Decentration and tilt of polymethyl methacrylate, silicone, and acrylic soft intraocular lenses

Observation on the tilt and decentration of multifocal intraocular lens with optic capture in Berger space for pediatric cataract

PURPOSE

This study aimed to observe the tilt and decentration of multifocal intraocular lens (IOL) with optic capture in Berger space within 2 years after pediatric cataract surgery.

METHODS

This is a prospective observational study. The implantation of multifocal IOL (Tecnis ZMB00) with optic capture in Berger space was performed on 33 patients (48 eyes) with pediatric cataract at Qingdao Eye Hospital. Tilt and decentration of IOL was measured using Scheimpflug system (Pentacam) at 1 month and 2 years postoperatively.

RESULTS

All the multifocal IOLs were successfully implanted in Berger space with optic capture and no visually significant complications were detected during the follow-up. The mean tilt of IOLs was 2.779° ± 0.950° in the vertical plane and 2.399° ± 0.898° in the horizontal plane at 1 month postoperatively, and the mean length of the decentration was 0.207 ± 0.081 mm in vertical plane and 0.211 ± 0.090 mm in the horizontal plane. Compared with 1 month after surgery, the angle of tilt decreased by a mean of 0.192° and decentration increased by a mean of 0.014 mm at the vertical meridian at 2 years postoperatively (P = 0.37 and P = 0.27, respectively), meanwhile, tilt increased by 0.265° and decentration increased by 0.012 mm at the horizontal meridian (P = 0.11 and P = 0.22, respectively).

CONCLUSIONS

The follow-up results suggest the tilt and decentration of multifocal IOL implantation with optic capture in Berger space remain stable in an acceptable range within 2 years after cataract surgery in children above the age of 5.

TRIAL REGISTRATION

The study was approved by the Ethics Committee of Qingdao Eye Hospital, and registered on Chinese Clinical Trial Registry (ChiCTR identifier: 1900023155).

EFFECT OF DECENTRATION ON THE QUALITY OF VISION: A COMPARISON BETWEEN ASPHERIC BALANCE CURVE DESIGN AND POSTERIOR ASPHERIC DESIGN INTRAOCULAR LENSES

PURPOSE

To study the effect of decentration on the quality of vision in two aspheric intraocular lenses (IOLs): aspheric balance curve(ABC) design Vivinex iSert XY1(Hoya Surgical Opticals, Inc.) and posterior aspheric design AcrySof IQ SN60WF (Alcon Laboratories, Inc.).

SETTING

Advanced Eye Centre, PGIMER, Chandigarh, India.

DESIGN

Randomised Prospective Trial using Random number table.

METHODS

Eighty-five eyes were randomized to Group 1 (Vivinex XY1) and Group 2 (Acrysof IQ) with 40 and 45 eyes respectively. The HOA profile, Strehl's ratio, decentration of IOL from the visual axis (DVA) and the geometric axis (DGA), angle Alpha and Kappa were recorded on the iTrace aberrometer and contrast sensitivity was measured using the Functional Acuity Contrast Test at 12 weeks post-surgery.

RESULTS

The mean values of the Strehl's ratio (p=0.48) and the HOA's (p=0.12) of both IOLs were comparable. The HOA's gradually increased with increasing DVA for both lenses at 3, 4 and 5mm pupil sizes. On comparing the HOA's with the DGA a statistically insignificant positive correlation was observed. The Strehl's ratio did not deteriorate with increasing angle alpha in the Vivinex XY1 group, however worsened in the Acrysof IQ group. The contrast sensitivity was comparable in both the IOLs except at 1.5cpd under photopic conditions where Acrysof IQ was better.

CONCLUSIONS

Decentration of the lens is best measured with respect to the visual axis. In eyes with a large alpha, the ABC design induced lesser HOA's and maintained a better Strehl's ratio.

Measurement of Force Required for Anterior Displacement of Intraocular Lenses and Its Defining Parameters

Intraocular stability during or after cataract and glaucoma filtration surgeries and vitreous surgery with a gas/silicone oil tamponade might differ among intraocular lenses (IOLs). We used six different one-piece IOL models and measured the force that displaced the IOLs from the vitreous cavity to anterior chamber as a measure of stability against the pressure gradient between the anterior and posterior IOL surfaces. We measured IOL hardness, haptics junction area, and posterior IOL bulge to identify what determines the IOL displacement force. The KOWA YP2.2 IOL (1.231 mN) required significantly greater force than the HOYA XY1 (0.416 mN, p = 0.0004), HOYA 255 (0.409 mN, p = 0.0003), Alcon SN60WF (0.507 mN, p = 0.0010), and Nidek NS60YG (0.778 mN, p = 0.0186) IOLs; J&J ZCB00V IOL (1.029 mN) required greater force than the HOYA XY1 (p = 0.0032) and HOYA 255 (p = 0.0029) IOLs; the Nidek NS60YG IOL required greater force than the HOYA 255 (p = 0.0468) IOL. The haptics junction area was correlated positively with the IOL displacement force (r = 0.8536, p = 0.0306); the correlations of the other parameters were non-significant. After adjusting for any confounding effects, the haptics junction area was correlated significantly with the IOL displacement force (p = 0.0394); the IOL hardness (p = 0.0573) and posterior IOL bulge (p = 0.0938) were not. The forces that displace IOLs anteriorly differed among one-piece soft-acrylic IOLs, and the optics/haptics junction area was the major force determinant.

Changes in corneal astigmatism during 20 years after cataract surgery

PURPOSE

To examine how corneal astigmatism changes with age over 20 years after cataract surgery and to assess whether the changes differ from those in eyes that did not have surgery.

SETTING

Hayashi Eye Hospital, Fukuoka, Japan.

DESIGN

Retrospective case study.

METHODS

Using an autokeratometer, corneal astigmatism was measured preoperatively, at baseline (the day the surgically induced astigmatism stabilized), and 10 years and 20 years after baseline. The change in corneal astigmatism between baseline and 10 years, 10 years and 20 years, and baseline and 20 years was determined using power vector analysis and compared between the time intervals and between groups.

RESULTS

The study assessed 74 eyes that had phacoemulsification with a horizontal scleral incision more than 21 years ago (surgery group) and 68 eyes that did not have surgery (no-surgery group). The mean vertical/horizontal change in corneal astigmatism (J0) between baseline and 20 years was -0.64 diopter (D) in the surgery group and -0.49 D in the no-surgery group. The oblique change (J45) was -0.03 D in the surgery group and 0.07 D in the no-surgery group. Using multivariate comparison, the mean J0 and J45 values were not significantly different between baseline and 10 years or between 10 years and 20 years in both groups (P ≥ .2350). The J0 and J45 values were not significantly different between the 2 groups at any time interval (P ≥ .1331).

CONCLUSIONS

Corneal astigmatism continues to change toward against-the-rule astigmatism over 20 years after cataract surgery. This change was similar in eyes that did not have surgery.

Assessment of tilt and decentration of crystalline lens and intraocular lens relative to the corneal topographic axis using anterior segment optical coherence tomography

Purpose

To investigate the tilt and decentration of the crystalline lens and the intraocular lens (IOL) relative to the corneal topographic axis using anterior segment ocular coherence tomography (AS-OCT).

Methods

A sample set of 100 eyes from 49 subjects (41 eyes with crystalline lenses and 59 eyes with IOLs) were imaged using second generation AS-OCT (CASIA2, TOMEY) in June and July 2016 at Okayama University. Both mydriatic and non-mydriatic images were obtained, and the tilt and decentration of the crystalline lens and the IOL were quantified. The effects of pupil dilation on measurements were also assessed.

