Personalized aspheric intraocular lens implantation based on corneal spherical aberration: a review

IOL decentration sensitivity according to spatial frequencies

BACKGROUND/AIMS

Investigation of the decentration sensitivity of monofocal intraocular implants with a focus on different aberration corrections depending on different spatial frequencies.

METHODS

Using an optical bench, the decentration sensitivities of an intraocular lens (IOL) with a high spherical aberration correction of -0.27 µm (ZCB00 Johnson & Johnson), an IOL with an aberration correction of -0.20 µm (Primus HD OphthalmoPro) and an IOL with an aberration neutral design (CT Asphina 409MP Carl Zeiss Meditec) were evaluated for Strehl ratio values and for 25, 50 and 100 lp/mm. Two different corneas with +0.13 µm and +0.28 µm were used. The lenses were tested in the best centration and up to a decentration of 0.5 mm.

RESULTS

Decentration sensitivity affects high spatial frequencies more than lower ones. The possible decentration sensitivity is determined by the amount of spherical aberration of the cornea. The effective decentration sensitivity is determined by the extent to which these spherical aberrations are compensated. If these are not compensated, there is hardly any decentration sensitivity.

CONCLUSION

High spatial frequencies are more affected by decentration sensitivity. The decentration sensitivity of an IOL is determined by the extent to which the spherical aberration of the cornea is corrected.

Bibliometric analysis of research relating to refractive cataract surgery over a 20-year period: from 2003 to 2022

AIM

To investigate the research trend on refractive cataract surgery, compare the contributions of different countries, institutions, journals, and authors in the past 20y, and explore its potential research hotspots.

METHODS

All publications were extracted relating to refractive cataract surgery from 2003 to 2022 from Web of Science. Document types were limited to original articles and reviews, and the language was limited to English. Quantitatively and qualitatively of the publications were analyzed through Microsoft Excel and GraphPad Prism. VOSviewer and CiteSpace were used for bibliometric and visualized analysis.

RESULTS

A total of 2090 publications were enrolled. The United States contributed the most publications (434, 20.8%), followed by China (345, 16.5%) and England (163, 7.80%). Publications from the United States were cited more frequently (9552 citations) with the highest H-index of 48. China ranked second in the total number of publications, the papers were not cited that frequently (3237 citations), and the H-index ranked sixth (H-index=29). Journal of Cataract and Refractive Surgery published the most papers (333, 15.9%), and the University of London had the highest number of publications (75, 3.59%). Dick HB from Germany published the most papers. Corneal astigmatism-related research, cataract surgery method-related research, postoperative visual-quality relate to research, and postoperative complications-relate research are the hotspots in this field. The most significant limitation was that the database was updated frequently and the latest publications were not included.

CONCLUSION

The bibliometric analysis shows a brief summarization of the contribution of the authors, institutions, countries, and journals. Corneal astigmatism, cataract surgery method, postoperative visual-quality and postoperative complications related researches have become the emerging hotspots, which can give a direction in the future researches.

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.

Spherical Aberration of Cataractous Eyes and Its Relationship With Age, Ocular Biometry, and Various IOL Platforms

PURPOSE

To determine the median spherical aberration (SA) of the cataractous population, how it relates to biometry, and the theoretical effect of different intraocular lens (IOL) platforms.

METHODS

A retrospective chart review of patients undergoing cataract surgery evaluation with a high quality Pentacam (Oculus Optikgeräte GmbH) were included. Age, gender, Q-value, mean total SA, higher order aberration root mean square wavefront error, and equivalent keratometry were collected from the Holladay report and axial length and anterior chamber depth (ACD) from the IOLMaster 700 (Carl Zeiss Meditec AG).

RESULTS

Data from 1,725 eyes of 999 patients were collected. SA had a median of 0.37 µm (95% confidence interval: 0.36 to 0.38. Age (r = .136, P < .001), Q-factor (r = .743, P < .001), and higher order aberration root mean square wavefront error (r = .307, P < .001) were positively correlated with SA. Average equivalent keratometry (r = -.310, P < .001) was negatively correlated with SA. Axial length (r = -0.037, P = .120) and ACD (r = .004, P = .856) had no association with SA. Up to 1,499 (86.9%) theoretically had SA moved closer to zero with IOLs that had negative SA. Up to 102 (5.9%) had SA theoretically worsened.

CONCLUSIONS

SA is not normally distributed, suggesting that there may be no "average" SA that IOLs should aim to correct. Patients might benefit from tailoring IOL choice to individual SA. Without access to SA data, eyes with steeper average keratometry or younger patients may have less SA, which could influence IOL choice. [J Refract Surg. 2023;39(2):89-94.].

