Aspheric Intraocular Lens Research Articles

Evaluation of the Safety and Efficacy of Foldable One-Piece Intraocular Lens A1-UV for the Treatment of Cataracts: Summary of Two Clinical Trials

Objective: Through the combined analysis of data from two clinical trials, the clinical safety and efficacy of aspheric intraocular lens A1-UV implantation in cataract patients was evaluated at 1 year after surgery. Methods: A total of 239 subjects (239 eyes) were enrolled, including 117 subjects in the A1-UV group (study group), 61 subjects in the SN60WF group (control group 1) and AQBHL group (control group 2), respectively. Follow-up time points included: preoperative, intraoperative and postoperative 1~2days, 1 week, 1 month, 3 months, 6 months and 1 year. The evaluation indexes included: visual acuity, refraction, contrast sensitivity, intraocular pressure and complications. Statistical methods mainly include Wilcoxon rank-sum test, independent samples t-test, chi-square test or Fisher exact probability test. Results: The uncorrected distance visual acuity of the A1-UV group increased from logMAR 0.77±0.33 preoperatively to 0.15±0.22 at 1 year after surgery, from 0.74±0.33 in the SN60WF group to 0.18±0.23 at 1 year after surgery, and from 0.78±0.34 in the AQBHL group to 0.21±0.24 at 1 year after surgery. For best-corrected distance visual acuity, the A1-UV group increased from logMAR 0.60±0.36 preoperatively to 0.05±0.10 at 1 year after surgery, the SN60WF group increased from 0.59±0.36 preoperatively to 0.07±0.15 at 1 year after surgery, and the AQBHL group increased from 0.59±0.35 preoperatively to 0.08±0.11 at 1 year after operation. There was no significant difference between the A1-UV group and the other two groups (all P>0.05). At different follow-up times after surgery, the residual diopters was significantly lower than that before operation (all P<0.05), and the refractive error before operation was effectively corrected. The contrast sensitivity was high, and the visual function was better. The mean intraocular pressure of the subjects implanted with A1-UV was within the normal range during each follow-up period after surgery. None of the patients had serious adverse events related to intraocular lens. Conclusion: The efficacy and safety of A1-UV foldable one-piece intraocular lens in cataract treatment are good

Comparison Between Monofocal and Aspheric Monofocal Intraocular Lens With Higher Order Aspheric Optic in Pediatric Patients: Early Outcomes.

To retrospectively compare the visual acuity outcomes for far, intermediate, and near vision of an aspheric monofocal intraocular lens (IOL) with higher order aspheric optic with a monofocal IOL in pediatric patients. Thirty-eight eyes of 38 patients (mean age: 9.0 ± 2.3 years) affected by monolateral infantile cataract were evaluated 6 months after surgery performed with simultaneous IOL implantation. The Tecnis Eyhance ICB00 aspheric monofocal IOL (Johnson & Johnson Vision) was implanted in 17 eyes (Tecnis Eyhance group, mean age: 8.9 ± 2.5 years) and the Tecnis PCB00 monofocal IOL (Johnson & Johnson Vision) was implanted in 21 eyes (control group, mean age: 9.1 ± 2.2 years). Corrected visual acuity expressed in logarithm of the minimum angle of resolution (logMAR) was assessed for distance (CDVA) and, expressed in Jaeger standard, for intermediate (DCIVA) and near vision (CNVA). DCIVA was measured with distance correction and without addition. The Mann-Whitney test for two independent samples was performed, and a P value less than .05 was considered statistically significant. Six months postoperatively, mean CDVA was 0.20 ± 0.2 logMAR and mean DCIVA and CNVA were 5 ± 1 and 2 ± 1 Jaeger, respectively, in the Tecnis Eyhance group. In the control group, mean CDVA was 0.21 ± 0.2 logMAR and mean DCIVA and CNVA were 8 ± 1 and 3 ± 1 Jaeger, respectively. Only DCIVA showed a significant statistical difference between groups (P < .0001). In pediatric patients, the aspheric monofocal IOL with higher order aspheric optic seems to provide better intermediate distance visual acuity than a monofocal one, whereas no significant difference was observed for CDVA and CNVA. [J Refract Surg. 2024;40(10):e724-e727.].