Results

The crystalline lens showed an average tilt of 5.15° towards the inferotemporal direction relative to the corneal topographic axis under non-mydriatic conditions and 5.25° under mydriatic conditions. Additionally, an average decentration of 0.11 mm towards the temporal direction was observed under non-mydriatic conditions and 0.08 mm under mydriatic conditions. The average tilt for the IOL was 4.31° towards the inferotemporal direction relative to the corneal topographic axis under non-mydriatic conditions and 4.65° in the same direction under mydriatic conditions. The average decentration was 0.05 mm towards the temporal direction under non-mydriatic conditions and 0.08 mm in the same direction under mydriatic conditions. A strong correlation was found between the average tilt and decentration values of the crystalline lens and the IOL under both non-mydriatic and mydriatic conditions (all Spearman correlation coefficients, r ≥ 0.800; all P < 0.001).

Conclusion

When measured using second generation AS-OCT, both the crystalline lens and the IOL showed an average tilt of 4–6° toward the inferotemporal direction relative to the corneal topographic axis and an average decentration of less than 0.12 mm towards the temporal direction. These results were not influenced by pupil dilation and they showed good repeatability.

The Repeatability Assessment of Three-Dimensional Capsule-Intraocular Lens Complex Measurements by Means of High-Speed Swept-Source Optical Coherence Tomography

Purpose

To rebuild the three-dimensional (3-D) model of the anterior segment by high-speed swept-source optical coherence tomography (SSOCT) and evaluate the repeatability of measurement for the parameters of capsule-intraocular lens (C-IOL) complex.

Methods

Twenty-two pseudophakic eyes from 22 patients were enrolled. Three continuous SSOCT measurements were performed in all eyes and the tomograms obtained were used for 3-D reconstruction. The output data were used to evaluate the measurement repeatability. The parameters included postoperative aqueous depth (PAD), the area and diameter of the anterior capsule opening (Area and D), IOL tilt (IOL-T), horizontal, vertical, and space decentration of the IOL, anterior capsule opening, and IOL-anterior capsule opening.

Results

PAD, IOL-T, Area, D, and all decentration measurements showed high repeatability. Repeated measure analysis showed there was no statistically significant difference among the three continuous measurements (all P > .05). Pearson correlation analysis showed high correlation between each pair of them (all r >0.90, P<0.001). ICCs were all more than 0.9 for all parameters. The 95% LoAs of all parameters were narrow for comparison of three measurements, which showed high repeatability for three measurements.

Conclusion

SSOCT is available to be a new method for the 3-D measurement of C-IOL complex after cataract surgery. This method presented high repeatability in measuring the parameters of the C-IOL complex.

Optical performance of toric intraocular lenses in the presence of decentration

AIM

To evaluate the optical performance of toric intraocular lenses (IOLs) after decentration and with different pupil diameters, but with the IOL astigmatic axis aligned.

METHODS

Optical performances of toric T5 and SN60AT spherical IOLs after decentration were tested on a theoretical pseudophakic model eye based on the Hwey-Lan Liou schematic eye using the Zemax ray-tracing program. Changes in optical performance were analyzed in model eyes with 3-mm, 4-mm, and 5-mm pupil diameters and decentered from 0.25 mm to 0.75 mm with an interval of 5° at the meridian direction from 0° to 90°. The ratio of the modulation transfer function (MTF) between a decentered and a centered IOL (MTFDecentration/MTFCentration) was calculated to analyze the decrease in optical performance.

RESULTS

Optical performance of the toric IOL remained unchanged when IOLs were decentered in any meridian direction. The MTFs of the two IOLs decreased, whereas optical performance remained equivalent after decentration. The MTFDecentration/MTFCentration ratios of the IOLs at a decentration from 0.25 mm to 0.75 mm were comparable in the toric and SN60AT IOLs. After decentration, MTF decreased further, with the MTF of the toric IOL being slightly lower than that of the SN60AT IOL. Imaging qualities of the two IOLs decreased when the pupil diameter and the degree of decentration increased, but the decrease was similar in the toric and spherical IOLs.

CONCLUSIONS

Toric IOLs were comparable to spherical IOLs in terms of tolerance to decentration at the correct axial position.

Agreement between refractive and corneal astigmatism in pseudophakic eyes

PURPOSE

To examine the agreement and relationship between refractive and corneal astigmatism in a population of pseudophakic eyes.

METHODS

Patients of age at least 40 years, visual acuity 20/40 or better, and no ocular disease were included (n = 111). Refractive astigmatism was obtained by subjective refraction. Corneal astigmatism was measured by automated keratometry and Scheimpflug scanning analysis. All refractive values were converted to power vector components J0 and J45 for comparison and regression analysis of refractive versus corneal astigmatism. Main outcome measures were refractive and corneal astigmatism components.

RESULTS

Median single Jackson cylinder (J) was similar in refractive [0.37 diopter (D)], keratometric (0.46 D), and Pentacam astigmatism (0.49 D) (P = 0.157). Median J0 astigmatic component was slightly negative, indicating against-the-rule (ATR) astigmatism, in refractive and Scheimpflug, but not in keratometric astigmatism (refractive J0: -0.10 D; keratometric J0: 0.05 D; Pentacam J0: -0.08 D) (P = 0.049). J45 astigmatic component was nearly zero and similar with the 3 methods (P = 0.416). Refractive and keratometric J0 were significantly correlated (r = 0.7, P < 0.01), as well as the corresponding J45 values (r = 0.65, P < 0.01). Refractive and Pentacam astigmatic components were worse correlated (J0: r = 0.36, P = 0.01; J45: r = 0.45, P < 0.01). Keratometric and Pentacam astigmatic components were also significantly correlated (J0: r = 0.58, P < 0.01; J45: r = 0.51, P < 0.01).

CONCLUSIONS

Mean internal ATR astigmatism, which comes mainly from the posterior corneal surface, adds to anterior corneal astigmatism, resulting in ATR refractive astigmatism. Correlation between refractive and corneal astigmatism components is better when keratometric data are used.

Design and qualification of a diffractive trifocal optical profile for intraocular lenses

PURPOSE

To theoretically and experimentally assess a new aspheric diffractive trifocal intraocular lens (IOL).

SETTING

Centre Spatial de Liège, Liège, Belgium.

DESIGN

Evaluation of diagnostic test or technology.

METHODS

The theoretical profile of the IOL was designed using software simulation and validated by optical calculation software tools that enabled complete theoretical characterization. These data resulted in a new aspheric diffractive trifocal IOL. The IOL theoretically allows improved intermediate vision without impairing near and far vision and favors distance vision in mesopic conditions without increasing halos or glare perception under dim light or large pupil conditions. The theoretical findings were compared with those of in vitro testing on the optical bench.

RESULTS

There was good agreement between the theoretical profile and achieved IOL profile. The simulated and achieved light distribution and focus distribution showed good concordance. The FineVision aspheric trifocal IOL provided intermediate addition at 1.75 diopters.

CONCLUSION

The combination of 2 diffractive profiles to achieve far, intermediate, and near correction is validated. Further clinical investigations are required to validate these principles.

FINANCIAL DISCLOSURE

Dr. Houbrechts has no financial or proprietary interest in any material or method mentioned. Additional disclosures are found in the footnotes.

