Intraocular Lens Models Research Articles

Evaluation of Long-term Rotational Stability and Functional Performance of Two Toric Multifocal IOL Models Beyond 5 Years.

To assess visual outcomes and stability of lens alignment more than 3 years after implanting either the AT Lisa Tri Toric (Carl Zeiss Meditec) or the Acrysof IQ Restor Toric (Alcon Laboratories, Inc) intraocular lens (IOL). Patients who had received either the AT Lisa Tri Toric or the Acrysof IQ Restor Toric IOL were included in the study. The average follow-up period was 5.4 years for the AT Lisa Tri Toric group and 7.9 years for the Acrysof IQ Restor group. The examinations covered included: subjective refraction, monocular and binocular corrected and uncorrected visual acuity at far (4 m), intermediate (75 cm), and near (40 cm) distances, binocular best-corrected defocus curve analysis (4 m), contrast sensitivity evaluation, assessment of IOL axial position, and presence of positive dysphotopsia. A total of 42 eyes were evaluated. Both groups exhibited good long-term lens axial stability. The AT Lisa Tri Toric group had a mean misalignment of 4.8 ± 3.2° from the preoperatively determined axis, whereas the Acrysof IQ Restor Toric group had an average misalignment of 5.4 ± 4.5° (no statistically significant difference, P = .578). Mean achieved spherical equivalent was -0.19 ± 0.36 diopters (D) for the AT Lisa Tri Toric group and 0.15 ± 0.39 D for the Acrysof IQ Restor Toric group. In the AT Lisa Tri Toric group, 18 eyes (72%) achieved an uncorrected distance visual acuity of 0.10 logarithm of the minimum angle of resolution (20/25 Snellen) or better, compared to 15 eyes (88%) in the Acrysof IQ Restor Toric group. Overall, 21 eyes (84%) in the AT Lisa Tri Toric group and 14 eyes (83%) in the Acrysof IQ Restor Toric group achieved a postoperative spherical equivalent refraction between -0.50 and +0.50 D. Both the AT Lisa Tri Toric and the Acrysof IQ Restor Toric IOLs showed good long-term stability and functional outcomes. They proved to be effective options for restoring vision at far, intermediate, and near distances, providing a viable solution for presbyopia correction even several years after implantation. [J Refract Surg. 2024;40(11):e845-e853.].

Impact of pupil size and corneal spherical aberrations on the performance of monofocal intraocular lenses: an experimental model

In this study, an in vitro comparison of the optical performances of three models (spherical, aberration-neutral, and aberration-correcting) of monofocal intraocular lenses (IOLs) is proposed. A comprehensive model is employed, encompassing a wide range of corneal models and aperture sizes, reflecting the high variability of corneal spherical aberrations (SA) and pupil sizes in both normal and postoperative refractive corneal surgery populations. Analysis of average through-focus modulation transfer function (MTF) curves reveals significant differences in optical performance attributable to pupil size and corneal SA. These differences depend on the IOL model and affects MTFmax (representing contrast at best focus), depth of focus, refractive error tolerance, and the effective power of the lens.

Impact of the Minimization of Standard Deviation Before Zeroization of the Mean Bias on the Performance of IOL Power Formulas.

In cataract surgery, accurate intraocular lens (IOL) power calculations are crucial for optimal postoperative refractive outcomes. This study explores the impact of prioritizing the reduction of the standard deviation (SD) of prediction errors before mean prediction error (PE) adjustment on IOL calculation formula precision and accuracy. We conducted a retrospective analysis of 4885 eyes from 2611 patients, all implanted with the same IOL model, comparing four traditional IOL power calculation formulas: SRK/T, Holladay 1, Haigis, and Hoffer Q. We introduced new constants aiming to minimize the SD of PE (new_const) against traditionally optimized constants (classic_const), using a heteroscedastic statistical method for comparison. Validation of precision improvements used a secondary dataset of 262 eyes from 132 patients. We observed significant reductions in mean absolute error (MAE) across training and test sets for Hoffer Q, Holladay, and Haigis formulas, indicating accuracy enhancements. Optimized constants significantly reduced SDs for Haigis from 0.3255 to 0.3153 and for Hoffer Q from 0.3521 to 0.3387. These optimizations also increased the proportion of eyes achieving PE within ±0.25D. SRK/T showed improved SD from 0.3596 to 0.3585. However, Holladay 1 showed minimal change with no significant improvement. In the test dataset, significant reductions in SD were observed for Haigis and Hoffer Q. Prioritizing SD minimization before adjusting mean PE significantly improves the precision of selected IOL power formulas, enhancing postoperative refractive outcomes. The effectiveness varies among formulas, underscoring the need for formula-specific adjustments. The study presents a novel two-step approach for optimizing IOL power calculations.

