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 Table of Contents  
STUDY PROTOCOL
Year : 2016  |  Volume : 1  |  Issue : 4  |  Page : 187-192

Safety and efficacy of two multifocal intraocular lenses in the treatment of senile cataract: study protocol for a randomized controlled trial


Department of Ophthalmology, Affiliated Hospital of Qinghai University, Xining, Qinghai Province, China

Date of Web Publication30-Dec-2016

Correspondence Address:
Ping Yu
Department of Ophthalmology, Affiliated Hospital of Qinghai University, Xining, Qinghai Province
China
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Source of Support: This study was financially supported by the Scientific Support Project of Qinghai Province in China., Conflict of Interest: None


DOI: 10.4103/2468-5658.196986

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  Abstract 

Background: Phacoemulsification with intraocular lens (IOL) implantation has become a well-established treatment for senile cataract. The ideal IOL is characterized by good biocompatibility and resolution, with no spherical aberration. The Acri.LISA 366D is a refractive/diffractive multifocal IOL that differs from traditional multifocal IOLs. Its unique optical design can improve the patient's vision and reduce incident ray scattering, glare and halo. The goal of this study is to perform a comparative analysis between the Acri.LISA 366D and the Tecnis Z9001 diffractive multifocal IOL, to determine if there are any differences in biocompatibility and improvement in visual acuity.
Methods/Design: A prospective, single-center, randomized, double-blind, parallel-controlled study will be conducted at the Affiliated Hospital of Qinghai University in China. Forty cataract patients aged 50-80 years will be randomly assigned to either the Acri.LISA 366D or Tecnis Z9001 IOL (n = 20 per group). The primary outcome of the trial is to investigate the biocompatibility of the IOL after implantation. The secondary outcome is the best corrected visual acuity. Outcome measures will be evaluated at 1, 3, 6 months, 1, 2 years after IOL implantation.
Discussion: It is anticipated that the data collected from this trial will provide evidence for IOL selection in senile cataract patients.
Trial registration: ClinicalTrials.gov identifier: NCT02966496; registered on 9 November 2016.
Ethics: This trial has been approved by the Ethics Committee, Affiliated Hospital of Qinghai University, China (approval number: QHY1107K) and will be performed in accordance with the Declaration of Helsinki, formulated by the World Medical Association.
Informed consent: Signed informed consent will be obtained from the patients or their guardians.

Keywords: clinical trial; intraocular lens; multifocal intraocular lens; aspheric intraocular lens; refractive/diffractive; cataract; aged; randomized controlled trial


How to cite this article:
Yu P, Wang Q, Liu Ll. Safety and efficacy of two multifocal intraocular lenses in the treatment of senile cataract: study protocol for a randomized controlled trial. Clin Trials Degener Dis 2016;1:187-92

How to cite this URL:
Yu P, Wang Q, Liu Ll. Safety and efficacy of two multifocal intraocular lenses in the treatment of senile cataract: study protocol for a randomized controlled trial. Clin Trials Degener Dis [serial online] 2016 [cited 2019 Apr 21];1:187-92. Available from: http://www.clinicaltdd.com/text.asp?2016/1/4/187/196986


  Introduction Top


History and current studies

Aging-induced degenerative diseases are the leading cause of senile cataract (Ren et al., 2015). Phacoemulsification with intraocular lens (IOL) implantation is a commonly employed surgical technique for the treatment of cataract (Giménez et al., 2016). A traditional IOL is spherical and monofocal. Traditional monofocal IOL implantation allows cataract patients to obtain good postoperative distant visual acuity but loss of accommodation results in poor near visual acuity. Following monofocal IOL implantation, most patients still require the use of glasses. Fortunately, the presence of multifocal IOLs solves this problem (Kretz et al., 2015; Shah et al., 2015). Studies have shown that aspheric IOLs with zero or negative spherical aberration can eliminate or reduce the spherical aberration of the whole eye and can improve contrast sensitivity and night visual acuity compared with a spherical IOL.