Three-haptic intraocular lens for myopia: early results

PURPOSE

To report the intraoperative experience and early postoperative results of implantation of an intraocular lens (IOL) developed specifically for myopic eyes.

SETTING

Wolverhampton Eye Infirmary, Wolverhampton, United Kingdom.

METHODS

This retrospective study evaluated consecutive highly myopic eyes having implantation of a Bigbag IOL from November 2003 to December 2007. Before IOL placement, a 2.8 mm clear corneal incision was created and phacoemulsification performed. The IOL was implanted using the dedicated folder and injector supplied by the manufacturer.

RESULTS

The study evaluated 67 eyes (48 patients) with a mean follow-up of 8.5 months (range 0.75 to 31 months). Intraoperative complications were IOL haptic damage from the injector system (3 eyes; 4.5%) and posterior capsule tear (1 eye; 1.5%). Postoperative complications were posterior capsule opacification (29 eyes; 43%), retinal detachment (1 eye; 1.5%), and iritis (1 eye; 1.5%). The postoperative corrected distance visual acuity was 0.10 logMAR or better in 24 eyes (35.8%) and 0.18 to 0.48 logMAR in 32 eyes (47.8%). Forty-three eyes (64.2%) were within +/-1.00 diopter of the intended refractive outcome.

CONCLUSION

Preliminary results indicate that this 3-haptic IOL is safe and appropriate for use in highly myopic patients having cataract surgery.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Two-year results of cataract extraction with implantation of the hydrophilic acrylic B-lens

PURPOSE

To evaluate the safety and efficacy of a hydrophilic acrylic intraocular lens (B-Lens((R)), Hanita, Israel) during a 2-year follow-up period.

SETTING

Department of Ophthalmology, Meir Hospital, Sapir Medical Center, Kfar-Saba, Israel.

PATIENTS & METHODS

Slit lamp biomicroscopy, refraction, visual function and patient satisfaction were recorded in 147 patients at 1 week, and at 1, 3, 12, and 24 months after surgery.

RESULTS

Nine cases (6%) were associated with partial rupture of the superior haptic intraoperatively, which did not preclude in-the-bag centration of the IOL in all cases. Postoperative complications were mild or reversible and rarely observed. The posterior capsule opacification (PCO) rate increased considerably (from 0.35 to 0.80) from 1 to 2 years but was for the most clinically insignificant; 16 of the 90 cases (18%) with PCO at 2 years had clinically significant opacification of the posterior capsule. No IOL discoloration was observed. BCVA stabilized by the third month and refraction was at the predicted level at two years. Eighty-one of 91 cases (89%) had BCVA equal to or more than 20/40 and 43 of 91 (47%) gained a BCVA of 20/20 at two years.

CONCLUSION

Hydrophilic acrylic B-Lens((R)) implantation is safe and effective for patients with cataract.

Tilt and decentration of spherical and aspheric intraocular lenses: effect on higher-order aberrations

PURPOSE

To determine the impact of spherical and aspheric foldable intraocular lens (IOL) tilt and decentration on optical quality after cataract surgery in an intraindividual comparative study.

SETTING

Department of Ophthalmology, Goethe-University, Frankfurt am Main, Germany.

METHODS

Randomized implantation of a spherical IOL (Sensar AR40e) was performed in 1 eye and of an aspheric IOL with negative spherical aberration (Tecnis Z9000) in the contralateral eye. Three to 4 months postoperatively, the wavefront was measured and higher-order aberrations (HOAs) were calculated for virtual pupil diameters of 3.5 mm and 6.0 mm. Tilt and decentration of the IOLs were measured using Scheimpflug photography. The tilt and decentration, HOAs, and best corrected visual Strehl ratio of the optical transfer function (BCVSOTF) calculated from the wavefront aberration were compared. The effect of tilt and decentration on HOAs and optical quality was assessed using multiple regression analysis.

RESULTS

The mean optic tilt was 2.89 degrees +/- 1.46 (SD) for the spherical IOL and 2.85 +/- 1.36 degrees for the aspheric IOL. The mean optic decentration was 0.19 +/- 0.12 mm and 0.27 +/- 0.16 mm, respectively. No significant intergroup differences in IOL tilt or decentration were found. Tilt and decentration did not significantly affect the BCVSOTF with either IOL.

CONCLUSIONS

The amounts of tilt and decentration of both IOLs were not large enough to cause deterioration of optical quality. Thus, when IOL tilt and decentration are within normal limits, they do not compromise the correction of spherical aberration by the aspheric IOL.

One-year prospective intrapatient comparison of aspherical and spherical intraocular lenses in patients with bilateral cataract

PURPOSE

To conduct longitudinal, intrapatient comparisons of aspherical and spherical silicone intraocular lenses (IOL) of the same material and platform in patients undergoing bilateral cataract surgery.

DESIGN

Prospective, randomized study.

METHODS

Sixty-two eyes of 31 patients were randomized to receive a silicone aspherical IOL (Tecnis Z9000; AMO Inc, Santa Ana, California, USA) in 1 eye and a silicone spherical IOL (CeeOn 911A; AMO Inc) in the other eye. Best spectacle-corrected visual acuity (BSCVA); corneal and ocular wavefront aberrations; contrast sensitivity under photopic (180 lux), intermediate (75 lux), and scotopic (15 lux) illumination; amount of IOL decentration and tilt; and degree of posterior capsular opacification were measured at 1, 3, 6, and 12 months after surgery. All-distance visual acuity (VA) was measured 3 months after surgery.

RESULTS

There were no significant differences between IOLs with regard to BSCVA, amount of IOL decentration and tilt, degree of posterior capsule opacification, and all-distance VA at any point after surgery. Regarding corneal wavefront aberrations, there was no difference in third- and fourth-order root mean square (RMS). In ocular wavefront aberrations, aspherical IOLs showed significantly lower fourth-order RMS (P < .001) than spherical IOLs throughout the study, but not in third-order RMS. Contrast sensitivity under photopic and mesopic conditions was not different between IOLs, but contrast sensitivity under scotopic conditions was significantly better with aspherical IOLs than with spherical IOLs (P < .01) at all measurement points.

CONCLUSIONS

The silicone aspherical IOL (Tecnis Z9000; AMO Inc) significantly reduced ocular spherical aberration and improved scotopic contrast sensitivity, and these results were consistent through the 1-year follow-up.

All-distance visual acuity and contrast visual acuity in eyes with a refractive multifocal intraocular lens with minimal added power

PURPOSE

To compare visual acuity (VA) from far to near distances, photopic and mesopic contrast VA, and contrast VA in the presence of a glare source (glare VA), between eyes with a new refractive multifocal intraocular lens (IOL) with added power of only +3.0 diopters and those with a monofocal IOL.

DESIGN

Comparative, nonrandomized, interventional study.

PARTICIPANTS

Forty-four eyes of 22 patients who were scheduled for implantation of a refractive multifocal IOL (Hoya SFX MV1; Tokyo, Japan) and 44 eyes of 22 patients scheduled for implantation of a monofocal IOL.

INTERVENTION

All patients underwent phacoemulsification with bilateral implantation of either multifocal or monofocal IOLs.

MAIN OUTCOME MEASURES

At approximately 3 months after surgery, monocular and binocular VA from far to near distances was measured using the all-distance vision tester (Kowa AS-15; Tokyo, Japan), whereas photopic and mesopic contrast VA and glare VA were examined using the Contrast Sensitivity Accurate Tester (Menicon CAT-2000, Nagoya, Japan). Pupillary diameter and the degree of IOL decentration and tilt were correlated with VA at all distances.

