Intraindividual Comparison of Aspherical and Spherical Intraocular Lenses of Same Material and Platform

Spherical aberrations and their role in modern ophthalmology

Spherical aberration is an imperfection of the optical system of the human eye. The role of spherical aberration of the human eye in the quality of vision and pseudoaccommodation is reviewed. Spherical aberration is an imperfection of the optical system of the human eye. In most cases, due to well-developed neuroadaptation, it is insignificant for the perception of the image. Nevertheless, its role in modern ophthalmology is far from straightforward. On the one hand, there are clinical scenarios in which an excess of spherical aberration degrades the retinal image and leads to a high dissatisfaction rate among patients.©Recently, there is a growing interest in the modulation of spherical aberration in the clinical setting. Modern intraocular lenses as well as laser refractive procedures are aimed at interfering with spherical aberrations of the optical system in order to increase range of pseudoaccommodation. Here, we review the role of spherical aberration of the human eye in the quality of vision and pseudoaccommodation.

Analysis of visual quality after multifocal intraocular lens implantation in post-LASIK cataract patients

With the development of refractive corneal surgery, excimer laser in situ keratomileusis (LASIK) has become a common refractive surgery procedure. However, post-LASIK patients are at increased risk of developing cataracts as they age and often require IOL implantation. The choice of IOLs is particularly important for these patients, who have smaller residual refractive error and have higher requirements for post-cataract vision recovery and visual quality than the general population. Multifocal IOLs are widely used in clinical practice for patients with high visual acuity needs, such as cataract patients after refractive keratomileusis, due to their advantages of providing excellent near and distance visual acuity; however, compared to monofocal IOLs, multifocal IOLs can lead to postoperative problems related to visual quality such as increased higher order aberrations and decreased contrast sensitivity. Therefore, whether multifocal IOLs have advantages for post-LASIK cataract patients, such as improving the visual quality of such patients, has attracted attention. In this paper, we analyze the current status of research on the implantation of multifocal IOLs in post-LASIK cataract patients by domestic and foreign experts, review and summarize the relevant literature, and propose further discussion in the context of the actual situation of postoperative visual quality and vision recovery.

Improvement of neural contrast sensitivity after long-term adaptation in pseudophakic eyes

An adaptive optics (AO) system was used to investigate the effect of long-term neural adaptation to the habitual optical profile on neural contrast sensitivity in pseudophakic eyes after the correction of all aberrations, defocus, and astigmatism. Pseudophakic eyes were assessed at 4 and 8 months postoperatively for changes in visual performance. Visual benefit was observed in all eyes at all spatial frequencies after AO correction. The average visual benefit across spatial frequencies was higher in the pseudophakic group (3.31) at 4 months postoperatively compared to the normal group (2.41). The average contrast sensitivity after AO correction in the pseudophakic group improved by a factor of 1.73 between 4 and 8 months postoperatively. Contrast sensitivity in pseudophakic eyes was poorer, which could be attributed to long-term adaptation to the habitual optical profiles before the cataract surgery, in conjunction with age-related vision loss. Improved visual performance in pseudophakic eyes suggests that the aged neural system can be re-adapted for altered ocular optics.

Impact of decentration and tilt on spherical, aberration correcting and specific aspherical intraocular lenses; an optical bench analysis

Introduction The human eye is not optically symmetrical, and very few IOLs are perfectly centered in the eye. That is why contrast sensitivity can degrade in some conditions, especially in low light. In an optical bench analysis, we compare spherical (A), aberration correcting (B) and specific aspherical lenses (C) in terms of impact of decentration and tilt on the modulation transfer function as well as the simulated overall quality with USAF test targets.

MATERIAL AND METHODS

The OptiSpheric IOL PRO2 was used to measure the optical performance of IOLs (A,B,C). In order to assess the optical quality of the IOLs, the optical quality parameters for the aperture size of 3.0 mm and 4.5 mm at the IOL plane were assessed. Through Frequency Modulation Transfer Function (MTF) and Strehl Ratio (SR) values, as well as the "US Airforce 1951 resolution test chart images" as qualitative simulation, were analyzed. All measurements (ISO) were repeated and done for centered, decentered (1mm) and tilted (5°) IOLs.

RESULTS

Centered: The MTF (mean) at 50 lp/mm (IOL A, B, C) with 3.0 mm aperture was 0.794/0.716/0.797 (ISO 1 cornea) and 0.673/0.752/0.723 (ISO 2 cornea) and with 4.5 mm aperture 0.728/0.365/0.751 (ISO 1) and 0.276/0.767/0.505 (ISO 2). The Strehl ratio (mean) with 3.0 mm aperture was 0.763/0.829/0.898 and with 4.5 mm aperture 0.228/0.386/0.432. Decentered by 1mm: The MTF (mean) at 50 lp/mm with 3.0 mm aperture was 0.779/0.459/0.726 (ISO 1) and 0.695/0.381/0.662 (ISO 2). The MTF (mean) at 50 lp/mm with 4.5 mm aperture was 0.732/0.348/0.653 (ISO 1) and 0.355/0.069/0.346 (ISO 2). The Strehl ratio (mean) with 3.0 mm aperture was 0.829/0.543/0.397 and with 4.5 mm aperture 0.259/0.145/0.192. Tilted by 5 degree: The MTF (mean) at 50 lp/mm with 3.0 mm aperture was 0.731/0.705/0.751 (ISO 1) and 0.623/0.727/0.732 (ISO 2). The MTF (mean) at 50 lp/mm with 4.5 mm aperture was 0.579/0.406/0.701 (ISO 1) and 0.277/0.512/0.429 (ISO 2). The Strehl ratio (mean) with 3.0 mm aperture 0.539/0.478/0.514 and with 4.5 mm aperture 0.262/0.136/0.201.

