Comparative study of aspheric intraocular lenses with negative spherical aberration or no aberration

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.

Correlations of Corneal Curvature with Corneal Spherical Aberration and Anterior Chamber Parameters in Eyes with Shallow Anterior Chambers

INTRODUCTION

This study aimed to investigate the distribution of corneal spherical aberration (CSA) and the relationship between corneal curvature with CSA and anterior chamber parameters in age-related cataract patients with normal axial lengths and shallow anterior chambers.

METHODS

Preoperative data of age-related cataract patients were collected in this retrospective comparative study. According to the average corneal curvature, the eyes were divided into groups of K_m < 42 diopters (D), 42 D ≤ K_m < 45 D, and K_m ≥ 45 D. The axial length (AL) and corneal curvature were obtained using IOLMaster. CSA, anterior chamber depth (ACD), anterior chamber volume (ACV), anterior chamber angle (ACA), and corneal diameter (CD) were acquired according to Pentacam. The above parameters were compared among the three groups. Correlation analysis was applied to these parameters.

RESULTS

The average CSA value of 753 eyes was 0.41 ± 0.27 μm, with no significant difference among the three groups. Overall, CSA was significantly correlated with corneal curvature and ACD. The comparison of ACD among the three groups showed significant differences between the K_m ≥ 45 D group, K_m < 42 D group, and 42 D ≤ K_m < 45 D group. Corneal curvature was positively correlated with ACD, and further analysis confirmed that the relationship was significant only in the K_m ≥ 45 D group. There were statistically significant differences in CD between the three groups. A significant correlation was found in corneal curvature and CD in all eyes, which was also found in the 42 D ≤ K_m < 45 D group and the K_m ≥ 45 D group. Concerning ACV and ACA, no correlation with corneal curvature was found. In addition, the mean ACV and ACA of the three groups did not show any significant difference.

CONCLUSIONS

CSA was higher in this population and had individual variance. Compared with ACD, ACV and ACA were more stable in different corneal curvatures and more objective in representing the anterior chamber space.

Effect of larger corneal spherical aberration in improving the near visual acuity of eyes implanted with the TECNIS Symfony

Purpose

To explore the effect of corneal spherical aberration on the visual acuity and visual quality of eyes implanted with the TECNIS Symfony intraocular lens (IOL).

Methods

A total of 43 patients with age-related cataract (60 eyes) undergoing phacoemulsification and TECNIS Symfony IOL implantation were enrolled in this study. The uncorrected distance (UDVA), intermediate (UIVA), near visual acuity (UNVA), corrected distance visual acuity (CDVA), contrast sensitivity, and ocular spherical aberration were recorded 3 months after surgery. Preoperative and postoperative corneal spherical aberration were also measured using the iTrace device. Objective scattering index (OSI), modulation transfer function cut-off frequency (MTF cut-off), and Strehl ratio (SR) were measured by the Optical Quality Analyzing System. Catquest-9SF questionnaire were applied too. Spearman's correlation analysis was used to evaluate the relationship between spherical aberration and visual quality parameters.

Results

Patients were satisfied with their postoperatively visual quality. And the postoperative logMAR UDVA, UIVA, UNVA, and CDVA was 0.05 ± 0.07, 0.04 ± 0.06, 0.15 ± 0.07, and 0.03 ± 0.05, respectively. The mean preoperative corneal spherical aberration was 0.24 ± 0.10 μm, which is the only factor influencing postoperatively UNVA, and it was negatively correlated with UNVA and glare contrast sensitivity under 18 cpd (cycle/degree, cpd) spatial frequency (r = -0.403, -0.300, -0.360; all P < 0.05). Additionally, the greater the residual spherical aberration of the cornea, the better the near vision after operation. The mean postoperative ocular spherical aberration was -0.03 ± 0.07 μm, it was not correlated with visual acuity, contrast sensitivity, and visual quality (all P > 0.05).

Conclusion

Preoperative positive spherical aberration can benefit near vision while decrease contrast sensitivities at high spatial frequencies when implanted with the TECNIS Symfony IOL.