RESULTS

Mean VA in both the multifocal and monofocal IOL groups decreased gradually from far to near distances. When comparing the 2 groups, however, both uncorrected and best distance-corrected intermediate VA at 0.5 m and near VA at 0.3 m in the multifocal IOL group were significantly better than those in the monofocal IOL group (P<or=0.0037), although there was no significant difference in far VA or in intermediate VA at 0.7 and 1.0 m. Photopic and mesopic contrast VA and glare VA were similar between the 2 groups. In both the multifocal and monofocal IOL groups, no significant correlation was found between VA at any distance and pupillary diameter or between VA and the degree of IOL decentration and tilt.

CONCLUSIONS

A new refractive multifocal IOL with minimal added power provides significantly better intermediate and near VA than does a monofocal IOL; contrast VA and glare VA are not impaired with this multifocal IOL. Visual acuity at all distances with this IOL is not correlated with pupillary diameter or with IOL decentration and tilt.

Aberration and contrast sensitivity comparison of aspherical and monofocal and multifocal intraocular lens eyes

BACKGROUND

Higher-order aberrations and contrast sensitivity were evaluated in patients who underwent phacoemulsification cataract extraction followed by implantation of aspherical, monofocal or multifocal intraocular lens (IOL) replacements.

METHODS

In this comparative trial, 124 patients with an average age of 66.8+/-5.2 years and their 124 eyes were randomly divided into three surgical implantation groups to receive one of three types of IOLs in replacement of cataract lenses. The patients of group 1 were given an aspherical IOL Z9001 (AMO, Santa Ana, CA, USA) replacement, and group 2 was implanted a monofocal IOL SA60AT (Alcon, Fort Worth, TX, USA) and group 3 the multifocal IOL SA40N (AMO). Post-surgical best-corrected visual acuity, corneal aberrations, total ocular aberrations, pupil diameters, capsulorhexsis sizes and contrast sensitivity were measured and compared.

RESULTS

There was no statistical difference for mean best-corrected visual acuity, pupil diameter, curvilinear capsulorhexis size and corneal aberration among the three groups. For the spherical aberration, fourth-order higher-order aberration and total ocular higher-order aberration, the SA40N group was higher than the SA60AT group and the SA60AT group was higher than the Z9001 group, and the differences between the three groups were statistically significant for these measurements. Contrast sensitivity was higher for the Z9001 group than the SA60AT group and the SA60AT group was higher than the SA40N group, and the difference was statistically significant in all the spatial frequencies of 3, 6, 12 and 18.

CONCLUSIONS

Although the multifocal IOL can provide near vision, it can increase higher-order aberration and negatively influence contrast sensitivity. However, the aspherical IOL can reduce aberration and improve contrast sensitivity as compared with the monofocal IOL.

Intraocular lens centration and visual outcomes after bag-in-the-lens implantation

PURPOSE

To examine the centration and visual outcomes after cataract surgery using the bag-in-the-lens (BIL) implantation technique.

SETTING

University Hospital Antwerp, Department of Ophthalmology, Edegem, Belgium.

METHODS

This study comprised 180 eyes of 125 patients who had cataract surgery with implantation of the BIL intraocular lens (IOL) between March 2002 and September 2005. Postoperative data at 5 weeks, 6 months, and 1 year were evaluated. The geometric center of the IOL, measured on a red reflex slitlamp photograph, was compared with the geometric center of the pupil and the limbus.

RESULTS

The mean decentration compared with the limbus was 0.304 mm+/-0.17 (SD) at a mean angle of -24.9+/-113.3 degrees. Compared with the dilated pupil, the mean deviation was 0.256+/-0.15 mm at a mean angle of -5.2+/-119.0 degrees. The amount of decentration was stable during the postoperative follow-up period. There was no correlation between the amount of decentration and the visual outcomes (pupil: r=-0.07, P=.494; limbus: r=0.11, P=.304).

CONCLUSIONS

Surgeon-controlled BIL centration was predictable 5 weeks and unchanged 6 months and 1 year postoperatively. It can therefore be concluded that capsular bag healing has no influence on BIL IOL centration over time.

Theoretical Comparison of Aberration-correcting Customized and Aspheric Intraocular Lenses

PURPOSE

To assess the performance and optical limitations of standard, aspheric, and wavefront-customized intraocular lenses (IOLs) using clinically verified pseudophakic eye models.

METHODS

White light pseudophakic eye models were constructed from physical measurements performed on 46 individual cataract patients and subsequently verified using the clinically measured contrast sensitivity function (CSF) and wavefront aberration of pseudophakic patients implanted with two different types of IOLs. These models are then used to design IOLs that correct the astigmatism and higher order aberrations of each individual eye model's cornea and to investigate how this correction would affect visual benefit, subjective tolerance to lens misalignment (tilt, decentration, and rotation), and depth of field.

RESULTS

Physiological eye models and clinical outcomes show similar levels of higher order aberration and contrast improvement. Customized correction of ocular wavefront aberrations with an IOL results in contrast improvements on the order of 200% over the control and the Tecnis IOLs. The customized lenses can be, on average, decentered by as much as 0.8 mm, tilted > 10 degrees , and rotated as much as 15 degrees before their polychromatic modulation transfer function at 8 cycles/degree is less than that of the Tecnis or spherical control lens. Correction of wavefront aberration results in a narrower through focus curve but better out of focus performance for +/- 0.50 diopters.

CONCLUSIONS

The use of realistic eye models that include higher order aberrations and chromatic aberrations are important when determining the impact of new IOL designs. Customized IOLs show the potential to improve visual performance.

Potential Effect on the Retinoscopic Reflex of Scleral Expansion Surgery for Presbyopia

PURPOSE

In this initial study, we model the impact of crystalline lens movement and tilt, which we postulate are a potential consequence of scleral expansion surgery (SES). We demonstrate the possibility that these lead to an improvement in near vision with no concurrent restoration of lens accommodative function. With the implantation of scleral expansion bands (SEB), Schachar predicts an increase in the amplitude of accommodation not observed objectively. We postulate that the SEB implants cause the crystalline lens to be shifted forward and become misaligned. Using mathematical models of the optics of the human eye, we assess the effects of our postulate on the power of the eye, the depth of field, optical aberrations, and the appearance of the horizontal retinoscopic reflex.

METHODS

Using anatomically based models of the human eye, the postulated effects of SES are theoretically modeled and optically analyzed in Code V for unintentional lens anterior movement, tilts, and decentrations of up to 1 mm, +/- 3 degrees , and +/- 0.3mm, respectively. The transverse aberrations are calculated before and after SES. Because it has been reported that the appearance of the retinoscopic reflex is consistent with the presence of excess aberrations, we also predict the appearance of the one-dimensional retinoscopic reflex for our models. The change in refractive error is also determined. RESULTS.: Unintentional lens shift, tilt, and decentration, as might occur as a result of SES surgery, would result in an increase in the total power of the eye along with an increase in asymmetric aberrations and little change in symmetric aberrations. The calculated appearances of the retinoscopic reflexes pre- and postsurgery are consistent with observations in the literature.

CONCLUSIONS

Scleral expansion surgery could produce an improvement in near vision through an unintentional anterior displacement of the crystalline lens in combination with excess tilts and decentrations rather than as a result of a restoration of lens accommodation. There is a need for measurements and further analysis of the optical and visual properties of SES patients postsurgery.

