Journal of Refractive Surgery

Original Article 

Objective Accommodation Measurement of the Crystalens HD Compared to Monofocal Intraocular Lenses

Katherine V. Zamora-Alejo, MD; Sacha Pierre Moore, FRCOphth; Douglas G. A. Parker, BMedSc, MBBS, PhD; Katja Ullrich, BM, BS; Adrian Esterman, PhD, MSc, DLSHTM; Michael Goggin, FRCSI(Ophth), FRANZCO, MS

Abstract

PURPOSE:

Objective evaluation of accommodation with a bilateral accommodating intraocular lens (IOL) versus monofocal IOLs.

METHODS:

Patients received accommodating IOL (Crystalens HD; Bausch & Lomb, Rochester, NY) bilaterally after cataract surgery. These were compared to a matched group receiving monofocal IOLs. Preoperative and postoperative distance corrected distance, intermediate, and near vision were evaluated. Objective accommodation was measured with the WAM-5500 Binocular Autorefractor/Keratometer (Grand Seiko, Pty Ltd., Hiroshima, Japan).

RESULTS:

Nineteen patients were included. Ten received the Crystalens HD in both eyes and nine received one of three monofocal lenses in each eye. Mean postoperative distance corrected distance visual acuity was not statistically different between the two groups. Mean distance corrected intermediate vision was better in the Crystalens HD group (logMAR 0.24 ± 0.11 [control], logMAR 0.11 ± 0.10 [Crystalens HD], P = .033). The groups did not differ significantly for mean distance corrected near vision (logMAR 0.54 ± 0.12 [control], logMAR 0.42 ± 0.15 [Crystalens HD], P = .087). However, a significantly greater proportion of Crystalens HD eyes achieved 0.4 or 0.3 logMAR for near wearing their distance correction (P = .013). With distance correction, the mean spherical equivalent failed to show any myopia with accommodative effort in either group. Low contrast and low luminance contrast acuity were not significantly different.

CONCLUSION:

The Crystalens HD showed some benefit for intermediate visual function compared to the monofocal IOLs with both groups wearing full correction for distance. There were no significant signs of accommodation in either group.

From the Department of Ophthalmology, The Queen Elizabeth Hospital, South Australian Institute of Ophthalmology, University of Adelaide, Adelaide, Australia (KVZ-A, SPM, DGAP, KU, MG); and Sansom Institute of Health Research, University of South Australia, South Australia, Australia (AE).

The authors have no financial or proprietary interest in the materials presented herein.

AUTHOR CONTRIBUTIONS

Study concept and design (MG, SPM); data collection (MG, SPM, DGAP, KU); analysis and interpretation of data (AE, MG, SPM, KVZ-A); drafting of the manuscript (MG, DGAP, KU, KVZ-A); critical revision of the manuscript (AE, MG, SPM, KVZ-A); statistical expertise (AE); supervision (MG)

Correspondence: Michael Goggin, FRCSI(Ophth), FRANZCO, MS, 28 Woodville Road, Woodville South SA 5011, Australia. E-mail: Michael.Goggin@health.sa.gov.au

Received: June 14, 2012
Accepted: December 11, 2012

Abstract

PURPOSE:

Objective evaluation of accommodation with a bilateral accommodating intraocular lens (IOL) versus monofocal IOLs.

METHODS:

Patients received accommodating IOL (Crystalens HD; Bausch & Lomb, Rochester, NY) bilaterally after cataract surgery. These were compared to a matched group receiving monofocal IOLs. Preoperative and postoperative distance corrected distance, intermediate, and near vision were evaluated. Objective accommodation was measured with the WAM-5500 Binocular Autorefractor/Keratometer (Grand Seiko, Pty Ltd., Hiroshima, Japan).

RESULTS:

Nineteen patients were included. Ten received the Crystalens HD in both eyes and nine received one of three monofocal lenses in each eye. Mean postoperative distance corrected distance visual acuity was not statistically different between the two groups. Mean distance corrected intermediate vision was better in the Crystalens HD group (logMAR 0.24 ± 0.11 [control], logMAR 0.11 ± 0.10 [Crystalens HD], P = .033). The groups did not differ significantly for mean distance corrected near vision (logMAR 0.54 ± 0.12 [control], logMAR 0.42 ± 0.15 [Crystalens HD], P = .087). However, a significantly greater proportion of Crystalens HD eyes achieved 0.4 or 0.3 logMAR for near wearing their distance correction (P = .013). With distance correction, the mean spherical equivalent failed to show any myopia with accommodative effort in either group. Low contrast and low luminance contrast acuity were not significantly different.