Assessing the predictability of five intraocular lens calculation methods in eyes with prior myopic keratorefractive lenticule extraction.

To evaluate and compare the predictability of five methods of intraocular lens (IOL) calculation in eyes with prior keratorefractive lenticule extraction (KLEx) for the treatment of myopia. A retrospective case study included 100 eyes of 52 patients who underwent myopia and myopia with astigmatism treatment with small incision lenticule extraction (SMILE). Preoperative and 3-month postoperative measurements of optical biometry and corneal tomography were obtained. The spherical equivalent of the refractive change induced by surgery was converted to the corneal plane (SMILE-dif). A physically well-defined method was developed in which the same IOL model was implanted before and after SMILE. IOL power was calculated using ray-tracing (RT-Sirius), and several IOL power calculation formulas (Kane, EVO 2.0, Barrett Universal II Formula, Hoffer QST) before surgery. After surgery, IOL power was calculated with RT-Sirius, Kane using Mean Pupil Power at 5.5mm by ray tracing, EVO 2.0 Post Myopic LASIK/PRK, Barrett True K and Hoffer QST Post Myopic LASIK/PRK after surgery. The difference between the refractive error induced by the IOL before and after SMILE in the corneal plane (IOL-dif) was compared with SMILE-dif. The predicted error (PE) was calculated as the difference between SMILE-dif and IOL-dif. The PE obtained was 0.26 ± 0.55 diopters (D), 0.10 ± 0.45 D, 0.40 ± 0.37 D, -0.03 ± 0.36 D, 0.02 ± 0.51 D, with RT-Sirius, Kane, EVO 2.0, Barrett True K, and Hoffer QST respectively. PE was not statistically significantly different between Barrett True K and Hoffer QST, with differences being more homogeneous with Barrett, (variance σ2 = 0,13). The absolute EP obtained with Barrett True K achieved 84% of cases within ± 0.5 D, followed by Kane (72%), Hoffer QST (65%), EVO (61%) and RT-Sirius (59%). Barrett True K formula was the most accurate method for IOL calculation in eyes that had undergone SMILE for the correction of myopia. What is known The literature regarding IOL power calculation after SMILE is sparse, and the methods used to estimate corneal power following LASIK/PRK may not be applicable to SMILE procedures. The most common approach to investigating the predictability of IOL calculation formulas involves a theoretical model encompassing the virtual implantation of an IOL. What is new The Hoffer QST formula, Kane formula using Mean Pupil Power at 5.5mm, EVO 2.0, and Sirius' Ray Tracing software had not been previously evaluated using this approach. The Barrett True K formula was the most accurate method for IOL calculation in eyes that had undergone SMILE for myopia correction, outperforming Ray Tracing.

Comparative analysis of modulation transfer function in various intraocular lenses under normal, decentration, and tilt conditions

PurposeThis study aims to compare the modulation transfer function (MTF) of different intraocular lenses (IOLs) under normal, decentration, and tilt conditions to evaluate their optical performance. DesignExperimental setting. MethodsA total of 12 IOL models (+20 D diopter, n = 3 each) were measured for MTF using the OptiSpheric IOL system with a 3 mm aperture diameter at a water temperature of 35 °C. Measurements were made with a spatial frequency of 0 - 200 lp/mm at the normal, decentration of 0.5 mm, and tilt of 5° positions. ResultsThe MTF values were significantly different between normal and decentration conditions for XY1A (monofocal, toric) (P = 0.03), Tecnis ZCB00V (P = 0.0009), and NS-60YG (P = 0.004). Differences were significant between normal and tilt conditions for MP70 (P = 0.009), XY1 (P = 0.0005), and Clareon (P = 0.049), and were significant between decentration and tilt conditions only for LentisComfort (bifocal) (P = 0.01). With normal condition, MTF of Eyhance DIB00V (extended depth of focus) showed significant differences with 11 other IOLs (P < 0.0001), while LentisComfort exhibited differences with 10 other IOLs (P < 0.0001) except for XY1A (P = 0.0002). Similarly, with decentration condition, Eyhance DIB00V differed significantly from 11 other IOLs (P < 0.0001). With tilt condition, Eyhance DIB00V showed significant differences with 10 other IOLs (P < 0.0001) except for LentisComfort, which itself differed significantly from 10 other IOLs (P < 0.0001). ConclusionsIn the experimental settings, while specialized IOLs can address specific visual issues, monofocal IOLs remain superior in terms of overall contrast transfer quality and resolution even in the implanted IOL position is not ideal. These results provide a basis for recommending the use of monofocal IOLs in cases where the anterior chamber depth and lens position are prone to instability, such as in eyes with weakened zonules or following glaucoma filtering surgery.