CONCLUSION

Aberration correcting IOLs perform best when perfectly centered. The optical performance of aberration correcting IOLs can be markedly downgraded by misalignment. The examined ZO optic performed well in decentration and tilt. The ZO concept seems to be a good alternative to aspheric lenses, as it achieves to combine benefits of spherical and aspheric intraocular lenses. There is no perfect IOL, but fitting and choosing the right one for the individual case seems to be crucial to take advantage of benefits and minimize disadvantages. This is why knowledge of optical properties is also mandatory for the surgeon.

The simply modified intrascleral fixation using round flange (SMURF) technique for intrascleral intraocular lens fixation

We describe a simply modified intrascleral fixation using round flange (SMURF) technique and report the clinical outcomes of the surgery. Forty-one eyes of 41 consecutive patients, with intraocular lens (IOL) dislocation, crystalline lens subluxation, and zonular weakness, who underwent surgery using the SMURF technique were included. The modified technique included the use of a conventional 27-gauge needle, a non-bent needle, oblique sclerotomy, direct threading of the leading haptic, and simple placement of the following haptic. IOLs were successfully placed and showed good centring. There were no cases of wound leakage or hypotony during the early postoperative period. Postoperative complications included vitreous haemorrhage in one eye (2.4%), intraocular pressure elevation in one eye (2.4%), and iris capture in six eyes (14.6%). There were no cases of postoperative retinal detachment, cystoid macular oedema, endophthalmitis, or IOL dislocation during the follow-up period. We proposed a few modifications in the intrascleral flanged technique for IOL fixation. The modified technique is a simple, easy, and minimally invasive procedure for successful IOL intrascleral fixation.

Impact of vitrectomy and air tamponade on aspheric intraocular lens tilt and decentration and ocular higher-order aberrations: phacovitrectomy versus cataract surgery

PURPOSE

To evaluate the impact of vitrectomy and air tamponade on aspheric intraocular lens (IOL) tilt and decentration and postoperative internal higher-order aberrations (HOAs) in combined cataract surgery and vitrectomy (phacovitrectomy).

STUDY DESIGN

Prospective comparative observational study.

METHODS

Forty-five eyes that underwent phacovitrectomy using aspheric IOLs and 18 eyes that only underwent cataract surgery also using aspheric IOLs were prospectively evaluated. The subjects were divided into three groups: phacovitrectomy without fluid-air exchange (F/Ax) or with F/Ax and cataract surgery alone (Groups A, B, and C, respectively) Surgery-induced changes in lens tilt and decentration and internal HOAs were compared between each pair of groups. Subgroup analysis was conducted for cases with largely tilted (> 7°) or decentered (> 0.40 mm) IOLs 1 month postoperatively.

RESULTS

Surgery-induced changes in lens tilt in Group B were significantly more pronounced than those in Group C at 1 week, 1 month, and 3 months postoperatively (P = 0.007, 0.009, and 0.043, respectively), while there was no significant difference in surgery-induced changes in lens decentration among the groups. IOLs in Group B were tilted and decentered toward the inferonasal direction. In contrast, there was no significant difference in internal HOAs among the groups at any postoperative visit. Only Group B included cases with largely decentered IOLs, and the internal total HOAs in these cases were significantly larger than those in the others (P = 0.015).

CONCLUSION

Although largely decentered IOLs were occasionally found in Group B, aspheric IOLs could be effectively used in phacovitrectomy.

Distribution of corneal spherical aberration in a Tanzanian population

Purpose

To investigate the distribution of corneal spherical aberration (SA) in Tanzanian people of African descent, and to examine the correlation between corneal SA and ocular parameters.

Design

Cross-sectional population-based study.

Methods

Residents aged 40 years and older in three villages in the Mkuranga district in Tanzania were enlisted as study participants. Corneal higher-order aberrations (HOAs) for the right eye were measured with a wavefront analyzer (KR-1W, Topcon) and calculated for the central 6.0-mm zone. Corneal curvature radius (CR), corneal astigmatism, and axial length (AL) were also measured and their correlation with corneal SA was assessed.