A simultaneous post-LASIK sequential bilateral implantation of multifocal IOLs aimed at refraction correction. A clinical case

The article presents a clinical example of intraocular presbyopia correction in a patient who previously underwent laser vision correction by LASIK for mild myopia. Before the surgery, the distance VA mono- and binocular was 1.0, ADD for reading distance 40 cm +2.0 D, objective refraction sph +0.5 D cyl -0.25 D ax 980, left eye sph +0.75 D cyl -0.25 D ax 660. The patient was given a simultaneous bilateral refractive lens exchange with an implantation of a trifocal aspheric intraocular lens in the right eye and a trifocal toric aspheric intraocular lens in the left eye. We used the following IOL calculation formulas: ASCRS mean IOL power, Shammas formula, Barrett true K formula, Masket formula, Modified Masket formula, Haigis-L formula. 1 week postop: UDVA OU = 1.0, UNVA 40 cm = 1.0, UVA 70 cm = 0.7. The objective refraction OD was sph +0.0, D cyl -0.75 D ax 163, OS sph +0.25 D, cyl -0.0 D. The compliance with the modified algorithms of pre-and intraoperative behavior of the operating team, thorough preparation of the patient, careful calculation of the IOL allowed us to obtain the predictive refractive result with a high level of visual satisfaction and absence of undesirable postoperative phenomena. The patient underwent the examination with Salzburg reading desk before and after the surgery, to confirm the excellent functional results of the treatment. Despite the fact that simultaneous same day IOL implantation in both eyes, especially in eyes with previously operated corneas, is still disputable, the above case confirms that with modern equipment, precise multi formula calculation, and ample experience help achieve excellent functional and refractive results.

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

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

Clinical Result of One-Piece Aspheric Intraocular Lens in Mild Zonule-Weakness

Purpose: To compare the clinical outcomes of one-piece aspheric intraocular lens in the patient group with mild zonule weakness and control group.Method: Among the patients who underwent cataract surgery since 2017, 30 patients (average age of 68.26 ± 8.99 years, 14 men, 16 women) and 35 eyes were selected. Prior to surgery, information on LOCS staging, endothelial cell count, intraocular pressure, axial length, and corneal refractive index were analyzed retrospectively. The average follow-up period after surgery was 3 months. The absolute value of the difference between the spherical equivalent value and the target refractive value in the patient group and the control group at 1 month and 3 months after surgery was compared.Results: The absolute value of the difference in refractive value after 1 month in the patient group was found was 0.61 ± 0.41 Diopters and 0.51 ± 0.42 Diopters in the control group, showing no statistically significant difference (&lt;i&gt;p&lt;/i&gt; &gt; 0.05). After 3 months, the absolute value of the refractive value difference was 0.46 ± 0.27 Diopters in the patient group and 0.46 ± 0.32 Diopters in the control group, indicating no statistically significant difference (&lt;i&gt;p&lt;/i&gt; &gt; 0.05).Conclusions: The one-piece aspheric intraocular lens enVista MX60 does not show statistically significant clinical difference in the difference between the postoperative refractive value and the target refractive value in the patient group, so it may be actively considered for use in the patient with mild zonule weakness.

Aspheric hydrophobic acrylic intraocular lens outcomes in patients with additional ocular pathology

Objectives: The objective of the study was to examine the real-world visual performance, refractive outcomes, and glistening occurrence of a hydrophobic acrylic aspheric monofocal intraocular lens (IOL) in patients with ocular comorbidities. Materials and Methods: All cases of cataract surgery with the implantation of a hydrophobic acrylic aspheric monofocal IOL in a single centre between September 2020 and March 2022 were reviewed in a retrospective cohort study. Refraction (autorefract), visual acuity, peri- and post-operative complications, and the presence of posterior capsular opacification (PCO) and glistenings were recorded. Due to facility and surgeon preference, this lens was utilised predominantly for younger patients with additional ocular pathology. Results: Data regarding 15 patients (21 eyes) were collected. The mean age was 57.3 years (Range: 37–70). Eleven patients (73%) had ocular pathology in addition to cataracts. One patient was excluded due to a lack of follow-up. Post-operative refraction was available for 13 eyes (61%). The median follow-up time was five months. Corrected distance visual acuity (logarithm of the minimum angle of resolution) improved from 0.52 ± 0.54 to 0.17 ± 0.21 (mean ± standard deviation; P = 0.01); 95% confidence interval 0.08–0.26). 77% of eyes were within 0.5 D of the refractive target, and 92% were within 0.7 D. Six patients (30%) had documented PCO, with two requiring YAG capsulotomy. No patients had IOL glistenings. Conclusion: The hydrophobic aspheric monofocal IOL performs well for young patients with ocular pathology in addition to cataracts. Further, long-term follow-up will help to support its use for patients who require greater than standard longevity from an IOL.

