Surg 2005;31:363e8. 29. Chang D. Prospective functional and clinical comparison of Bilateral ReZoom and ReSTOR intraocular lenses in patients 70 years or younger. J Cataract Refract Surg 2008;34:934e41. 30. Marchini G, Mora P, Pedrotti E, Manzotti F, Aldigeri R, Gandolfi S. Functional assessment of two different accommodative intraocular lenses compared with a monofocal intraocular lens. Ophthalmology 2004;114:2038e43. 31. Neuhann T. Four-year European data on the Crystalens. Cataract Refract Surg Today 2004:58. 32. Li XR, Zhao L, Hu BJ. Clinical research of accommodating intraocular lens. Chin J Ophthalmol [Zhonghua yan ke za zhi] 2009;45:328e31.
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33. Hancox J, Spalton D, Heatley C, Jayaram H, Marshall J. Objective measurement of intraocular lens movement and dioptric change with a focus shift accommodating intraocular lens. J Cataract Refract Surg 2006; 32:1098e103. 34. Harman FE, Maling S, Kampougeris G. Comparing the 1CU accommodative, multifocal, and monofocal intraocular lenses: a randomized trial. Ophthalmology 2008;115:993e1001. 35. Wolffsohn J, Naroo S, Motwani N, Shah S, Hunt O, Mantry S, et al. Subjective and objective performance of the Lenstec KH-3500 “accommodative” intraocular lens. Br J Ophthalmol 2006;90:693e6. 36. Dogru M, Honda R, Omoto M. Early visual results with the 1CU accommodating intraocular lens. J Cataract Refract Surg 2005;31:895e902. 37. Sauder G, Degenring RF, Kamppeter B. Potential of the 1CU accommodative intraocular lens. Br J Ophthalmol 2005;89:1289e92. 38. Legeais JM, Werner L, Abenhaim A. Pseudoaccommodation: BioComfold versus a foldable silicone intraocular lens. J Cataract Refract Surg 1999;25:262e7. 39. Mastropasqua L, Toto L, Nubile M, Falconio G, Ballone E. Clinical study of the 1CU accommodating intraocular lens. J Cataract Refract Surg 2003;29: 1307e12. 40. Findl O, Leydolt C. Meta-analysis of accommodating intraocular lenses. J Cataract Refract Surg 2007;33:522e7. 41. Heatley CJ, Spalton DJ, Hancox J. Fellow eye comparison between the 1CU accommodative intraocular lens and the Acrysof MA30 monofocal intraocular lens. Am J Ophthalmol 2005;140:207e13.
Contents lists available at SciVerse ScienceDirect
Taiwan Journal of Ophthalmology journal homepage: www.e-tjo.com
Review article
Accommodation in pseudophakic eyes Ming Chen a, b, * a b
University of Teesside, UK University of Hawaii, Honolulu, HI, USA
a r t i c l e i n f o
a b s t r a c t
Article history: Received 8 March 2012 Received in revised form 4 April 2012 Accepted 4 May 2012 Available online 11 July 2012
Purpose: Today, many patients who have undergone cataract surgery want to enjoy good non-spectacle corrected distant vision and nonspectacle corrected near vision with glasses independence. According to the literature, the implantation of an accommodative intraocular lens (AIOLs) can achieve the level of vision after cataract surgery. However, there is a debate regarding the true accommodative capability of the AIOLs (i.e., whether the IOLs can move forward when attempting to accommodate like the natural crystalline lens of a phakic eye). This review aims to answer the following questions: (1) Can pseudophakic eye accommodate? (2) If pseudophakic eyes can accommodate, how long does this accommodation last? (3) Is there pseudoaccommodation? Methods: This is a systematic review of randomized and nonrandomized controlled trials that have compared different IOLs in accommodation using subjective and objective methods of testing accommodation. All peer reviewed randomized and nonrandomized controlled trials that compared different IOLs in accommodation were included. Results: There was evidence of pseudophakic accommodation up to 12 months postoperatively for AIOLs (mostly 1CU): subjective accommodation [95% confidence interval (CI), 0.36e0.98], objective optic shift (95% CI, 0.12e0.76). However, accommodation decreased at 12 months postoperatively (95% CI, 0.55e1.00). In addition, several papers have reported evidence of pseudoaccommodation. Conclusion: There is pseudophakic accommodation up to 1 year post cataract surgery, mostly 1CU AIOL. Pseudoaccommodation may coexist. Copyright Ó 2012, The Ophthalmologic Society of Taiwan. Published by Elsevier Taiwan LLC. All rights reserved.