As first reported by Keatea et al. (1987), multifocal IOLs were introduced to provide improved visual acuity, thus eliminating the need to wear glasses and improving the patient's quality of life (Lv, 2006). Increasing evidence-based medicine findings have shown that multifocal IOLs are more adapt to improving near visual acuity than single-focus IOLs (Leyland and Pringle, 2006; Calladine et al., 2012; Leyland and Zinicola, 2001, 2003a, b). To date, various types of multifocal IOLs have been developed and according to different design principles, clinically used multifocal IOLs have been divided into refraction type, diffraction type and refraction/diffraction type. Since emergence in 2002, the Tecnis Z9001 diffractive multifocal aspherical IOL (Abbott Medical Optics, CA, USA) has been clinically proven to give patients improved contrast visual acuity and visual quality when compared with the common IOL (Holladay et al., 2002; Mester et al., 2003), although deficiencies include postoperative glare and reduced contrast sensitivity. Emerging designs for multifocal IOLs aim to provide improvements in postoperative visual quality. The Acri.LISA 366D multifocal aspheric IOL (Carl Zeiss, Oberkochen, Germany) is a relatively novel refractive/diffractive multifocal IOL that is different from traditional IOLs (Muρoz et al., 2012). Its unique optical design improves the patient's visual acuity at different distances and reduces the incidence of light scattering, glare and halo, which is expected to deliver better clinical outcomes. However, its long-term clinical performance and the potential incidence of complications still need further evaluation.

It is worth noting that as age increases, the increase in presbyopia, aberrations and lens scattering reduces the compensation for corneal aberrations, thereby resulting in a decrease in visual acuity and contrast sensitivity (Artal et al., 2001; Holladay et al., 2002). Given this, ideal IOLs should have good biocompatibility and good resolution with no spherical aberration (Apple et al., 2000; Vilarrodona et al., 2004).

Objective

This trial is designed to compare the biocompatibility and long-term visual outcomes of the Tecnis Z9001 and Acri.LISA 366D multifocal IOLs used for the treatment of senile cataract. The aim is to provide a safer biomaterial for senile cataract treatment, achieving better postoperative visual quality and fewer complications.

Novelty of this study

Interventional effects of the Acri.LISA 366D multifocal aspheric IOL on the visual acuity of cataract patients have been described in cohort studies (Muρoz et al., 2012). A comparative analysis of visual quality outcomes following treatment of cataract patients with the Tecnis Z9001 aspheric IOL versus an ordinary IOL has also been reported (Lv, 2006). However, there is no study directly comparing the Tecnis Z9001 and Acri.LISA 366D multifocal IOLs for use in the treatment of cataract, including measurement of outcomes such as biocompatibility and visual acuity.


  Methods/Design Top


Study design

A prospective, single-center, double-blind, randomized, parallel-controlled trial.

Study setting

This trial will be completed at the Affiliated Hospital of Qinghai University, Qinghai, China.

Study procedures

(1) Forty cataract patients will be enrolled according to the inclusion criteria and these patients will be randomly assigned into either test group or control group, with 30-40 eyes in each group.

(2) The Acri.LISA 366D and Tecnis Z9001 multifocal aspheric IOLs will be used in the test group and control group, respectively.

(3) Biocompatibility and long-term visual outcomes of both IOLs will be compared between the two groups at 1, 3, 6 months, 1, 2 years after implantation.

(4) Flow chart of the study protocol is shown in [Figure 1].
Figure 1: Flow chart of the trial.
Note: IOLs: Intraocular lenses.


Click here to view


Study participants

We will recruit 40 cataract patients at the Department of Ophthalmology, Affiliated Hospital of Qinghai University in China.

Inclusion criteria

Patients satisfying all the following criteria will be included in the trial:

  • Clinically diagnosed as age-related cataract
  • Corneal astigmatism < 1.0 D
  • Lens hardness, II-III
  • Initial surgery on the eye
  • Healthy and able to tolerate anesthesia and surgery
  • Age 50-80 years


Exclusion criteria

Patients presenting with any of the following criteria will be excluded from the trial:

  • Glaucoma or secondary vision loss resulting from diabetes, hypertension, intracranial tumors and neurological diseases
  • Fundus disease, corneal edema, corneal opacity, endophthalmitis, and/or iris adhesion.
  • Prior experience of eye surgery
  • Failure to make regular referrals
  • Autoimmune disease, mental illness or other serious systemic disease
  • Inability to cooperate with the researchers
  • Inability to tolerate surgery
  • Sensitivity, anxiety or the pursuit of perfection
  • Inability to give informed consent


Sample size

In accordance with a previous report (Muρoz et al., 2012), we hypothesized that the sample size would be estimated based on the primary outcomes. With a predicted dropout rate of 20%, the required sample size will be 40 cases (n = 20 per group). Sample size calculation will be performed in accordance with the intention-to-treat principle.