Effect of cataract incision type on corneal spherical aberration

Corneal spherical aberration (CSA) plays an important role in the ocular refractive system. However, ophthalmologists have not considered the effect of difference cataract incisions on it. The purpose of this study is to investigate the effect of transparent corneal incision (TCI) and scleral tunnel incision (STI) on CSA after the cataract phacoemulsification with foldable IOLs. One hundred ninety-three eyes (61 males and 79 females) for 1-month observation and 114 eyes (29 males and 51 females) for 3-month observation with age-related cataracts (ARC) were included in this study. CSA was measured with dilated pupil by Pentacam Scheimpflug system at 1 day preoperative and 1, 3-month postoperative. Preoperative CSA >1.00 μm was excluded. Both TCI and STI are 3 mm incisions with Infiniti system and Ozil handpiece. No significant difference of age or gender was found between TCI and STI groups in 1 or 3-month observation. In 1-month observation, preoperative CSA for TCI and STI are 0.31 ± 0.29 and 0.41 ± 0.19 μm, which of postoperative are 0.42 ± 0.17 and 0.44 ± 0.35 μm, respectively. The change of CSA is 0.11 ± 0.32 and 0.04 ± 0.33 μm (P = .233). For 3-month observation, preoperative CSA for TCI and STI are 0.32 ± 0.28 and 0.36 ± 0.23 μm, which of postoperative are 0.43 ± 0.16 and 0.39 ± 0.26 μm, respectively. The change of CSA is 0.10 ± 0.34 and 0.03 ± 0.21 μm (P = .312). For the phacoemulsification combined with foldable IOL implantation, STI has minimal effect on CSA, but TCI might increase postoperative CSA.

Matching the Patient to the Intraocular Lens: Preoperative Considerations to Optimize Surgical Outcomes

The intraocular lens (IOL) selection process for patients requires a complex and objective assessment of patient-specific ocular characteristics, including the quality and quantity of corneal astigmatism, health of the ocular surface, and other ocular comorbidities. Potential issues that could be considered complications after surgery, including dry eye disease, anterior or epithelial basement membrane dystrophy, Salzmann nodular degeneration, and pterygium, should be addressed proactively. Aspheric IOLs are designed to eliminate the positive spherical aberration added by traditional IOLs to the pseudophakic visual axis. Spherical aberration may be a consideration with patient selection. Patient desire for increased spectacle independence after surgery is one of the main drivers for the development of multifocal IOLs and extended depth-of-focus (EDOF) IOLs. However, no one single multifocal or EDOF IOL suits all patients' needs. The wide variety of multifocal and EDOF IOLs, their optics, and their respective impact on patient quality of vision have to be understood fully to choose the appropriate IOL for each individual, and surgery has to be customized. Patients who have undergone previous LASIK or who have radial keratotomy and ocular pathologic features, including glaucoma, age-related macular degeneration, and epiretinal membrane, require specific considerations for IOL selection. Subjectively, patient-centered considerations, including visual goals, lifestyle, personality, profession, and hobbies, are key elements for the surgeon to assess and factor into an IOL recommendation. This holistic approach will help surgeons to achieve optimal surgical outcomes and to meet (and exceed) the high expectations of patients.

Static and Dynamic Factors Associated With Extended Depth of Focus in Monofocal Intraocular Lenses

PURPOSE

To analyze factors affecting depth of focus (DOF) and near vision functionality in eyes implanted with aspheric monofocal intraocular lenses (IOLs).

METHODS

This prospective study included 111 eyes of 74 patients that underwent phacoemulsification with monofocal IOL implantation. Ninety-one normal eyes were randomized to receive aberration-free (n = 30) or negative-spherical aberration (SA) IOLs (n = 61). Twenty post-hyperopic femto-LASIK eyes received aberration-free IOLs. Corneal higher-order aberrations (SA, coma, trefoil, and corneal asphericity) for a 6 mm pupil were measured by Scheimpflug tomography. Ray-tracing metrics (visual Strehl optical transfer function [VSOTF], effective range of focus [EROF], sphere shift [SS], EROF-SS), pupil size measurements at far and near, and ocular and corneal SA were obtained using ray-tracing aberrometry. Distance-corrected near visual acuity (DCNVA) and subjective defocus curves up to ±4.0 diopters were evaluated.

RESULTS

Multivariable logistic regression found corneal profile and IOL type to be determinants of extended DOF with monofocal IOLs. The aberration-free IOL group showed significantly better DCNVA and higher total SA than the negative-SA group. Post-hyperopic LASIK eyes showed significantly better DCNVA; higher negative SA, coma, and Q value (P < .05), and smaller pupil size (P = .05) than normal eyes implanted with aberration-free IOLs.

