Functional Classification of Intraocular Lenses Based on Defocus Curves: A Scoping Review and Cluster Analysis.

PURPOSE: To explore a potential functional classification of intraocular lenses (IOLs) based on monocular visual acuity defocus curves (VADCs) as a primary end-point. METHODS: A systematic literature search was conducted using PubMed. Two independent reviewers screened the literature for inclusion and data extraction. Inclusion criteria were full-text primary clinical studies of IOLs, published in English from 2010 onward, involving patients undergoing cataract or refractive lens exchange. A cluster analysis was conducted to explore similarities in the range of field (RoF) and increase of visual acuity from intermediate to near (ΔVA). RESULTS: A total of 107 studies were ultimately included from the 436 identified in the systematic search, with an additional 5 studies added through the snowballing technique search. The cluster analysis was conducted using 69 reports that included monocular VADCs. Two main categories were identified based on the achieved RoF for 0.2 and 0.3 logMAR: full (FRoF) and partial (PRoF) RoF IOLs. Three subcategories were identified for FRoF depending on ΔVA: continuous (FRoF-C), smooth (FRoF-Sm), and steep (FRoF-St). On the other hand, PRoF IOLs shared the characteristic of monotonous decrease in visual acuity and were subclassified into two subcategories depending on the achieved RoF: narrowed (PRoF-N) and extended (PRoF-Ex). An additional subcategory was added to PRoF, enhanced (PRoF-En), for 7 reports alternating between PRoF-N and PRoF-Ex depending on the use of 0.2 or 0.3 logMAR as a cut-off for calculating the RoF. CONCLUSIONS: IOLs can be functionally classified into six types depending on the RoF and shape of the monocular VADC. [J Refract Surg. 2024;40(2):e108-e116.].

Screening of positive dysphotopsia before multifocal intraocular lens implantation.

PURPOSE: To assess the photic phenomena (PP) and positive dysphotopsia in candidates for presbyopia or cataract surgery and to evaluate their relationship with cataract grading systems. DESIGN: Retrospective observational. METHODS: Monocular data for 82 subjects measured during the preoperative screening were retrospectively retrieved from our database. The evaluated variables consisted of two methods for PP measurement: light distortion index (LDI) and parameters obtained from a simulator, both of which were combined with subjective bother related to PP. The cutoff for LDI that better predicted patients passing from slightly to moderately bothersome was estimated. The relationships between LDI and the following objective cataract grading methods were also assessed: objective scatter index (OSI), dysfunctional lens index (DLI), and Pentacam Nucleus Staging (PNS). RESULTS: LDI was the best method for measuring PP, which showed a significant correlation with the bothersome question (rho = 0.34, P = 0.002) and also with OSI (rho = 0.67, P < 0.0005), DLI (rho = -0.29, P = 0.007), and PNS (rho = 0.48, P < 0.0005). The number/percentage of patients who found it bothersome was as follows: "Not at all" (18/22%), "Slightly" (41/50%), "Moderately" (15/18.3%), and "Very" (8/9.7%). The cutoff value that predicted the transition from slightly to moderately bothersome was ≥15.20% according to LDI, which could be estimated with the following values for grading: ≥2.8 for OSI, ≤7.6 for DLI, and ≥2 for PNS. CONCLUSIONS: Patients reporting moderately or higher bothersome levels in the preoperative period and with LDI <15.20%, <2.8 for OSI, >7.6 for DLI, and <2 for PNS might deserve special attention in the multifocal intraocular lens selection.

Simulations of Multifocal Vision in Patients With Previous Monofocal Intraocular Lens Implantation.

PURPOSE: To evaluate the effectiveness and patient acceptance of multifocal vision simulation in patients with previous monofocal intraocular lens (IOL) implantation, and to explore their willingness-to-pay (WTP) and willingness-to-accept (WTA) based on the perceived advantages and disadvantages of multifocal vision. METHODS: Seventeen patients with previous monofocal IOL implantation participated in this cross-sectional study. The SimVis Gekko device (2EyesVision SL) was used to simulate monofocal (Evaluation B) and multifocal (Evaluation C) visual experiences, compared to their existing vision (Evaluation A). Visual acuity at three distances and defocus curves were measured. Patients responded to inquiries about visual quality in each evaluation, bothersomeness of photic phenomena, probability to select the visual experience, and the monetary value they associated with enhanced WTP or diminished WTA visual quality. RESULTS: The simulations underestimated the visual acuity reported for the IOL in existing literature by one or two lines, depending on the testing distance. This underestimation was more pronounced in defocus curves. However, 70.6% of patients were likely or very likely to opt for multifocal vision, indicating they perceived the benefits of multifocality. The WTP for multifocal vision was twice that of monofocal vision, and the WTP/WTA ratio exceeded 1, suggesting the perceived vision benefits outweighed potential drawbacks. CONCLUSIONS: Despite underestimating the expected postoperative visual performance, the multifocal simulation enabled patients to perceive the benefits of multifocal vision to some extent. This system could be beneficial in avoiding potential postoperative complaints, but the possible rise in false-positive results should be considered and evaluated in future research. [J Refract Surg. 2023;39(12):831-839.].