Baseline assessment

Baseline data, including age, sex, general disease history, physical examination, laboratory examination, general and special ophthalmic testing will be collected from the participants prior to randomization ([Table 1]).
Table 1: Schedule for baseline assessment

Click here to view


Recruitment

Potential participants will be recruited through a physician's recommendation, posters, leaflets, newspapers or advertisements left in telephone stations. Interested patients can discuss the trial with their attending doctors and contact the principal investigator by telephone, e-mail, or WeChat. After written informed consent is given, the participants will be screened according to the inclusion and exclusion criteria.

Randomization

After baseline assessment, eligible patients will be randomized into test and control groups at a ratio of 1:1. A randomized serial number for each patient will be generated using SPSS 19.0 software (IBM, Armonk, NY, USA) by a researcher who will not participate in the trial. These assigned numbers will be password protected and provided to the research team until the end of the trial.

Blinding

Patients and outcome assessors will not be aware of grouping information and interventions but surgeons will be informed of the grouping information.

Interventions

Surgical materials


The Tecnis Z9001 aspheric IOL used in the control group is a three-piece foldable IOL manufactured by Abbott Medical Optics. The optical component is made of silicone gel. The C-type loop, with an angle of 6΀, is made of polyfluoroethylene. The front surface of the lens is an aspherical surface with a negative spherical aberration of 0.27 ΅m at a pupil diameter of 6 mm. The optical surface has a diameter of 6 mm and a total diameter of 13 mm.

The Acri.LISA 366D multifocal aspherical IOL used in the experimental group is a one-piece, four-loop foldable hydrophilic acrylic IOL manufactured by Carl Zeiss. It is a new type of refractive/diffractive multifocal aspheric IOL. In accordance with the principle of refraction-diffraction, the optical part is divided into 49 regions with 25 diffraction regions and 24 refraction regions alternately arranged. The optical part has a diameter of 6 mm and a total diameter of 11 mm.

Preoperative examination

(1) Routine examination

  • Visual acuity measurement: An international standard E visual acuity chart (Changsha Pharmaceutical Equipment Company, Changhsa, China) will be used to measure 5 m distant visual acuity. A standard near visual acuity chart will be used to measure near visual acuity at 30 cm.
  • Anterior segment examination: A slit-lamp microscope will be used to observe the conjunctiva, cornea, sclera, anterior chamber, iris, pupil and lens.
  • Fundus examination: All participants will be examined using direct ophthalmoscopy, to observe the condition of the fundus and record the cup-to-disc ratio.
  • Intraocular pressure measurement: All participants will have their intraocular pressure measured while in the supine position.
  • A whole body physical assessment will include routine blood, urine, stool, clotting time, chest X-ray and electrocardiography examinations.


(2) Special examination: Examination with an IOLMaster (Carl Zeiss) or A-scan ultrasound will be used for measurement of corneal curvature, central anterior chamber depth and axial length. B-scan ultrasound examination will be used to exclude retinal detachment, vitreous opacity. Corneal topography will be used to assess corneal curvature. Macular optical coherence tomography and visually evoked potential test will be used to detect the presence of fundus lesions. The IOL diopter will be calculated using SRK/T or Holladay II formula based on different axial lengths. The IOL will be selected at the postoperative refractive range of −0.5 to +0.5 D.

Surgical procedures

Surgery will be conducted under topical anesthesia. A 3-mm clear corneal incision will be made in the upper 11-12 o'clock position and a viscoelastic agent will be injected, followed by central continuous curvilinear capsulorhexis with a diameter of 5.0-5.5 mm. After hydrodissection, the crystalline lens nucleus in the lens capsule will be removed using phacoemulsification and a perfusion aspiration system will be employed to remove the residual lens cortex. Following polishing, the viscoelastic agent will be injected into the lens capsule and the propeller will be inserted into the lens capsule to fully absorb the viscoelastic agent by adjusting the position of the IOL. All procedures will be performed by the same experienced physician.