CONCLUSION

Corneal profile and type of IOL implanted were the most important factors influencing near vision functionality with aspheric monofocal IOLs. Higher positive SA in the aberration-free group potentially led to better DCNVA than the negative-SA group in normal eyes. Hyperprolate corneas had better DOF curves and DCNVA than normal corneas. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

Objective optical quality in eyes with customized selection of aspheric intraocular lens implantation

BACKGROUND

To compare the postoperative optical quality in eyes with customized selection and random selection of aspheric intraocular lens (IOL) implantation.

METHODS

A prospective, nonrandomized study was implemented in adult cataract patients who underwent unilateral phacoemulsification with aspheric IOL implantation. Patients were allocated into two treatment groups: a customized group and a control group. In the customized group, the aspheric IOL selection was based on the corneal spherical aberration to enable the postoperative target ocular spherical aberration closest to zero; in the control group, the aspheric IOLs were chosen using a random strategy. Primary outcome measurements included the following objective optical quality assessments: higher-order aberrations obtained by a Hartmann-shack aberrometer at 4 mm and 6 mm pupil diameters; objective scatter index (OSI), modulation transfer function (MTF) cut-off, Strehl ratio (SR) and a simulated contrast visual acuity-optical quality analysis system value (OV) obtained by a double-pass system with a 4-mm aperture. Subjective visual acuity was measured as secondary outcome. All the patients were followed up for 3 months.

RESULTS

Eighty-four patients in the customized group and 78 patients in the control group were evaluated. There was no significant difference in postoperative visual acuity between the two groups (P > 0.05). Significantly less ocular higher-order aberrations were shown in the customized group (P < 0.05). No significant difference was shown in OSI, MTF cut-off, SR and OV between the two groups (P > 0.05).

CONCLUSIONS

Although customized selection of aspheric IOL implantation showed less postoperative ocular aberrations, it performed similarly to random selection of aspheric IOL implantation in terms of postoperative visual acuity, simulated contrast visual acuity, intraocular scatter, modulation transfer function and Strehl ratio.

TRIAL REGISTRATION

Retrospectively registered on 07/06/2019. Registration number: ChiCTR1900024356 .

Comparison of clinical outcomes of toric intraocular lens, Precizon vs Tecnis: a single center randomized controlled trial

Background

To compare the clinical outcome of Precizon toric intraocular lens (IOL) (Ophtec Inc.) to that of Tecnis toric IOL (Abbott Medical Optics Inc.).

Methods

This randomized comparative study included 40 eyes (Precizon, 20 eyes; Tecnis, 20 eyes) of 40 patients with visually significant cataract and corneal astigmatism who underwent cataract surgery. Changes in uncorrected distant visual acuity (UCDVA), best corrected distant visual acuity (BCDVA), uncorrected intermediate visual acuity (UCIVA), refraction, residual astigmatism, rotation of the IOL axis, and higher order aberrations at 3 months postoperatively were evaluated. Vector analysis was performed using the Alpins method.

Results

Both groups showed significant reduction in refractive astigmatism after the surgery (Precizon: − 1.06 ± 0.94 Diopter (D) to − 0.31 ± 0.29 D, p = 0.042; Tecnis: − 1.83 ± 1.29 D to − 0.41 ± 0.33 D, p = 0.015). There was no significant (p > 0.05) difference in postoperative UCDVA, BCDVA, or residual astigmatism between the two groups, although a tendency of better UCIVA was observed in the Precizon group. Vector analysis parameters showed no statistically significant difference beween groups(P > 0.05). Significant difference in rotation of toric IOL axis was found between the two groups (Precizon: 1.50° ± 0.84, Tecnis: 2.56° ± 0.68, p = 0.010). Spherical aberration in the Precizon group was significantly (p = 0.005) lower than that in the Tecnis group.

Conclusions

The Precizon toric IOL group had better rotational stability at 3-month postoperatively. Both Precizon toric IOL and Tecnis toric IOL could be effectively used by cataract surgeons to correct preexisting corneal astigmatism through cataract surgery.

Trial registration

http://clinicaltrials.gov, NCT03085901, retrospectively registered on 21 March 2017.

Electronic supplementary material

The online version of this article (10.1186/s12886-018-0955-3) contains supplementary material, which is available to authorized users.

Influence of spherical aberration, stimulus spatial frequency, and pupil apodisation on subjective refractions

PURPOSE

To test competing hypotheses (Stiles Crawford pupil apodising or superior imaging of high spatial frequencies by the central pupil) for the pupil size independence of subjective refractions in the presence of primary spherical aberration.