Positive dysphotopsia after implantation of an EDOF intraocular lens

Introduction: This report describes a case of positive dysphotopsia (PD) after refractive lens exchange (RLE) with implantation of an extended depth-of-focus (EDOF) intraocular lens (IOL). Patient and Clinical Findings: A healthy 48-year-old man underwent RLE with bilateral implantation of a nontoric EDOF IOL and suffered from monocular triplopia in both eyes. The visual acuity was suboptimal with an uncorrected distance visual acuity of 20/25 in the right eye and 20/30 in the left eye. Diagnosis, Intervention and Outcomes: Slitlamp examination showed well-centered implanted IOLs, without capsular distension syndrome. Bilateral IOL exchange was performed with an aspheric monofocal IOL with a 7.0 mm optic diameter, which diminished the PD complaints. Conclusions: This case report describes disturbing PD after bilateral implantation of an EDOF IOL. Exchange of these EDOF IOLs with a larger optical diameter monofocal IOL resulted in resolution of symptoms.

Effectiveness and tolerability of the fixed combination of preservative-free drugs timolol and travoprost in glaucoma patients after cataract surgery

PURPOSE. The aim of the study was to evaluate the tolerability and effectiveness of the preservative-free combination eye drops timolol 0,5%/travoprost (Travapress Duo, ROMPHARM Company) when changing therapy in patients with initial and moderate stages of glaucoma after phacoemulsification of age-related cataract.METHODS. The study included 38 patients with disorders of the ocular surface with specific complaints, initial and moderate stages of glaucoma compensated for therapy with β-blockers and prostaglandin F2-α analogues. The patients were using monodrugs of these groups, or their fixed combinations. All patients had previously undergone phacoemulsification of age-related cataract with implantation of a monofocal aspherical intraocular lens. The main group consisted of 18 patients who underwent a change in antiglaucoma therapy to a preservative-free combination eye drops timolol 0,5%/travoprost (Travapress Duo, ROMPHARM Company) with once-per-day instillation regimen. Participants included in the control group (20 patients) remained on the treatment they had been using. All patients completed a questionnaire survey of subjective complaints and their condition, underwent assessment of the level of intraocular pressure (IOP), visual functions, parameters of the state of ocular surface (Schirmer test, epitheliopathy according to the Oxford scale), perimetric data on Humphrey 860 (Humphrey Field Analyzer III 860, Zeiss, USA), as well as morphometric parameters and indicators of retinal blood flow and optic nerve on OCT Cirrus 5000 Angioplex (Zeiss, USA) over three months of observation.RESULTS. After switching the drug all patients of the main group experienced a significant improvement in their subjective condition and gave less complaints about the ocular surface. At the same time, stable IOP compensation and no changes in retinal light sensitivity were achieved according to the results of perimetry, the morphometric data and indicators of retinal and optic nerve blood flow.CONCLUSION. The combined preservative-free eye drops timolol 0,5%/travoprost (Travapress Duo, ROMPHARM Company) is well tolerated by patients and is an effective antiglaucoma drug that allows achieving target IOP level with stabilization of morphological and functional parameters in patients with initial and moderate stages of glaucoma after previous cataract phacoemulsification.

The Novel Optical Design and Clinical Classification of a Wavefront-Shaping Presbyopia-Correcting Intraocular Lens.