Influence of tilt and decentration of scleral-sutured intraocular lens on ocular higher-order wavefront aberration

AIM

To investigate the influence of tilt and decentration of scleral-sutured intraocular lenses (IOLs) on ocular higher-order wavefront aberrations.

METHODS

In 45 eyes of 36 patients who had undergone scleral suture fixation of posterior chamber IOL, tilt and decentration of IOLs were determined by Scheimpflug videophotography, and higher-order aberration for a 4-mm pupil was measured using the Hartmann-Shack aberrometer. In another 100 eyes of 100 patients after standard cataract surgery with posterior chamber IOL implantation, ocular higher-order aberration was measured.

RESULTS

In eyes with scleral-sutured IOL, the mean (SD) tilt angle and decentration were 4.43 degrees (3.02 degrees ) and 0.279 (0.162) mm, respectively. Ocular coma-like aberration in the sutured IOL group was 0.324 (0.170) microm, which was significantly greater than that of the standard cataract surgery group (0.169 (0.061) microm, p<0.001, Student's t test). No significant difference was found in ocular spherical-like aberration between the sutured IOL group (0.142 (0.065) microm) and standard surgery group (0.126 (0.033) microm; p = 0.254). In the sutured IOL group, IOL tilt significantly correlated with ocular coma-like aberration (Pearson's correlation coefficient r = 0.628, p<0.001), but no significant correlation was found between IOL tilt and ocular spherical-like aberration (r = 0.222, p = 0.175). The IOL tilt did not correlate with corneal coma-like (r = 0.289, p = 0.171) and spherical-like (r = 0.150, p = 0.356) aberrations. The IOL decentration did not correlate with any higher-order aberrations.

CONCLUSION

In eyes with scleral-sutured posterior chamber IOL, tilting of the lens induces considerable amount of ocular coma-like aberrations.

Corneal and total wavefront aberrations in phakic and pseudophakic eyes after implantation of monofocal foldable intraocular lenses

PURPOSE

To compare the correlation between corneal and total wavefront aberrations in normal phakic and pseudophakic eyes after implantation of foldable monofocal intraocular lenses (IOLs).

SETTING

University Hospital, Eye Clinic, Zurich, Switzerland.

METHODS

Wavefront aberrations and corneal topography of 29 eyes that had cataract surgery with implantation of hydrophobic monofocal foldable IOL (AcrySof, Alcon Labs) were measured at least 2 months postoperatively and compared with wavefront measurements performed in 33 normal young phakic eyes. The total wavefront aberrations were measured by means of a Tscherning wavefront sensor at a wavelength of 660 nm (Allegro Wave Analyzer, WaveLight Laser Technology). The corneal aberrations were derived from corneal topography measurements ascertained with a Placido-based topography system (Keratograph 70600, Oculus). The correlations between corneal and total wavefront aberrations were calculated for all Zernike coefficients from 2nd up to 6th order.

RESULTS

There was a significant correlation between corneal and total wavefront aberrations in astigmatism C3 and C5 as well as for all 3rd-order Zernike coefficient in both groups (except C8 in the pseudophakic group). The correlation between corneal and total astigmatism (C3 and C5) was higher in the pseudophakic than in the phakic eyes. In contrast, the correlation for the coma-like aberrations was weaker in the pseudophakic eyes (R>0.18) than in the group of phakic eyes (R>0.58). In both groups, there was no significant correlation between spherical aberration C12 of the cornea and the C12 of the total eye.

CONCLUSION

After cataract surgery with an IOL implantation, both vertical and horizontal coma, as well as spherical aberration, were of higher value than in normal eyes. The compensation effect for corneal aberrations of the natural lens is absent in the IOL and explains these findings. The corneal aberrations in pseudophakic eyes reflect better the optical quality of the total eye than the phakic eyes. Nevertheless, the missing correlation in some specific aberrations, such as C8 and C10, shows the inability of corneal topography to provide suitable information on the optical quality of the total eye after cataract surgery. Thus, both corneal and total wavefront measurements are relevant for the assessment of outcomes after cataract surgery.

Analysis of crystalline lens position

PURPOSE

To study normal crystalline lens position to provide a comparative baseline for future studies of crystalline lens or intraocular lens shift.

SETTING

Taipei Municipal Yang-Ming Hospital, Taipei, Taiwan.

METHODS

A Scheimpflug anterior segment analyzer (EAS-1000, Nidek) was prospectively applied to measure the cycloplegic crystalline lens position in subjects who had not had previous ocular surgeries or who had been diagnosed previously with major ocular diseases such as glaucoma, retinal detachment, or cataract. Measurements included anterior chamber depth (ACD), magnitudes, direction of lens decentration, and lens tilt. Refractive error was measured with an autorefractometer, and multiple linear regression was used to verify revealed relationships. The aging effect was determined with the Pearson correlation test.

RESULTS

Thirty-nine eyes of 30 subjects (15 men, median age 13 years, range 4 to 53 years) were included. The center of the anterior lens surface was decentered 0.25 mm superotemporally. The lens tilted 2.85 degrees with the anterior lens surface facing the inferotemporal quadrant. The mean ACD was 3.26 mm; it tended to increase before subjects reached 20 years of age and to decrease thereafter. With age, the lens tended to exhibit less tilt. Lens position did not affect the spherical equivalent or the magnitude of astigmatism.

CONCLUSION

The crystalline lens was not aligned perfectly along the visual axis, but its effect on refraction was limited.

Prospective Intrapatient Comparison of 6.0-Millimeter Optic Single-Piece and 3-Piece Hydrophobic Acrylic Foldable Intraocular Lenses

PURPOSE

To compare postoperative performance and stability of 6.0-mm optic single- and 3-piece acrylic foldable intraocular lenses (IOLs).

DESIGN

Prospective, randomized, self-controlled trial.

PARTICIPANTS

Eighty eyes of 40 patients with bilateral senile cataracts.

INTERVENTION

Phacoemulsification and IOL implantation were performed. One eye of a patient was randomly assigned to the SA60AT single-piece IOL, and the contralateral eye was allocated to the MA60AC 3-piece IOL.

MAIN OUTCOME MEASURES

Best-corrected visual acuity (BCVA), spherical equivalent, aqueous flare intensity, anterior chamber depth, amount of IOL decentration and tilt, area of anterior capsule opening, and degree of posterior capsule opacification (PCO) were measured 2 days, 1 week, and 1, 3, 6, and 12 months after surgery. Specular microscopy was performed at 12 months postoperatively.

RESULTS

In the SA60AT group, the anterior chamber depth did not show significant changes after surgery (P>0.05; paired t test), and the refraction remained highly stable throughout the 1-year study period. The MA60AC group showed significant shallowing of the anterior chamber (P<0.05) and a myopic shift (P<0.05) up to 1 month after surgery. There were no significant differences between the 2 groups (P>0.05) in BCVA, aqueous flare intensity, the amount of IOL decentration, IOL tilt, area of anterior capsule opening, and degree of PCO throughout the 12-month follow-up period.

CONCLUSIONS

Both the SA60AT single-piece and MA60AC 3-piece lenses showed a minimum amount of decentration, tilt, anterior capsule contraction, and PCO. Although the MA60AC showed significant forward shift and myopic refractive changes after surgery, the SA60AT displayed little axial movement associated with highly stable refraction after surgery. This feature of the SA60AT should facilitate earlier spectacle prescription and quicker visual/social rehabilitation of patients after cataract surgery.