Keywords: accommodation cataract surgery intraocular lens implant intraocular lens optic shift pseudoaccommodation
1. Introduction The ability of accommodation in accommodative intraocular lens (AIOLs) has been demonstrated in multiple studies by objective and subjective methods.1 Accommodation involves three mechanisms: contraction of the ciliary muscle, convergence of the eye, and constriction of the pupil.2 Accommodation is a necessary physiological mechanism that enables the human eye to see things up close. Pseudophakic accommodation refers to the accommodation of an eye when its crystal lens has been replaced by an intraocular lens (IOL) during cataract surgery. This change in the power of the eye may be accomplished by a forward movement the intraocular lens upon contraction of the ciliary muscle; at that point, convergence of the eye, and constriction of the pupil are actively occurring.
* 55 South Kukui Street, Honolulu, HI, USA. E-mail address: [email protected].
Some eyes that were corrected for distant vision with a monofocal IOL (nonaccommodative) also achieved a high level of near visual acuity with distance correction after cataract surgery.3 This raises the question, “Is there a pseudoaccommodative effect?” Pseudoaccommodation is not a true accommodation of pseudophakic eyes; rather, it is the ability of the eyes to allow near vision, possibly due to various aberrations in the optical system of the eyes. These optical aberrations are independent of the ciliary muscle’s contraction.4e9 The factors that allow for pseudoaccommodation include the depth of field, which may be affected by pupil size, ptotic eyelids, and squinting.10 Pseudoaccommodation may also involve residual myopic astigmatism and polychromatic and monochromatic higher-order aberrations of the eye (e.g., spherical aberration and coma).10 Therefore, subjective tests alone cannot easily distinguish the accommodative and pseudoaccommodative components that together allow near vision. In the control trials analyzed in this review, the following methods were used to measure accommodation: objective techniques (PlusOptix PowerRefractor videorefractometry, streak
2211-5056/$ e see front matter Copyright Ó 2012, The Ophthalmologic Society of Taiwan. Published by Elsevier Taiwan LLC. All rights reserved. http://dx.doi.org/10.1016/j.tjo.2012.05.002
118
M. Chen / Taiwan Journal of Ophthalmology 2 (2012) 117e121
retinoscopy) and subjective techniques [subjective near point (push-up test, accommodometer), defocusing]; static with pharmacologic stimulation after Pilocarpine 2% eye drops directly (conventional refractometry); indirectly (change in the anterior chamber depth with Zeiss IOLMaster).11e15 Objective measurements of accommodation are necessary to evaluate commercially available AIOLs in a scientific manner. The objective parameters include measurements of changes in the anterior chamber depth as well as measurements of autorefraction.
Points were deducted if The method of randomization was described but was inappropriate. The method of blinding was described but was inappropriate.
2.5. Data extraction Data were collected for the following outcome measures:
2. Methods The meta-analysis was not considered because the trials were not all homogeneous. In order to draw some conclusion for a relative merit of this topic, a systematic review of the best-quality data is necessary. Peer-reviewed randomized and nonrandomized control trials were selected because of their validity and the objective outcomes. 2.1. Inclusion criteria 2.1.1. Types of studies All peer-reviewed randomized and nonrandomized controlled trials that compared different IOLs in the context of accommodation were included. 2.1.2. Types of participants The participants were individuals aged 19 years or older who had undergone cataract surgery and received intraocular lens implants. 2.2. Exclusion criteria Congenital cataract patients were excluded from the study due to potential differences in the treatment plans. 2.3. Search methods: electronic search The Cochrane Central Register of Controlled Trials (Central) on the Cochrane Library, MEDILINE, Journal of Cataract and Refractive Surgery, and PubMed from 1966 to 2010 were searched. Seventeen papers were identified as meeting the inclusion criteria for this review. These included 13 randomized control studies and four nonrandomized control studies. A total of 1111 eyes were included in the 17 trials. 2.4. Assessment of study validity and quality Trial quality was assessed according to the methods described in Section 6 of The Cochrane Handbook for Systematic Reviews of Interventions.16 A score ranging from 0 to 5 was allocated according to the method of Jadad et al.17 Each question required either a “yes” or “no” answer. Each “yes” answers would score a single point and each “no” answers scored zero points. The questions were as follows: 1. Was the study described as randomized? 2. Was the study described as double blind? 3. Was there a description of withdrawals and dropouts? Additional points were given if The method of randomization was described in the paper, and the method was appropriate. The method of blinding was described and it was appropriate.