Descemet membrane endothelial keratoplasty combined with presbyopia-correcting and toric intraocular lenses - a narrative review.

Fuchs endothelial corneal dystrophy (FECD) is the leading indication for EK and may coexist with cataract and presbyopia. Notably, the outcomes of phacoemulsification in FECD patients are not as favorable as those in eyes without this condition. Historically, only monofocal intraocular lenses (IOLs) were recommended for these patients. However, recent reports have described the implantation of Premium-IOLs (such as Multifocal IOLs, Enhanced Depth of Focus IOLs, and Toric IOLs) in FECD eyes undergoing cataract surgery and Descemet membrane endothelial keratoplasty (DMEK). While the results are encouraging, they are not as optimal as those from unoperated eyes, especially when comparing simultaneous procedures to sequential ones. It's advised to perform the DMEK first to improve the accuracy of IOL calculations. Still, even successfully operated eyes may experience secondary graft failure or graft rejection after DMEK. The success rate of a secondary DMEK is typically lower than that of the initial procedure. Furthermore, if the postoperative thickness after DMEK is less than anticipated, laser enhancements might not be an option. There's a pressing need for more controlled and randomized clinical trials to ascertain the safety and effectiveness of Premium-IOLs for FECD eyes. This narrative review aims to collate evidence on the use of Premium IOL technologies in eyes receiving EK and to underscore key points for surgeons performing EK combined with cataract surgery.

Refraction and defocus curves in eyes with monofocal and multifocal intraocular lenses

Several clinical techniques have been described to evaluate visual performance and optical quality with intraocular lenses (IOL). However, subjective refraction remains one of the most important methods for assessing post-surgery results, taking decisions about retreatments, advanced spectacle prescription and the refinement of the constant for the formula used in the IOL power calculation. Beyond clinical refraction, defocus curve measurement has been described as a complementary tool for assessing visual performance and taking clinical decisions. However, to date, there are no clinical guidelines or evidence-based protocols published in the scientific literature recommended for pseudophakic patients implanted with either monofocal or multifocal IOLs. This narrative review highlights the importance of clinical refraction in pseudophakic eyes, its utility in the decision of different types of IOL implantation, and describes a clinical refraction protocol for eyes implanted with monofocal and multifocal IOLs. (AU)

One-year follow-up of a multifocal intraocular lens with optimized elevated phase shift.

PURPOSE: To evaluate the standard outcomes of a multifocal intraocular lens (mIOL) with optimized elevated phase shift (EPS). SETTING: Qvision, Ophthalmology Department, VITHAS Almería, Spain. DESIGN: Retrospective observational. METHODS: 41 patients, consecutively operated on cataracts or refractive lens exchange with the implantation of the Liberty 640PM (EPS 2.0) and followed during 12 months, were included in the analysis. Retrieved variables were visual acuities at far, intermediate, and near distances; defocus curves (VADC); and prediction error of 4 formulas optimized for IOLMaster 500 and Pentacam AXL Wave. Patient-reported outcomes were also obtained for assessing spectacle independence, satisfaction, bothersome to dysphotopsia, difficulties in daily life tasks, and decision to be operated with the same mIOL. RESULTS: The median monocular efficacy with best distance correction was 0, 0.1, and 0.1 logMAR at far, intermediate, and near distances, respectively, with patients achieving binocularly a median of 0 logMAR at the 3 distances. VADC showed a depth of field of 3 diopters (D) above 0.2 logMAR with a median increase of 0.07 logMAR from -1.5 to -2.5 D. Complete spectacle independence was achieved at far distance, whereas 97.6% and 85.4% was achieved at intermediate and near distances, respectively. 7.3% of patients were bothered by dysphotopsia, and 92.6% of patients were likely to be operated again. CONCLUSIONS: EPS 2.0 restored patients' vision in the full range of the depth of field with a nearly monotone decrease of visual performance from far to near, achieving high rates of spectacle independence at all distances and with low positive dysphotopsia rates ( ClinicalTrials.gov Identifier: NCT05735990).

