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ORIGINAL ARTICLE
Year : 2013  |  Volume : 20  |  Issue : 3  |  Page : 207-211  

Diffractive multifocal intraocular lens compared to pseudo-accommodative intraocular lens implant for unilateral cataracts in pre-presbyopic patients


Department of Ophthalmology, Indira Gandhi Government Medical College, Nagpur, Maharashtra, India

Date of Web Publication9-Jul-2013

Correspondence Address:
Rajesh Subhash Joshi
77, Panchtara Housing Society, Manish Nagar, Somalwada, Wardha Road, Nagpur - 440 015, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0974-9233.114792

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   Abstract 

Purpose: To evaluate the efficacy of diffractive multifocal and pseudo-accommodative IOLs in pre-presbyopes with cataract.
Materials and Methods: A prospective randomized control study was performed on patients with cataract in the pre-presbyopic age group. Patients were randomly allocated to 2 groups: Group 1 comprised 12 patients who underwent implantation of a diffractive multifocal IOL and Group 2 comprised 13 patients who underwent implantation of a pseudo-accommodative IOL after standard phacoemulsification. Efficacy was measured by postoperative distance and near uncorrected visual acuity, contrast sensitivity, spectacle independence, and glare and halo.
Between-group comparison was performed with the unpaired t test. Fisher's exact test was used for categorical variables. All the tests were two-sided with confidence interval set at 95%.
Results: The study patients were aged 22-35 years and included 14 females and 11 males. All examinations were performed 6 months postoperatively by a second observer unaware of the study objectives. Mean uncorrected distance visual acuity was 0.125 ± 0.1 LogMAR in Group 1 and 0.1385 ± 0.1 in Group 2 (P = 0.7993). Near visual acuity was 0.0917 ± 0.1 in Group 1 and 0.386 ± 0.2 in Group 2 (P < 0.0001). Contrast sensitivity was good in both groups based on the Pelli-Robson chart (P = 0.3919). Night-time glare was present in 3 (25%) patients in Group 1 and in 2 (15.4%) patients in Group 2. No patients in either group had difficulty driving during the day or night. Ten patients in Group 1 (83.3%) and 7 patients in Group 2 (53.85%) had spectacle independence (P = 0.1249).
Conclusion: Greater proportions of patients who underwent diffractive multifocal implantation achieved functional distance and near vision as compared to those in the pseudo-accommodative IOL group. There was greater variability in near vision in patients who received the pseudo-accommodative IOL as compared to those in the multifocal IOLs. Contrast sensitivity remained adequate in both the groups. There were more glare and halos in the multifocal group as compared to those in the pseudo-accommodative group. More patients achieved spectacle independence with multifocal IOLs.

Keywords: Accommodative IOL, Contrast Sensitivity, Diffractive Multifocal Intraocular Lens, Phacoemulsification, Pre-Presbyopic Cataract


How to cite this article:
Joshi RS. Diffractive multifocal intraocular lens compared to pseudo-accommodative intraocular lens implant for unilateral cataracts in pre-presbyopic patients. Middle East Afr J Ophthalmol 2013;20:207-11

How to cite this URL:
Joshi RS. Diffractive multifocal intraocular lens compared to pseudo-accommodative intraocular lens implant for unilateral cataracts in pre-presbyopic patients. Middle East Afr J Ophthalmol [serial online] 2013 [cited 2019 Nov 15];20:207-11. Available from: http://www.meajo.org/text.asp?2013/20/3/207/114792


   Introduction Top


Presbyopia correction is challenging in patients undergoing cataract surgery. An ideal intraocular lens (IOL) simulates the original function of the crystalline lens and provides the patient with multifocal vision. [1] Current strategies to correct postoperative presbyopia include reading glasses, contact lenses, or monovision. Each of these modalities has some inherent disadvantages.

Young patients with unilateral or bilateral cataracts due to a developmental reason, trauma, diabetes, and steroid-induced cataracts requiring cataract surgery may face difficulties adapting to postoperative presbyopia. Implanting monofocal IOL forces them to use bifocal glasses, which may be cosmetically unacceptable. Clinical studies have shown improved uncorrected near visual acuity and decreased spectacle dependence in patients with multifocal IOLs as compared to monofocal. [1] Pseudo-accommodative IOLs were also developed to reduce spectacle dependence. Implantation of either multifocal or accommodative lenses in the posterior chamber after cataract surgery improves both near and distance vision. But standard visual acuity is a crude measurement of visual performance and cannot represent all aspects of visual function. Therefore, objective evaluation of visual performance of these IOLs by contrast sensitivity testing is important.