To evaluate the clinical rationale of wavefront-shaping technology, describe how intraocular lenses (IOLs) using wavefront-shaping technology are differentiated from refractive or diffractive optical presbyopia-correcting designs, and describe the mode of action of this technology. Extended depth of focus (EDoF) IOLs are the latest class of presbyopia-correcting IOLs addressing the growing demand of patients for reduced spectacle dependence. These use various optical technologies, including diffractive designs (eg, TECNIS Symfony ZXR00 and AT LARA 29 MP) and non-diffractive designs such as small aperture (eg, IC-8 IOL and XtraFocus Pinhole Implant), spherical aberration (eg, MINI WELL Ready and LuxSmart), and wavefront shaping (eg, AcrySof IQ Vivity DFT015 and Clareon Vivity CNWET0). Despite some improvement in visual acuity at intermediate and near distances, these technologies can still be associated with increased rate of visual disturbances or poorer distance vision compared with monofocal IOLs. One way to overcome such limitations is using a wavefront-shaping optical principle. Clinical data show that wavefront-shaping technology results in a continuous EDoF compared with a monofocal IOL while exhibiting a minimal halo, similar to an aspheric monofocal IOL. Clinically, this translates to a lens that has proven to exceed the American National Standards Institute/American Academy of Ophthalmology criteria for an EDoF IOL. The novel wavefront-shaping optic technology allows patients to achieve a continuous range of vision from distance to functional near with low levels of visual disturbances comparable with aspheric monofocal IOLs.

Hypocalcemic cataract secondary to idiopathic hypoparathyroidism in an adolescent.

Idiopathic hypoparathyroidism is a rare endocrine disorder characterized by hypocalcemia secondary to inadequate parathyroid hormone secretion. Hypocalcemia-related cataract is most often observed in patients with postoperative hypoparathyroidism, whereas primary hypoparathyroidism-related cataract is rare and displays slow progression. Cataract usually occurs in people aged 18 to 50 years. Here, we describe a 17-year-old boy with bilateral cataract and a history of hypocalcemic tetany who was diagnosed with idiopathic hypoparathyroidism. Phacoemulsification with implantation of a monofocal aspherical intraocular lens was performed in the right eye; 6 months later, it was performed in the left eye. Elevated phosphorus and diminished calcium were observed in blood and aqueous humor. A deep anterior chamber, relatively thin central corneal thickness, large white-to-white distance, and thin lens were also observed. During follow-up, neither eye displayed intraocular lens decentration; best-corrected visual acuity was 20/20 in both eyes. These findings suggest that ophthalmologists should be vigilant when hypocalcemic tetany and cataract are present, especially in adolescents and young adults.

Laboratory Evaluation of Optical Performance of Aspheric Monofocal Intraocular Lenses With Various Anti-misalignment Designs Under the Influence of Decentration and Tilt.

To assess the effectiveness and characteristics of aspheric monofocal intraocular lenses (IOLs) with different anti-misalignment designs. Three types of anti-misalignment IOLs (with aspheric balance curve design, ZO optic design, and high-order optical aspheric surface design) and no anti-misalignment IOLs were involved. From each type of these IOLs, +8.00, +17.00, and +26.00 diopter (D) lenses were used for detection at the 3- and 4.5-mm apertures. The modulation transfer function (MTF) and 50% of the maximum value of the MTF (MTF50) were measured while IOLs were centered, decentered by 0.3, 0.5, and 0.7 mm, and tilted by 3, 5, and 7 degrees. Within the average clinical range of IOL malpositions (0.3-mm decentration or 3.00-D tilt), the anti-misalignment design slightly reduced the negative effect of decentration and tilt (P = .1845 and .6495, t test) on the optical performance of IOLs. Beyond the average range, the anti-misalignment design narrowed the reductions of MTF50 from 23.18% to 8.60% for decentration and from 40.31% to 27.96% for tilt (P = .0010, two-factor analysis of variance). The optical performance varied in anti-misalignment IOLs with different diopters, types, and degrees of malpositions at different aperture sizes. In both photopic and mesopic conditions and all probable misalignments, from the perspective of MTF50, better sharpness generally may be achieved with the 8.00-D ZO optic designed lens and 17.00-D high-order optical aspheric surface designed lens. For 26.00-D IOLs with different misalignments, the ABC design was more resistant to decentrations, whereas the high-order optical aspheric surface design was more resistant to tilts. Aspheric monofocal IOLs with an anti-misalignment design can effectively resist decentration and tilt. Anti-misalignment IOLs for complicated cataract could be selected according to diopter of IOL and types and degrees of probable IOL malpositions. [J Refract Surg. 2023;39(7):446-455.].