Optical analysis of an accommodating intraocular lens

PURPOSE

To model the feasibility of an accommodating intraocular lens (IOL) that allows near vision by means of an anterior translation within the capsular bag.

SETTING

University of Waterloo, Waterloo, Ontario, Canada.

METHODS

Model eyes were constructed and analyzed based on experimental data using Code V, a computerized optical design tool. The potential near vision of IOLs of different powers was calculated as they were moved anteriorly within the capsular bag. The conditions under which a spherical lens performs well and when an aspheric design should be considered were determined.

RESULTS

Accommodation (the dioptric change from the far to the near point) varies linearly with lens movement and is sensitive to corneal and IOL powers. Simple equations were derived and accurately predicted induced accommodation. Retinal image quality varies significantly with pupil size and IOL power. However, image quality is minimally affected by the amount of induced accommodation.

CONCLUSIONS

From an optical standpoint accommodation with adequate image quality can be achieved by anterior movement of a spherical IOL within the capsular bag.

Tilt and decentration of three-piece foldable high-refractive silicone and hydrophobic acrylic intraocular lenses with 6-mm optics in an intraindividual comparison

PURPOSE

Intraindividual comparison of tilt and decentration of three-piece foldable intraocular lenses (IOLs) with 6-mm optics and different edge design and material.

DESIGN

Prospective randomized study.

METHODS

Twenty-five patients with senile cataract (group I) received a foldable silicone, sharp optic edge IOL in one eye and a silicone, rounded optic edge IOL in the other eye. Group II (n = 28) received the foldable silicone, sharp optic edge IOL in one eye and an acrylate, sharp optic edge IOL in the other eye. Scheimpflug photography was performed after the procedure with an anterior eye segment analysis system. Tilt and decentration of the IOL optic were measured 1 week, 6 months, and 12 months after the procedure.

RESULTS

In group I, the foldable silicone, sharp optic edge IOL showed a mean optic tilt of 3.03 +/- 1.79 degrees and an optic decentration of 0.24 +/- 0.13 mm; the silicone, rounded optic edge IOL showed a tilt of 3.26 +/- 1.69 degrees and a decentration of 0.23 +/- 0.13 mm. In group II, the foldable silicone, sharp optic edge IOL showed an average tilt of 2.34 +/- 1.81 degrees and a decentration of 0.29 +/- 0.21 mm after 12 months; the acrylate, sharp optic edge IOL had a tilt of 2.32 +/- 1.41 degrees and a decentration of 0.24 +/- 0.10 mm. There were no significant differences in either group.

CONCLUSION

The examined IOLs showed a stable position regarding tilt and decentration in the first 12 postoperative months, independent of material and edge design. Slight deviations from the optical axis might affect the outcome in aspheric or multifocal IOLs.

Funktionelle Ergebnisse nach Implantation multifokaler Intraokularlinsen (MIOL)

BACKGROUND

A multifocal intraocular lens (MIOL) with diffractive and aspherical optical design and asymmetrical light distribution (Acri. Twin, Acri.Tec) was compared to the standard MIOL, the Array SA40.

PATIENTS AND METHODS

After 6 months, 16 patients with bilateral implantation of the Acri. Twin and 14 patients with bilateral Array IOL were examined to assess uncorrected and best corrected visual acuity for distance and near, contrast sensitivity under photopic and mesopic conditions, stereopsis, pupil diameter, and centration of the IOL.

RESULTS

A significant difference was observed between the two MIOL in improved near visual acuity of the Acri. Twin MIOL (0.8 vs 0.4). Most of the patients described dysphotic phenomena, which were somewhat different for both MIOL, but expressed general satisfaction except for one patient. Concerning contrast sensitivity both MIOL were significantly inferior to data published for an aspherical monofocal IOL.

A theoretical study of intraocular lens tilt and decentration on perceptual image quality

Maps of perceptual image quality were generated for a range of intraocular (IOL) tilts and decentrations, using a perceptually based metric i.e. the square integral (SQRI) metric. Maps were generated for a well-corrected eye, and for hyperopic (-0.1 mm) and myopic (+0.1 mm) image planes (for 2 and 4 mm pupils). These perceptually based results were compared with a standard optical measure (i.e. the equivalent SQRI for given spectacle power added at the cornea). The image quality changes in maps were small, but detectable (exceeding the perceptual just noticeable difference (jnd) or 1 jnd threshold). Clockwise (negative) tilt combined with decenter fell below the 'contrast reserve' modulation transfer functions (MTFs) for 0.25 and 0.5 D defocus, 4 mm pupil. These errors were larger than those found previously, probably because of the shape-factor of the IOL used. Pupil size contributed the largest drop in SQRI value, followed by clockwise tilt combined with decenter. Anticlockwise tilt with decenter produced image quality improvements for the hyperopic eye. Spot diagrams confirmed defocus and the balance of coma-like aberration and astigmatism as causes of the changes in SQRI values. The SQRI maps conveniently summarize imaging, and may be a useful tool in assessing image quality in eye modelling applications.

Limitations of Correcting Spherical Aberration With Aspheric Intraocular Lenses

PURPOSE

Aspheric intraocular lenses (IOLs) are deigned to correct spherical aberration in pseudophakic eyes. We predict the benefit from correcting spherical aberration based on simulations and aberrometry of pseudophakic eyes implanted with spherical IOLs.

METHODS

Ray tracing was performed through a model eye with an equi-biconvex spherical IOL and with a spherical aberration-correcting aspheric IOL. The IOLs were increasingly tilted and/or displaced, and the resulting transverse aberrations of 169 rays were transformed into Zernike coefficients for different pupil sizes. The benefit from correcting spherical aberration at individual esopic pupils was investigated by canceling C4(0) in the sets of Zernike coefficients for 41 eyes implanted with spherical IOL.

RESULTS

Both the model eye and the real eye data predict that age-related miosis reduces spherical aberration in the eye implanted with a spherical IOL to approximately 1/3 of the spherical aberration at a 6-mm pupil. A reduction of similar magnitude occurs when spherical aberration-induced non-paraxial defocus is corrected by a spectacle lens. For natural mesopic pupils, canceling the Zernike C4(0) coefficient improved the objective image quality at a rate similar to changing defocus by 0.05 diopters. Average decentration and tilt levels diminish the lead of aspheric IOLs over spherical IOLs, depending on the direction of decentration.

CONCLUSIONS

The benefit from correcting spherical aberration in a pseudophakic eye is limited for some or all of the following reasons: wearing glasses, age-related miosis, tilt and decentration of IOL, small contribution of spherical aberration to all aberrations, and intersubject variability.

Effect of tilt of 2 acrylic intraocular lenses on high-order aberrations

PURPOSE

To investigate the high-order aberrations (HoAs) in pseudophakia between 2 foldable acrylic intraocular lenses (IOL) with differences in the tilt of IOL.

SETTING

Department of Ophthalmology, Nara Medical University, Nara, Japan.

METHOD

Sixty-four eyes that had uncomplicated phacoemulsification and IOL implantation were assigned to 1 of 2 groups: Acryfold 60BB (HOYA [n=30 eyes]) and AcrySof MA60AC (Alcon [n=34 eyes]). All patients had best corrected visual acuity better than 20/25. High-order aberrations were measured using the Hartmann-Shack aberrometer at 4.0 mm and 6.0 mm wavefront aperture diameters, and the IOL tilt and decentration were measured using Scheimpflug videophotography.