CONCLUSION:

The Crystalens HD showed some benefit for intermediate visual function compared to the monofocal IOLs with both groups wearing full correction for distance. There were no significant signs of accommodation in either group.

From the Department of Ophthalmology, The Queen Elizabeth Hospital, South Australian Institute of Ophthalmology, University of Adelaide, Adelaide, Australia (KVZ-A, SPM, DGAP, KU, MG); and Sansom Institute of Health Research, University of South Australia, South Australia, Australia (AE).

The authors have no financial or proprietary interest in the materials presented herein.

AUTHOR CONTRIBUTIONS

Study concept and design (MG, SPM); data collection (MG, SPM, DGAP, KU); analysis and interpretation of data (AE, MG, SPM, KVZ-A); drafting of the manuscript (MG, DGAP, KU, KVZ-A); critical revision of the manuscript (AE, MG, SPM, KVZ-A); statistical expertise (AE); supervision (MG)

Correspondence: Michael Goggin, FRCSI(Ophth), FRANZCO, MS, 28 Woodville Road, Woodville South SA 5011, Australia. E-mail: Michael.Goggin@health.sa.gov.au

Received: June 14, 2012
Accepted: December 11, 2012

The Crystalens HD (Bausch & Lomb, Rochester, NY) is marketed as an accommodating IOL. It is a single optic IOL with a hinged plate haptic designed to respond to accommodative effort by allowing changes in the position and shape of the optic.1,2 The mechanism of action suggested by the manufacturer is that an accommodative effort causes a bulking up of the ciliary muscle within the vitreous cavity, increasing the vitreous pressure against the posteriorly vaulted optic and causing a temporary forward movement of the optic.2 Forces from the ciliary muscle contraction and increased vitreous pressure cause the Crystalens HD optic to arch, which purportedly creates more spherical aberration, resulting in an increased depth of field, a steeper central optical zone, and anterior movement of the best plane of focus. This effect is accentuated by the modification of the Crystalens HD lens optic, which has 3 to 5 μm central thickening with a small optical zone, accounting for a 1-diopter (D) add that extends the depth of field.3

Movement of the Crystalens AT-45 has been studied using ultrasound biomicroscopy and partial coherence interferometry. The ultrasound biomicroscopy study showed an anterior displacement of the Crystalens HD and corresponding anterior rotation of the ciliary body during near vision. This movement was proportional to the accommodation capacity.4 Partial coherence interferometry showed a counterproductive active backward shift of the IOL when ciliary contraction was induced by pilocarpine 2%.5

One study6 reported that the use of the Crystalens HD provided better uncorrected near visual acuity and accommodation, using defocus curves, compared to a monofocal IOL group. Although these results are promising, there have been reports that subjective methods of measuring accommodation, such as the push-up technique, tend to overestimate the accommodative amplitude. Moreover, subjective measurements of near vision may show that accommodation is present when it is not. This may be due to learning of near visual acuity card letters with repeated testing, increased depth of field due to pupil constriction, and induced aberrations with surgery.7

There is a need to assess accommodation objectively by measuring a change in the optical power of the eye. This would differentiate true accommodation from pseudoaccommodation.7 The use of open-field autorefractors, such as the WAM-5500 Auto Ref/Keratometer (Grand Seiko, Pty Ltd., Hiroshima, Japan), have been validated in various studies of and reviews on accommodation.8–10

This study aims to evaluate objective accommodation between a group of patients with bilateral implantation of a newer generation accommodating IOL lens and a control group with bilateral implantation of monofocal IOLs using the WAM-5500 Auto Ref/ Keratometer.

Patients and Methods

Patient Selection

This observational, blinded, case–control series included patients with significant bilateral cataracts having good visual potential. Exclusion criteria were corneal astigmatism of greater than 1.25 diopters, ocular pathology other than cataract, and previous eye surgery. Control subjects were matched for age and visual acuity, having undergone bilateral cataract surgery with monofocal IOLs. Exclusion criteria were identical between groups.