Visual function assessment of Chinese cataract patients after individual aspheric intraocular lens implantation according to preoperative cornea spherical aberration

BACKGROUND: Aspheric intraocular lens (IOLs) implantation has been widely applied in cataract surgery. However, there is no consensus on the optimal guidance for the operations in IOLs implantation. OBJECTIVE: This study evaluated the visual function of Chinese cataract patients six months after cataract surgery with two different guiding ideologies. METHODS: We evaluated 50 patients (61 eyes) with implantation of different aspheric IOLs (SN60WF IOLs, ZCB00 IOLs, PY-60AD IOLs, AO IOLs) 6 months after cataract surgery. Twenty-four patients (30 eyes) under individual implantation were ascribed to group 1 and 26 patients (31 eyes) with randomized implantation were ascribed to the control group (group 2). Postoperatively parameters included monocular best-corrected visual acuity (BCVA), contrast sensitivity (CS), total spherical aberration Z (4, 0) at 5 mm pupil size, and patient satisfaction. The quality of life after operation was assessed through the National Eye Institute Visual Function Questionnaire-25 (NEI VFQ-25). RESULTS: Six months after cataract operation, the contrast sensitivity with glare of group 1 at 2.5∘ was 0.697 ± 0.027, and 0.532 ± 0.049 in group 2. Besides, there was no significant difference at any other special frequency. The mean spherical aberration Z (4, 0) at 5 mm pupil size in group 1 was 0.015 ± 0.028 um, and in group 2 was 0.043 ± 0.109 um, with a significant difference (p< 0.01). The mean scores obtained from NEI VFQ-25 were not significantly different. CONCLUSION: It is effective to implant aspheric IOLs individually according to preoperative corneal spherical aberration. Patients obtained better contrast sensitivity with glare at 2.5∘, but there was no significant difference in BCVA, contrast sensitivity at other special frequency, and subjective visual function.

Translation model for anterior segment tomographic data to corneal spherical aberration derived from a Monte-Carlo simulation based on raytracing

BACKGROUND

Intraocular lenses with a negative aspherical design for correction of corneal spherical aberration (SA) have gained popularity in recent decades. In most cases, a 'one size fits all' concept is followed, where all eyes receive lenses with the same SA correction. The purpose of this study is to develop a strategy based on raytracing using anterior segment tomography data to extract corneal SA and to provide simple multivariable linear models for prediction of corneal SA.

METHODS

The analysis was based on a large dataset of 8737 measurements of 8737 eyes from 1 clinical centre, using the Casia2 anterior segment tomographer. An optical model based on: corneal front and back surface radius Ra and Rp, asphericities Qa and Qp, corneal thickness CCT, anterior chamber depth ACD, and pupil centre position (X-Y position: Pup_X and Pup_Y ), was defined for each measurement. Corneal SA was derived using a 6-mm aperture perpendicular to the incident ray and centred on the chief ray, and linear prediction models were derived for SA using biometric data. Cross-validation was used for model performance evaluation.

RESULTS

Using raytracing, the wavefront error within an aperture (6-mm diameter centred on the intersection of the chief ray with the cornea) was calculated and corneal SA was extracted. After identifying the relevant effect sizes (Ra, Qa, Rp Qp, ACD, Pup_X and Pup_Y ) using stepwise linear regression, linear mixed-effects models (model 1: all effect sizes, model 2: Ra, Qa, Rp and Qp, model 3: Ra and Qa) were set up on the training data in terms of a Monte-Carlo simulation. On the test data (training data), model 1 with a mean absolute/root-mean-squared prediction error of 0.0095/0.0130 (0.0095/0.0127) performed similarly to model 2 with 0.0097/0.0131 (0.0096/0.0127), and both outperformed model3 with 0.0152/0.0197 (0.0148/0.0190).

CONCLUSION

Based on the Casia2 anterior segment tomographer, corneal SA could be derived using shape data (curvature and asphericities) of both corneal surfaces (model 2). This information could easily be used for selection of the appropriate negative aspherical lens design in cataract surgery.

Visual and patient-reported factors leading to satisfaction after implantation of diffractive EDOF and trifocal intraocular lenses

PURPOSE

To evaluate factors that influence postoperative satisfaction in patients with diffractive EDOF and multifocal IOLs.

SETTING

Department of Ophthalmology, Goethe University Frankfurt, Germany.

DESIGN

Observational case study.

METHODS

Patients were evaluated after implantation of a diffractive EDOF (Symfony, J&J, USA; AT LARA, CZM, Germany) or tri-/quadrifocal (AT LISAtri, CZM, Germany; Panoptix, Alcon, USA) 3 months postoperatively. A subjective refraction was performed, uncorrected and corrected visual acuity was tested for distance (UDVA, CDVA), intermediate (at 60 & 80cm, UIVA, DCIVA), and near (at 40cm, UNVA, DCNVA). A test for contrast sensitivity was done and the patients filled out two different questionnaires on daily activities and optical phenomena. Parameters with a potential correlation to the postoperative overall satisfaction were investigated.