RESULTS

There was a significant difference in the IOL tilt (60BB=2.22 degrees +/- 1.44 (SD), 60AC=3.18 +/- 1.84 degrees; P=.041, Mann-Whitney U test), but no difference in IOL decentration (P>.05). In the cornea, there were no differences between the 2 groups in HoAs at 4.0 mm and 6.0 mm aperture diameters (P>.05, Mann-Whitney U test). In the whole eye, there was no difference between the 2 groups in spherical-like aberrations, coma-like aberrations, and total aberrations at the 4.0 mm and 6.0 mm aperture diameters (P>.05). The compensation of the internal optics with the 60BB group was better than with the 60AC group for coma-like (P=.037) and total aberrations (P=.010) at 6.0 mm aperture diameter.

CONCLUSION

The smaller tilt of the IOL induced more compensation for the coma-like and total aberrations at the 6.0 mm aperture diameter. The IOL tilt should be small, especially in a large pupil, with regard to HoAs.

Visual acuity and contrast sensitivity comparison between Tecnis and AcrySof SA60AT intraocular lenses: A multicenter randomized study

PURPOSE

To evaluate best corrected visual acuity (BCVA) and photopic and mesopic contrast sensitivity in pseudophakic patients implanted either with the aspheric intraocular lens (IOL) designed to correct for corneal spherical aberration or with a conventional IOL.

SETTING

Three surgical centers participated this prospective randomized masked comparative study.

METHODS

Thirty eyes of 30 patients after aspheric lens implantation (Pfizer/Pharmacia Tecnis Z9000) were compared with 30 eyes of 30 age-matched patients after conventional lens implantation (Alcon AcrySof SA60AT). Two to three months after surgery, best spectacle corrected distance visual acuity was measured using the Early Treatment Diabetic Retinopathy Study chart. Contrast sensitivity was measured by sinusoidal grating charts for distance at photopic (85 cd/m(2)) and mesopic (6 cd/m(2)) luminance level with optical correction in place. Tested spatial frequencies were 1.5, 3, 6, 12, and 18 cycles per degree (cpd).

RESULTS

The mean BCVA was -0.053 +/- 0.044 logMAR in eyes with the aspheric Tecnis IOL and 0.006 +/- 0.059 logMAR in eyes with the conventional AcrySof IOL (P=.0001). Eyes with the aspheric IOL showed better contrast sensitivity at spatial frequencies of 3 cpd (P<.05) and 6, 12, and 18 cpd (P<.01) in photopic and in mesopic conditions. Peak improvement occurred at 18 cpd and was 36% (0.29 log units) in photopic and 54% (0.27 log units) in mesopic conditions.

CONCLUSIONS

The aspheric Tecnis IOL yielded better BCVA and better distance contrast sensitivity than the conventional IOL. The differences were clinically significant for higher spatial frequencies. The results give some suggestions for further studies.

Optical performance of 3 intraocular lens designs in the presence of decentration

PURPOSE

To study the theoretical optical performance of 3 intraocular lens (IOL) designs in the presence of IOL decentration.

SETTING

Optics Center, Bausch & Lomb, Rochester, New York, USA.

METHODS

A ray-tracing program was used to evaluate the effect of IOL decentration on the optical performance of 3 silicone IOLs (LI61U, Bausch & Lomb; Tecnis Z9000, Advanced Medical Optics; and a new aberration-free IOL [SofPort AO, Bausch & Lomb]) in an experimental model eye. The study was done using pupil diameters of 3.0 mm, 4.0 mm, and 5.0 mm and IOL decentrations of 0 mm, 0.25 mm, 0.50 mm, 0.75 mm, and 1.00 mm. The modulation transfer functions were computed and plotted. A Monte Carlo simulation analysis with 1000 trials with IOL decentration randomly varying for each pupil size was performed.

RESULTS

Decentration of LI61U and Tecnis Z9000 IOLs led to asymmetrical higher-order aberrations that adversely affected the optical performance of the model eye; performance was not affected with the aberration-free IOL because it lacks inherent spherical aberration. Optical performance with the aberration-free IOL was better than with the LI61U IOL as the former has less spherical aberration and did not introduce other aberrations when decentered. Performance with the aberration-free IOL was better than with the Tecnis Z9000 IOL for 3.0 mm, 4.0 mm, and 5.0 mm pupils when decentration exceeded 0.15 mm, 0.30 mm, and 0.38 mm, respectively. Performance with the LI61U IOL was better than with the Tecnis Z9000 IOL for 3.0 mm, 4.0 mm, and 5.0 mm pupils when decentration exceeded 0.3 mm, 0.5 mm, and 0.5 mm, respectively. Monte Carlo simulations showed the expected postoperative results of the LI61U IOL and aberration-free IOL would be repeatable and predictable, whereas the outcomes with the Tecnis Z9000 IOL would vary widely.

CONCLUSIONS

The optical performance of the model eye was not affected by decentration of an aspheric IOL designed to have no inherent spherical aberration. With decentration, the performance with the new IOL was better than with a conventional spherical IOL and an aspheric IOL designed to offset the spherical aberration of an average cornea.

Comparison of tilt and decentration of 1-piece and 3-piece hydrophobic acrylic intraocular lenses

PURPOSE

To determine the amount of tilt and decentration of 1-piece and 3-piece hydrophobic acrylic intraocular lenses (IOLs) in patients having cataract surgery.

SETTING

Department of Ophthalmology, Gulhane Military Medical Academy and Medical School, Ankara, Turkey.

METHODS

Eighty-eight patients having phacoemulsification with IOL implantation were divided into 2 groups. One group received a 3-piece hydrophobic acrylic IOL with 12.5 mm poly(methyl methacrylate) haptics and the other, a 1-piece hydrophobic acrylic IOL with 12.5 mm haptics. The amount of IOL decentration and tilt was quantitated using Purkinje reflections and photographic documentation at the last postoperative control. The results of the 2 groups were compared.

RESULTS

Bag fixation of the IOL and an intact continuous curvilinear capsulorhexis (CCC) were confirmed in all cases at the last postoperative control, which was at a mean of 27.1 months +/- 5.4 (SD) and 26.7 +/- 4.4 months in the 3-piece group and 1-piece group, respectively (P = 0.659). There was no significant difference between groups in the percentage of patients with measurable tilt and decentration and of patients without measurable tilt and decentration (P = .956). The mean IOL tilt was 2.72 +/- 0.55 degrees in the 3-piece group and 2.70 +/- 0.84 degrees in the 1-piece group and the mean IOL decentration, 0.39 +/- 0.13 mm and 0.34 +/- 0.08 mm, respectively. There were no significant between-group differences in tilt or decentration (P = .897 and P = .103, respectively).

CONCLUSION

There were no significant differences in tilt and decentration between 1-piece and 3-piece hydrophobic acrylic IOLs in eyes with capsular bag IOL implantation and an intact CCC.

Comparison of the stability of 1-piece and 3-piece acrylic intraocular lenses in the lens capsule

PURPOSE

To compare the degrees of intraocular lens (IOL) decentration, tilt, and longitudinal movement; the refractive change; and anterior capsule contraction after cataract surgery between eyes with a 1-piece acrylic IOL with soft acrylic loops and eyes with a 3-piece acrylic IOL with rigid poly(methyl methacrylate) loops.

SETTING

Hayashi Eye Hospital, Fukuoka, Japan.