Preoperative Examination

Automated refraction and keratometric readings were obtained using the Nidek Auto Ref/Keratometer 510A (Nidek Inc., Fremont, CA). Biometry was performed using the IOLMaster (Carl Zeiss Meditec) or the Ocuscan RxP (Alcon Laboratories, Inc.) immersion ultrasound A-scan for eyes with cataract too dense for measurement with laser interferometry.

The spherical equivalent postoperative target was the smallest possible error (myopic or hyperopic) given the available IOL powers in the dominant eye and the lowest possible myopic error in the non-dominant eye for eyes receiving the Crystalens HD. All of the control eyes received the IOL targeted to produce the lowest possible myopic error.

Surgical Technique

Two experienced surgeons (MG, SPM) performed all surgeries under peribulbar block. Coaxial micro-incision phacoemulsification was performed through a 1.8-mm temporal corneal incision. This incision was enlarged to 2.8 mm for the insertion of the Crystalens HD, and remained unenlarged for the insertion of monofocal IOLs. One drop of atropine sulfate was administered at the end of the procedure to the patients in the Crystalens HD group. All patients were given dexamethasone 0.1% reducing over a period of 4 weeks and chloramphenicol 0.5% drops postoperatively for 1 week.

Postoperative Examination

At a mean of 11 weeks postoperatively for the Crystalens HD recipients and 23 weeks for the monofocal IOL recipients, postoperative uncorrected and distance corrected visual acuity was determined at 6 m, 80 cm, and 40 cm. To facilitate data collection, patients were all evaluated on the same day. Measurements of the dioptric amount of accommodation were performed using the WAM-5500 Auto Ref/Keratometer with the patients wearing full distance correction. This device allows autorefraction of either eye while the patient views distant or near objects through a semi-reflective screen. The patient can wear spectacles or a trial frame with lenses during the measurement. The autorefraction device uses the light from the semi-reflective screen for the measurement and is located below the visual path of the subject. With their best manifest refraction correction in place while autorefraction was performed through the correcting lenses, patients were asked to focus on the 6/6 line (0 logMAR) of a distance chart and measurements were recorded. A near target was introduced and measurements were recorded for 50, 40, 33, 25, and 20 cm. Autorefraction measurements were converted to spherical equivalent values.

Cycloplegic subjective refraction was performed and compared to the manifest subjective refraction to examine for the presence of a myopic difference.

Low contrast acuity was tested using the CSV-1000RS chart (VectorVision, Greenville, OH). The chart was placed at a distance of 8 feet (243 cm) as recommended by the manufacturer. With the patient’s best correction plus an add of 0.5 D, performance was recorded using three letters per line. A threshold of two of three letters was used to determine the patient’s visual acuity and measured at 100%, 25%, and 12.5% contrast.

Low contrast under low luminance conditions for near vision was tested using the Smith-Kettlewell Institute Low Luminance (SKILL) card. This has one side with a high contrast (greater than 90%) black-on-white letter chart, and the other a low contrast (14%) chart composed of black letters on a dark gray background, simulating reduced luminance conditions.11 Holding the card at 40 cm, with their distance correction plus an add of 2.5 D, patients read the high contrast side and then the low contrast side. The SKILL score was the difference in number of letters read between the high contrast and low contrast sides. This test was done with both eyes open, and then each eye was tested separately.

Surgically Induced Astigmatism

Keratometric measurements were compared pre-operatively and postoperatively. Surgically induced astigmatism was derived, case by case, by vector analysis from these two data sets using the Alpins method.12

Statistical Analysis

None of the variables had a normal distribution, and a non-parametric analysis was indicated due to the relatively small sample size. Right and left eyes were included in the dataset, which precluded the use of the Mann–Whitney U test. Because there are no usual statistical procedures to handle this situation, variables were first ranked and then entered into a clustered linear regression model with the ranked variable as the dependent variable and group as the independent variable. Statistical analyses were undertaken using the Stata 11 statistical package (StataCorp, College Station, TX). For continuous variables, the test of significance used mean ranks rather than medians.