Efficacy of Presbyopia-Correcting Contact Lenses: A Systematic Review.

PURPOSE: To analyze critically the clinical trials on presbyopia correction with contact lenses (CLs) to investigate the quality of the research performed. METHODS: A search was performed in PubMed database on clinical trials evaluating the efficacy of the presbyopia correction with different CLs, including multifocal or simultaneous vision contact lenses (MCLs). After a comprehensive analysis of the relevant publications found, quality assessment of such publications was performed by means of Critical Appraisal Skills Programme checklist tool according to the five types of evaluations: MCL versus spectacles, MCL versus pinhole CLs, MCL versus monovision, comparison between MCL designs, and MCL versus extended depth of focus CLs. RESULTS: A total of 16 clinical trials were selected for evaluation. All evaluated studies addressed a clearly focused research question and were randomized, with a crossover design in most of the cases. Blinding was not possible in all cases due to the physical appearance of some of the CLs evaluated (pinhole or hybrid designs). Most of studies analyzed reported outcomes with complete data, providing the statistical tests used and the P -values, but some of the authors did not provide the statistical power associated to the sample size evaluated. The small sample size in some trials as well as the scarce information about the effect of addition on visual performance was the main limitations found in the peer-reviewed literature revised. CONCLUSIONS: There is a high-quality scientific evidence supporting the use of presbyopia-correcting CLs, with several randomized controlled clinical trials conducted to this date.

Managing low corneal astigmatism in patients with presbyopia correcting intraocular lenses: a narrative review.

Cataract surgery has become a refractive procedure in which emmetropia is the goal, with the implantation of extended depth-of-focus or multifocal intraocular lenses (IOLs) being the commonly selected option to restore vision beyond the far distance. The selection criteria for implanting these lenses can differ from those for monofocal IOLs and even between technologies, as eye characteristics can affect postoperative visual performance. Corneal astigmatism is an eye characteristic that can affect visual performance differently, depending on the implanted IOL. The magnitude of corneal astigmatism, the tolerance of the IOL to this astigmatism, economic aspects, comorbidities, and the efficacy of astigmatism treatment are factors that can make surgeons' doubt as to what astigmatism treatment should be applied to each patient. This review aims to summarize the current evidence related to low astigmatism tolerance in presbyopia-correcting lenses, the efficacy achieved through corneal incisions, and their comparison with the implantation of toric IOLs.

Agreement between Two Devices for Measuring Pupil Diameter in Patients Implanted with Multifocal Intraocular Lenses.

The purpose of this study was to evaluate the agreement between three methods for measuring pupil size in patients implanted with multifocal intraocular lenses (MIOLs): Keratograph 5M (K5M), Pentacam AXL Wave (PW), and a simple hand ruler. Sixty-nine subjects implanted with MIOLs and measured at the three-month follow-up visit were included in this retrospective analysis. K5M and PW were used to measure the photopic (PP) and mesopic (MP) pupil sizes, and a hand ruler was used to measure the pupil under environmental light conditions (135 lux). The Bland-Altman method with its limits (LoAs) was used to assess the agreement. The median PP was 2.8, 2.95, and 3 mm for K5M, PW, and the ruler, respectively (p < 0.05). Differences in PP were statistically significant for all paired comparisons (p < 0.0005) except between PW and the ruler (p = 0.44). The LoAs for the difference in PP between K5M and PW was 0.63 mm. The mean difference for MP between K5M and PW was 0.04 mm (p = 0.34) with LoAs of 0.72 mm. MP measured with K5M and PW could be considered interchangeable, although a correction of -0.3 mm (IC95%: -0.23 to -0.39) should be applied to PP measured with PW to attain the K5M mean.

Effectiveness of SMILE Combined with Micro-Monovision in Presbyopic Patients: A Pilot Study.