Results

The right eyes of 657 participants (336 male, 321 female) were analyzed. The mean age of the subjects was 57.2 ± 10.3 years (mean ± SD). The mean corneal SA (Zernike spherical aberration coefficient C₄⁰) was 0.188 ± 0.095 μm (-0.242 to 0.613). The SAs in about three-quarters of all subjects were between 0.10 and 0.30 μm. The root mean squares of total corneal HOAs and the third- and fourth-order aberrations were 0.629 ± 0.250 μm, 0.539 ± 0.236 μm, and 0.269 ± 0.110 μm, respectively. Corneal SA showed weak significant correlations with CR (Spearman’s rank correlation coefficient, r = -0.177, p < 0.001), corneal astigmatism (r = -0.142, p < 0.001), AL (r = -0.168, p < 0.001), and age (r = -0.085, p < 0.05).

Conclusions

This finding may be beneficial for selecting aspheric intraocular lens in this population.

Age-Related Changes in Corneal Spherical Aberration

PURPOSE

To analyze the age-related changes in corneal spherical aberration (CSA) and higher order aberrations (HOAs) and to develop a novel model to estimate the change in CSA with age.

METHODS

This was a cross-sectional study of the right eyes of 3,769 patients. Anterior corneal spherical aberration (ASA), posterior corneal spherical aberration (PSA), total corneal spherical aberration (TSA), and the root mean square of corneal HOAs were measured using a Scheimpflug tomographer. Smoothed fitting curves were plotted as a function of age and the average change in spherical aberration was calculated for different ages.

RESULTS

The mean magnitude of ASA, PSA, TSA, and HOAs (6 and 4 mm) were 0.270 ± 0.111, -0.144 ± 0.031, 0.228 ± 0.120, 0.453 ± 0.194, and 0.141 ± 0.075 µm, respectively. All parameters showed a statistically significant non-linear change with age. The age after which the aberrations increased at a faster rate, namely the turning points of age, were 39 years for ASA, PSA, TSA, and 6-mm HOAs (95% confidence interval [CI]: 35 to 42, 36 to 41, 36 to 42, and 35 to 56 years, respectively) and 46 years for 4-mm HOAs (95% CI: 36 to 56 years). There were significant increases in increment rates after the turning points. The average change of TSA was -0.013 µm/10 years from 18 to 39 years and 0.057 µm/10 years after 39 years. There were statistically significant correlations between ASA and TSA (r = 0.976, P < .001) and PSA and TSA (r = 0.192, P < .001), but not between ASA and PSA (r = -0.003, P = .835).

CONCLUSIONS

CSA and HOAs increased non-linearly with age and became more positive after 39 and 46 years of age, respectively. Based on the increment rates and turning points of age, a novel model is provided to help calculate the value required to compensate for the increasing CSA associated with the aging cornea. [J Refract Surg. 2018;34(11):760-767.].

Assessment of contrast sensitivity by Spaeth Richman Contrast Sensitivity Test and Pelli Robson Chart Test in patients with varying severity of glaucoma

PURPOSE

This study was designed to assess the efficacy, reliability and repeatability of SPARCS (Spaeth Richman Contrast Sensitivity Test) as compared to the conventional Pelli Robson Chart Test for the assessment of contrast sensitivity in patients with glaucoma.

MATERIALS AND METHODS

We evaluated 135 eyes of 135 patients who were age and sex matched into three groups (controls, disc suspects and glaucoma) of 45 patients each. The glaucoma subgroup was further divided into subgroups of mild, moderate and severe based on the visual field damage.

RESULTS

There was a strong positive correlation between Pelli Robson scores and SPARCS scores (S = 0.807, P < 0.001). Intraclass correlation coefficient (ICC) for Pelli Robson Test was 0.952 and 0.988 for SPARCS. The coefficient of repeatability (COR) for mean SPARCS was 5.65%, while COR of Pelli Robson Test was 12.44%. SPARCS was found to have better repeatability than Pelli Robson Test based on COR values. Pelli Robson score had a sensitivity of 80% and a specificity of 65.6% for detecting glaucoma patients as compared to 84.4% and 70%, respectively, for SPARCS scores.

CONCLUSION

SPARCS is a better alternative to conventional Pelli Robson Chart Test for assessment of contrast sensitivity in patients with glaucoma. Being independent of the effects of literacy and educational status, it offers a universal way to measure contrast sensitivity. It can also be reliably used in patients with varying severity of glaucoma.

Visual and Refractive Outcomes following Bilateral Implantation of Extended Range of Vision Intraocular Lens with Micromonovision

Purpose

To evaluate the outcomes following bilateral ERV intraocular lens implantation with micromonovision.

Methods

25 subjects underwent bilateral Tecnis Symfony IOL implantation with micromonovision. The dominant eye was targeted for emmetropia and the nondominant eye for myopia of -0.75 D. Uncorrected and corrected distance (UDVA, CDVA), intermediate (UIVA, CIVA), and near visual acuity (UNVA, DCNVA); reading performance; defocus curve; and contrast sensitivity were studied. Follow-ups were conducted at 1 week and 1 and 6 months postoperatively.