Results

The preoperative baseline characteristics of the patients are seen in Table 1. There was no statistically significant difference between the two groups in axial length, anterior chamber depth, and implanted IOL power. Nineteen patients were included; a twentieth patient belonging to the control group was withdrawn from the study, having been lost to follow-up. Twenty eyes of 10 patients (mean age: 69 ± 11 years; range: 51 to 84 years; 5 males) were implanted with the Crystalens HD. Eighteen eyes of 9 patients (mean age: 69 ± 9 years; range: 52 to 77 years; 6 females) were included in the control group. Nine eyes were implanted with the Akreos MI60 (Bausch & Lomb), 8 with the Acri. Tec 46LC (Carl Zeiss Meditec, Dublin, CA), and 1 with the Acrysof SN60WF (Alcon Laboratories, Inc., Fort Worth, TX). One patient in the Crystalens HD group had a posterior capsular tear intraoperatively. The IOL was inserted in the capsular bag, which had remained stable to the time of examination. One patient in the control group suffered localized orbital inflammation postoperatively, presumably an allergic reaction to the hyaluronidase given with the peribulbar anesthetic. This patient recovered after treatment with oral steroids.

Preoperative Baseline Characteristics of the Two Groups

Table 1: Preoperative Baseline Characteristics of the Two Groups

Subjective Refractive Outcome

The mean manifest subjective refraction spherical equivalents were 0.077 ± 0.630 and −0.453 ± 0.775 D for the control and Crystalens HD groups, respectively, with this difference not being statistically significant.

Cycloplegic Refractive Outcome

The mean cycloplegic spherical equivalent for the control group was −0.01 ± 0.58 D versus the Crystalens HD group with −0.36 ± 0.79 D (P = .163). These did not differ significantly. The change in mean spherical equivalent from “dry” refraction to cycloplegic was 0.08 ± 0.25 D for the control group and −0.09 ± 0.19 D for the Crystalens HD group, which, although statistically significant (P = .025), is clinically negligible.

Mean Visual Acuity

Table 2 shows the mean postoperative distance corrected visual acuity for distance, intermediate, and near. Mean postoperative uncorrected distance visual acuity was logMAR 0.04 ± 0.14 (control) and 0.06 ± 0.16 (Crystalens HD) and corrected visual acuity was better than 0.0 logMAR (20/20 Snellen). The mean postoperative distance visual acuity (corrected or uncorrected) was not statistically different between the two groups. There was no difference in mean distance corrected visual acuity between the Crystalens HD and control groups for distance and near targets. However, there was a statistical difference for mean intermediate vision with distance correction, with the Crystalens HD eyes performing better.

Postoperative Visual Acuity Data Comparing the Two Groups

Table 2: Postoperative Visual Acuity Data Comparing the Two Groups

Proportion of Eyes Attaining Up to logMAR 0.3 at Each Distance

With distance correction in place (Figure 1), there was a significant benefit for intermediate vision in the Crystalens HD group and a significantly greater proportion of Crystalens HD eyes achieved 0.4 or 0.3 log-MAR for near wearing their distance correction.

Distance corrected distance, intermediate, and near vision. Percentage of eyes obtaining a visual acuity of 0.4 logMAR or better for distance corrected (A) distance, (B) intermediate, and (C) near visual acuity. P values obtained using the chi-square test.

Figure 1. Distance corrected distance, intermediate, and near vision. Percentage of eyes obtaining a visual acuity of 0.4 logMAR or better for distance corrected (A) distance, (B) intermediate, and (C) near visual acuity. P values obtained using the chi-square test.

WAM-5500 Autorefraction

All measurements with this device were made with the patients wearing their distance correction in a trial frame. At all distances, the WAM-5500 measured spherical equivalent was arithmetically less in the Crystalens HD group (Table 3). However, nearly all mean spherical equivalents indicated slight hyperopia, not myopia. For these mean values, no progression into myopia was observed with diminishing reading distance in either group. It was only at a distance of 40 cm that a mean measured spherical equivalent that might be construed as greater accommodation in the Crystalens HD eyes (+0.01 ± 0.57 D) was significantly less (arithmetically, indicating myopic shift) compared to the patients with monofocal IOLs (+0.45 ± 0.52 D, P = .027). However, the mean spherical equivalent remained hyperopic, not myopic.

WAM-5500–Measured Spherical Equivalent for Comparisons Between the Two Groupsa

Table 3: WAM-5500–Measured Spherical Equivalent for Comparisons Between the Two Groups

In a further attempt to look for increasing myopia with accommodative effort, the change in spherical equivalent of the autorefractive measurements between 6 m and 40 cm viewing was compared. No significant difference was seen.