(1) More accommodative power in accommodative IOLs compared to controls (2) More optic shift in accommodative IOLs compared to controls (3) Postoperative time at time of study
2.6. Data synthesis Data syntheses were performed by creating a table listing all 17 papers with the comparison among accommodative IOLs and standard IOL in terms of accommodation, optic shift, and the postoperative time. This study has been approved by the institutional review board of the University of Teesside for ethical issues and complied with the Declaration of Helsinki. 3. Results 3.1. Search results The initial electronic searches found a total of 332 papers: PubMed 33, Cochrane 11, Medline 109, Journal of Cataract Refractive Surgery 168, and Reference & Manufacturer 11. A total of 164 titles and abstracts were selected for review, as shown in Table 1.18,19,25e27,30e41 After reading the full text as a second selective procedure, 17 papers were identified as meeting the inclusion criteria for this review (PubMed 2, Cochrane 2, Medline 7, JCRS 6). There were 13 randomized control studies and four nonrandomized control studies. A total of 1111 eyes were included from the 17 trials as shown in Table 2. 3.2. Quality of the included studies (1) The Jadad scores for the 17 trials included were as follows: 76.4% had a score of 2 or higher, 23.6% had a score of 0, 42.4% had a score of 2, 10% had a score of 3, and 24% had a score of 4 (Fig. 1).
Table 1 Search results. Number discarded due to irrelevance
Number duplicated from another database
Number reviewed by title and abstract
Database or method
Number of articles found
PubMed Medline Cochrane JCRS Reference & Manufacturer Total
33 109 11 168 11
23 54 8 79 4
2 3 1 12 0
10 55 3 89 7
332
168
18
164
M. Chen / Taiwan Journal of Ophthalmology 2 (2012) 117e121
(2) The Critical Appraisal Skills Program (CASP) was used to evaluate randomized control trials. Most trials complied with the requirements for validity (Fig. 2). Table 2 Results after reading the full text of articles from the first selection. Database or method
PubMed Medline Cochrane JCRS Reference & Manufacturer Total
Number reviewed by title and abstract (first selection)
Number selected after reading the full text (second selection)
10 55 3 889 7
2 7 2 6 0
164
17
119
Power: Did the study have enough participants? One trial Results: What were the main results, and how were the results presented? All 17 trials Precise: Were the results precise? All 17 trials Apply: Could the outcome be applied to other populations? Sixteen trials (Tables 3 and 4). Table 3 List of standard monofocal posterior chamber IOLs compared in this review. Material PMMA MA30AC MA60BM AcrysoftIQ SN60AT Akeros
Polymethylmethacrylate Hydrophobic acrylic Hydrophobic acrylic Hydrophobic acrylic Hydrophobic acrylic Hydrophobic acrylic
Manufacturers
Design
Various companies Alcon Alcon Alcon Alcon Bausch-Lomb
Multi-piece Multi-piece Multi-piece Single-piece Single-piece Single-piece
Table 4 List of accommodative IOLs (AIOLs) compared in this review. Material ICU Tetraflex Crystalens BioComfold
Hydrophobic acrylic Hydrophobic acrylic Silicone elastomer Silicone
Manufacturers
Design
HumanOptics AG Lenstec, Inc. Eyeonics, Inc. Morcher
Single-piece Single-piece Single-piece Single-piece
3.3. Results of data synthesis Results of data synthesis are shown in Table 5. Table 5 A list of control trials that demonstrated the presence or absence of “more accommodation” and “more optic shift” in AIOLs compared to standard IOLs.
Fig. 1. Pie distribution of Jadad’s scores for the17 trials: 76.4% had scores of 2 and above.