Clinical outcomes with an aspheric monofocal and a new enhanced monofocal intraocular lens with modified optical profile

PurposeThis study aimed to evaluate and compare the clinical outcomes obtained after cataract surgery with an aspheric monofocal intraocular lens (IOL) and an enhanced IOL with a modified optical profile.MethodsRandomised clinical trial enrolling 70 patients (age, 52–87 years) undergoing cataract surgery. Two groups were created according to the type of IOL implanted: Vivinex iSert from Hoya Surgical Optics (Vivinex group, 35 patients) and Tecnis Eyhance ICB00 from Johnson & Johnson Vision (Eyhance group, 35 patients). Uncorrected (UDVA) and corrected distance visual acuity (CDVA), uncorrected (UIVA) and distance-corrected intermediate visual acuity (DCIVA), refraction, and self-perceived visual function (Catquest-9SF) were evaluated during a 3-month follow-up.ResultsNo significant differences were found between IOL groups in UDVA and CDVA (p ≥ 0.093). In contrast, monocular and binocular UIVA and DCIVA were significantly better in the Eyhance group at 1 (p ≤ 0.015) and 3 months postoperatively (p ≤ 0.002). Postoperative DCIVA 20/25 or better was obtained in 71.4% and 20.0% of patients in Eyhance and Vivinex groups, respectively. Differences in postoperative Rasch calibrated Catquest scores between Eyhance and Vivinex groups did not reach statistical significance (p ≥ 0.102). However, significant correlations were only found between the change in UIVA and Catquest scores (0.364 ≤ r ≤ 0.444, p ≤ 0.041) in the Eyhance group.ConclusionsThe modified monofocal IOL evaluated provides better intermediate visual function in comparison with a standard aspheric monofocal IOL, but the impact of this benefit on the self-perceived level of vision achieved after surgery according to the patient seemed to be limited.

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

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. This study evaluated the visual function of Chinese cataract patients six months after cataract surgery with two different guiding ideologies. 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). 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. 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.

Preconditioning of clinical data for intraocular lens formula constant optimisation using Random Forest Quantile Regression Trees

PurposeTo implement a fully data driven strategy for identifying outliers in clinical datasets used for formula constant optimisation, in order to achieve proper formula predicted refraction after cataract surgery, and to assess the capabilities of this outlier detection method. Methods2 clinical datasets (DS1/DS2: N = 888/403) of eyes treated with a monofocal aspherical intraocular lens (Hoya XY1/Johnson&Johnson Vision Z9003) containing preoperative biometric data, power of the lens implant and postoperative spherical equivalent (SEQ) were transferred to us for formula constant optimisation. Original datasets were used to generate baseline formula constants. A random forest quantile regression algorithm was set up using bootstrap resampling with replacement. Quantile regression trees were grown and the 25% and 75% quantile, and the interquartile range were extracted from SEQ and formula predicted refraction REF for the SRKT, Haigis and Castrop formulae. Fences were defined from the quantiles and data points outside the fences were marked and removed as outliers before recalculating the formula constants. ResultsNB = 1000 bootstrap samples were derived from both datasets, and random forest quantile regression trees were grown to model SEQ versus REF and to estimate the median and 25% and 75% quantiles. The fence boundaries were defined as being from 25% quantile - 1.5·IQR to 75% quantile + 1.5·IQR, with data points outside the fence being marked as outliers. In total, for DS1 and DS2, 25/27/32 and 4/5/4 data points were identified as outliers for the SRKT/Haigis/Castrop formulae respectively. The respective root mean squared formula prediction errors for the three formulae were slightly reduced from: 0.4370 dpt;0.4449 dpt/0.3625 dpt;0.4056 dpt/and 0.3376 dpt;0.3532 dpt to: 0.4271 dpt;0.4348 dpt/0.3528 dpt;0.3952 dpt/0.3277 dpt;0.3432 dpt for DS1;DS2. ConclusionWe were able to prove that with random forest quantile regression trees a fully data driven outlier identification strategy acting in the response space is achievable. In a real life scenario this strategy has to be complemented by an outlier identification method acting in the parameter space for a proper qualification of datasets prior to formula constant optimisation.

