Spherical aberration for expanding depth of focus

BCLA CLEAR presbyopia: Mechanism and optics

With over a billion adults worldwide currently affected, presbyopia remains a ubiquitous, global problem. Despite over a century of study, the precise mechanism of ocular accommodation and presbyopia progression remains a topic of debate. Accordingly, this narrative review outlines the lenticular and extralenticular components of accommodation together with the impact of age on the accommodative apparatus, neural control of accommodation, models of accommodation, the impact of presbyopia on retinal image quality, and both historic and contemporary theories of presbyopia.

Impact of Aspheric Monofocal Intraocular Lens Implantation on Uncorrected Intermediate Visual Acuity: a Combined Analysis

Purpose

To evaluate binocular intermediate visual acuity (IVA), depth of focus, and other visual outcomes achieved with a monofocal aspheric intraocular lens (IOL) using pooled data from 2 randomized, double-masked, controlled trials.

Patients and Methods

The studies conducted at 32 sites included patients aged ≥22 years with bilateral cataracts, preoperative corneal astigmatism 1.0 D, and lens power 18.0-25.0 D. Patients received bilateral AcrySof IQ IOLs (SN60WF). Primary endpoint data were collected at month 6. Binocular uncorrected and corrected distance visual acuity (UDVA and CDVA) at 4 m, binocular uncorrected and corrected IVA (UIVA and DCIVA) at 66 cm, manifest refraction spherical equivalent (MRSE), and binocular defocus curve at 4 m were assessed under photopic conditions. Validated questionnaires were used to assess spectacle use and quality of vision.

Results

Of 233 patients who received SN60WF, 228 had visual acuity data at 6 months. Under photopic conditions, 51% of the eyes had pupils >4 mm, 40% had pupils 3-4 mm, and 9% had pupils <3 mm. Mean ± SD UDVA and CDVA were -0.019 ± 0.110 and -0.088 ± 0.082 logMAR, respectively. Mean ± SD UIVA and DCIVA were 0.125 ± 0.145 and 0.196 ± 0.139 logMAR, respectively. UIVA and DCIVA of 20/32 or better were achieved by 83% (188/228) and 71% (162/228) of patients, respectively. Mean ± SD MRSE was -0.007 ± 0.404 D for the first eye and 0.036 ± 0.371 for the second eye. The defocus curve demonstrated binocular vision of 0.24 logMAR or better from +1.2 to -1.5 D. Spectacle independence for distance and intermediate vision was reported by 86% and 41% of the patients, respectively. Based on questionnaires, 61%, 79%, and 65% of the patients did not experience starbursts, halos, or glare.

Conclusion

A monofocal aspheric IOL (SN60WF) assessed in a large, pooled study provided excellent distance vision and clinically functional intermediate vision.

Light adjustable intraocular lenses in cataract surgery: considerations

PURPOSE OF REVIEW

Light adjustable intraocular lens (LAL) is a promising concept in cataract surgery. This review explores considerations for the use of LALs.

RECENT FINDINGS

Through updates, the safety of LALs and light delivery devices have been enhanced, enabling more efficient treatment with lower ultraviolet (UV) energy. Preoperative topography and aberration are essential for understanding indications for LALs. Furthermore, when determining intraocular lens power, it is crucial to factor in potential postoperative myopia or hyperopic adjustments. This is achieved by establishing a proper postimplantation refractive target and considering potential wavefront changes. Postoperative adjustments for defocus and astigmatism have demonstrated excellent outcomes. Monovision strategy by adjustable blended vision of LALs revealed distance vision of 20/20 along with near vision of J2 in 96% of patients. However, the results of clinical studies on postrefractive cataract surgery showed contrasting outcomes at distance, indicating the need for further research results regarding its effectiveness. A new postoperative workflow needs to be designed to enable a systematic follow-up process.

SUMMARY

LALs are safe and demonstrate promising refractive outcomes. To achieve appropriate results, understanding the changes in optical characteristics associated with adjustment and constructing a new postoperative workflow are necessary.

Effect of spherical aberration on visual acuity and depth of focus in pseudophakic eyes

PURPOSE

To assess the performance of 4 intraocular lenses (IOLs) in various spherical aberration (SA) conditions, using the VAO adaptive optics simulator.