Through-focus performance and off-axis effects in aspheric monofocal intraocular lenses.

This study aimed to determine the through-focus performance and the effect of misalignment on the optical quality of different aspheric monofocal intraocular lenses (IOLs). To this end, optical quality was assessed in three IOL models with different optic surfaces: standard aberration neutral model and two spherical aberration (SA) correcting, one of which utilizes higher-order aspheric terms. The optical quality was measured by means of the modulation transfer function at 3- and 4.5-mm pupils and under monochromatic and polychromatic light with different corneal SA. The optically derived range of vision and tolerance to misalignment were also tested. The study demonstrated that the type of IOL surface affects the monofocal implant's performance. Although a standard primary-SA correction may improve scotopic image quality, misalignment may diminish this advantage. The higher-order aspheric surface used to correct SA provided an improved performance against decentration and offered a higher optical quality than the aberration-neutral design when tested in a model eye. The latter, however, demonstrated a high tolerance to misalignment, offering a slight extension of the range of vision, potentially resulting from uncorrected optical aberrations.

Unintended placement of intraocular lens haptics in the sulcus and its association with posterior capsular opacification in pseudophakic post-mortem eyes

ObjectiveTo assess the prevalence of unintended placement of intraocular lens (IOL) haptics in the sulcus and its association with posterior capsular opacification (PCO). DesignCross-sectional study. Participants428 post-mortem pseudophakic human eyes. MethodsEyes were obtained from the Lions Gift of Sight and imaged in Miyake-Apple view (MAV). IOL haptic placement (bag–bag, bag–sulcus, sulcus–sulcus) was determined from the MAV images. IOL-capsular bag complexes were extracted and analyzed via Automated Detector Opacification Software to quantify PCO and Soemmering's Ring (SR). SR distribution was categorized as focal, diffuse, or none. Mean differences in PCO and SR between haptic groups were assessed via Welch's t-test. Odds ratios were used to compare the risk of SR distribution patterns between both haptic groups. Sex, clinical history (diabetes, smoking, hypertension, glaucoma, cancer, age-related macular degeneration [AMD], hypercholesterolemia, cardiovascular disease), and IOL model and specifications were collected. Results20 eyes (4.67%) had unintended sulcus placement of haptics. Mean PCO (p = 0.0367) and SR (p = 0.0414) were significantly higher in sulcus eyes. Sulcus eyes were significantly more at risk of focal SR distribution (OR 8.715; p < 0.0001) and significantly less at risk of diffuse SR distribution (OR 0.168; p = .0007). Sulcus eyes had significantly higher frequencies of glaucoma (p < 0.0001) and AMD (p = 0.0023) on clinical history. ConclusionsThis study demonstrates that unintended sulcus placement of IOL haptics may be associated with an increased risk of PCO and SR formation. This study offers clinical signs of sulcus haptic placement that may prompt physicians to seek earlier appropriate intervention.