Results

At 6 months postoperatively, the mean binocular UDVA, CDVA, UNVA, and DCNVA were -0.036 ± 0.09, -0.108 ± 0.07, 0.152 ± 0.11, and 0.216 ± 0.10 logMAR, respectively. Binocular UIVA and DCIVA were 0.048 ± 0.09 and 0.104 ± 0.08 logMAR, respectively, at 60 cm and -0.044 ± 0.09 and 0.012 ± 0.09 logMAR, respectively, at 80 cm. All patients had ≥0.2 logMAR UDVA and UNVA. Reading acuity and reading speeds showed improvement over time. Between defocus range of -2.50 and +1.00 D, the visual acuity remained ≥0.2 logMAR. Contrast sensitivity scores were within the normal range. 4 patients used reading glasses for very fine print.

Conclusion

Bilateral ERV IOL implantation leads to excellent outcomes for far and intermediate vision, satisfactory outcomes for near vision, and good tolerance to micromonovision at the end of the 6 months. This trial is registered with CTRI/2015/10/006246.

Effect of Spherical Aberration on the Optical Quality after Implantation of Two Different Aspherical Intraocular Lenses

PURPOSE

To compare the effect of spherical aberration on optical quality in eyes with two different aspherical intraocular lenses.

METHODS

120 eyes of 60 patients underwent phacoemulsification. In patients' eyes, an aberration-free IOL (Aspira-aA; Human Optics) or an aberration-correcting aspherical IOL (Tecnis ZCB00; Abott Medical Optics) was randomly implanted. After surgery, contrast sensitivity and wavefront measurements as well as tilt and decentration measurements were performed.

RESULTS

Contrast sensitivity was significantly higher in eyes with Aspira lens under mesopic conditions with 12 cycles per degree (CPD) and under photopic conditions with 18 CPD (p = 0.02). Wavefront measurements showed a higher total spherical aberration with a minimal pupil size of 4 mm in the Aspira group (0.05 ± 0.03) than in the Tecnis group (0.03 ± 0.02) (p = 0.001). Strehl ratio was higher in eyes with Tecnis (0.28 ± 0.17) with a minimal pupil size larger than 5 mm than that with Aspira (0.16 ± 0.14) (p = 0.04). In pupils with a minimum diameter of 4 mm spherical aberration had a significant effect on Strehl ratio, but not in pupils with a diameter less than 4 mm.

CONCLUSIONS

Optical quality was better in eyes with the aberration-correcting Tecnis IOL when pupils were large. In contrast, this could not be shown in eyes with pupils under 4 mm or larger. This trial is registered with Clinicaltrials.gov NCT03224728.

A comparative study on visual and optical performance of Akreos AO and Kontur AB IOLs after phacoemulsification cataract surgery

PURPOSE

Akreos AO and Kontur AB are two commonly used intraocular lenses (IOLs) in Iran. This study was designed to evaluate the visual performance of these lenses.

METHODS

In a comparative interventional study, 35 patients (70 eyes) were recruited, and each IOL was implanted in one eye of the patients, randomly. Best corrected visual acuity (BCVA), contrast sensitivity, aberrometric analysis, and depth of focus were evaluated 1 month and 3 months postoperatively. A visual quality questionnaire was also filled for each eye, and the results were compared.

RESULTS

Mean age of the patients was 60.97 ± 7.00 years. BCVA was not significantly different between the two eyes, before, 1 month, and 3 months postoperatively (p > 0.05 for all). Photopic and mesopic contrast sensitivity was not different between the two lenses instead of photopic 18 cycles per degree, 3 months postoperatively and in mesopic 6 cycles per degree 1 month postoperatively (p = 0.034 and p = 0.002, respectively). Aberrometric factors including HoRMS, Total RMS, and Higher order without Z(4,0) were not significantly different between the two lenses (p > 0.05 for all), but they were slightly lower for Akreos AO. Post-operative distance-corrected visual acuity for intermediate and near vision were not different between the two groups (p > 0.05, respectively).

CONCLUSION

Visual performance of Akreos AO and Kontur AB is similar. However, contrast sensitivity and aberrometric parameters are slightly better for Akreos AO IOL.

Clinical study of customized aspherical intraocular lens implants

AIM

To compare if there is an improvement in visual functions with age-related cataracts between patients receiving a aspherical intraocular lens (IOL) based on corneal wavefront aberration and patients randomly assigned lenses.

METHODS

A total of 124 eyes of 124 patients with age-related cataracts were placed in experimental group and a group receiving randomly assigned (RA) lenses. The experimental group was undergone Pentacam corneal spherical aberration measurement before surgery; the targeted range for residual total spherical aberration after surgery was set to 0-0.3 µm. Patients with a corneal spherical aberration <0.3 µm were implanted with a zero-spherical aberration advanced optics (AO) aspherical IOL and patients with an aberration ≥0.3 µm received a Tecnis Z9003 aspherical lens in experimental group. RA patients were randomly implanted with an AO lens or a Tecnis Z9003 lens. Three months after surgery total spherical aberration, photopic/mesopic contrast sensitivities, photopic/mesopic with glare contrast sensitivities, and logMAR vision were measured.