Outcome measures

Outcome assessments will be made at 1, 3, 6 months, 1, 2 years after IOL implantation.

Primary outcome measure

  • Percentage of patients with poor biocompatibility of IOL implants, including posterior capsular opacification, anterior capsule opacification, capsular shrinkage, anterior chamber flare and cell deposition in the front of the IOL.


Secondary outcome measure

  • Best corrected visual acuity.


Flow chart of the trial is shown in [Table 2].
Table 2: Timing of outcome assessment

Click here to view


Data collection, management, analysis, and open access

Data collection


Clinical data will be collected and managed using an electronic data capture system. All data relevant to the trial will be recorded in electronic case report forms that will be provided by the sponsor personnel. The case report will be completed after the interview.

Data management

After completion of follow-up and data confirmation, only the project manager will lock the database. The locked data will be unable to be altered and will be preserved for future reference by the Affiliated Hospital of Qinghai University in China.

Data analysis


All data will be statistically analyzed by professional statisticians.

Open data

Anonymized published data will be released at http://www.figshare.org.

Statistical analysis

All data will be statistically analyzed by statisticians using SPSS 19.0 software. Normally distributed measurement data will be expressed as the mean ± SD, while non-normally distributed data will be expressed as quartiles and medians. Categorical variables will be expressed as counts and percentages. Two-sample t-test or Mann-Whitney U-test will be used for intergroup comparison of visual acuity and diopter. The chi-squared test or Fisher's exact test will be used for intergroup comparison of incidence of histocompatibility reactions between the implant and host tissues and the percentage of complications. A value of P < 0.05 will be considered statistically significant.

Auditing

Trial progress will be reported to the ethics committee of the Affiliated Hospital of Qinghai University semi-annually or annually and the trial status will be updated in the registration database after each report.

Confidentiality

  • The collection and use of the trial data will be confidential and comply with the relevant laws and regulations to protect the privacy of each participant.
  • During the trial, the personal information of each participant will not be exposed to any non-authorized persons, will not be destroyed accidentally or unlawfully and will not be lost or altered. Sponsor personnel who have access to the participant's personal data will keep it confidential throughout the trial.



  Trial Status Top


This study protocol has been approved by the Ethics Committee of Affiliated Hospital of Qinghai University of China (approval number: QHY1107K) and will be performed in accordance with the guidelines of the Declaration of Helsinki, formulated by the World Medical Association. Signed informed consent regarding trial procedure and treatment will be obtained from each patient or their guardians prior to the trial. Patient recruitment is ongoing at the time of submission.


  Discussion Top


Significance of this study

IOL replacement has become the only effective way to improve the visual quality of cataract patients. The choice of IOL is essential for postoperative visual recovery. This study will focus on the choice of IOL and is the first to compare the biocompatibility, visual quality and complications after implantation of the Tecnis Z9001 aspheric IOL versus the Acri.LISA 366D multifocal aspheric IOL.

Advantages and limitations of this study

Advantages of the study: This study is a prospective, randomized, controlled trial that will explore whether the Tecnis Z9001 aspheric IOL or Acri.LISA 366D multifocal aspherical IOL is the better and safer choice for senile cataract patients in terms of distant and near visual acuity and visual quality improvement. If the Acri.LISA 366D multifocal aspherical IOL is the superior choice, it will be beneficial for patients with higher requirements for postoperative visual improvement.

Limitations of the study: Quality of life is also an important indicator of the assessment of surgical effectiveness but owing to the limitations of human and material resources, we are unable to conduct a series of assessments, such as the 36-Item Short Form Health Survey, which will be remedied in future research.