Intraocular aphakia correction in patients with prior keratorefractive surgery: literature review. Part 1

Introduction. An increasing number of patients with a history of keratorefractive surgeries are presenting to ophthalmologists with complaints of vision loss due to cataracts. Treating this group poses surgeons with a range of unique challenges: high demands for vision quality, complexities in selecting the appropriate intraocular lens (IOL) power calculation formula and IOL model, target refraction, as well as the need to modify cataract extraction techniques and address specific postoperative considerations. Despite advancements in the development of new IOL designs and calculation formulas, clinical and functional outcomes in this group remain inferior to those in patients without prior keratorefractive procedures. A paradigm shift is emerging, advocating for a personalized approach in the diagnosis and management of cataracts in these patients. However, discussing all aspects within a single review proved impractical, leading us to divide it into two parts. The objective of the first part of this study is to assess the specific considerations for aphakia correction in patients who have undergone keratorefractive procedures, based on literature data, while taking into account the long-term complications of refractive surgery. Additionally, this part will address the fundamental principles of the design and functionality of pseudoaccommodating intraocular lenses (IOLs). Materials and methods. A selection of over 200 peer-reviewed publications from resources such as PubMed, eLibrary, CyberLeninka, Science Direct, and Google Scholar over the past 30 years was conducted. The first part of the review includes 49 publications. This work represents an analysis of contemporary literature, reflecting the impact of keratorefractive surgeries on the successful performance of phacoemulsification with IOL implantation. Results. The findings from the first part of the analysis indicate that a detailed medical history of previously performed keratorefractive corrections – specifically their type and potential long-term complications – play a significant role in determining the surgical treatment strategy. Standard examination methods do not always fully reflect the optical characteristics of the cornea in these patients. Extended preoperative assessments, including specialized techniques such as keratotopography and keratotomography, are crucial for identifying corneal irregularities and for the subsequent selection of the type of intraocular lens (IOL) for aphakia correction in patients who have undergone keratorefractive surgeries. Studies show high effectiveness not only in using monofocal lenses but also in the potential application of pseudoaccommodating IOLs, including those with extended depth of focus and multifocal lenses. The selection of optimal formulas for IOL calculation, as well as the clinical aspects influencing refraction in the postoperative period, will be addressed in the second part of the literature review. Conclusion. The increase in the number of refractive surgeries has led to a growing population of patients with cataracts following ametropia correction. This has spurred the development of new IOL variants with extended depth of focus. However, literature data on their effectiveness in patients who have undergone keratorefractive procedures remain limited. Multicenter prospective studies are needed to evaluate new IOL models and to determine the optimal surgical strategies for this category of patients.

Clinical Outcomes after Implantation of a Novel Binocular Complementary Extended Depth-of-Focus Intraocular Lens Compared to Bilateral Low Near-Add Multifocal Intraocular Lenses

Introduction: Nowadays, patients expect to be less spectacle dependent at all distances after cataract surgery. However, all intraocular lens (IOL) models that currently offer this function can also have negative visual effects. Aim of this study was therefore to compare the visual function performance of a novel and a conventional IOL solution for multifocality. Methods: Patients scheduled for bilateral cataract surgery were randomized to receive one of two different IOL combinations: either a binocular complementary extended depth-of-focus IOL set or a low near-add MIOL. Patients had visual acuity (VA) assessment at distance, intermediate, and near as well as evaluation of contrast sensitivity, halometry, and reading performance. Results: In total, 56 eyes of 28 patients were enrolled. At 6 months, there were no statistically significant differences in binocular VA between the ARTIS SYMBIOSE and the AT LARA. Contrast sensitivity, measured binocularly, at 1.5 cycles per degree under photopic conditions without glare was 1.54 logCS with the ARTIS SYMBIOSE and 1.43 logCS with the AT LARA (p = 0.046), under mesopic conditions with glare at 1.5 and 3 cycles per degree 1.31 logCS and 1.28 logCS with the ARTIS SYMBIOSE, respectively, compared to 0.58 logCS and 0.51 logCS with the AT LARA (p = 0.002; p = 0.006). Binocular halos and reading performance between both groups were similar. Conclusion: There were no significant differences between both groups in VA at different distances, reading ability, or halometry. The contrast sensitivity at low spatial frequencies was better in the ARTIS SYMBIOSE group under photopic conditions without glare as well as mesopic conditions with glare, which could potentially improve quality of vision with these IOLs, especially under mesopic conditions.