RESULTS

Statistical analysis on logMAR vision showed no significant difference between two groups (P=0.413). The post-surgical total spherical aberration was 0.126±0.097 µm and 0.152±0.151 µm in the experimental and RA groups, respectively (P=0.12). The mesopic contrast sensitivities at spatial frequencies of 6, 12 and 18 c/d in the experimental group were significantly higher than of the RA group (P=0.00; P=0.04; P=0.02). The mesopic with glare contrast sensitivity in the experimental group at a spatial frequency of 18 c/d was also significantly higher vs the RA group (P=0.01).

CONCLUSION

Pre-surgical corneal spherical aberration measurement in cataract patients followed by customized selection of aspherical IOL implants improved mesopic contrast sensitivities at high spatial frequencies, and thus is a superior strategy compared to the random selection of aspherical IOL implants.

Prospective Comparison of One-Piece and Three-Piece Tecnis Aspheric Intraocular Lenses: 1-year Stability and its Effect on Visual Function

PURPOSE

To compare the stability and visual function of one-piece hydrophobic intraocular lens (IOL) (ZCB00, Abbot Medical Optics) and a three-piece hydrophobic IOL (ZA9003, Abbot Medical Optics) after cataract surgery.

MATERIALS AND METHODS

Eighteen eyes of 18 patients with the one-piece IOL and 20 eyes of 20 patients with the three-piece IOL who underwent cataract surgery were evaluated prospectively on best corrected distance visual acuity, postoperative refractive error, IOL decentration and tilt, anterior chamber depth (ACD), spherical aberration and contrast sensitivity. Measurements were performed 1 week and 1, 3, 6 and 12 months postoperatively. The postoperative outcomes were compared between the two groups.

RESULTS

In the one-piece group, a hyperopic refractive error (p < 0.002) and deeper ACDs during 1-year post-operatively were observed compared with the three-piece group. There were no significant differences in BCVA, IOL tilt, spherical aberration or contrast sensitivity.

CONCLUSIONS

The stability of the one-piece IOL was greater than that of the three-piece IOL. The postoperative ACD and refractive error demonstrated that an anteriorly offset haptic in the one-piece IOL allowed incremental fixation to the posterior capsule.

Aspheric intraocular lenses implantation for cataract patients with extreme myopia

Objective. To evaluate the postoperative visual quality of cataract patients with extreme myopia after implantation of aspheric intraocular lenses (IOLs). Methods. Thirty-three eyes were enrolled in this prospectivestudy. Eighteen eyes with an axial length longer than 28 mm were included in the extreme myopia group, and the other 15 eyes were included in the nonextreme myopia group. Phacoemulsification and aspheric IOL implantation were performed. Six months after cataract surgery, best-corrected visual acuity (BCVA), contrast sensitivity, and wavefront aberrations were measured, and subjective visual quality was assessed. Results. The BCVA improved significantly after surgery for both groups, and patients in the nonextreme myopia group achieved better postoperative BCVA due to better retinal status of the eyes. The evaluation of contrast sensitivity without glare was the same in both groups, whereas patients in the nonextreme myopia group performed better at intermediate spatial frequencies under glare conditions. The two groups did not show a significant difference in high-order aberrations. With regard to subjective visual quality, the composite scores of both groups did not differ significantly. Conclusions. Aspheric IOLs provided good visual outcomes in cataract patients with extreme myopia. These patients should undergo careful evaluation to determine the maculopathy severity level before surgery.

Comparison of visual quality between aspheric and spherical IOLs

PURPOSE

To determine if aspheric intraocular lens (IOL) implantation produces the same degree of postoperative ocular aberration and contrast sensitivity as spherical IOL implantation.

METHODS

In this randomized prospective comparative study, 60 eyes of 30 cataract surgery patients were randomly assigned to receive a spherical IOL (Rayner 620H) in one eye and an aspheric IOL (Rayner 920H) in the contralateral eye. All patients were examined at 1 month postoperatively. Primary outcomes of contrast sensitivity and ocular wavefront higher order aberrations (HOAs) were assessed.

RESULTS

Aspheric IOLs (median total HOAs 0.26 root mean square [RMS]; range 0.13-0.82 RMS) produced significantly lower total HOAs than spherical IOLs (median total HOAs 0.34 RMS; range 0.18-1.08 RMS; p<0.05). Contrast sensitivity was significantly better with aspheric IOLs (median contrast sensitivity 1.8 log units; range 1.35-1.8 log units) than with spherical IOLs (median contrast sensitivity 1.65 log units; range 1.35-1.8 log units; p<0.05).

CONCLUSIONS

When compared with a structurally (platform and material) similar spherical IOL (Rayner 620H), aspheric IOLs (Rayner 920H) appear to significantly reduce HOAs and yield better levels of contrast sensitivity under photopic conditions.

Changes in higher-order aberrations after iris-fixated phakic intraocular lens implantation

PURPOSE

To evaluate surgically induced changes in corneal, internal, and ocular higher-order aberrations (HOAs) after phakic intraocular lens (PIOL) implantation and compare them between two PIOLs with different pupillary diameters.