Vamosi et al18 Chen19 Rocha et al25 Shentu et al26 Altan-Yaycioglu et al27 Marchini et al30 31
Schneider Li et al32 Hancox et al33 Harman et al34 Wolffsohn et al35 Dogru et al36 Sauder et al37 Legeais et al38 Fig. 2. Summary of the appraisal of 17 trials with CASP (Critical Appraisal Skills Program). RCT (Randomized control Trials).
The following criteria were assessed for the (CASP) program: Question: Was there a clearly focused question? All 17 trials RCT: Was this a randomized controlled trial? Thirteen trials (76%) Allocation: Were participants appropriately allocated to the intervention and control groups? All 17 trials Blind: Were the participants, staff, and study personnel “blind” to the participants’ study groups? Four trials Drop out: Did any of the participants who entered the study subsequently leave? One trial Data collection: Were data collected in the same way for all the groups? All 17 trials
Mastropasqua et al39 Findl and Leydolt40 Heatley et al41
IOL
More More optic accommodation shift
Post op
Akeros vs. MA60BM AcrysoftIQ vs. MA30AC AcrysoftIQ vs. SN60AT AcrysoftIQ vs. SN60AT Acrysoft vs. PMMA
Positive Positive
Yes N/A
N/A
No
12 mo 71/ 2 mo N/A
Positive
No
N/A
N/A
No
N/A
1CU & Crystalens vs. mono 1CU vs. PMMA Tetraflex vs. Acrysoft 1CU vs. MA30AC 1CU vs. monofocal Tetraflex vs. Softec 1CU vs. Acrysoft 1CU vs. foldable IOL BioComfold vs. foldable 1CU vs. IFP6.0
Positive
Yes
2 mo
Negative Positive Positive Negative Positive Positive Positive Negative
No N/A Yes N/A N/A N/A Yes Yes
3 mo 6 mo N/A 18 mo 6 mo 6 mo 8 mo N/A
Positive
N/A
6 mo
1CU vs. MA30AC
Positive
Yes
3 mo
1CU vs. MA30AC
Positive
N/A
6 mo/ 1y
Five studies in this list were the comparison between standard IOLs. N/A ¼ not available; Post-op ¼ postoperative time at time of study.
3.4. Summary of the results Of the 17 trials, 12 investigated AIOLs (71%) and nine trials investigated 1CU AIOLs (75%). Two trials investigated Tetraflex AIOLs, one studied the Crystalens AIOLs, and one studied the BioComfold AIOLs.
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Six out of the nine 1CU trials (67%) showed more accommodation in diopters compared to the standard IOL [95% confidence interval (CI), 0.36e0.98] when measurements were obtained from 2 months to 1 year postoperatively. Four out of the nine 1CU AIOLs (44%) trials demonstrated an optic shift (95% CI, 0.12e0.76). There were two Tetraflex accommodative IOL trials. Both demonstrated an increase in accommodation but no optic shift compared to the control IOL at up to 6 months postoperatively. Some nonaccommodative IOLs (NAIOLs) such as the Akeros and the AcrysoftIQ had more accommodation compared to the other NAIOLs. Akeros IOL (Hydrophilic Acrylic, Bausch-Lomb) showed more accommodation and optic shift compared to MA60BM (Alcon, multipiece Acrysof) at up to 1 year.18 Overall, 75% of the trials found more accommodation in AIOLs compared to standard IOLs. However, seven out of the nine trials (78%) that reported more accommodation in accommodative IOLs showed a decrease in accommodation as the postoperation time increased to 12 months (95% CI, 0.55e1.00). The remaining accommodation could not be differentiated from pseudoaccommodation. 4. Discussion This review included 17 trials that measured and compared pseudophakic accommodation among AIOL and NAIOLs. Trial quality was rigorously evaluated using the Jadad score and the CASP. Most trials complied with the requirements for validity. However, some showed weakness in blinding, power, or description of dropouts. Most of the trials investigated 1CU AIOLs, indicating that the results were mostly pertinent to 1CU AIOLs. According the result, patients who received AIOLs after cataract surgery enjoyed more accommodation compared to those patients who received NAIOLs up to 1 year. There was one trial that demonstrated more accommodation from the Akeros