Comparison of contrast sensitivity, depth of field and ocular wavefront aberrations in eyes with an IOL with zero versus positive spherical aberration

Optimal incision sites to reduce corneal aberration variations after small incision phacoemulsification cataract surgery

AIM

To analyze the effect of steep meridian small incision phacoemulsification cataract surgery on anterior, posterior and total corneal wavefront aberration.

METHODS

Steep meridian small incision phacoemulsification cataract surgery was performed in age-related cataract patients which were divided into three groups according to the incision site: 12 o'clock, 9 o'clock and between 9 and 12 o'clock (BENT) incision groups. The preoperative and 3-month postoperative root mean square (RMS) values of anterior, posterior and total corneal wavefront aberration including coma, spherical aberration, and total higher-order aberrations (HOAs), were measured by Pentacam scheimpflug imaging. The mean preoperative and postoperative corneal wavefront aberrations were documented.

RESULTS

Total corneal aberration and total lower-order aberrations decreased significantly in three groups after operation. RMS value of total HOAs decreased significantly postoperatively in the 12 o'clock incision group (P<0.001). Corneal spherical aberration was statistically significantly lower after steep meridian small incision phacoemulsification cataract surgery in BENT incision group (P<0.05) and Pearson correlation analysis indicated that spherical aberration changes had no significant relationship with total astigmatism changes in all three corneal incision location.

CONCLUSION

Corneal incision of phacoemulsification cataract surgery can affect corneal wavefront aberration. The 12 o'clock corneal incision eliminated more HOAs and the spherical aberrations decreased in BENT incision group obviously when we selected steep meridian small incision. Cataract lens replacement using wavefront-corrected intraocular lens combined with optimized corneal incision site would improve ocular aberration results.

Index of contrast sensitivity (ICS) in pseudophakic eyes with different intraocular lens designs

PURPOSE

To evaluate the index of contrast sensitivity (ICS) in eyes after cataract surgery with various intraocular lens designs and to compare with the area under log contrast sensitivity curve (AULCSF).

METHODS

The study comprised 395 eyes of 198 patients in the age of 73.1 ± 7.86 years receiving 11 different aspheric IOL designs (aberration-free and correcting) and a spherical (IOL) as control group. Follow-up examination after bilateral cataract surgery was completed within 71 ± 21.4 days after second IOL implantation. Patients underwent complete examination and biometry before surgery. The follow-up examination included visual acuity, pupil diameter, residual spherical aberration and mesopic as well as photopic contrast sensitivity (CS) measured with the Optec 6500 Functional Vision Analyzer. From the contrast sensitivity, we calculated the ICS according to Haughom and Strand.

RESULTS

The median mesopic ICS was -144, -131 and -85, and the median photopic ICS was -289, -285 and -212 for the spherical, aberration-free and aberration-correcting IOL group, respectively. While we could not detect a significant difference between the aberration groups in some spatial frequencies, the ICS showed a significant difference between the aberration-correcting and the aberration-free or the spherical group, respectively. No significant difference was found between the aberration-free and the spherical group.

CONCLUSIONS

The ICS is a useful index for evaluation of overall CS and comparison of different patient groups. With aberration-correcting IOLs, ICS was statistically better than with aberration-free or spherical IOLs, whereas the latter two showed no significant difference.

Safety and effectiveness of a single-piece hydrophobic acrylic intraocular lens (enVista®) - results of a European and Asian-Pacific study

Purpose

To evaluate the safety and effectiveness of a single-piece hydrophobic acrylic intraocular lens (IOL) (enVista® MX60; Bausch and Lomb Incorporated, Rochester, NY, USA) following implantation to correct aphakia subsequent to extracapsular cataract extraction in adults.

Subjects and methods

This was an open-label, non-interventional, observational study conducted in 19 university and private-practice settings in Europe and the Asia-Pacific region to investigate clinical outcomes of the MX60 IOL in standard practice. Eligible subjects were at least 18 years of age and had undergone standard phacoemulsification and extracapsular cataract extraction with implantation of the MX60 IOL. The primary safety endpoint was the occurrence of adverse events, and the primary effectiveness endpoints included visual and refractive outcomes and stability, with data collected up to 2 years post-procedure.