SETTING

Cullen Eye Institute, Baylor College of Medicine, Houston, Texas.

DESIGN

Prospective case series.

METHODS

Distance-corrected visual acuities at distance (CDVA), intermediate (DCIVA), and near (DCNVA) were measured in 42 dilated pseudophakic eyes at baseline and with ocular SA ranging from -0.4 to +0.4 μm in increments of 0.2 μm (6.0-mm pupil). 4 IOL types were assessed: monofocal IOLs with zero-SA, enhanced-monofocal, extended depth-of-focus (EDOF), and continuous range-of-vision.

RESULTS

Compared with SA = 0 μm, significant changes (all P < .05) were: (1) zero-SA monofocal IOLs' DCNVA at high contrast improved by 0.13 logMAR with SA = -0.4 μm and worsened by 0.09 and 0.10 logMAR with SA = +0.2 and +0.4 μm, respectively. DCNVA at low contrast worsened by 0.09 logMAR with SA = +0.4 μm; and (2) with SA = -0.4 μm, the enhanced monofocal IOL lost 0.06 logMAR of CDVA at high contrast and gained 0.09 logMAR of DCNVA at low contrast. There were no significant changes from SA = 0 μm for EDOF and continuous range-of-vision IOLs.

CONCLUSIONS

Zero-SA and EDOF IOLs were the most and least sensitive to SA modulation, respectively. In perfect optical systems where all the optical elements are aligned, induction of targeted amounts of negative SA improved the depth of focus of some IOL types. No benefit was found with positive SA.

Incidence and factors for pseudoaccommodation after monofocal lens implantation: the Monofocal Extended Range of Vision study

PURPOSE

To screen patients with a monofocal intraocular lens (IOL) for incidence of unaided 20/40 and 0.3 LogMAR for distance and near (pseudoaccommodation) and to find factors for pseudoaccommodation.

SETTINGS

University Hospitals Sussex NHS Foundation Trust, Brighton, United Kingdom.

DESIGN

Prospective study.

METHODS

This was a single-eye study ( ClinicalTrials.gov : NCT04011696). At 3 to 9 months, refraction, uncorrected and corrected distance and uncorrected near visual acuity (logMAR), spherical equivalent (SEQ), mesopic pupil size (PS), total eye spherical (Z 40 ), vertical coma (Z 3-1 ) aberrations, reading speed and smallest print size were assessed. Refractive astigmatism (RA) was classified as against-the-rule, with-the-rule, oblique and no astigmatism. Data on preoperative axial length (AL) and anterior chamber depth (ACD) were collected.

RESULTS

29 patients (9.6%, 95% CI, 6.5-13.5) had pseudoaccommodation. In cases vs controls, median SEQ, PS, total Z 40 , Z 3-1 , reading speed, smallest print size, preoperative ACD, preoperative AL were: -0.39 vs 0.0 diopters; 3.62 vs 4.10 mm; 0.01 vs 0.02 μm; 0.018 vs 0.022 μm; 106 vs 133 words per minute; 0.30 vs 0.50 logMAR; 2.94 vs 3.13 mm, 23.4 vs 23.7 mm, respectively. RA was not different between the groups. Univariate analysis revealed preoperative ACD (odds ratio [OR], 0.38, 95% CI, 0.16-0.94, P = .04), SEQ (OR, 0.61, 95% CI, 0.42-0.88, P = .01), total Z 40 (OR, 0.0003, 95% CI, 0.00-0.39, P = .03) and PS (OR, 0.39, 95% CI, 0.22-0.69, P < .041) to be significant. Whereas multivariable logistic regression identified: preoperative AL (OR, 0.62, 95% CI, 0.42-0.91, P = .02), SEQ (OR, 0.49, 95% CI, 0.31-0.78, P = .01), Z 40 (OR, 0.00, 95% CI, 0.0-0.01, P = .01) and PS (OR, 0.41, 95% CI, 0.23-0.75, P = .01) to be significant.

CONCLUSIONS

A combination of low myopic SEQ, lower Z 40 , shorter preoperative AL, and smaller PS increases the chances of pseudoaccommodation.