Photopic Contrast Acuity and Low Luminance Contrast Acuity

Photopic mean acuity logMAR values at 100% contrast were statistically significantly better (P = .001) for the control group (logMAR 0.01 ± 0.12) compared to the Crystalens group (logMAR 0.04 ± 0.09), but the difference (0.03 logMAR) is not clinically significant. As seen in Table A (available as supplemental material in the PDF version of this article), at 25% and 12.5% contrast, the difference between the groups was not significant (P = .427 and .236, respectively). Although there was a loss in low contrast acuity with decreasing contrast, the contrast acuity loss from 100% to 25% was not significantly different between the two groups (P = .557).

Mean SKILL scores were not significantly different (P = .511) between the Crystalens HD (36 ± 7) and control (34 ± 8) groups.

Surgically Induced Astigmatism

Vector-derived keratometric surgically induced astigmatism was 0.45 ± 0.27 D for the Crystalens HD group versus 0.53 ± 0.50 D for the control group, the difference being statistically insignificant (P = .73).

Discussion

Accommodating IOLs have the potential to restore native accommodation of the eye without the photic phenomena usually encountered with multifocal approaches.3 To our knowledge, ours is the first study that has objective measurement of accommodation in eyes implanted with the Crytalens HD accommodating lens.

In this study, all patients achieving a distance corrected distance visual acuity of 0.2 logMAR or better, similar to previous studies done on the parent IOL model, the Crystalens AT-45.13,14 Any difference in distance corrected distance visual acuity between the two groups in this study was not statistically significant and the improvement in postoperative visual acuity suggests that both the Crystalens HD and monofocal IOLs used in this study are comparable and safe for use in patients undergoing cataract surgery.

The mean spherical equivalent postoperatively was +0.077 ± 0.630 and −0.453 ± 0.775 D for the control and Crystalens HD groups, respectively. Cycloplegic refraction demonstrated no clinically significant change in spherical equivalent versus manifest refraction, implying that accommodative tone did not contribute to the low mean myopic outcome in the Crystalens HD group.

Testing with distance correction in place, mean near visual acuity did not differ significantly between Crystalens HD and control eyes, but mean intermediate vision was better for the Crystalens HD group. This difference in mean distance corrected intermediate visual acuity is not large in clinical terms (0.11 vs 0.24 logMAR). However, even with distance correction in place, a significantly greater proportion of Crystalens HD eyes achieved levels of acuity greater than 0.4 logMAR, for intermediate viewing and for near (Figure 1). Our findings are consistent with previous studies, which showed that the Crystalens AT-45 provides better intermediate vision compared to both monofocal and multifocal IOLs.1,14

It is important to determine whether these types of lenses really restore accommodation. Many studies have used distance corrected near visual acuity and subjective tests (push-up technique, defocus curves) to determine functional vision, but do not prove that accommodation (increasing dioptric power of the eye) is truly present.15 Such tests do not differentiate whether near vision is due to the accommodative capability of the IOL or to pseudoaccommodative factors. Moreover, subjective methods have been shown to produce larger accommodative values and overestimate accommodation compared to objective methods.3,8–10,15 Subjective testing of pseudophakic patients may show functional benefits, but objective methods are needed to show IOL movement and accommodative optical changes.16

Objective measurement of accommodation requires the use of an instrument such as a refractometer or an autorefractor that measures the optical power or refractive state of the eye.17 In an attempt to measure accommodation objectively, we used the Grand Seiko WAM-5500 Auto Ref/Keratometer. This is a binocular open-field autorefractor and keratometer that permits recording of refraction during accommodative effort. It has been reported to be a reliable and valid objective refraction tool for general optometric practice, with important additional features, increasing its usefulness postoperatively after implantation of accommodating IOLs.9 Using this device, no consistent increase in myopia with near effort was demonstrable for either the Crystalens HD or control groups in this study. A significant difference was seen only when the patients were viewing at 40 cm. However, even then the Crystalens HD group only demonstrated less hyperopia than the control group, not greater myopia, casting doubt on the clinical significance of the finding.