METHODS

Subjective refractions were obtained with a variety of test stimuli (high contrast letters, urban cityscape, high and low spatial frequency gratings) while modulating pupil diameter, levels of primary spherical aberration and pupil apodisation. Subjective refractions were also obtained with low-pass and high-pass stimuli and using 'darker' and 'sharper' subjective criteria.

RESULTS

Subjective refractions for stimuli containing high spatial frequencies focus a near paraxial region of the pupil and are affected only slightly by level of Seidel spherical aberration, degree of pupil apodisation and pupil diameter, and generally focused a radius of about 1-1.5 mm from the pupil centre. Low spatial frequency refractions focus a marginal region of the pupil, and are significantly affected by level of spherical aberration, amount of pupil apodisation, and pupil size. Clinical refractions that employ the 'darker' or 'sharper' subjective criteria bias the patient to use lower or higher spatial frequencies, respectively.

CONCLUSIONS

In the presence of significant levels of spherical aberration, the pupil size independence of subjective refractions occurs with or without Stiles Crawford apodisation for refractions that optimise high spatial frequency content in the image. If low spatial frequencies are optimised by a subjective refraction, spherical refractive error varies with spherical aberration, pupil size, and level of apodisation. As light levels drop from photopic to scotopic, therefore, we expect a shift from pupil size independent to pupil size dependent subjective refractions. Emphasising a 'sharper' criterion during subjective refractions will improve image quality for high spatial frequencies and generate pupil size independent refractions.

[Use of "mix-and-match" aspheric intraocular lenses in cataract surgery to enhance depth of field and stereoscopic performance]

INTRODUCTION

One of the remaining challenges in cataract surgery is to compensate for lost accommodative function. The purpose of our study is to evaluate reading ability with a combination of two different aspheric intraocular lenses.

PATIENTS AND METHODS

This retrospective study included 40 eyes (20 patients). The control group (28 eyes, 14 patients) received two negative aspheric intraocular lenses (Acrismart 36A(®), Carl Zeiss Meditec), while the aspheric-optimized group (12 eyes, six patients) received an AcriSmart 36A(®) in the dominant eye and a zero-aspheric intraocular lens (Acrismart 46 LC(®), Carl Zeiss Meditec) in the fellow eye. Patients with corneal asphericity between 0.15 and 0.30 μm and a bilateral monocular postoperative visual acuity of at least 20/20 were eligible for inclusion. Uncorrected and best corrected visual acuity was measured for near, intermediate and distance vision. Corneal and total higher-order aberrations, monocular and binocular defocus curve, and stereoscopic performance were assessed.

RESULTS

Postoperative spherical equivalent and best corrected distance visual acuity were not significantly different between the two groups (P=0.11 and P=0.82 respectively). However, the aspheric-optimized group (36A(®)/46 LC(®)) exhibited better near and intermediate visual acuity (P<0.05), and better stereoscopic vision (P=0.027).

DISCUSSION

The depth of field results in pseudophakes implanted with "mix-and-match" aspheric lenses demonstrates that the binocular combination of two different aspheric profiles seems to improve near vision without affecting stereoscopic vision.

Visual and optical performance of eyes with different corneal spherical aberration implanted with aspheric intraocular lens

AIM

To compare the visual and optical performance of eyes with different corneal spherical aberration (SA) implanted with spherical aberration-free intraocular lens (IOLs).

METHODS

Thirty-six patients with different corneal SA had phacoemulsification with implantation of spherical aberration-free IOLs. Patients were divided into 3 groups according to the value of preoperative corneal SA. Eyes with corneal SA <0.10µm were assigned to group A, those with 0.10 ≤corneal SA <0.20µm to Group B, and those with 0.20≤ corneal SA <0.35µm to Group C. Best-corrected visual acuity (BCVA), contrast sensitivity, corneal SA, total ocular aberrations, and depth of focus were recorded 3 months postoperatively. Distance-corrected near and intermediate visual acuity was studied to measure depth of focus.

RESULTS

BCVA and contrast sensitivity were similar between groups. There were no significant differences in distance-corrected near or intermediate visual acuity. Corneal SA was similar before and 3 months after surgery in the 3 groups. With a 5.0mm pupil diameter, root mean square values for total ocular higher-order aberrations (HOAs) were lower in groups A and B than in group C. Total ocular SA was lower in group A than in groups B and C. SA was also lower in group B than in group C. Coma and trefoil were similar between the groups.