Results

In this multicenter study, pooled data of 255 eyes were collected and analyzed. Excellent visual and refractive outcomes and stability were demonstrated. At postoperative visit 4 (61–180 days postoperative), 62.2% of subjects achieved a Snellen best-corrected distance visual acuity (CDVA) of 20/20 (decimal 1.00), and 97.8% of subjects achieved a CDVA of 20/40 (decimal 0.50) or better. One eye (1.0%) underwent neodymium:yttrium aluminum garnet capsulotomy at 12 months post-procedure. No glistenings of any grade were reported for any subject at any visit. Adverse events were infrequent and were consistent with incidences generally reported with cataract surgery.

Conclusion

This study, which enrolled all comers, provided evidence of the excellent safety and effectiveness of the MX60 IOL in standard practice. Favorable clinical outcomes included outstanding visual and refractive outcomes and stability. No glistenings were reported at any postoperative visit.

Comparing the effect of two different intraocular lenses on optical aberrations in bilaterally operated eyes for cataract

OBJECTIVE

To assess high order and spherical aberrations results of hydrophobic acrylic AMO Sensar AR40E and hydrophobic acrylic Alcon AcrySof SA60AT intraocular lenses after implantation in cases with bilateral cataract.

METHODS

Cases diagnosed as bilateral cataract were included in the study and preoperative aberration measurements were recorded by using Nidek OPD SCAN-ARK 1000. Groups were created by implanting AMO Sensar AR40E to one eye of the patients, while Alcon AcrySof SA60AT into the other in a prospective and randomized manner. Aberration measurements were recorded after one and two months of surgery.

RESULTS

Overall, 40 eyes in 20 patients (11 women and 9 men) were included in the study. All patients underwent bilateral phacoemulsification surgery due to cataract. There were 20 eyes in both groups. Mean age was 62.4 (range: 31-82) years. There was no significant difference in aberrations recorded before surgery and one and two months after surgery in both groups. (p<0.05).

CONCLUSION

There was no difference among spherical intraocular lenses used in this study.

Visual performance of 2 aspheric toric intraocular lenses: comparative study

PURPOSE

To compare the visual and aberrometric outcomes of 2 aspheric toric intraocular lenses (IOLs).

SETTING

Fatebenefratelli e Oftalmico Hospital, Milan, Italy.

DESIGN

Prospective randomized comparative study.

METHODS

Astigmatic patients had cataract surgery with implantation of an Acrysof SN6AT IOL (Group A) or an AT Torbi 709M IOL (Group B). The uncorrected (UDVA) and corrected (CDVA) distance visual acuities, net refractive astigmatism, spherical equivalent (SE), IOL misalignment, and optical quality were evaluated 3 months postoperatively.

RESULTS

The study included 72 eyes. No statistically significant difference was found in UDVA, CDVA, residual refractive astigmatism, intraocular or total higher-order aberrations (Z(n,i) (order of aberrations calculated: 3≤n≤8), coma Z(3,±1), or trefoil Z(3,±2). The UDVA was 0.3 logMAR or better in all eyes and 0.1 logMAR or better in 55.5% of eyes in Group A and in 61.1% of eyes in Group B. Considering polar value analysis, 94.4% of eyes in both groups had a refractive astigmatism value within ±0.50 diopter at KP90 (polar value along 90-degree meridian). The SE was closer to emmetropia in Group A (P=.01). Intraocular lens misalignment of less than 5 degrees was present in 61.1% of cases in Group A (maximum 9 degrees) and in 66.6% in Group B (maximum 11 degrees). Spherical aberration Z(4,0) was significantly lower in Group B.

CONCLUSIONS

Both IOLs had similar clinical effectiveness in term of astigmatism correction, rotational stability, and optical quality. Eyes in Group A appeared significantly nearer to emmetropia, while the IOL in Group B induced significantly less spherical aberration.