METHODS

Twenty-three eyes with an Artisan PIOL (Ophtec BV, Groningen, The Netherlands) (Artisan group) and 30 eyes with an Artiflex PIOL (Ophtec BV) (Artiflex group) were retrospectively evaluated. The corneal, internal, and ocular HOAs and refractive data were recorded preoperatively and 6 months postoperatively. The root mean squares (RMSs) of the total HOAs from the third- to sixth-order Zernike coefficients were calculated. The RMSs of the third- and fourth-order coefficients represented coma-like aberrations (S3) and spherical-like aberrations (S4), respectively. The main outcome measures were the differences in the parameters among the groups with different pupillary diameters.

RESULTS

The mean postoperative spherical equivalents decreased from -11.84 ± 4.90 to -0.16 ± 0.40 diopters and -9.78 ± 3.20 to -0.09 ± 0.26 diopters in the Artisan and Artiflex groups, respectively. With the 4- and 5-mm pupillary diameters, the postoperative internal and ocular spherical aberrations (Z4(0)) were significantly lower in the Artiflex group than in the Artisan group (4 mm, P = .002, .024; 5 mm, P = .004, .022, respectively). With the 6-mm pupillary diameter, there were no significant postoperative differences in any parameter measured between groups; both groups had positive spherical aberration values.

CONCLUSIONS

The postoperative ocular spherical aberrations were positive after Artisan and Artiflex implantation. The postoperative ocular spherical aberration was greater in the Artisan group, possibly due to differences in the SAs of both PIOLs.

The impact on vision of aspheric to spherical monofocal intraocular lenses in cataract surgery: a systematic review with meta-analysis

PURPOSE

To provide a summary of the impact on vision of an aspheric intraocular lens (IOL) compared with a spherical IOL in cataract surgery.

DESIGN

Systematic review with meta-analysis.

PARTICIPANTS

Patients from published randomized controlled trials (RCTs) of cataract surgery with aspheric compared with spherical monofocal IOL implantation.

METHODS

We systematically searched the peer-reviewed literature in MEDLINE, EMBASE, Web of Science, BIOSIS, and the Cochrane Library according to the Cochrane Collaboration method to identify relevant RCTs. The inclusion criteria were RCTs on cataract surgery comparing the use of aspheric versus spherical IOL implantation that assessed visual acuity, contrast sensitivity, or quality of vision. The effects were calculated as mean differences or standardized mean differences (Hedges' g) and pooled using random-effect models.

MAIN OUTCOME MEASURES

Best-corrected visual acuity (BCVA), contrast sensitivity, and subjective perception of the quality of vision.

RESULTS

Forty-three studies provided data and were included, comprising 2076 eyes implanted with aspheric IOLs and 2034 eyes implanted with spherical IOLs. The BCVA showed a significant difference for aspheric IOLs (-0.01 logarithm of the minimum angle of resolution; 95% confidence interval [CI], -0.02 to -0.00). For contrast sensitivity, a significant advantage for aspheric IOLs was found under photopic and mesopic light conditions (photopic: Hedges' g 0.42, 95% CI 0.24-0.61 (3 cycles per degree [cpd]) to 0.53, 95% CI 0.33-0.73 (12 cpd); mesopic: Hedges' g 0.49, 95% CI 0.23-0.75 (1.5 cpd) to 0.76, 95% CI 0.52-1.00 (18 cpd)). Questionnaires targeting the subjective perception of quality of vision yielded less conclusive results.

CONCLUSIONS

Overall, a patient may achieve better contrast sensitivity with an aspheric IOL than with a spherical IOL, especially under dim light. There was no clinically relevant difference in BCVA between aspheric and spherical IOL implantation. The findings on the subjective perception of visual quality were heterogeneous with no clear result favoring either option.

Change in efficiency of aspheric intraocular lenses based on pupil diameter

PURPOSE

To measure the effect of spherical aberration correction by aspheric intraocular lenses (IOLs) based on pupil diameter, and to determine the minimum pupil diameter for each aspheric IOL.

DESIGN

Retrospective cross-sectional study.

METHODS

Eight-six patients (169 eyes) who were implanted with a HOYA AF-1 NY-60 (HOYA Corporation) or Tecnis ZCB00 1-piece IOL (Abbott Medical Optics Inc) were enrolled. Ocular, corneal, and internal spherical aberrations were measured at the 1-month postoperative visit using the Wavefront Analyzer KR-1W (Topcon). Minimum pupil diameter, which is required for each aspheric IOL to be effective, was calculated using a regression equation.

RESULTS

The mean value of internal spherical aberration of the Tecnis ZCB00 group (-0.09 ± 0.094 μm) was lower than that of the HOYA NY-60 group (-0.05 ± 0.072 μm) (P = .005). The original negative spherical aberrations of the HOYA NY-60 (-0.18 μm) were measured at a pupil diameter of 5.6 mm, and for the Tecnis ZCB00 (-0.27 μm) at a pupil diameter of 6.1 mm. The aspheric IOL efficiency dropped to 0% when the pupil diameter was 3.47 mm for the Tecnis ZCB00 group and 3.71 mm for the HOYA NY-60 group.