Young patients' activities range from driving, reading, writing, and computer work, which are better indicators of visual performance of these two types of lenses. Considering this reason, we performed a study to compare accommodative and diffractive multifocal IOLs in a randomized, control trial in pre-presbyopic patients with cataract. In this study, we compared the efficacy, visual acuity, contrast sensitivity, spectacle independence, and glare and halos of the two different lenses.


   Materials and Methods Top


The study comprised of 25 patients who were pre-presbyopic with cataracts who were randomly allocated to receive either an accommodating or multifocal IOLs from January 2007 through February 2008 in a medical college. Research and ethical approval for the study was obtained from the Research and Ethics Committee of the medical college.

The patients were divided into 2 groups based on the type of IOL that was implanted: Group 1 was comprised of 12 patients implanted with multifocal diffractive IOLs (i-diff, Care group, India) and Group 2 was comprised of 13 patients who underwent implantation with an accommodating IOL (Ultrasmart, Appasamy associates, India).

Inclusion criteria were pre-presbyopic age with a unilateral cataract, corneal astigmatism less than 1.0 D, axial length between 22.0 to 25.0 mm, and preoperative pupil size less than or equal to 6 mm. Exclusion criteria were subluxated cataracts, distorted pupil, retinal pathology, prior retinal surgery or laser treatment, high myopia and hyperopia, amblyopia, glaucoma, history of previous refractive surgery, other eye with a monofocal implant and monocular patients. Intraoperative exclusion criteria were zonular damage, vitreous loss, capsulorhexis tear, and pupillary trauma during the surgery.

All patients underwent a thorough informed consent procedure that involved a discussion of the risks and benefits of the implants. This study adhered to the tenets of the Declaration of Helsinki. Patients were randomized to receive either a multifocal diffractive IOL with a 4.0 D additions or a pseudo-accommodative IOL. The randomization schedule was generated by software from Geoffrey C. Urbainiak available online (www.randomizer.org). On the day of surgery, the patient was asked to select two envelopes containing either a multifocal or accommodative IOL. The surgeon was not aware of the patient intervention until the selection. A second observer performed all the examinations after 6 months. The results were disclosed after analysis of data. Considering near visual acuity as the most important criteria, the power of study was 85% with the available sample size (n = 25).

Preoperatively, all patients underwent a thorough examination that included measurement of distance and near visual acuity with an Early Treatment Diabetic Retinopathy Study (ETDRS) chart, slit lamp evaluation, grade of cataract (Emery and Little classification), [2] applanation tonometry, keratometry, and dilated fundus examination. Axial length was measured by immersion biometry. IOL power was calculated with the Sanders, Retzlaff, and Kraff-II theoretical formula (A-Constant of diffractive multifocal and pseudo-accommodative IOL = 118.0).

A single experienced surgeon performed all cataract extractions with the patient receiving topical (0.5%) proparcaine 5 min prior to the surgery. The topical anesthetic was supplemented with 0.5 ml subconjunctival injection of 2% xylocaine nasally. All patients underwent a 2.8 mm clear corneal temporal incision. A 5.5 mm capsulorhexis was created to cover a 6 mm optic of the IOL. The phacoemulsification settings were vacuum 250 cc, flow rate 30 cc, and power 30-50% in a pulse mode (Swisstech, Oertli phacoemulsification system, Switzerland). A thorough cortical wash and vacuum polishing of the posterior capsule was performed. After completion of the procedure, patients received either multifocal diffractive IOL with a 4.0 D additions or a pseudo-accommodative IOL, placed in the capsular bag. All the operations were uneventful.

The diffractive multifocal IOL has a 6 mm optic with 12.5 mm overall diameter, whereas the pseudo-accommodative IOL has a 6 mm optic with 11 mm overall length with 4 flexible haptics designed to allow the lens to move anteriorly in the capsular bag secondary to ciliary muscle contraction. Both the lenses have an aspheric optic, 360° square edge and are made of hydrophilic acrylic material.