FINANCIAL DISCLOSURE

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

Safety and effectiveness of a glistening-free single-piece hydrophobic acrylic intraocular lens (enVista)

Purpose

To evaluate the safety and effectiveness of a single-piece hydrophobic acrylic intraocular lens (IOL; enVista model MX60; Bausch & Lomb, Rochester, NY, USA) when used to correct aphakia following cataract extraction in adults.

Methods

This was a prospective case series (NCT01230060) conducted in private practices in the US. Eligible subjects were adult patients with age-related cataract amenable to treatment with standard phacoemulsification/extracapsular cataract extraction. With follow-up of 6 months, primary safety and effectiveness end points included the rates of US Food and Drug Administration (FDA)-defined cumulative and persistent adverse events and the percentage of subjects who achieved best-corrected visual acuity (BCVA) of 20/40 or better at final visit. To evaluate rotational stability, subjects were randomized (1:1:1:1) to have the lens implanted in one of four axis positions in 45° increments.

Results

A total of 122 subjects were enrolled. The rate of cumulative and persistent adverse events did not significantly exceed historical controls, as per FDA draft guidance. At the final postoperative visit, all subjects (100%) achieved a BCVA of 20/40 compared with the FDA historical control of 96.7%. Rotation of the IOL between the two final follow-up visits was ≤5° for 100% of eyes, and refractive stability was demonstrated. A low evaluation of posterior capsule opacification score was demonstrated, and no glistenings of any grade were reported for any subject at any visit.

Conclusion

This study demonstrated the safety and effectiveness of the MX60 IOL. Favorable clinical outcomes included preserved BCVA, excellent rotational and refractive stability, no glistenings, and a low evaluation of posterior capsule opacification score.

Prospective evaluation of visual outcomes with three presbyopia-correcting intraocular lenses following cataract surgery

PURPOSE

To compare the visual acuity and quality of vision achieved with three widely-used intraocular lenses (IOLs) in subjects with bilateral cataracts.

PATIENTS AND METHODS

This three-arm, parallel, prospective, partially masked, single-surgeon study randomized 78 subjects to receive bilateral Crystalens® Advanced Optics (AO) accommodating IOLs, AcrySof® IQ ReSTOR® +3.0 multifocal IOLs, or TECNIS® Multifocal IOLs. Examinations were assessed through days 120 to 180.

RESULTS

The Crystalens AO group had statistically significantly better monocular and binocular, high-contrast (HC) and low-contrast (LC) uncorrected intermediate visual acuity, HC and LC distance-corrected intermediate visual acuity, and significantly fewer monocular and binocular halos and starbursts than did the ReSTOR and TECNIS groups. Monocular and binocular, HC and LC uncorrected near visual acuity exhibited no significant differences among the three lenses. For monocular and binocular HC distance-corrected near visual acuity, the Crystalens AO performed significantly better than the TECNIS and was not significantly different from the ReSTOR. For monocular and binocular LC distance-corrected near visual acuity, the Crystalens AO performed significantly better than both the ReSTOR and the TECNIS. Contrast sensitivity was clinically similar between groups. The Crystalens AO produced statistically fewer halos and starbursts.

CONCLUSION

All three IOLs had excellent uncorrected acuity results at all distances and had good safety, confirming the established safety and effectiveness of these IOLs. Distance and near vision were similar between all three IOLs, and the Crystalens AO provided statistically significantly better intermediate vision.

Comparison of through-focus image sharpness across five presbyopia-correcting intraocular lenses

PURPOSE

To assess through-focus polychromatic image sharpness of 5 FDA-approved presbyopia-correcting intraocular lenses (IOLs) through a range of object vergences and pupil diameters using an image sharpness algorithm.

DESIGN

Laboratory investigation.

METHODS

A 1951 USAF resolution target was imaged through Crystalens AO (AO), Crystalens HD (HD), aspheric ReSTOR +4 (R4), aspheric ReSTOR +3 (R3), and Tecnis Multifocal Acrylic (TMF) IOL in a model eye and captured digitally for each combination of pupil diameter and object vergence. The sharpness of each digital image was objectively scored using a 2-dimensional gradient function.