RESULTS

We included 94 patients with a mean age of 66 years ± 19. Patients with a better UDVA and UIVA at 60cm were more likely to choose the same IOL again. The intensity of subjective optical phenomena and the visual quality at different tasks of daily living influenced the overall satisfaction. UIVA at 80cm, UNVA, and corrected VA demonstrated no significant influence on patient satisfaction. The uncorrected visual acuity at specific distances had a direct impact on the subjective visual quality regarding the task performed at those distances.

CONCLUSION

For patients with diffractive EDOF and multifocal IOLs, the UDVA and UIVA at 60cm seem to be more important than the UNVA and UIVA at 80cm. Subjective visual quality and optical phenomena influence patient satisfaction, as well.

Normative Values of Corneal Spherical Aberration, Pupil Size, and Other Key Refractive and Topographic Parameters in a Large Cohort of Egyptian Cataract Surgery Candidates

Purpose

To determine the spherical aberration, pupil size, and other key refractive and topographic parameters in a large cohort of Egyptian cataract surgery candidates, and to investigate any existent relations between the spherical aberration and other possibly related parameters.

Methods

This is a cross-sectional, descriptive study that was conducted at Ain Shams University Hospitals, Cairo, Egypt. The study was performed on the right eyes of 1658 cataract surgery candidates. The mean corneal spherical aberration [Z4] and the pupil diameter, both photopic [P. Pupil] and mesopic [M. Pupil], were measured by the Oculus Keratograph 3, while the white-to-white corneal diameter [WTW], average keratometric readings [average K], axial length measurements [AL] and Anterior Chamber Depth [ACD] were all obtained from the IOL Master 500.

Results

The mean age was 65 ± 11.3 years. The mean value of the Z4 was +0.26 ± 0.12 μm [95% Confidence Interval “CI” (0.2570–0.2681)]. The mean values of the measured parameters were: P. Pupil 2.43 ± 0.87 mm [95% CI (2.3867–2.4700)], M. Pupil 4.61 ± 0.91 mm [95% CI (4.5683–4.6557)], WTW 11.72 ± 0.44 mm [95% CI (11.6969–11.7394)], average K 43.89 ± 1.89 D [95% CI (43.7938–43.9701)], AL 24.23 ± 2.21 mm [95% CI (24.1118–24.3166)], and ACD 3.16 ± 0.43 mm [95% CI (3.1414–3.1827)]. Weak statistically significant correlations were found between the Z4 and each of age (r = 0.049, p = 0.044), average K (r = 0.191, p < 0.001), and ACD (r = 0.122, p < 0.001). Multivariate analysis showed weaker relations between Z4 and both average K (beta coefficient= 0.091) and ACD (beta coefficient= 0.130), with an r² = 0.024.

Conclusion

This is the first normative data report of corneal spherical aberration [Z4], pupil size, and related refractive and topographic parameters in an old Egyptian population. The detected correlations have a weak clinical relevance and negate the existence of significant relations between the Z4 and the studied refractive and topographic parameters.

Misalignment and tilt effect on aspheric intraocular lens designs after a corneal refractive surgery

PURPOSE

To numerically evaluate and compare the tolerance to misalignment and tilt of aspheric intraocular lenses (IOLs) designed for three eyes: with standard cornea and with simulated corneas after myopic and hyperopic laser ablation surgery.

METHODS

Three aspheric IOLs of +20.00 diopter (D) with different spherical aberration (SA) ([Formula: see text]) values have been designed using a theoretical model eye. Drastic changes on the theoretical eye anterior corneal asphericity have been performed to simulate myopic and hyperopic refractive surgeries. The effect of IOL misalignment and tilt on the image quality has been evaluated using a commercial optical software design for the three eye models. Image quality was assessed from the modulation transfer function (MTF), root mean square (RMS) values of defocus, astigmatism, coma and spherical aberration ([Formula: see text]), and retinal images obtained from a visual simulator using an aleatory optotype of 0.00 LogMar visual acuity (VA).

RESULTS

IOL misalignment and tilt reduced MTF values in general, and increased wavefront aberrations errors. Aberration-free IOLs maintained best the MTF values when misalignments were applied, together with good on-axis optical quality. IOLs with negative SA ([Formula: see text]) correction decreased the MTF value under 0.43 for misalignments values higher than 0.50 mm with the three corneas. The effect of misalignment on RMS astigmatism and coma was correlated with the IOL SA ([Formula: see text]) and with the three corneas.

CONCLUSIONS

This theoretical study shows that the largest degradation in image quality arises for the IOL with the highest amount of spherical aberration ([Formula: see text]). Moreover, it has been found that the aspherical design has a more influential role in misalignment tolerance than in tilt tolerance.