IOL (Hydrophilic Acrylic, Bausch-Lomb NAIOL) compared to another NAIOL MA60BM (Alcon, multipiece Hydrophobic Acrysof) at up to 1 year. Therefore, the design and the material of AIOLs or NAIOLs may be the contributing reason to those patients to have short-term ability of accommodation. There was a lack of valid studies on other AIOLs such as the Crystalens. In this review, the characteristics of pseudoaccommodation were studied and described to explain the ability of pseudophakic participants in these studies to read without accommodation. Pseudoaccommodation and monovision may contribute to the success of AIOLs despite a decrease in accommodation over time. For clinical and practical reason, in the attempt to allow patients to use a standard NAIOL without reading glasses, the following features of pseudoaccommodation can be considered. (1) Achieving less negative accommodation (back shift of the IOL).19 (2) Incorporating the formula of for mini-monovision in the IOL power calculation.20e22 (3) Leaving 1e2 diopters of myopic astigmatism and virtually no sphere in the nondominant eye.23 (4) Leaving the eyes with larger vertical coma aberrations that can achieve a larger range of accommodation.24 (5) Maintaining total spherical aberration without aspheric IOL implantation, which may enhance distance-corrected near and intermediate vision.25,26 (6) The posterior position of the IOL in the eye (closer to the nodal point). (7) The presence of a small pupil (Increased depth perception). (8) An uncomplicated small-incision phacoemulsification surgery with a continuous curvilinear capsulorhexis and an in-the-bag implanted soft lens.27
(9) The improvement of distance-corrected near vision is better with a larger continuous curvilinear capsulorhexis and with less overlapping of the optic.28 (10) Good patient selection and preoperative consultation.29 Future studies should focus on how to further develop new generation of accommodative IOLs such as the Synchrony (dualoptic design) or NuLens. 5. Conclusion This review showed evidence of pseudophakic accommodation in AIOLs and NAIOLs up to 12 months postoperatively (mainly in 1CU AIOLs). However, most of the IOLs showed a decrease in accommodation as the postoperative time increased to 12 months. Pseudoaccommodation may play a role in the ability to attain distant corrected near vision. References 1. Cumming JS, Colvard M, Dell S. Clinical evaluation of the Crystalens AT-45 accommodating intraocular lens: results of the U.S. Food and Drug Administration clinical trial. J Cataract Refract Surg 2006;32:812e25. 2. Coleman DJ, Fish SK. Presbyopia, accommodation, and the mature catenary. Ophthalmology 2001;108:1544e51. 3. Leyland MD, Langan L, Goolfee F. Prospective randomized double-mask trial of bilateral multifocal, bifocal or monofocal intraocular lens. Eye 2002;16:481e90. 4. Huber C. Myopic astigmatism: a substitute for accommodation in pseudophakic. Doc Ophthalmol 1981;52:123e78. 5. Trindade F, Oliveira A, Frasson M. Benefit of against-the-rule astigmatism to uncorrected near acuity. J Cataract Refract Surg 1997;23:82e5. 6. Nakazawa M, Ohtsuki K. Apparent accommodation in pseudophakic eyes after implantation posterior chamber intraocular lenses: optical analysis. Invest Ophthalmol Vis Sci 1984;25:1458e60. 7. Fukuyama M, Oshika T, Amano S, Yoshitomi F. Relationship between apparent accommodation and corneal multifocality in pseudophakic eyes. Ophthalmology 1999;106:1178e81. 8. Oshika T, Mimura T, Tanaka S, Amano S, Fukuyama M, Yoshitomi F. Apparent accommodation and corneal wavefront aberration in pseudophakic eyes. Invest Ophthalmol Vis Sci 2002;43:2882e6. 9. Hardman Lea SJ, Rubinstein MP, Haworth SM. Pseudophakic accommodation? A study of the stability of capsular bag supported one piece, rigid tripod, or soft flexible implants. Br J Ophthalmol 1990;74:22e5. 