Binocular summation along all defocus range after a micro-monovision procedure has scarcely been studied. The aim of this pilot study was to evaluate the efficacy of SMILE combined with different levels of micro-monovision in presbyopic patients and to assess the binocular summation effect on contrast sensitivity defocus curves (CSDC) at the 6-month follow-up. Efficacy was assessed on the basis of visual acuity (VA) and stereopsis at far, intermediate, and near distances. Patient-reported outcomes (PROs) and binocular CSDC were also evaluated. Six patients completed the study with a programmed median anisometropia of 0.81 Diopter. The median binocular uncorrected VA was better than 0 logMAR at the three evaluated distances, and stereopsis was not impaired in any patient, achieving a median of ≤119 arcsec at any distance. CSDC increased binocularly after surgery, significantly in the range of -2 to -3 D (p < 0.05). No clinically relevant changes were observed in PROs compared with the preoperative period, and all patients achieved spectacle independence at intermediate/near distance and were likely or very likely to undergo the same surgery. In conclusion, micro-monovision with SMILE could be an effective procedure, with results that might be comparable to other laser correction techniques specifically designed for presbyopia correction.

Positioning of enhanced monofocal intraocular lenses between conventional monofocal and extended depth of focus lenses: a scoping review.

BACKGROUND: New intraocular lenses (IOLs) have emerged since the originally coined monofocal and multifocal IOLs. The extended depth of focus (EDoF) and enhanced monofocal IOLs (mono-EDoF) that have appeared in the last decade have caused some confusion in their classification. The aim of this review was to summarize the outcomes provided by mono-EDOF IOLs and to determine which of the endpoints, described by the American National Standard (ANSI) for EDoF IOLs, are fulfilled. METHODS: The MEDLINE, EMBASE, and WEB OF SCIENCE databases were searched. Two independent reviewers screened the studies for inclusion and data extraction. The search strategy was limited to studies published between 2020 and 2022, but not by language. The results are presented as a narrative summary accompanied by tables, in alignment with the objectives of this scoping review. Compliance with the endpoints for clinical outcomes described in the American National Standard Z80.35-2018 (ANSI) for EDoF lenses was checked and additional endpoints were defined. RESULTS: Two systematic reviews, 13 laboratory, 21 clinical, and two mixed studies were included. Tecnis Eyhance was the mono-EDOF with the highest volume of evidence to date. Although laboratory studies included other IOLs, clinical evidence for them is still scarce, with only one study of IsoPure compared to a standard monofocal IOL. Evidence in comparison to EDoF lenses is also scarce, even for Tecnis Eyhance, with only three studies including this lens in comparison to an EDoF lens. After evaluation of the ANSI criteria, agreement was found in the failure for the increase in depth of field equal to or greater than 0.5 D for a visual acuity (VA) level of 0.2 logMAR and none of the studies supported that the median monocular VA at intermediate distance was at least 0.2 logMAR. CONCLUSIONS: Additional clinical evidence is required for other mono-EDOF IOLs beyond Tecnis Eyhance. Until the arrival of a standard classification, mono-EDOF should be better still classified as monofocal because the ANSI standards were not fully met.

Influence of a multifocal intraocular lens centration and eye angles on light distortion and ocular scatter index.

PURPOSE: To assess how eye axes and multifocal intraocular lens (MIOL) centration may impact the light distortion index (LDI) and ocular scatter index (OSI). METHODS: Fifty-eight subjects implanted with the trifocal MIOL Q-Flex M 640PM or Liberty 677MY (Medicontur) were included in this retrospective analysis. The following variables were collected with the Pentacam Wave (Oculus) considering the vertex normal as the coordinates center: chord-mu to the center of the pupil, chord-alpha to the geometrical center of the cornea, and chord-MIOL to the center of the diffractive ring. These measurements were correlated with OSI (HD Analyzer, Visiometrics) and LDI (light distortion analyzer, CEORLab). RESULTS: Chord-MIOL centroid was 0.12 mm at 62°, chord-mu was 0.09 mm at 174°, and chord-alpha was 0.38 mm at 188°. A relationship was found between OSI and LDI, rho = 0.58, p < 0.0005). No relationships were found between chord-mu or chord-alpha and the LDI or OSI, neither for the total magnitude, nor the decomposition in orthogonal components (p > 0.05). The LDI was significantly correlated with the temporal centration of the MIOL versus the vertex normal (rho = 0.32, p = 0.02). CONCLUSIONS: As opposed to what has been previously described, the temporal centration of the MIOL was related to a decrease in the LDI. Future studies with extreme values of the included variables are required to establish cut-offs for considering these variables as exclusion criteria in the implantation of a MIOL.