CONCLUSIONS

When the pupil diameters of patients are smaller than 3.4 mm for the Tecnis ZCB00 and 3.7 mm for the HOYA NY-60, the spherical aberration correction using these aspheric IOLs seems to be ineffective. Approximately 10% of the eyes showed smaller pupil size than the minimum effective diameter under mesopic conditions.

Effect of a single-piece aspheric hydrophobic acrylic intraocular lens design on centration and rotation

PURPOSE

To assess the rotation and centration stability of the new design features of a 1-piece aspheric hydrophobic acrylic intraocular lens (IOL).

SETTING

National Eye Hospital, Cairo, Egypt.

DESIGN

Randomized clinical trial.

METHODS

Patients in this study had implantation of a 1-piece Tecnis 1 ZCB00 IOL or a 3-piece Sensar AR40e IOL. Decentration and rotation were recorded immediately postoperatively, and 2 to 3 days and 8 weeks postoperatively. This was done using 2 slitlamp eyepieces and referring to constant corneal landmarks (ie, the limbus and the phaco incision).

RESULTS

Thirty-two 1-piece IOLs and 30 3-piece IOLs were implanted. Although the 1-piece IOLs moved toward the corneal center more than the 3-piece IOLs between 3 days and 8 weeks postoperatively (P=.054), the difference was not statistically significant between 0 day and 3 days or during the entire follow-up (P=.546 and P=.367, respectively). There were no statistically significant differences in the horizontal or vertical components of this movement between the 2 groups (P=.883 and P=.636, respectively). The mean rotation was 2.5 degrees ± 9.1 (SD) in the 1-piece IOL group and 0 ± 6.5 degrees in the 3-piece IOL group, with no statistically significant difference between the groups (P=.521).

CONCLUSION

The new 1-piece design showed relatively good centration and stability in the horizontal, vertical, and rotational aspects.

Effect of decentration on the optical performance in multifocal intraocular lenses

AIMS

To evaluate the influence of decentration on optical performance in multifocal intraocular lenses (IOLs) using eye models.

METHODS

This study evaluated 4 types of multifocal IOLs (ReSTOR SA60D3, Alcon; TECNIS Multifocal ZM900, AMO; ReZoom, AMO; SFX-MV1, Hoya). The evaluations were based on measurements of the near and far modulation transfer function (MTF) and visualized actual near images (newspaper) using eye models with the IOL horizontally displaced 0, 0.25, 0.5, 0.75 and 1.0 mm from the center.

RESULTS

For the diffractive ReSTOR the near MTF decreased with increasing decentration. The near images (newspaper characters) became difficult to distinguish at a decentration of 1.0 mm. For the diffractive ZM900, the near and far MTFs gradually decreased with increasing decentration. For the refractive ReZoom and SFX-MV1, we observed almost no change in the near MTF from a decentration of 0-1.0 mm. However, the far MTF clearly decreased starting at a decentration of 1.0 mm for ReZoom and 0.75 mm for SFX-MV1.

CONCLUSION

The MTFs and near images are affected to a different extent depending on the design of multifocal IOLs; clinically relevant effects are not to be expected up to a decentration of 0.75 mm.

Visual performance of the Tecnis one-piece lens ZCB00

Synopsis

The aspheric, one-piece design of the Tecnis^® ZCB00 intraocular lens provided higher mesopic contrast sensitivity and relatively constant refraction at different pupil sizes compared to the Sensar^® AR40e.

Purpose

Comparing the impact on functional vision of the aspheric Tecnis^® ZCB00 one-piece lens compared to the spherical Sensar^® AR40e three-piece lens.

Setting

National Eye Hospital, Cairo, Egypt.

Methods

In this prospective study, we implanted 32 Tecnis ZCB00 (Abbott Medical Optics, Santa Ana, CA) and 30 Sensar AR40e (Pharamacia and Upjohn LLC, North Peapack, NJ) lenses. Twenty-three patients in the ZCB00 group and 13 patients in the AR40e group provided reliable, reproducible data, and were therefore included in the statistical analysis. After 8 weeks, we measured photopic contrast sensitivity (PCS) at 85 cd/m² and mesopic contrast sensitivity (MCS) at 5 cd/m². Uncorrected and best-corrected visual acuity were measured. Myopic shift was analyzed by comparing the manifest refraction spherical equivalent at 3 days and 8 weeks after surgery in the normal and dilated pupil.

Results

The Tecnis ZCB00 group showed significantly better MCS than the Sensar AR40e group at a spatial frequency of six cycles per degree (cpd) (P = 0.037), but not at 3, 12, or 18 cpd (P = 0.299, P = 0.226, and P = 0.396, respectively). There were no significant differences between groups in corrected distance visual acuity (P = 0.175) or PCS at 3, 6, 12, or 18 cpd spatial frequencies (P = 0.440, P = 0.176, P = 0.365, and P = 0.251, respectively). The ZCB00 group showed less myopic shift in normal and dilated pupils between 3 days and 8 weeks after surgery compared to the AR40e group, but this difference was not significant.