10. Millodot M. Dictionary of optometry and visual science. 7th ed. Taipei: ButterworthHeinemann; 2009. 11. Langenbucher A, Huber S, Nguyen NX, Seitz B, Gusek-Schneider GC, Kuchle M. Measurement of accommodation after implantation of an accommodating posterior chamber intraocular lens. J Cataract Refract Surg 2003;29:677e85. 12. Rosenfield M, Portello JK, Blustein GH, Jang C. Comparison of clinical techniques to assess the near accommodative response. Optom Vis Sci 1996;73:382e8. 13. Rosenfield M, Cohen AS. Repeatability of clinical measurements of the amplitude of accommodation. Ophthalmic Physiol Opt 1996;16:247e9. 14. Kragha IKOK. Amplitude of accommodation: population and methodological differences. Ophthalmic Physiol Opt 1986;6:75e80. 15. Rutstein RP, Fuhr PD, Swiatocha J. Comparing the amplitude of accommodation determined objectively and subjectively. Optom Vis Sci 1993;70:496e500. 16. Higgins JPT, Green S, editors. Assessing study quality. Cochrane handbook for systematic reviews of interventions 4.2.5 (updated May 2005); Section 6 the Cochrane Library 2005, Issue 3 Chichester, UK: John Wiley & Sons. 17. Jadad A, Moore A, Carroll D, Jenkinson C, Reynold J, Gavaghan D. Assessing the quality of reports of randomized clinical trials: is blinding necessary? Control Clin Trials 1996;17:1e12. 18. Vamosi P, Nemeth G, Berta A. Pseudophakic accommodation with 2 models of foldable intraocular lenses. J Cataract Refract Surg 2006;32:221e6. 19. Chen M. A study to compare single piece IOL (SN60WF) vs. multipiece IOL (MA30AC) in accommodation using cycloplegic auto refraction. J Clin Exp Ophthalmol 2010;1:111. 20. Chen M, Chen M. A study of monofocal intraocular lens (Acrysoft) in minimonovision (MMV) and premium multifocal implantation of ReStor. Clin Optometry 2009;1:1e3. 21. Chen M, Atebara N, Chen T. A comparison of a monofocal Acrysoft IOL using the “Blended Monovision” formula with the multifocal Array IOL to glasses independence after cataract surgery. Ann Ophthalmol 2007;39:237e40. 22. Ito M, Shimizu K, Amano R, Niida T, Totsuka S, Lida Y, et al. Assessment of visual function and satisfaction in pseudophakic monovision. Nippon Ganka Gakkai Zasshi 2008;112:531e8. 23. Bradbury JA, Hillman JS, Cassells-Brown A. Optimal postoperative refraction for good unaided near and distance vision with monofocal intraocular lenses. Br J Ophthalmol 1992;76:300e2.
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33. Hancox J, Spalton D, Heatley C, Jayaram H, Marshall J. Objective measurement of intraocular lens movement and dioptric change with a focus shift accommodating intraocular lens. J Cataract Refract Surg 2006; 32:1098e103. 34. Harman FE, Maling S, Kampougeris G. Comparing the 1CU accommodative, multifocal, and monofocal intraocular lenses: a randomized trial. Ophthalmology 2008;115:993e1001. 35. Wolffsohn J, Naroo S, Motwani N, Shah S, Hunt O, Mantry S, et al. Subjective and objective performance of the Lenstec KH-3500 “accommodative” intraocular lens. Br J Ophthalmol 2006;90:693e6. 36. Dogru M, Honda R, Omoto M. Early visual results with the 1CU accommodating intraocular lens. J Cataract Refract Surg 2005;31:895e902. 37. Sauder G, Degenring RF, Kamppeter B. Potential of the 1CU accommodative intraocular lens. Br J Ophthalmol 2005;89:1289e92. 38. Legeais JM, Werner L, Abenhaim A. Pseudoaccommodation: BioComfold versus a foldable silicone intraocular lens. J Cataract Refract Surg 1999;25:262e7. 39. Mastropasqua L, Toto L, Nubile M, Falconio G, Ballone E. Clinical study of the 1CU accommodating intraocular lens. J Cataract Refract Surg 2003;29: 1307e12. 40. Findl O, Leydolt C. Meta-analysis of accommodating intraocular lenses. J Cataract Refract Surg 2007;33:522e7. 41. Heatley CJ, Spalton DJ, Hancox J. Fellow eye comparison between the 1CU accommodative intraocular lens and the Acrysof MA30 monofocal intraocular lens. Am J Ophthalmol 2005;140:207e13.