RESULTS

AO had the best distance image sharpness for all pupil diameters and was superior to the HD. With a 5-mm pupil, the R4 distance image sharpness was similar to the HD and at 6 mm the TMF was superior to the HD, R3, and R4. The R3 moved the near focal point farther from the patient compared to the R4, but did not improve image sharpness at intermediate distances and showed worse distance and near image sharpness. Consistent with apodization, the ReSTOR IOLs displayed better distance and poorer near image sharpness as pupil diameter increased. TMF showed consistent distance and near image sharpness across pupil diameters and the best near image sharpness for all pupil diameters.

CONCLUSIONS

Differing IOL design strategies to increase depth of field are associated with quantifiable differences in image sharpness at varying vergences and pupil sizes. Objective comparison of the imaging properties of specific presbyopia-correcting IOLs in relation to patient's pupil sizes can be useful in selecting the most appropriate IOL for each patient.

Effect of interaction of macroaberrations and scattered light on objective quality of vision in pseudophakic eyes with aspheric monofocal intraocular lenses

PURPOSE

To assess the impact of wavefront ocular aberrations on objective vision quality and depth of focus in pseudophakic patients.

SETTING

University Hospital Bretonneau of Tours, Francois Rabelais Medicine Faculty of Tours, France.

DESIGN

Cohort study.

METHODS

Consecutive eyes having implantation of an aspheric monofocal intraocular lens (IOL) (Acri.Smart) were studied. Aberrometry measurements were performed under mesopic conditions with a 6.0 mm pupil using a Wavescan aberrometer. Objective evaluation of optical vision quality was performed using the Optical Quality Analysis System II. The 3 measurements were the modulation transfer function values (MTF cutoff); objective depth of focus, which was computed as the focus range at which Strehl ratio did not fall below 50% of the maximum; and the objective scatter index.

RESULTS

Fifty-four eyes (30 patients) were enrolled. Six months postoperatively, MTF cutoff values were increased with decreasing total ocular spherical aberration, ocular trefoil, and 2nd-order astigmatism (P<.05). Objective depth of focus was positively correlated with 2nd-order astigmatism (r(2) = 0.171, P<.001) and total spherical aberration (r(2) = 0.091, P=.028). Objective scatter was more beneficial for depth of focus, with a significantly positive correlation with this parameter (r(2) = 0.28, P=.002), than compromising of optical quality (no significant correlation with MTF measurements in same multiple regression analysis).

CONCLUSION

Three ocular aberrations (2nd-order astigmatism, trefoil, spherical aberration) seemed to interact with objective contrast sensitivity and depth of focus, whereas residual spherical aberration exerted opposite effects on image quality in individual patients.

Effect of variation in derived corneal wavefront aberrations by calculation methods on intraocular lens selection

PURPOSE

To compare topographically derived corneal wavefront aberrations between the NIDEK Magellan corneal topographer with built-in software (NIDEK Co Ltd) and VOL-CT software (Sarver and Associates) and determine their effects on intraocular lens (IOL) choice based on spherical aberration profiles.

METHODS

Data were collected prospectively for 28 eyes without existing corneal disease prior to undergoing cataract surgery. Corneal higher order aberrations were calculated using Zernike polynomial expansions from topographic data and compared between the builtin NIDEK software and VOL-CT software.

RESULTS

Using two-tailed paired t tests, statistically significant (P<.05) differences were found between the two calculations at 4 mm for 4th order aberrations (NIDEK: 0.2005 μm, VOL-CT: 0.1202 μm) and 6th order aberrations (NIDEK: 0.0985 μm, VOL-CT: 0.0546 μm). Statistically significant differences were noted between the two calculations at 6 mm for 5th order aberrations (NIDEK: 0.2757 μm, VOL-CT: 0.1618 μm) and 6th order aberrations (NIDEK: 0.2641 μm, VOL-CT: 0.0920 μm). No statistically significant differences existed for 3rd order, spherical aberration, and total higher order aberrations. However, using spherical aberration-based IOL selection criteria, the ultimate IOL selection would have differed in 13 eyes if calculated using the NIDEK versus VOL-CT software.