Higher phosphate concentrations as in aqueous humor of diabetic patients increase intraocular lens calcification

BackgroundClinical evidence suggests an association between phosphate concentrations in aqueous humor and the risk of intraocular lens (IOL) calcification. To test this hypothesis the influence of different phosphate concentrations on IOL calcification was evaluated in an in vitro electrophoresis model.Methods20 IOLs of two hydrophilic IOL models (CT Spheris 204, Zeiss; Lentis L-313, Oculentis) and one hydrophobic control IOL model (Clareon CNA0T0, Alcon) were exposed to physiologic and elevated phosphate concentrations, similar to diabetic aqueous humor. IOL calcification was analyzed by alizarin red staining, von Kossa staining, scanning electron microscopy, energy dispersive x-ray spectroscopy and transmission electron microscopy with electron diffraction.ResultsHigher phosphate concentrations were associated with IOL calcification. Analyses of IOL surfaces and cross-sections documented calcification in no CT Spheris and 4 Lentis IOLs following exposure to 10 mM Na2HPO4, compared with 7 and 11 positive analyses following exposure to 14 mM Na2HPO4, respectively. Furthermore, a clear association between IOL calcification and the duration of electrophoresis was demonstrated, confirming increased phosphate concentrations and duration of exposure as risk factors of IOL calcification.ConclusionsFindings suggest that higher phosphate concentrations in aqueous humor, as seen in diabetic patients, contribute to an increased IOL calcification risk, potentially explaining clinical observations showing an increased risk of IOL calcification in patients with diabetes.

Objective analysis of capsulorrhexis factors and posterior capsular opacification in 420 postmortem eyes

ObjectiveTo evaluate the capsulorrhexis structure in postmortem eyes and determine factors associated with posterior capsular opacification (PCO). DesignExperimental study. ParticipantsPostmortem pseudophakic human eyes (n = 420). MethodsPostmortem eyes were obtained and examined. Photographs were taken of the eyes in Miyake-Apple view and of the extracted lens-capsule complexes. PCO and Soemmering's ring (SR) were quantified using automated detector opacification software as factors of intensity and area. Miyake-Apple views and ImageJ were used to assess capsulorrhexis diameter, area of anterior capsule-optic overlap, length of the shortest anterior capsular leaflet, and area and angle of capsulorrhexis-optic nonoverlap. Linear regression analysis and Welch's t test were used to determine the relationship of these factors with PCO and SR. All analyses were repeated in sample groups specific to the 5 most common intraocular lens models. ResultsCapsule-optic overlap was positively correlated with PCO (P < 0.0001) and SR (P = 0.0016). Capsulorrhexis diameter was negatively correlated with PCO (P < 0.0001) and SR (P = 0.014). Leaflet length was positively correlated with PCO (P = 0.009). Area and angle of capsulorrhexis-optic nonoverlap were not correlated with PCO or SR. Slopes and coefficients of determination were relatively low for all significant results. ConclusionsThe pathogenesis of PCO development after cataract surgery is multifactorial. This study shows that with modern operating technology, capsulorrhexis factors have at best a modest influence on PCO formation. Factors such as time from surgery to death and intraoperative techniques such as laser capsule polishing, posterior capsule vacuuming, and cortical cleanup are likely to play a more significant role.

Complex optical systems for individualized correction of presbyopia

Amultitude of available intraocular lens (IOL) models enable apersonalized approach to presbyopia correction in order to meet each patient's needs. This review article discusses more complex approaches which can be useful in selected cases. The concept of reversible trifocality enables correction of presbyopia using asupplementary intraocular lens (IOL), which can be removed if necessary (e.g., intolerance to multifocal optics). The use of capsulotomy-fixated IOLs enables high precision for positioning of the lens and better stability compared to conventional capsular bag-fixated IOLs, which can be particularly advantageous in multifocal optics. The mix and match concept enables acombination of different IOLs with various optical principles to achieve the desired binocular effect. Binocular IOL systems, which consist of two complementary IOLs, can be seen as afurther development of the mix and match concept. Knowledge of the available options and their application can further improve correction of presbyopia.