Retinal detachment after refractive lens exchange: A narrative review

Refractive lens exchange (RLE) allows to correct ametropias and presbyopia by replacing the crystalline lens with an extended depth of focus or multifocal intraocular lens (IOL). Retinal detachment (RD) is one of the most serious adverse events after RLE. This study aimed to review the evidence related to the risk of RD after RLE and clinical outcomes. A search using PubMed and a snowball search approach was conducted to identify articles and case reports. According to the literature, the risks of RD should be considered in patients <60 years old with axial lengths >23 mm. Only nine articles reported visual acuity (VA) after RD in RLE, and only 25% of eyes had a VA > 20/40. Considering that the decrease in VA might be uniform for all types of IOLs after RD, surgeons should focus on selecting the patient to prevent RD rather than on a particular IOL optical design based on the potential risk of DR.

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.

Comparison of corneal aberrations from anterior segment swept source OCT versus Placido-topography combined spectral domain OCT in cataract patients

BACKGROUND

To comprehensively evaluate the agreement of component corneal aberrations from the newly updated wavefront analysis software of a swept-source optical coherence tomographer (SS-OCT) and a referential Placido-topography combined OCT device in elderly cataract patients.

METHODS

Retrospective study including 103 eyes from 103 elderly patients scheduled for cataract surgery that were measured on the same day with a SS-OCT (Heidelberg Engineering, Germany) device and a Placido-topography combined OCT device (CSO, Italy). Anterior, total, and posterior corneal wavefront aberrations were evaluated for their mean differences and limits of agreement (LoA) via Bland-Altman plots. Vector analysis was additionally employed to compare corneal astigmatism measurements in dioptric vector space.

RESULTS

Mean differences of all corneal aberrometric parameters did not exceed 0.05 μm. Total corneal aberrations were not significantly different from 0 except for vertical coma (- 0.04 μm; P = 0.003), spherical aberration (- 0.01 μm, P < 0.001), and root mean square (RMS) higher-order aberration (HOA) (0.03 μm, P = 0.04). The 95% LoA for total corneal aberration parameters between both devices were - 0.46 to 0.42 μm for horizontal astigmatism, - 0.37 to 0.41 μm for oblique astigmatism, - 0.19 to 0.17 μm for oblique trefoil, - 0.33 to 0.25 μm for vertical coma, - 0.20 to 0.22 μm for horizontal coma, - 0.22 to 0.20 μm for horizontal trefoil, - 0.11 to 0.08 μm for spherical aberration, and - 0.22 to 0.28 μm for RMS HOA. Vector analysis revealed no statistically significant mean differences for anterior, total, and posterior corneal astigmatism in dioptric vector space.

CONCLUSION

In eyes undergoing cataract surgery with a regular elderly cornea, corneal wavefront analysis from the SS-OCT device showed functional equivalency to the reference device. Nevertheless, clinically relevant higher order aberration parameters should be interpreted with caution for surgical decision-making.

Visual outcomes, satisfaction, and spectacle independence with a nondiffractive extended vision intraocular lens targeted for slight monovision

PURPOSE

To evaluate vision, satisfaction, and spectacle independence of the AcrySof IQ Vivity intraocular lens when the nondominant eye is targeted for slight myopia.

SETTING

1 clinical practice in the United States.

DESIGN

Prospective unmasked nonrandomized clinical trial.

METHODS

Patients presenting for cataract surgery interested in reducing their dependence on spectacles were enrolled, with the dominant eye targeted for emmetropia and the nondominant eye targeted for slight monovision (-0.50 diopters [D]). Visual disturbances, satisfaction, and spectacle independence were evaluated. Visual acuity (VA) was tested at distance (4 m), intermediate (66 cm), and near (40 cm) at 3 months postoperatively when uncorrected, with both eyes corrected to emmetropia and with 1 eye adjusted for monovision. 2 binocular defocus curves were also collected under the latter 2 conditions.

RESULTS

Data from 31 patients were analyzed. The mean refractive spherical equivalent was 0.45 D more myopic in the nondominant eye, resulting in worse uncorrected VA at distance but better uncorrected VA at near. The binocular defocus curve with monovision showed significantly better VA from -2.0 to -3.0 D, and patients reported less need for spectacles (and better vision) at near than reported with binocular emmetropia. Glare, blurred vision, and starbursts were the most reported visual disturbances. Although not correlated with the difference in refraction, glare and blurred vision were significantly correlated with overall satisfaction.