CONCLUSIONS

Statistically significant differences were present in wavefront aberration calculations using the NIDEK versus VOL-CT software for 4- and 6-mm pupil sizes. These differences in spherical aberration could influence wavefront-optimized IOL selection for cataract surgery.

In vivo Assessment of Higher-Order Aberrations after Acrysof Toric Intraocular Lens Implantation: A Comparative Study

Purpose

To compare higher-order aberrations (HOAs) and optical quality in eyes implanted with AcrySof SN60TT toric intraocular lens (IOL) or with non-toric AcrySof SN60AT IOL (Alcon Laboratories, Inc., Fort Worth, TX).

Methods

This was a prospective, consecutive, nonrandomized, interventional, comparative study. One hundred eyes with cataract in 56 patients were included (SN60TT group, n=50; SN60AT group, n=50). Patients underwent phacoemulsification through a 2.2-mm temporal corneal incision. Postoperative HOAs, point spread function (PSF) and modulation transfer function (MTF), residual objective refractive astigmatism, and IOL alignment were evaluated using Optical Path Difference (OPD)–Scan II (Nidek, Gamagori, Japan). A novel technique to calculate IOL axis alignment was introduced.

Results

One year postoperatively, no statistical difference in corneal, intraocular, and total HOAs, Strehl ratio, and MTF based on HOAs was found between groups. Toric IOL patients had a net residual refractive astigmatism (M) of 0.44 D±0.47; the difference between expected and obtained astigmatism (M) was 0.043 D (p=0.16). Toric IOL axis misalignment was 2.65±2.39 degrees and no correlation with HOAs was found.

Conclusions

AcrySof SN60TT determines HOAs comparable to the non-toric version providing a good optical quality, and predictably corrects corneal cylinder with a stable postoperative alignment. The OPD-Scan II might be regarded as a fast and reliable method of toric IOL analysis.

Visual impact of Zernike and Seidel forms of monochromatic aberrations

PURPOSE

The aim of this study was to examine the impact of different aberrations modes (e.g., coma, astigmatism, spherical aberration [SA]) and different aberration basis functions (Zernike or Seidel) on visual acuity (VA).

METHODS

Computational optics was used to generate retinal images degraded by either the Zernike or Seidel forms of second through fourth-order aberrations for an eye with a 5-mm pupil diameter. High contrast, photopic VA was measured using method of constant stimuli for letters displayed on a computer-controlled, linearized, quasimonochromatic (lambda = 556 nm) display.

RESULTS

Minimum angle of resolution (MAR) varied linearly with the magnitude (root mean square error) of all modes of aberration. The impact of individual Zernike lower- and higher-order aberrations (HOAs) varied significantly with mode, e.g., arc minutes of MAR per micrometer of root mean square slopes varied from 7 (spherical defocus) to 0.5 (quadrafoil). Seidel forms of these aberrations always had a smaller visual impact. Notably, Seidel SA had 1/17th the impact of Zernike SA with the same wavefront variance, and about 1/4th the impact of Zernike SA with matching levels of r wavefront error. With lower-order components removed, HOAs near the center of the Zernike pyramid do not have a large visual impact.

CONCLUSIONS

The majority of the visual impact of high levels of fourth-order Zernike aberrations can be attributed to the second-order terms within these polynomials. Therefore, the impact of SA can be minimized by balancing it with a defocus term that flattens the central wavefront (paraxial focus) or maximizes the area of the pupil with a flat wavefront. Over this wide range of aberration types and levels, image quality metrics based on the Point Spread Function (PSF) and Optical Transfer Function (OTF) can predict VA as reliably as VA measures can predict retests of VA, and, thus, such metrics may become valuable predictors of both VA and, via optimization, refractions.