Following surgery, the patients were treated with combined antibiotic and steroids drops 4 times per day for 1 month. All patients had a routine 1-day postoperative examination. All study examinations were performed 6 months postoperatively by the second examiner, who was unaware of the objective of the study. The examination included measurement of uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA) at 4 m with an illuminated chart for distance visual acuity and 40 cm for near visual acuity with an ETDRS chart. Photopic lighting conditions were maintained for all visual acuity tests.

Contrast sensitivity was tested at 1 meter with the Pelli-Robson chart. Spectacle independence was based on whether patients required glasses for routine work. The data were entered in an excel sheet and statistical analysis was performed with SPSS software, 13.0 (IBM Corp., New York, NY, USA). Between-group comparison was performed with the unpaired t-test. Fisher's exact test was used for categorical variables. All the tests were two-sided with confidence interval set at 95%.

A P-value < 0.05 indicated statistical significance.


   Results Top


Patients ranged in age from 22 years to 35 years (29.52 ± 4.1 years and included 14 females (56%) and 11 males (44%). Grade 1 nuclear sclerosis was present in 18 (72%) patients and grade 2 in 7 (28%) patients. All patients underwent unilateral IOL implantation. Surgery was uneventful and successful in all patients. The capsulorhexis remained intact in all patients with the IOLs were well-centered inside the capsular bag. There were no cases of rupture of posterior capsule or vitreous loss.

The postoperative course was uneventful in all patients. During follow-up, the IOL remained well-centered in the capsular bag in all patients. One patient in each group developed posterior capsular opacification (PCO) that did not require YAG capsulotomy as it was thin and not affecting vision. There were no "signs of shrinkage" of rim of the anterior capsular margin in the follow-up period.

Visual acuity and contrast sensitivity

The mean uncorrected distance visual acuity was 0.125 ± 0.1 logMar (range, 0 logMAR to 0.3 logMAR) in Group 1 and 0.1385 ± 0.1 logMAR (range, 0 logMAR to 0.3 logMAR) in Group 2 (P = 0.7993, two tailed analysis). Of note, both groups had the same range.

There was a statistically significant difference between groups in near vision. Mean near vision was 0.0917 ± 0.1 in Group 1 and 0.3846 ± 0.2 in Group 2 (P < 0.0001). The range of visual acuity in group 2 was variable from 0.1-0.6.

Mean contrast sensitivity was 1.527 ± 0.1 in Group 1 and 1.575 ± 0.2 in Group 2 (P = 0.3919).

Spectacle independence

Spectacle independence was assessed at 6 months according to a pre-prepared questionnaire [Table 1]. Group 1 patients were satisfied with unaided visual acuity. Two patients (16.7%) in this group required spectacles, of which 1 patient (8.33%) required spectacles full time.
Table 1: Spectacle independence in both patients who underwent monocular implantation of a multifocal or accommodating intraocular lens

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In Group 2, 7 patients (53.85%) did not require spectacles. The difference between groups was not statistically significant (P = 0.1249).

Glare and halos

Postoperative night-time glare was present in 3 (25%) patients in multifocal group and 2 (15.4%) patients in Group 2. One patient in Group 2 complained of halos. No patients in either group had difficulty in driving in photopic or scotopic conditions.


   Discussion Top


A major concern after implantation of monofocal lens in a young patient with a unilateral cataract is near vision. The loss of accommodation in this group of patients can be particularly difficult because of their active lifestyle. Patients implanted with monofocal IOLs have little or no depth of focus in an operated eye, yet normal accommodation in a fellow un-operated eye. For binocular functioning, we believe that young patients with an uncomplicated unilateral cataract are suitable to undergo implantation of either diffractive or accommodative lenses, which provide distance and near vision.