Conclusion

The Tecnis one-piece ZCB00 provided higher MCS at moderate spatial frequency than the three-piece Sensar AR40e, and was associated with relatively constant refraction at different pupil sizes.

Visual function and subjective quality of life in Chinese cataract patients after implantation with aspheric intraocular lenses

PURPOSE

To evaluate and compare the objective and subjective visual function after implantation of 2 aspheric intraocular lenses (IOLs) in Chinese cataract patients.

METHODS

Forty-one eyes of 28 patients with cataract were randomly assigned to receive either the MC X11 ASP IOL or the AcrySof IQ IOL. Three months postoperatively, best-corrected visual acuity (BCVA), contrast sensitivity, wavefront aberrations, and subjective visual quality were measured. The degree of posterior capsule opacification (PCO) was recorded at last follow-up.

RESULTS

Postoperative mean monocular BCVA was 0.05±0.13 logMAR in the MC X11 group and 0.05±0.08 logMAR in the IQ group. There was no significant difference in visual acuity, contrast sensitivity, subjective visual quality, and degree of PCO between the 2 groups. For a 6-mm pupil diameter, the mean spherical aberration (Z40) was 0.075±0.076 µm in the MC X11 group and 0.056±0.111 µm in the IQ group. However, 45.5% and 57.9% of the eyes in the MC X11 and IQ groups had values >0.10 µm, respectively. The mean RMS values of the high-order aberrations were similar between the 2 groups except the higher fifth- and sixth-order aberrations, which were significantly higher in the MC X11 group.

CONCLUSIONS

Both IOLs provided similar and good visual outcomes. However, the data suggest that the amount of negative spherical aberration generated by current available aspheric IOLs might not be optimal for Chinese eyes.

Optical quality in eyes implanted with aspheric and spherical intraocular lenses assessed by NIDEK OPD-Scan: a randomized, bilateral, clinical trial

PURPOSE

To determine whether implantation of an intraocular lens (IOL) with an aspheric surface (Akreos AO, Bausch & Lomb Inc) results in reduced ocular aberrations (spherical aberration) and improved Strehl ratio and modulation transfer function (MTF) after cataract surgery.

METHODS

In an intraindividual, randomized, double-masked, prospective study of 50 eyes (25 patients) with bilateral cataract, an IOL with modified anterior and posterior surfaces (Akreos AO) was implanted in one eye and a biconvex IOL with spherical surfaces (Akreos Fit, Bausch & Lomb Inc) implanted in the fellow eye. Ocular aberrations, Strehl ratio, and MTF curve with 4.5-, 5.0-, and 6.0-mm pupils were measured with a NIDEK OPD-Scan dynamic retinoscopy aberrometer 3 months after surgery. Uncorrected and corrected distance visual acuity (UDVA and CDVA, respectively) were also measured.

RESULTS

No statistically significant difference was noted between eyes in postoperative UDVA and CDVA at 1 month. At 3 months, the Akreos AO IOL group obtained statistically significant lower values of higher order and spherical aberrations with 4.5-, 5.0-, and 6.0-mm pupil diameters than the Akreos Fit IOL group (P<.05). The value of Strehl ratio was statistically significantly higher in eyes with the Akreos AO IOL for 4.5- and 6.0-mm pupils (P<.05). The MTF curve was better in the Akreos AO IOL group in 4.5-, 5.0-, and 6.0-mm pupils (P<.05).

CONCLUSIONS

The aspheric Akreos AO IOL induced significantly less spherical aberration than the Akreos Fit IOL for 4.5-, 5.0-, and 6.0-mm pupils. Modulation transfer function and Strehl ratio were also better in eyes implanted with the Akreos AO IOL than the Akreos Fit.

Mesopic contrast sensitivity and ocular higher-order aberrations in eyes with conventional spherical intraocular lenses

PURPOSE

To investigate relationship between mesopic contrast sensitivity (CS) function and ocular higher-order aberrations in eyes implanted with conventional spherical intraocular lenses (IOL).

DESIGN

Prospective, nonrandomized case series.

METHODS

Sixty-eight eyes of 48 patients who attained best spectacle-corrected visual acuity (BSCVA) of 20/20 or better after phacoemulsification and spherical IOL implantation were included in the study. At 2 months postoperatively, mesopic CS was measured with the Mesotest II (Oculus; Wetsler, Germany), and ocular higher-order aberrations for a 4-mm pupil were measured with the Hartmann-Shack aberrometer. CS and letter CS under photopic conditions were recorded with the CSV-1000 charts (Vector Vision Co, Greenville, Ohio, USA).

RESULTS

There was significant correlation between mesopic CS and ocular fourth-order root mean square (RMS) of wavefront aberration (Spearman r(s) = -0.293; P = .017), but no correlation was found between mesopic CS and ocular third-order RMS (r(s) = 0.196; P = .189). Ocular third- and fourth-order RMS did not correlate with other parameters, including BSCVA, and CS and letter CS under photopic conditions.

CONCLUSIONS

Mesopic CS is significantly associated with ocular fourth-order RMS of wavefront aberrations in eyes implanted with conventional spherical IOLs.