CONCLUSIONS

Implanting this IOL with a target of slight myopia in the nondominant eye appears to be a viable way to improve near vision, although with an increased potential for visual disturbances.

Clinical outcomes of presbyopia correction with the latest techniques of presbyLASIK: a systematic review

The aim of this study was to collect the scientific literature on the correction of presbyopia with laser in situ keratomileusis (presbyLASIK) in last years and to analyse the quality of such scientific evidence using a validated methodology for conducting a systematic review. A total of 42 articles were initially identified, but after applying the selection criteria and an additional manual search a total of 23 articles were finally included: 2 non-randomized controlled clinical trials (NRCT) and 21 case series. Quality assessment of NRCTs and case series was performed with the ROBINS-I and the 20-criterion quality appraisal checklist defined by Moga et al. (IHE Publ 2012), respectively. For NRCT, the risk of bias was moderate in one study and serious in the other NRCT, being the main sources of risk, the domains related to confounding, selection of participants and measurement of outcomes. For case series studies, the main source of risk of bias was subjects not entering the study at the same point of the conditions (different levels of presbyopia). Likewise, a significant level of uncertainty was detected for the following items: consecutive recruitment of patients, blinding of outcome assessors to the intervention that the patient received, and conclusions of the study not supported by the results. Research on presbyLASIK to this date is mainly focused on case series generating a limited level of scientific evidence. The two NRCTs identified only demonstrated the potential benefit of combining the multiaspheric profile with some level of monovision in the non-dominant eye.

Analysis of Asphericity and Corneal Longitudinal Spherical Aberration of 915 Chinese Myopic Adult Eyes

Purpose

To analyze the corneal asphericity, longitudinal spherical aberration (LSA), and related factors in Chinese myopic adult eyes.

Methods

This was a retrospective study of myopic adult patients. The corneal asphericity and LSA were measured at 3.0, 4.0, 5.0, 6.0, and 7.0 mm diameter apertures using corneal tomography. Age and refractive power were recorded for correlation analysis.

Results

In total, 531 females and 384 males were included. At the above five diameter settings the corneal asphericity values (Q) of the anterior surface were -0.09±0.21, -0.14±0.16, -0.15±0.13, -0.17±0.11, and -0.20±0.11, and those of the posterior surface were 0.23±0.49, 0.06±0.29, -0.01±0.22, -0.07±0.16, and -0.08±0.15, respectively. The anterior corneal LSA values at these diameters were 0.39±0.19, 0.63±0.27, 0.97±0.36, 0.90±0.30, and 0.83±0.29 D, respectively and the whole corneal values were 0.26±0.20, 0.44±0.27, 0.70±0.36, 0.66±0.30, and 0.59±0.28 D, respectively. Corneal asphericity and peripheral LSA showed no or weak correlation with age or spherical equivalent (all r < 0.2).

Conclusion

Corneal anterior and posterior Q values in myopia patients are negatively correlated with corneal diameter. Corneal anterior and whole corneal LSA increased significantly with diameter up to 5 mm, then decreased slightly with diameter. Corneal asphericity and peripheral LSA showed very weak or no correlation with age or spherical equivalent.

Clinical Trial Registration Number

ChiCTR1800015985.

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.

Evaluating the effect of ocular aberrations on the simulated performance of a new refractive IOL design using adaptive optics

Adaptive optics (AO) visual simulators are excellent platforms for non-invasive simulation visual performance with new intraocular lens (IOL) designs, in combination with a subject own ocular aberrations and brain. We measured the through focus visual acuity in subjects through a new refractive IOL physically inserted in a cuvette and projected onto the eye's pupil, while aberrations were manipulated (corrected, or positive/negative spherical aberration added) using a deformable mirror (DM) in a custom-developed AO simulator. The IOL increased depth-of-focus (DOF) to 1.53 ± 0.21D, while maintaining high Visual Acuity (VA, -0.07 ± 0.05), averaged across subjects and conditions. Modifying the aberrations did not alter IOL performance on average.