CONCLUSION

Implantation of spherical aberration-free IOLs in eyes with different corneal SA results in similar visual performance at BCVA, contrast sensitivity and depth of focus.

A new method of cornea modulation with excimer laser for simultaneous correction of presbyopia and ametropia

PURPOSE

To investigate the outcomes of simultaneous correction of presbyopia and ametropia by a bi-aspheric cornea modulation technique, based on the creation of a central area hyperpositive for near vision and leaving the pericentral cornea for far vision in hyperopic, emmetropic, and myopic presbyopic patients.

SETTING

Sixty eyes of 30 patients were treated with the PresbyMAX technique by one surgeon (D.U.) at the Eye Hospital Bellevue, Kiel, Germany.

METHODS

Twenty eyes with hyperopic presbyopia, 20 eyes with emmetropic presbyopia, and 20 eyes with myopic presbyopia underwent Femto-Lasik, and were assessed up to 6 months postoperatively. All eyes underwent cornea treatment using the PresbyMAX® software, delivering a bi-aspheric multifocal ablation profile developed by SCHWIND eye-tech-solutions (Kleinostheim, Germany). All flaps were created by Ziemer LDV Femtolaser (Port, Switzerland).

RESULTS

The mean binocular distance of uncorrected visual acuity (DUCVA) improved in the hyperopic group from 0.28 ± 0.29 logMAR to -0.04 ± 0.07 logMAR, in the emmetropic group from -0.05 ± 0.07 logMAR to 0.02 ± 0.11 logMAR, and in the myopic group from 0.78 ± 0.27 logMAR to 0.09 ± 0.08 logMAR. The mean binocular near uncorrected visual acuity (NUCVA) increased in the hyperopic group from 0.86 ± 0.62 logRAD to 0.24 ± 0.23 logRAD, and in the emmetropic group from 0.48 ± 0.14 logRAD to 0.18 ± 0.11 logRAD. The myopic presbyopes showed a decrease of the mean binocular NUCVA from 0.04 ± 0.19 logRAD to 0.12 ± 0.18 logRAD. The mean postoperative spherical equivalent for distance refraction was -0.13 ± 0.61 D for the hyperopic presbyopia, -0.43 ± 0.35 D for the emmetropic presbyopia, and -0.68 ± 0.42 D for the myopic presbyopia group, whereas the software took aim at -0.50 D in all groups.

CONCLUSIONS

In presbyopic patients without symptomatic cataracts, but refractive errors, PresbyMAX® will decrease the presbyopic symptoms and correct far distance refraction in the same treatment, offering spectacle-free vision in daily life in most of the treated patients. Further investigation is necessary to evaluate the overall benefit of this procedure.

Predictability of ocular spherical aberration after cataract surgery determined using preoperative corneal spherical aberration

PURPOSE

To evaluate the predictability of total postoperative spherical aberration after aspheric intraocular lens (IOL) implantation using preoperative corneal spherical aberration.

SETTING

Keio University Hospital, Tokyo, Japan.

METHODS

Corneal and ocular higher-order aberrations (HOAs) were analyzed preoperatively and postoperatively in eyes having cataract extraction with aspheric IOL implantation. The predicted postoperative total spherical aberration Z(4,0) was calculated by adding the preoperative corneal spherical aberration and the labeled spherical aberration of the IOL. The prediction error of the postoperative total spherical aberration was calculated by subtracting the predicted postoperative total spherical aberration from the postoperative total spherical aberration. Surgically induced corneal spherical aberration was calculated by subtracting the postoperative from the preoperative corneal spherical aberration.

RESULTS

There were no statistically significant differences between preoperative and postoperative corneal spherical aberration, 3rd-order aberration, or HOAs. The prediction error of the postoperative total spherical aberration was within +/-0.05 microm in 9 (24.3%) of the 37 eyes evaluated and within +/-0.10 microm in 18 eyes (48.6%). Statistically significantly correlations were found between the surgically induced corneal spherical aberration and prediction error of postoperative total spherical aberration, the preoperative corneal spherical aberration and surgically induced corneal spherical aberration, and the preoperative corneal spherical aberration and prediction error of postoperative total spherical aberration.

CONCLUSIONS

Predictability of postoperative ocular spherical aberration after cataract surgery with aspheric IOL implantation was insufficient because of the surgically induced corneal spherical aberration. Considering surgically induced corneal spherical aberration could improve the predictability of postoperative ocular spherical aberration.