METHODS

Fifty-six patients had implantation of a 1-piece acrylic IOL in 1 eye and a 3-piece acrylic IOL in the fellow eye. The degree of IOL decentration and tilt, the anterior chamber depth (ACD), and the area of anterior capsule opening were measured using Scheimpflug videophotography 3 days and 1, 3, and 6 months postoperatively. The postoperative refractive status was also examined.

RESULTS

The mean degrees of decentration and tilt in the 1-piece IOL group were similar to those in the 3-piece IOL group throughout the follow-up. The ACD did not change after surgery in the 1-piece group but showed significant shallowing in the 3-piece group (P < .0001). The spherical equivalent (SE) did not change in the 1-piece group, while the SE had a significant myopic shift of approximately 0.4 diopter in the 3-piece group. The percentage of anterior capsule contraction was similar between the groups.

CONCLUSIONS

The degree of IOL decentration and tilt and percentage of anterior capsule contraction in eyes with a 1-piece acrylic IOL with soft acrylic loops were similar to those in eyes with a 3-piece acrylic IOL. The longitudinal movement of the 1-piece IOL was less than the movement of the 3-piece IOL, resulting in less postoperative myopic shift.

Comparison of Tilt and Decentration between Phacoemulsification and Phacotrabeculectomy

PURPOSE

To determine the extent of intraocular lens (IOL) tilt and decentration values after combined surgery in patients with cataract and glaucoma.

MATERIALS AND METHODS

A total of 106 cataractous eyes undergoing IOL implantation were divided into 2 groups. Group 1 comprised 42 eyes undergoing phacotrabeculectomy surgery for cataract and primary open-angle glaucoma (POAG), and group 2 comprised 64 eyes undergoing phacoemulsification surgery for senile cataract. The length of IOL decentration and the angle of IOL tilt were quantitated by using Purkinje reflections and photographic documentation.

RESULTS

The differences regarding both the IOL tilt (2.84 +/- 0.37; 2.97 +/- 0.37, respectively) and decentration (0.39 +/- 0.27; 0.49 +/- 0.35, respectively) was insignificant (p > 0.05) between groups.

CONCLUSION

There is no increased effect of phacotrabeculectomy on tilt and decentration of IOLs in eyes with POAG when compared with eyes which underwent phacoemulsification surgery.

Influence of intraocular lens tilt and decentration on wavefront aberrations

PURPOSE

To investigate the influence of intraocular lens (IOL) tilt and decentration on higher-order aberrations (HOAs) using wavefront analysis.

SETTING

Department of Ophthalmology, Nara Medical University, Nara, Japan.

METHODS

Forty eyes of 40 patients with a 5.5 mm optic, foldable acrylic IOL were examined 4 to 48 months postoperatively. Ocular wavefront aberrations of the central 4.0 mm aperture diameter were measured using a Hartmann-Shack aberrometer. Higher-order aberrations from the 3rd to 4th order were calculated using Zernike polynomials. The relationship between IOL tilt and decentration, measured with a Scheimpflug camera, and ocular HOAs were investigated.

RESULTS

The correlation between IOL tilt and coma-like aberrations was significant (r=0.431, Spearman rank correlation coefficient; P=.007). However, the correlation between IOL tilt and the spherical-like and total aberrations was not significant (P>.05), nor was the correlation between IOL decentration and coma-like, spherical-like, and total aberrations (P>.05).

CONCLUSIONS

Intraocular lens tilt influenced ocular coma-like aberrations. The quality of the retinal image may improve by reducing IOL tilt.

Wavefront-customized intraocular lenses

PURPOSE OF REVIEW

Recent advances in ocular wavefront measurement and in intraocular lens materials and manufacturing methods have brought cataract surgery to the brink of a period in which customized correction of higher-order aberrations with intraocular lenses may become standard practice.

RECENT FINDINGS

Retinal image quality in pseudophakic eyes is limited by the wavefront aberrations of the cornea and the intraocular lens. The Tecnis Z9000 is the first commercially available intraocular lens designed to account for the wavefront aberrations of the cornea, specifically spherical aberration. Clinical findings with the Tecnis Z9000 intraocular lens show improved contrast sensitivity at low and mid spatial frequencies. However, if the lens decenters or tilts modestly, higher-order aberrations are created, and the lens may underperform relative to standard intraocular lenses. At present, one firm is developing an intraocular lens that may be modified in vivo with near ultraviolet energy. Such a technology offers tremendous potential for a fully customized intraocular lens.

SUMMARY

Wavefront-customized intraocular lenses offer the promise of near perfect retinal image quality, such that only diffraction, chromatic aberration, retinal sampling and neural factors will limit vision in pseudophakic eyes.

A prospective, randomised comparison of single and three piece acrylic foldable intraocular lenses

AIMS

To compare the postoperative performance of single and three piece acrylic foldable intraocular lenses (IOLs).

METHODS

20 patients underwent bilateral cataract surgery with a single piece SA30AL IOL in one eye and a three piece MA30BA IOL in the other eye. The eyes were randomly assigned to either a single or three piece lens. The amount of IOL decentration and tilt, area of anterior capsule opening, and degree of posterior capsule opacification were measured using the Scheimpflug anterior segment analysis system (Nidek EAS-1000). Visual acuity and contrast sensitivity were examined. Measurements were performed by masked examiners before and 1 day, 1 week, 1, 3, 6, and 18 months after surgery.

RESULTS

There were no significant differences between the two groups (p>0.05, paired t test) in the amount of IOL decentration, IOL tilt, area of anterior capsule opening, degree of posterior capsule opacification, best corrected visual acuity, and contrast sensitivity throughout the 18 month follow up period.

CONCLUSION

The single and three piece acrylic foldable IOLs are equally stable in the eye after surgery.

Improved functional vision with a modified prolate intraocular lens

PURPOSE

To evaluate whether the Tecnis Z9000 intraocular lens (IOL) (Pfizer) with a modified prolate anterior surface provides better quality of vision than a conventional spherical IOL.

SETTING

Oregon Eye Institute, Eugene, Oregon, USA.

METHODS

Patients presenting for cataract surgery who were randomly assigned to receive a Tecnis Z9000 IOL (Pfizer) or a Sensar OptiEdge AR40e IOL (AMO) in 1 eye were followed for 3 months postoperatively. The patient could elect to have the same type of IOL implanted in the fellow eye. The results of sine-wave grating contrast sensitivity testing under mesopic and photopic conditions were compared interindividually.

RESULTS

Monocular comparison was made between the 2 IOL groups, which comprised 15 patients each. The Tecnis IOL provided significantly better contrast sensitivity at 6 cycles per degree (cpd) under photopic conditions and at 1.5 and 3 cpd under mesopic conditions. Seven patients with a Tecnis IOL and 9 patients with an AR40e IOL had subsequent implantation in the fellow eye. In all eyes, including fellow eyes, having IOL implantation, the Tecnis provided significantly better contrast sensitivity at 3 and 6 cpd under photopic conditions and at 1.5, 3, and 6 cpd under mesopic conditions. The mean contrast sensitivity in fellow eyes showed that the Tecnis IOL produced significantly better results at some spatial frequencies.

CONCLUSIONS

Results show the Tecnis IOL with a modified prolate anterior surface may produce better contrast sensitivity than a standard spherical IOL under mesopic and photopic conditions. Because contrast sensitivity testing correlates well with functional vision, a goal of future research should be to evaluate patient performance using functional tests such as driving simulation.