Overview of intraocular lenses with optics for correcting presbyopia

In recent years intraocular lenses (IOLs) for correcting presbyopia have been significantly improved and diversified. There are currently many different IOL models based on awide variety of optical designs. The wide variety of available IOL solutions to correct presbyopia can be challenging for surgeons and patients. In everyday practice, the question is which IOL is best for which patient. This overview describes and categorizes the currently available implants. The respective optical properties are analyzed and clinical study results are discussed, in particular those evaluating visual performance and the occurrence of photic phenomena. Monofocal-plus IOLs provide improved intermediate visual acuity with optimal distant visual acuity and minimal photic phenomena. Extended depth of field (EDoF) IOLs extend the depth of field through different optical principles and provide good distant and intermediate visual acuity. Trifocal lenses enable the greatest independence from spectacles at the price of ahigher probability of dysphotopsia. The selection of the most suitable IOL for correction of presbyopia requires abalance between the patient's visual needs and possible side effects. An adequate knowledge of the currently available implants allows a patient-oriented selection of IOLs.

Comparison of keratometry and total corneal power, as measured by an SS-OCT-based optical biometer, for intraocular lens power calculation in Asian eyes.

To investigate whether standard keratometry (K) or total corneal power (TCP) leads to more accurate refractive outcomes for intraocular lens (IOL) power calculation. Public hospital. Retrospective evaluation of a diagnostic test instrument. Preoperatively, all patients underwent optical biometry with Anterion, a swept-source optical coherence tomography device providing both K and TCP. The same IOL model was implanted in all cases. The whole sample was divided into a training dataset, used to optimize the formula constants, and a testing dataset, used to investigate the spherical equivalent prediction error (SEQ-PE) of 8 IOL power formulas. Trueness, precision, and accuracy were evaluated by means of the robust 2-sample t test. Cochran Q test was performed to assess whether the percentage of eyes with an SEQ-PE within each threshold was significantly different; in such an event, the McNemar test was then applied. Both the training and testing datasets included 317 eyes. No significant differences were detected for trueness because of constant optimization. Precision and accuracy were better when K was entered, although a statistically significant difference was observed only with the EVO (precision: P = .02 and accuracy: P = .03) and Haigis ( P < .01 for both precision and accuracy) formulas. No significant differences were observed for the percentage of eyes with an absolute SEQ-PE within any threshold. With most formulas, IOL power calculation is not more accurate when TCP is used instead of K.

Visual Outcomes and Patient Satisfaction After Bilateral Refractive Lens Exchange With a Trifocal Intraocular Lens in 5,226 Patients With Presbyopia.

To assess visual and refractive outcomes and visual function after bilateral RayOne Trifocal toric and nontoric intraocular lens (IOL) (Rayner) implantation in patients with presbyopia. Charts of patients with presbyopia who underwent refractive lens exchange with bilateral implantation of the RayOne Trifocal IOL (toric and non-toric) were retrospectively reviewed. Visual and refractive outcomes were evaluated at 3 months. Patient satisfaction, spectacle independence, and visual disturbance profile were assessed by questionnaires. A total of 5,226 patients were assigned to one of two groups: 1,010 patients had toric IOL implantation (toric group) and 4,216 patients received the non-toric model (non-toric group). Mean ± standard deviation visual acuity at 3 months for the toric group was binocular uncorrected distance visual acuity (UDVA) of 0.07 ± 0.11 logMAR, monocular corrected distance visual acuity (CDVA) of 0.05 ± 0.07 logMAR, binocular uncorrected near visual acuity (UNVA) at 40 cm of 0.10 ± 0.09 logMAR, binocular uncorrected intermediate visual acuity (UIVA) at 40 cm of 0.13 ± 0.12 logMAR, postoperative spherical equivalent (SE) of -0.21 ± 0.47 diopters (D), and cylinder of -0.34 ± 0.40 D. The non-toric group had binocular UDVA of 0.04 ± 0.08 logMAR, monocular CDVA of 0.05 ± 0.07 logMAR, binocular UNVA of 0.10 ± 0.08 logMAR, binocular UIVA of 0.13 ± 0.11 logMAR, SE of -0.08 ± 0.38 D, and cylinder of -0.28 ± 0.34 D. No statistically significant differences were found in achieving spectacle independence and there were high levels of satisfaction in both groups. In this retrospective analysis with more than 5,000 patients, both the toric and non-toric RayOne Trifocal IOL models provided good visual performance at all distances, resulting in excellent levels of spectacle independence and patient satisfaction. [J Refract Surg. 2024;40(7):e468-e479.].

A New Method to Minimize the Standard Deviation and Root Mean Square of the Prediction Error of Single-Optimized IOL Power Formulas.