Refraction and defocus curves in eyes with monofocal and multifocal intraocular lenses.

Several clinical techniques have been described to evaluate visual performance and optical quality with intraocular lenses (IOL). However, subjective refraction remains one of the most important methods for assessing post-surgery results, taking decisions about retreatments, advanced spectacle prescription and the refinement of the constant for the formula used in the IOL power calculation. Beyond clinical refraction, defocus curve measurement has been described as a complementary tool for assessing visual performance and taking clinical decisions. However, to date, there are no clinical guidelines or evidence-based protocols published in the scientific literature recommended for pseudophakic patients implanted with either monofocal or multifocal IOLs. This narrative review highlights the importance of clinical refraction in pseudophakic eyes, its utility in the decision of different types of IOL implantation, and describes a clinical refraction protocol for eyes implanted with monofocal and multifocal IOLs.

Objective cataract grading methods and expected contrast sensitivity reestablishment with multifocal intraocular lenses.

PURPOSE: To determine the cut-off points for age and metrics provided by cataract grading objective systems for which a reestablishment in contrast sensitivity (CS) is expected after multifocal intraocular lens (MIOL) implantation. METHODS: One hundred seven subjects were included in this retrospective analysis carried out during the screening for presbyopia and cataract surgery. Monocular distance corrected contrast sensitivity defocus curve (CSDC) and visual acuity were measured, and crystalline lens sclerosis was graded with three objective metrics: Ocular Scatter Index (OSI), Dysfunctional Lens Index (DLI) and Pentacam Nucleus Staging (PNS). A CS value of 0.8 logCS at far distance, following published literature on this matter, was selected to compute the cut-off that maximized the detection of eyes exceeding this value at the preoperative screening, either for age or objective metrics. RESULTS: The CDCS showed a stronger correlation than CDVA with objective grading methods, whereas all objective metrics were significantly correlated between them (p < 0.05). The cut-offs for age, OSI, DLI and PNS were ≤ 62, ≤ 1.25, ≥ 7.67 and ≤ 1, respectively. The OSI provided the highest area under the receiver operating characteristic curve (0.85) followed by the age (0.84), DLI (0.74) and PNS (0.63). CONCLUSIONS: Surgeons conducting clear lens exchange should communicate the possible distance CS loss after surgery with MIOL implantation according to the previous described cut-offs points. Age in combination with any cataract grading objective system is recommended to detect possible inconsistencies.

Comitant strabismus etiology: extraocular muscle integrity and central nervous system involvement-a narrative review.

Strabismus is not a condition in itself but the consequence of an underlying problem. Eye misalignment can be caused by disease, injury, and/or abnormalities in any of the structures and processes involved in visual perception and oculomotor control, from the extraocular muscles and their innervations to the oculomotor and visual processing areas in the brain. A small percentage of all strabismus cases are the consequence of well-described genetic syndromes, acquired insult, or disease affecting the extraocular muscles (EOMs) or their innervations. We will refer to them as strabismus of peripheral origin since their etiology lies in the peripheral nervous system. However, in most strabismus cases, that is comitant, non-restrictive, non-paralytic strabismus, the EOMs and their innervations function properly. These cases are not related to specific syndromes and their precise causes remain poorly understood. They are generally believed to be caused by deficits in the central neural pathways involved in visual perception and oculomotor control. Therefore, we will refer to them as central strabismus. The goal of this narrative review is to discuss the possible causes behind this particular type of eye misalignment and to raise awareness among eyecare professionals about the important role the central nervous system plays in strabismus etiology, and the subsequent implications regarding its treatment. A non-systematic search was conducted using PubMed, Medline, Cochrane, and Google Scholar databases with the keywords "origins," "causes," and "etiology" combined with "strabismus." A snowball approach was also used to find relevant references. In the following article, we will first describe EOM integrity in central strabismus; next, we will address numerous reasons that support the idea of central nervous system (CNS) involvement in the origin of the deviation, followed by listing several possible central causes of the ocular misalignment. Finally, we will discuss the implications CNS etiology has on strabismus treatment.

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.

Recommendations for Writing Clinical Research Manuscripts: From Monofocal to Multifocal Intraocular Lenses.

Writing a manuscript is not an easy task, and publishing in peer-reviewed journals might prove difficult if the methodology is not appropriately described and results are not clearly presented [...].