Cillino et al., [3] compared a new generation of diffractive multifocal IOLs (Tecnis ZM 900; AMO Inc., Abbott Park, Ill., USA) with monofocal IOLs and found that multifocal IOLs provide better near and distance visual acuity and greater spectacle independence (87.5%) than monofocal IOLs (20%). A comparison of accommodative IOLs (Crystalens HD) with monofocal IOL (2010) also found that uncorrected near visual acuity was statistically significantly better in the accommodating IOL group as compared to the monofocal group (J5 versus J3; P = 0.01). [4] However, the accommodative benefit of accommodative IOLs decreases with time due to capsular fibrosis. [2]

Our study suggests that implantation of diffractive multifocal or accommodative IOLs in patient whose other eye is phakic provides good functional vision for distance. We did find a statistically significant difference in near vision between groups (P < 0.0001). Vries et al., [5] reported performance of an Acrysof ReSTOR IOL (FDA approved) at 6 months. They found that monocular uncorrected distance visual acuity was 0.128 ± 0.1 logMAR and near visual acuity was 0.020 ± 0.1 logMAR. [5] This correlates with the visual performance of the diffractive multifocal IOL in our study. Claoue [6] compared the Array multifocal (AMO Inc., Abbott Park, Ill., USA) with 1CU accommodating IOL (HumanOptics AG, Erlangen, Germany). Claoue [6] found a statistically significantly greater proportion of the multifocal IOL group achieved near UCVA of N/5 or better as compared to the accommodating IOL group (76.5% versus 44.4% respectively). Claoue [6] also found that 94.4% patients with multifocal IOLs and 50% with accommodating IOLs reported spectacle independence. These outcomes correlate with our study.

The mechanism of an accommodative IOL is the focus shift principle that allows pseudophakic accommodation. [7] We found the patients with an accommodative IOL had variable near vision performance ranging from 0.1 to 0.6 logMAR. This is in contrast to the near vision performance of the multifocal group, which was consistent (0-0.2 logMAR). This could be due to variable accommodation of the accommodative IOLs.

A long-term study of accommodative lenses has shown loss of accommodative power due to high incidence of anterior and posterior capsule opacification. [8] In our study, 1 patient in each group had faint PCO and no signs of anterior capsular fibrosis. Reduced PCO could be due to meticulous polishing of the posterior capsule and the square edge of the lens. However, long-term follow-up of these patients is important. Complications such as decreased near vision due to loss of accommodative power of the lens or lens shift in the bag due to capsular fibrosis needs to be considered while implanting these lenses in young patients. Development of posterior segment pathology requiring visualization of the peripheral retina and treatment of retinal lesions laser therapy or surgery should also be considered when opting for these lenses.

Ten (83.3%) patients in Group 1 and 7 (53.85%) patients Group 2 were spectacle independent (P = 0.1249). Two patients in Group 1 had to use spectacles for distance and near, while 5 patients in Group 2 had to depend on spectacles for near (P = 0.1070). However, the difference between groups was not statistically significant. This could be because of the small sample size. It is comparatively easy to recruit many patients with senile cataracts than in a younger age group. Second, the eye dominance with unilateral implantation could not be ascertained from our data.

Previous studies have reported a diminution in contrast sensitivity after implantation of multifocal lens as compared to monofocal implants. [5] This is because of the division of light energy through two focal points produced by a multifocal IOL. [9] In our study, contrast sensitivity values were lower in diffractive multifocal group as compared to accommodative group; however, there was no significant reduction in contrast (P = 0.3919). In an accommodative IOL, contrast sensitivity is less of an issue because the lens optic is similar to a monofocal implant and they work independent of the pupillary size. Mesci et al., [10] evaluated visual acuity and contrast sensitivity after accommodative, refractive, and diffractive multifocal IOL implantation. They concluded that diffractive multifocal IOL resulted in more favorable visual acuities and higher contrast values than accommodative and refractive multifocal IOLs. [10]

Glare and halos are dyphotopsias that occur with multifocal and accommodative IOLs. No patients in either group had daytime glare postoperatively; however, 25% patients in Group 1 and 15.4% patients in Group 2 had night-time glare. Studies from the western hemisphere have reported an incidence of glare and halos at 40.4% after diffractive multifocal IOL implantation. [11] Since high-contrast conditions, i.e., very bright light source in the presence of a very dark background, is required to stimulate halos for both distance and near, [12] day-time glare is less of an issue in our area. Night-time glare may be more likely because of non-cataractous phakic and intraocular stray light levels that are higher than levels in eyes with a monofocal or multifocal IOL. [13] These ocular stray lights may explain night glare reported with the diffractive multifocal group. In an accommodative IOL, the lens optic in the pupillary area is similar to a monofocal implant; however, once the pupil dilates, the edges of the diffractive steps present in the peripheral optic can cause glare. However, no patients in either group complained of difficulty in driving at night or daytime.