Evaluation of Visual and Patient-Reported Outcomes, Spectacle Dependence after Bilateral Implantation with a Non-Diffractive Extended Depth of Focus Intraocular Lens Compared to Other Intraocular Lenses

Purpose: To evaluate postoperative outcomes, spectacle dependance and the occurrence of the photic phenomena in patients after cataract surgery following the implantation of a non-diffractive extended depth of focus (EDOF) intraocular lens was compared to monofocal and multifocal lenses. Methods: We enrolled patients with bilateral cataracts who wanted to reduce their dependence on glasses in the study. They were followed for 6 months. The study group in which the EDOF lens was implanted consisted of 70 eyes in 35 patients. The control groups consisted of: 52 eyes in 26 patients in whom a multifocal was implanted and 52 eyes in 26 patients with implanted monofocal lens. After a total of 2 weeks, 2 months and 6 months post-surgery the following were evaluated: uncorrected and corrected visual acuity at 4 m, 80 cm, 40 cm, manifest refraction expressed as mean refractive spherical equivalent (MRSE), contrast sensitivity, intraocular pressure. A questionnaire on independence from ocular correction, the occurrence of photic phenomena, and patient satisfaction was also completed. Results: Monocular and binocular visual acuity and MRSE 6 months after the procedure were compared between three groups. All of the main analyses, except for comparisons of uncorrected distance visual acuity (both monocular and binocular) level, were significant. Contrast sensitivity was lower among patients with multifocal lens than among patients with EDOF lens. Halo and glare after 6 months were seen more often among patients with multifocal lens than among patients with the other lens (65% of eyes with multifocal lens vs. 6% of eyes with EDOF lens and 0% of eyes with monofocal lens). Glasses were needed by 35% of patients with EDOF lens, and by 96% of patients with monofocal lens and in none of the patients with multifocal lens. Conclusions: Most patients qualify for the implantation of a non-diffractive EDOF lens. Post-operative visual acuity improves at any distance. The best monocular visual acuity for intermediate distances is provided by an EDOF lens, and for near distance by a multifocal lens. The EDOF lens definitely increases independence from spectacle correction compared to monofocal lenses; however, the greatest degree of independence from spectacles is provided by multifocal lenses. The incidence of photic phenomena is slightly higher than that of a monofocal lens, and much lower for a multifocal lens.

Repeatability and Agreement of Wavefront aberrations of Pentacam AXL Wave- a new hybrid topographer and aberrometer with ITrace in healthy eyes

PURPOSE

To assess repeatability and agreement of Pentacam AXL Wave, with iTrace aberrometer.

SETTING

Narayana Nethralaya, Bangalore, India.

DESIGN

Prospective ,cross-sectional study.

METHODS

One hundred eyes of 100 patients underwent three sets of measurements, at a single visit, using Pentacam AXL Wave (Oculus, Germany) and iTrace (Tracey Technologies, USA).Lower-order aberration (LOA), higher-order aberration (HOA), Coma and Spherical Aberrations (SA) were analyzed. Repeatability was assessed using within-subject standard deviation (Sw), test-retest variability (TRT), within-subject coefficient of variation (COV) and Intraclass Correlation Coefficient (ICC). The Bland-Altman analysis was used to assess 95% limits of agreement (LoA) and the correlation coefficient (r) to determine strength of relationship between measurements.

RESULTS

All measurements with Pentacam AXL Wave had repeatability with an ICC for total ocular aberrations ranging from 0.84 for HOAto 0.92 for LOA and corneal from 0.76 for HOA to 0.86 for LOA The Sw, TRT, COV of all aberrations were significantly lower (better) than those of iTrace (p < 0.001). The mean differences between 2 devices were insignificant for the comparison of all parameters, except for spherical aberration (0.011(0.002571 to 0.02008; P= 0.01). Both devices showed excellent corelations for ocular aberrations (tHOA (P=0.12,LoA= -0.52 to 0.025; r= 0.89); LOA (P=0.14, LoA = -2.71 to 2.61  ; r= 0.96) coma (P=0.27, LoA = -0.11 to 0.12; r= 0.89) and in SA (P=0.01,  LoA = -0.09 to 0.07;r=0.97)).

CONCLUSIONS

The repeatability estimates for wavefront aberrations using Pentacam AXL Wave were significantly better than that using iTrace. Both devices showed excellent corelations for total ocular aberrations.