The purpose of this study was to develop a simplified method to approximate constants minimizing the standard deviation (SD) and the root mean square (RMS) of the prediction error in single-optimized intraocular lens (IOL) power calculation formulas. The study introduces analytical formulas to determine the optimal constant value for minimizing SD and RMS in single-optimized IOL power calculation formulas. These formulas were tested against various datasets containing biometric measurements from cataractous populations and included 10,330 eyes and 4 different IOL models. The study evaluated the effectiveness of the proposed method by comparing the outcomes with those obtained using traditional reference methods. In optimizing IOL constants, minor differences between reference and estimated A-constants were found, with the maximum deviation at -0.086 (SD, SRK/T, and Vivinex) and -0.003 (RMS, PEARL DGS, and Vivinex). The largest discrepancy for third-generation formulas was -0.027mm (SD, Haigis, and Vivinex) and 0.002mm (RMS, Hoffer Q, and PCB00/SN60WF). Maximum RMS differences were -0.021 and +0.021, both involving Hoffer Q. Post-minimization, the largest mean prediction error was 0.726 diopters (D; SD) and 0.043 D (RMS), with the highest SD and RMS after adjustments at 0.529 D and 0.875 D, respectively, indicating effective minimization strategies. The study simplifies the process of minimizing SD and RMS in single-optimized IOL power predictions, offering a valuable tool for clinicians. However, it also underscores the complexity of achieving balanced optimization and suggests the need for further research in this area. The study presents a novel, clinically practical approach for optimizing IOL power calculations.

Characterizing glare effects associated with diffractive optics in presbyopia-correcting intraocular lenses.

To objectively quantify glare of intraocular lenses (IOLs) utilizing a diffractive principle to extend visual range. To identify models with increased susceptibility to inducing glare. David J Apple Laboratory, Heidelberg, Germany. Laboratory investigation. Glare was assessed by means of straylight parameter with a standard C-Quant (Oculus GmbH) intended for 7°. In addition, two C-Quant modifications were used to test lower angles (i.e., 2.5° and 3.5°). The following IOL models were assessed: PanOptix (Alcon Inc.) and AT Lisa Tri (Zeiss Meditec), Synergy (J&J Vision), and Triumf (BVI Medical), the latter two with chromatic-aberration correction at distance. Straylight from trifocals was compared against a monofocal W-60R lens (Santen). The C-Quant test was performed through the studied IOLs via additional optical components attached to its ocular. Straylight (deg2sr-1) of the control was <1 at all tested angles, with the trifocal models showing comparable straylight at 7°. At 3.5°, Triumf's straylight increased to 15.5 ±0.6, followed by Synergy (6.2 ±1.1), PanOptix (4.1 ±0.3), and AT Lisa Tri (2.0 ±0.8). The chromatic-aberration correcting models demonstrated correspondingly high straylight (Synergy: 18.8 ±1.3; Triumf: 17.3 ±0.5) at 2.5° compared to PanOptix (4.3 ±0.4), AT Lisa Tri (2.1 ±0.1) and monofocal IOLs yielding minimal or no increase. Trifocal IOLs induced increased straylight, but it was limited to lower angles, which may cause difficulties detecting these effects using a standard clinical approach. The latest IOL designs featuring chromatic aberration correction at far-focus appear more susceptible than the established trifocals to inducing glare phenomena.

Phacoemulsification with implantation of a trifocal intraocular lens in eyes with asteroid hyalosis and synchysis scintillans

To compare the visual outcomes in both eyes of patients who undergo phacoemulsification and trifocal intraocular lens (IOL) implantation and have asteroid hyalosis (AH) or synchysis scintillans (SS) in only one eye. A retrospective comparative case series was performed. We evaluated uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), uncorrected intermediate visual acuity (UIVA), uncorrected near visual acuity (UNVA), predictability, safety, efficacy, and satisfaction after implantation of the same model of trifocal IOL in both eyes (PhysIOL FineVision Pod-F and Micro-F and Rayner RayOne Trifocal). A total of 164 eyes of 82 patients (41 females, 50%) met the inclusion criteria. There were no statistically significant differences in sphere, cylinder, spherical equivalent, UDVA, UIVA, or UNVA between the groups. Postoperative CDVA was slightly better in the control group (logMAR 0.03) than in the AH/SS group (logMAR 0.04) (P: 0.014). There were no statistically significant differences in predictability, safety index, or efficacy index between the groups. Overall subjective satisfaction was good (98.2%). Visual outcomes and satisfaction are good after implantation of trifocal IOLs in eyes with AH or SS. Therefore, trifocal IOLs should not be ruled out in these patients when no other vitreoretinal disorder is present.