Is summary, unilateral implantation of either diffractive multifocal or an accommodative IOL in a pre-presbyopic cohort with cataract provides good visual outcome. More patients with accommodative IOLs were dependent on spectacles for near vision; however, the difference between groups was not significant statistically. Despite that the sample size is small, this study is unique in comparing young patients with cataract.


   Acknowledgement Top


I thank Dr. Avinash Turankar, Associate Professor, Department of Pharmacology, Government Medical College and Hospital for the statistical assistance.

 
   References Top

1.Dolders MG, Nijkamp MD, Nuijts RM, van den Borne B, Hendrikse F, Ament A, et al. Cost effectiveness of foldable multifocal intraocular lenses compared to foldable monofocal intraocular lenses for cataract surgery. Br J Ophthalmol 2004;88:1163-8.  Back to cited text no. 1
    
2.Wolffsohn JS, Naroo SA, Motwani NK, Shah S, Hunt OA, Mantry S, et al. Subjective and objective performance of the Lenstec KH-3500 "accommodative" intraocular lens. Br J Ophthalmol 2006;90:693-6.  Back to cited text no. 2
    
3.Cillino S, Casuccio A, Di Pace F, Morreale R, Pillitteri F, Cillino G, et al. One-year outcomes with new-generation multifocal intraocular lenses. Ophthalmology 2008;115:1508-16.  Back to cited text no. 3
    
4.Alió JL, Piñero DP, Plaza-Puche AB. Visual outcomes and optical performance with a monofocal intraocular lens and a new-generation single-optic accommodating intraocular lens. J Cataract Refract Surg 2010;36:1656-64.  Back to cited text no. 4
    
5.de Vries NE, Webers CA, Monte´s-Mico´ R, Tahzib NG, Cheng YY, de Brabander J, et al. Long-term follow-up of a multifocal apodized diffractive intraocular lens after cataract surgery. J Cataract Refract Surg 2008;34:1476-82.  Back to cited text no. 5
    
6.Claoué C. Functional vision after cataract removal with multifocal and accommodating intraocular lens implantation: Prospective comparative evaluation of Array multifocal and 1CU accommodating lenses. J Cataract Refract Surg 2004;30:2088-91.  Back to cited text no. 6
    
7.Dick HB. Accommodative intraocular lenses: Current status. Curr Opin Ophthalmol 2005;16:8-26.  Back to cited text no. 7
    
8.Mastropasqua L, Toto L, Falconio G, Nubile M, Carpineto P, Ciancaglini M, et al. Longterm results of 1 CU accommodative intraocular lens implantation: 2-year follow-up study. Acta Ophthalmol Scand 2007;85:409-14.  Back to cited text no. 8
    
9.Kim CY, Chung SH, Kim TI, Cho YJ, Yoon G, Seo KY. Comparison of higher-order aberration and contrast sensitivity in monofocal and multifocal intraocular lenses. Yonsei Med J 2007;48:627-33.  Back to cited text no. 9
    
10.Mesci C, Erbil H, Ozdoker L, Karakurt Y, Bilge AD. Visual acuity and contrast sensitivity function after accommodative and multifocal intraocular lens implantation. Eur J Ophthalmol 2010;20:90-100.  Back to cited text no. 10
    
11.Javitt JC, Wang F, Trentacost DJ, Rowe M, Tarantino N. Outcomes of cataract extraction with multifocal intraocular lens implantation: Functional status and quality of life. Ophthalmology 1997;104:589-99.  Back to cited text no. 11
    
12.Pieh S, Lackner B, Hanselmayer G, Zöhrer R, Sticker M, Weghaupt H, et al. Halo size under distance and near conditions in refractive multifocal intraocular lenses. Br J Ophthalmol 2001;85:816-21.  Back to cited text no. 12
    
13.Cionni RJ, Osher RH, Snyder ME, Nordlund ML. Visual outcome comparison of unilateral versus bilateral implantation of apodized diffractive multifocal intraocular lenses after cataract extraction: Prospective 6-month study. J Cataract Refract Surg 2009;35:1033-9.  Back to cited text no. 13
    



 
 
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