Contribution to future studies

The aim of this study is to provide the clinical basis for the choice of IOLs in senile cataract patients, to ensure the safety of the implantation, improve the success rate of surgery and reduce the incidence of complications. This will provide patients with better visual quality after implantation and improve the quality of life for cataract patients undergoing IOL implantation. [16]

 
  References Top

1.
Apple DJ, Ram J, Foster A, Peng Q (2000) Elimination of cataract blindness: a global perspective entering the new millenium. Surv Ophthalmol 45 Suppl 1:S1-196.  Back to cited text no. 1
    
2.
Artal P, Guirao A, Berrio E, Williams DR (2001) Compensation of corneal aberrations by the internal optics in the human eye. J Vis 1:1-8.  Back to cited text no. 2
    
3.
Calladine D, Evans JR, Shah S, Leyland M (2012) Multifocal versus monofocal intraocular lenses after cataract extraction. Cochrane Database Syst Rev:CD003169.   Back to cited text no. 3
    
4.
Giménez M, Beersma D, Daan S, Pol Bv, Kanis M, van Norren D, Gordijn M (2016) Melatonin and sleep-wake rhythms before and after ocular lens replacement in elderly humans. Biology (Basel) 5. pii: E12.  Back to cited text no. 4
    
5.
Holladay JT, Piers PA, Koranyi G, van der Mooren M, Norrby NE (2002) A new intraocular lens design to reduce spherical aberration of pseudophakic eyes. J Refract Surg 18:683-691.  Back to cited text no. 5
    
6.
Keates RH, Pearce JL, Schneider RT (1987) Clinical results of the multifocal lens. J Cataract Refract Surg 13:557-560.  Back to cited text no. 6
    
7.
Kretz FT, Tandogan T, Khoramnia R, Auffarth GU (2015) High order aberration and straylight evaluation after cataract surgery with implantation of an aspheric, aberration correcting monofocal intraocular lens. Int J Ophthalmol 8:736-741.  Back to cited text no. 7
    
8.
Leyland M, Pringle E (2006) Multifocal versus monofocal intraocular lenses after cataract extraction. Cochrane Database Syst Rev:CD003169.  Back to cited text no. 8
    
9.
Leyland M, Zinicola E (2003a) Multifocal versus monofocal intraocular lenses in cataract surgery: a systematic review. Ophthalmology 110:1789-1798.  Back to cited text no. 9
    
10.
Leyland M, Zinicola E (2003b) Multifocal versus monofocal intraocular lenses after cataract extraction. Cochrane Database Syst Rev:CD003169.  Back to cited text no. 10
    
11.
Leyland M, Zinicola E (2001) Multifocal versus monofocal intraocular lenses after cataract extraction. Cochrane Database Syst Rev:CD003169.  Back to cited text no. 11
    
12.
Lv XF (2006) Clinical studies on TecnisZ9001 aspherical intraocular lens (IOL). Hangzhou, China: Zhejiang University.  Back to cited text no. 12
    
13.
Mester U, Dillinger P, Anterist N (2003) Impact of a modified optic design on visual function: clinical comparative study. J Cataract Refract Surg 29:652-660.  Back to cited text no. 13
    
14.
Muñoz G, Albarrán-Diego C, Javaloy J, Sakla HF, Cerviño A (2012) Combining zonal refractive and diffractive aspheric multifocal intraocular lenses. J Refract Surg 28:174-181.  Back to cited text no. 14
    
15.
Ren XT, Snellingen T, Gu H, Assanangkornchai S, Zou YH, Chongsuvivatwong V, Lim A, Jia W, Liu XP, Liu NP (2015) Use of cataract surgery in urban Beijing: a post screening follow-up of the elderly with visual impairment due to age-related cataract. Chin Med Sci J 30:1-6.  Back to cited text no. 15
    
16.
Shah S, Peris-Martinez C, Reinhard T, Vinciguerra P (2015) Visual outcomes after cataract surgery: multifocal versus monofocal intraocular lenses. J Refract Surg 31:658-666.  Back to cited text no. 16
    

Declaration of patient consent
The authors certify that they will obtain all appropriate patient consent forms. In the form the patient(s) will give his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients will understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity will not be guaranteed.
Conflicts of interest
None declared.
Author contributions
PY conceived and designed the study protocol, wrote the manuscript and will perform the surgery. QW and LLL will be responsible for data collection and processing. All authors approved the final version of the manuscript.
Plagiarism check
This paper was screened twice using CrossCheck to verify originality before publication.
Peer review
This paper was double-blinded and stringently reviewed by international expert reviewers.


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