It would appear that a significant proportion of patients are reasonably well served for intermediate and at least some near vision by Crystalens HD implantation (Figure 1). We were not able to identify any particular features of the eyes that benefited, distinguishing them from those that fared less well with Crystalens HD implantation. Furthermore, we were not able to demonstrate significant increasing myopia by autorefraction with increasingly near target viewing. This implies that classic accommodation (ie, increasing dioptric power of the eye) is not happening consistently with these implants and the greater intermediate and near function, by comparison to the monofocal IOLs, is provided by some other means in a proportion of eyes. The small multifocality provided by the central increase in IOL power in the Crystalens HD design may have assisted, or perhaps some form of optically useful lens distortion is taking place. We are unaware of any way to examine directly for this kind of distortion.

With the newer design of the Crystalens HD optic, there may be concern as to whether the central 3 to 5 μm thickening would affect low contrast acuity. Initial studies on the Crystalens HD showed that contrast sensitivity and depth of focus are improved compared to the parent AT-45 lens (personal correspondence with Bausch & Lomb). In this study, despite the presence of the small central power addition in the Crystalens HD design, there was no demonstrable loss in photopic low contrast acuity and low luminance, low contrast acuity by comparison with the monofocal group.

In this study examining outcome by mean visual acuity, the Crystalens HD showed some small benefit for intermediate visual function compared to the monofocal IOLs. With distance correction in place, the proportion of eyes seeing better than 0.4 logMAR for intermediate and near distances was significantly greater in the Crystalens HD group, implying that there is benefit from these IOLs for at least some patients. However, no objective sign of accommodation (ie, increasing myopic error with near viewing) was demonstrable using an autorefractor (the WAM-5500) capable of measurements during near viewing effort.

References

  1. Pepose JS, Qazi MA, Davies J, et al. Visual performance of patients with bilateral vs. combination Crystalens, ReZoom, and ReSTOR intraocular lens implants. Am J Ophthalmol. 2007;144(3):347–357. doi:10.1016/j.ajo.2007.05.036 [CrossRef]
  2. Glasser A. Restoration of accommodation: surgical options for correction of presbyopia. Clin Exp Optom. 2008;91(3): 279–295. doi:10.1111/j.1444-0938.2008.00260.x [CrossRef]
  3. Comander J, Pineda R 2nd, . Accommodating intraocular lenses: theory and practice. Int Ophthalmol Clin. 2010;50(1):107–117. doi:10.1097/IIO.0b013e3181c552c9 [CrossRef]
  4. Marchini G, Pedrotti E, Sartori P, Tosi R. Ultrasound biomicroscopic changes during accommodation in eyes with accommodating intraocular lenses. J Cataract Refract Surg. 2004;30(12):2476–2482. doi:10.1016/j.jcrs.2004.04.053 [CrossRef]
  5. Koeppl C, Findl O, Menapace R, et al. Pilocarpine-induced shift of an accommodating intraocular lens: AT-45 Crystalens. J Cataract Refract Surg. 2005;31(7):1290–1297. doi:10.1016/j.jcrs.2005.03.055 [CrossRef]
  6. Alió JL, Piñero DP, Plaza-Puche AB. Visual outcomes and optical performance with a monofocoal intraocular lens and a new-generation single-optic accommodating intraocular lens. J Cataract Refract Surg. 2010;36(10):1656–1664. doi:10.1016/j.jcrs.2010.04.040 [CrossRef]
  7. Wold J, Hu A, Chen S, Glasser A. Subjective and objective measurement of human accommodative amplitude. J Cataract Refract Surg. 2003;29(11):1878–1888. doi:10.1016/S0886-3350(03)00667-9 [CrossRef]
  8. Win-Hall DM, Ostrin LA, Kasthurirangan S, Glasser A. Objective accommodation measurement with the Grand Seiko and Hartinger coincidence refractometer. Optom Vis Sci. 2007;84(4):879–887. doi:10.1097/OPX.0b013e3181559ace [CrossRef]
  9. Sheppard AL, Davies LN. Clinical evaluation of the Grand Seiko Auto Ref/Keratometer WAM-5500. Ophthal Physiol Opt. 2010;30(2):143–151. doi:10.1111/j.1475-1313.2009.00701.x [CrossRef]
  10. Wolffsohn JS, Davies LN, Naroo SA, et al. Evaluation of an open-field autorefractor’s ability to measure refraction and hence potential to assess objective accommodation in pseudo-phakes. Br J Ophthalmol. 2011;95(4):498–501. doi:10.1136/bjo.2010.185009 [CrossRef]
  11. Haegerstrom-Portnoy G, Brabyn J, Schneck ME, Jampolsky A. The SKILL Card: an acuity test of reduced luminance and contrast. Invest Ophthalmol Vis Sci. 1997;38(1):207–218.
  12. Alpins NA. A new method of analyzing vectors for changes in astigmatism. J Cataract Refract Surg. 1993;19(4):524–533.
  13. Macsai MS, Padnick-Silver L, Fontes BM. Visual outcomes after accommodating intraocular lens implantation. J Cataract Refract Surg. 2006;32(4):628–633. doi:10.1016/j.jcrs.2006.01.027 [CrossRef]
  14. Cumming JS, Dolvard M, Dell SJ, et al. Clinical evaluation of the Crystalens AT-45 accommodating intraocular lens. J Cataract Refract Surg. 2006;32(5):812–825. doi:10.1016/j.jcrs.2006.02.007 [CrossRef]
  15. Win-Hall DM, Glasser A. Objective accommodation measurements in pseudophakic subjects using an autorefractor and ab-errometer. J Cataract Refract Surg. 2009;35(2):282–290. doi:10.1016/j.jcrs.2008.10.033 [CrossRef]
  16. Dick HB. Accommodative intraocular lenses: current status. Curr Opin Ophthalmol. 2005;16(1):8–26. doi:10.1097/00055735-200502000-00004 [CrossRef]
  17. Glasser A. Accommodation: mechanism and measurement. Ophthalmol Clin N Am. 2006;19(1):1–12.