Design and Optical Analysis of a Refractive Aspheric Intraocular Lens with Extended Depth of Focus

To obtain a continuous range of clear vision for pseudophakic eyes, a design of intraocular lens (IOL) with extended depth of focus (EDoF) was proposed. The IOL was optimized with a multi-configuration approach based on a pseudophakic eye model and the optical performances of the designed IOL were analyzed. The modulation transfer function (MTF) values remain above 0.2 at 50 lp/mm for object distance ranging from 0.35 m to infinity in both photopic vision and mesopic vision over a field of 4°. The optical performances remain stable when the pupil diameter changes from 2.25 mm to 5 mm. Besides, the presented theoretical analyses show the designed IOL has good optical performances for polychromatic light and corneal asphericity. The above shows that the IOL exhibits an excellent ability for pseudophakic eyes to see the object in a continuous range of distance.

Bootstrap Outlier Identification in Clinical Datasets for Lens Power Formula Constant Optimization

PurposeBootstrapping is a modern technique widely used in statistics to evaluate the performance of model parameters. The purpose of this study was to develop a strategy to identify and eliminate outliers in a dataset used for optimizing formula constants for lens power calculation.MethodsIn a dataset with N = 888 clinical cases treated with a monofocal aspherical intraocular lens (XC1/XY1, Hoya) constants for the SRKT, Haigis and Castrop formula were optimized and the prediction error PE calculated. The PE was bootstrapped NB = 1000 times, and the mean and trimmed mean of the bootstrapped PE were derived to generate the Bootlier plot showing the probability density function of the mean minus trimmed mean. With outliers this Bootlier plot shows some multimodality, and a Bootlier Index was extracted as a measure for multimodality. Outliers were removed from the tails of the PE distribution in a stepwise fashion until the Bootlier Index fell below a threshold of 0.001.ResultsWith the entire dataset the mean/SD/median/mean absolute/root mean squared PE using the optimized formula constants were -0.0045/0.44415/0.0134/0.3406/0.4412 dpt with SRKT, 0.0065/0.3711/-0.0056/0.2830/0.3710 dpt with Haigis, and 0.0034/0.3452/0.0023/0.2683/0.3451 dpt with the Castrop formula. After identifying and removing outliers the respective metrics for the PE were -0.0036/0.4028/0.0134/0.3205/0.4026 dpt for the SRKT (13 cases removed), 0.0050/0.3375/-0.0056/0.2656/0.3373 dpt with Haigis (11 cases removed), and 0.0035/0.3168/0.0023/0.2531/0.3166 dpt with Castrop (11 cases removed). The multimodality in the Bootlier plots was reduced from 0/0.1567/0.0587/0.0258/0.0007/0 with SRKT, 0/0.0981/0.0261/0.0202/0.0003/0 with Haigis, and 0.0006/0.0006/0.0161/0.0191/0.0005/0 with Castrop for the entire dataset to values below 1e-3 for trimming both tails of the PE distribution by ⅛, ¼, ½, 1, 2.5, and 5% respectively.ConclusionWe were able to prove that bootstrapping with outlier identification based on Bootlier plots and the Bootlier Index is a powerful tool to clean a dataset of outliers for formula constant optimization.

Optical Quality Variation of Different Intraocular Lens Designs in a Model Eye: Lens Placed Correctly and in an Upside-Down Position

Introduction: Intraocular lenses (IOLs) may lose their optical quality if they are not correctly placed inside the capsular bag once implanted. One possible malpositioning of the IOL could be the implantation in an upside-down position. In this work, three aspheric IOLs with different spherical aberration (SA) have been designed and numerically tested to analyse the optical quality variation with the IOL flip, and misalignments, using a theoretical model eye. Methods: Using the commercial optical design software OSLO, the effect of decentration and tilt was evaluated by numerical ray tracing in two conditions: in their designed position and flipped with respect to the planned position (IOL is implanted upside down). The theoretical model eye used was the Atchison model eye. Seven IOL designs of +27.00 diopters were used: a lens with negative SA to correct the corneal SA, a lens to partially correct the corneal SA, and a lens to not add any SA to the cornea (aberration-free IOL). These lenses were designed with the aspherical surface located on the anterior and posterior IOL surface. A lens with no aspherical surfaces was also included. For the optical quality analysis, the modulation transfer function (MTF) was used, together with the Zernike wavefront aberration coefficients of defocus, astigmatism, and primary coma. Results: Off-centring and tilting the IOL reduced overall MTF values and increased wavefront aberration errors. With the IOL correctly positioned within the capsular bag, an aberration-free IOL is the best choice for maintaining optical quality. When the IOL is flipped inside the capsular bag, the optical quality changes, with the aberration-free IOL and the IOL without aspheric surfaces providing the worst results. With the lens in an upside-down position, an IOL design to partially correct corneal SA shows the best optical quality results in decentration and tilt, in terms of MTF and wavefront aberrations. Conclusion: The aberration-free IOL is the best choice when minimal postoperative errors of decentration or tilt are predicted. With IOL flip, the negative SA lens design is the best choice, regarding the root mean square wavefront aberrations. However, in a proper IOL implantation, the IOL designed to partially compensate the corneal SA including asphericity on its posterior surface is the better possible option, even in the presence of decentration or tilt.