Implantation of Hydrophobic Acrylic Toric Intraocular Lens with High-Water Contents Using Swept-Source Optical Coherence Tomography Biometer Integrated with a Surgical Guiding System.

To evaluate postoperative outcomes after implantation of toric intraocular lenses (IOLs) made of high-water-content hydrophobic acrylic material in Japanese patients using a swept-source optical coherence tomography (SS-OCT) biometer integrated with a surgical guiding system. In this prospective observational study, toric IOL models CNW0T3 to CNW0T9 (Alcon) were implanted in 33 eyes of 33 patients and followed-up for one month. Powers and toric models were determined using an SS-OCT biometer ARGOS® Ver 1.5 (Alcon), and the IOLs were aligned using surgical guidance. Differences between planned and actual axis positions at the end of the surgery (misalignment) and rotations from the end of surgery to one month postoperatively were measured. Additionally, postoperative uncorrected visual acuity, refraction, and residual astigmatism were evaluated. Mean and median misalignments were 2.3° (standard deviation [SD]: 1.6, 95% confidence interval [CI]: 1.7-2.9) and 2°, and those of postoperative rotation were 2.4° (SD: 2.6, 95% CI: 1.5-3.4) and 2°, respectively. Mean postoperative refraction was 0.06 D (SD: 0.62). Prediction errors within ±0.5 and ±1.0 D were 69.7% and 93.9%, respectively. Mean residual astigmatisms were 0.19 D (SD: 0.41), and mean uncorrected visual acuity was 0.00 logMAR (SD: 0.11), and 64% of the eyes scored 20/20 or better. Implantation of high-water-content hydrophobic acrylic toric IOLs using SS-OCT biometry integrated with a surgical guiding system effectively corrected corneal astigmatism with accurate IOL alignment in Japanese patients.

Accuracy comparison of tomography devices for ray tracing-based intraocular lens calculation.

To evaluate the interchangeability of different tomography devices used for ray tracing-based intraocular lens (IOL) calculation. Eye clinic, Castrop-Rauxel, Germany. Retrospective analysis. Measurements from 3 Placido-Scheimpflug devices and 3 optical coherence tomography (OCT) devices were compared in 83 and 161 other eyes after cataract surgery, respectively. 2-dimensional matrices of anterior local corneal curvature and local corneal thickness are transferred to the ray-tracing software OKULIX. Calculations are performed with the same IOL in the same position of an eye with the same axial length. Differences in spherical equivalent (SE), astigmatism, and spherical aberration are evaluated. Furthermore, the influence of the size of the matrices (optical zone) on the accuracy is quantified. For the Placido-Scheimpflug devices, the deviations from the average of three measurements taken for each eye in SE (mean ± SD) were 0.17 ± 0.24 diopters (D), -0.26 ± 0.29 D, and 0.08 ± 0.39 D ( P < .001, analysis of variance [ANOVA]), for the centroids of the astigmatic differences 0.04 D/173 degrees, 0.14 D/93 degrees, and 0.10 D/7 degrees, and for the median of the absolute values of the vector differences 0.31 D, 0.33 D, and 0.29 D. For OCT devices, the corresponding results were 0.01 ± 0.21 D, -0.03 ± 0.21 D, and 0.02 ± 0.20 D ( P = .005, ANOVA); 0.18 D/120 degrees, 0.07 D/70 degrees, and 0.22 D/4 degrees; and 0.26 D, 0.30 D, and 0.33 D. The accuracy of the calculated spherical aberrations allows for an individual selection of the best fitting IOL model in most cases. The differences are small enough to make the devices interchangeable regarding astigmatism and spherical aberration. Although there are significant differences in SE between Scheimpflug and OCT devices, the differences between OCT devices are also small enough to make them interchangeable, but the differences between Placido-Scheimpflug devices are too large to make these devices interchangeable.