Preoperative Baseline Characteristics of the Two Groups

Characteristic Control Group Crystalens HD Group Pa
Axial length (mm) .788
  Mean ± SD 23.56 ± 0.93 23.68 ± 1.00
  Range 21.68 to 25.07 22.62 to 26.52
Anterior chamber depth (mm) .142
  Mean ± SD 3.21 ± 0.46 3.38 ± 0.23
  Range 2.49 to 4.21 2.82 to 3.67
Lens power (D) .810
  Mean ± SD 21.06 ± 1.88 20.31 ± 2.21
  Range 18.00 to 24.00 14.50 to 23.00

Postoperative Visual Acuity Data Comparing the Two Groups

Visual Acuity Control Group Crystalens Group Pa
DCDVA (logMAR) .329
  Mean ± SD −0.12 ± 0.07 −0.07 ± 0.09
  Range −0.18 to 0.00 −0.18 to 0.18
DCIVA (logMAR) .033
  Mean ± SD 0.24 ± 0.11 0.11 ± 0.10
  Range 0.10 to 0.40 −0.10 to 0.30
DCNVA (logMAR) .087
  Mean ± SD 0.54 ± 0.12 0.42 ± 0.15
  Range 0.30 to 0.70 0.10 to 0.70

WAM-5500–Measured Spherical Equivalent for Comparisons Between the Two Groupsa

Parameter Control Group Crystalens Group Pb
6 meters .800
  Mean (D) ± SD +0.05 ± 0.62 −0.03 ± 0.47
  Range −0.92 to +1.59 −0.65 to +1.20
50 cm .697
  Mean (D) ± SD +0.24 ± 0.65 +0.16 ± 0.57
  Range −0.93 to +1.98 −0.69 to +1.33
40 cm .027
  Mean (D) ± SD +0.45 ± 0.52 +0.07 ± 0.50
  Range −0.29 to +1.54 −0.53 to + 0.92
33 cm .162
  Mean (D) ± SD +0.43 ± 0.54 +0.06 ± 0.49
  Range −0.53 to +1.76 −0.97 to +0.94
25 cm .071
  Mean (D) ± SD +0.39 ± 0.33 +0.11 ± 0.46
  Range −0.14 to +0.99 −1.02 to +0.95
20 cm .364
  Mean (D) ± SD +0.31 ± 0.48 +0.16 ± 0.46
  Range −0.32 to +1.69 −0.61to +1.15
Change in SEc .157
  Mean (D) ± SD +0.37D ± 0.58 +0.1± 0.58
  Range −1.14 to +1.57 −0.61 to +1.09

10.3928/1081597X-20130117-09

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