Latest Development in Extended Depth-of-Focus Intraocular Lenses: An Update.

In recent years, there has been an overwhelming influx of different types of intraocular lenses (IOLs) as treatment for presbyopia. The extended depth-of-focus (EDOF) technology creates a single elongated focal point to enhance depth of focus, in contrast to the multiple foci of multifocal (MF) lenses. In this way, the EDOF lenses aim to reduce photic phenomena, glare, and halos, which have been reported in MF IOLs. A potential disadvantage of this is a blur due to decreased retinal image quality when the amount of the aberrations is increased excessively. Multifocality and EDOF characteristics are not exclusive of each other. Frequently, EDOF IOLs are combined with MF optical designs, a bifocal IOL may exhibit EDOF characteristics, likewise an aspheric monofocal IOL or a diffractive or refractive trifocal IOL. Thus, EDOF lenses are commonly subjected to confusion. A wide range of different types of EDOF lenses are available on the market to surgeons. In this practical update, we aim to clarify what is a true EDOF lens, classify the different types of the EDOF lenses based on their optical principle and review their recently reported outcomes. Comprehensive patient examination and selection, combined with knowledge of the most updated options and adequate patient counseling, can avoid dissatisfaction and yield the desired outcomes.

Comparison of postoperative satisfaction with low subscription power segmental intraocular lenses and high-order aspheric intraocular lenses

Comparison of postoperative satisfaction with low subscription power segmental intraocular lenses and high-order aspheric intraocular lenses

Evaluating intraocular lens power formula constant robustness using bootstrap algorithms.

Bootstrapping is a modern technique mostly used in statistics to evaluate the robustness of model parameters. The purpose of this study was to develop a method for evaluation of formula constant uncertainties and the effect on the prediction error (PE) in intraocular lens power calculation with theoretical-optical formulae using bootstrap techniques. In a dataset with N=888 clinical cases treated with the monofocal aspherical intraocular lens (Vivinex, Hoya) constants for the Haigis, the Castrop and the SRKT formula were optimised for the sum of squared PE using nonlinear iterative optimisation (interior point method), and the formula predicted spherical equivalent refraction (predSEQ) and the PE were derived. The PE was bootstrapped NB=1000 times and added to predSEQ, and formula constants were derived for each bootstrap. The robustness of the constants was calculated from the NB bootstrapped models, and the predSEQ was back-calculated from the NB formula constants. With bootstrapping, the 90% confidence intervals for the a0/a1/a2 constants of the Haigis formula were -0.8317 to -0.5301/0.3203 to 0.3617/0.1954 to 0.2100, for the C/H/R constants of the Castrop formula they were 0.3113 to 0.3272/0.1237 to 0.2149/0.0980 to 0.1621, and for the A constant of the SRKT formula they were 119.2320 to 119.3028. The back-calculated PE from the NB bootstrapped formula constants standard deviation for the mean/median/mean absolute/root mean squared PE were 5.677/5.735/0.401/0.318 e-3 dpt for the Haigis formula, 5.677/5.735/0.401/0.31829 e-3 dpt for the Castrop formula and 14.748/14.790/0.561/0.370 e-3 dpt for the SRKT formula. We have been able to prove with bootstrapping that nonlinear iterative formula constant optimisation techniques for the Haigis, the Castrop and the SRKT formulae yield consistent results with low uncertainties of the formula constants and low variations in the back-calculated mean, median, mean absolute and root mean squared formula prediction error.