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)

Desprendimiento de retina tras la cirugía de cristalino transparente con lentes intraoculares EDOF y multifocales: una revisión narrativa / Retinal detachment after refractive lens exchange with EDOF and multifocal intraocular lenses: A narrative review

La cirugía de cristalino transparente (RLE) permite corregir las ametropías y la presbicia mediante el reemplazo del cristalino por una lente intraocular (LIO), ya sea monofocal, multifocal (MIOL) o de profundidad de foco extendida (EDOF). El desprendimiento de retina (DR) es uno de los eventos adversos más graves tras la RLE. El objetivo de este estudio fue revisar la evidencia y los resultados clínicos relacionados con el riesgo de DR después de la RLE. Se realizó una búsqueda utilizando PubMed y un procedimiento de bola de nieve para identificar estudios originales y series de casos. Según la bibliografía, los pacientes < 60 años con longitudes axiales > 23 mm tienen el mayor riesgo de DR. Solo nueve artículos reportaron la agudeza visual (AV) tras el DR en RLE, y solo 25% de los ojos mostraron una AV > 20/40. Teniendo en cuenta que la disminución de la AV tras el DR se puede dar con todos los tipos de LIO independientemente de su diseño óptico, la actitud más acertada al realizar una RLE sería una cuidadosa selección del paciente, evitando aquellos ojos con factores de riesgo para DR (AU)

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

Visual and satisfaction results with implantation of the trifocal Panoptix (R) intraocular lens in cataract surgery

Purpose: To assess visual results (including the Lapid-Kushlin defocus coefficient), and satisfaction, following the implantation of PanOptix® a trifocal intraocular lens.Methods: Observational, retrospective cohort study. 130 eyes of 65 subjects with bilateral implantation were included. Binocular uncorrected visual acuities [distance (Binocular UDVA), intermediate (Binocular UIVA) and near (Binocular UNVA)] were measured. Also, the manifest refraction, binocular defocus curve and binocular contrast sensitivity were determined. The Lapid-Kushlin defocus coefficient, a new single numerical parameter based on the area under the curve of the defocus curve, was calculated. The validated Spanish CATQUEST-9SF satisfaction survey was applied.Results: Postoperative visual acuity ranges were: binocular UDVA 0.18 to 0.0 LogMAR, binocular UIVA 0.30 to 0.0 LogMAR and Binocular UNVA 0.18 to 0.0 LogMAR. The levels of contrast sensitivity both in bright light conditions (with and without glare) and low light conditions with glare, remained within the limits of normality. Under scotopic conditions without glare values below normality were found at lower spatial frequencies. The binocular defocus curve showed a plateau without a clearly evident peak. The Lapid-Kushlin defocus coefficient was 0.199. Two patients (3.1%) needed glasses after the procedure for near and intermediate vision. No patient manifested great visual difficulties or was dissatisfied with the results.Conclusions: The trifocal platform showed very good results in this series of patients. 96.9% of the patients achieved independence of the glasses and expressed a high degree of satisfaction. The Lapid-Kushlin defocus coefficient was better than those calculated from literature, for other multifocal intraocular lenses. (AU)

Influence of angle Kappa on the optimal intraocular orientation of asymmetric multifocal intraocular lenses

PURPOSE: to evaluate the effects of kappa angle and intraocular orientation on the theoretical performance of asymmetric multifocal intraocular lenses (MIOL). METHODS: For a total of 21 corneal aberrations, a computational analysis simulated the implantation of a computationally designed MIOL. An image quality parameter (IQ) (visually modulated transfer function metric) was calculated for a 5.0-mm pupil and for three conditions: distance, intermediate, and near vision. The procedure was repeated for each eye after a rotation of the MIOL with respect to the cornea from 0º to 360º in 5º steps. Kappa angles from 0 to 900 microns, in 150 microns steps, combined with two two variants of MIOL centration were tested: in the corneal apex or in the center of the entrance pupil. A p-value ≤ 0.05 was considered significant. RESULTS: There were statistically significant differences of the IQ depending of the intraocular orientation of the MIOL. If kappa angle was increased, there was a statistically significant decrease of the IQ. The IQ maintained stable when the optimal intraocular orientation was re-calculated for each kappa angle. In general, the inter-variability of the results between subjects was very high. There were no strong evidences supporting that there exists a preferable centration point. CONCLUSIONS: Our results suggest that kappa angle theoretically affects significantly the performance of asymmetric MIOL implantation. However, its negative effect can be compensated if a customized intraocular orientation is calculated taking into account the presence of the kappa angle

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Análisis de redes de citación sobre los diversos tipos de lentes intraoculares multifocales / Citation network analysis of the various types of multifocal intraocular lenses

Antecedentes y objetivo La implantación de lentes intraoculares (LIO) multifocales se ha incrementado en los últimos años, permitiendo a los pacientes una calidad de visión en todas las distancias, una independencia de la gafa y, en consecuencia, un aumento de la calidad de vida. El objetivo de este estudio es analizar las relaciones entre publicaciones y autores mediante las redes de citación, así como identificar las distintas áreas de investigación y determinar la publicación más citada. Material y método La búsqueda de publicaciones se realizó mediante la base de datos Web of Science, empleando los términos «Multifocal intraocular lens», «Bifocal intraocular lens», «Trifocal intraocular lens», «Diffractive intraocular lens», «Refractive intraocular lens», «Accommodative intraocular lens» y «Extended depth of focus intraocular lens», en un intervalo de tiempo entre 1989 y agosto del 2020. Para el análisis de las publicaciones se empleó el software Citation Network Explorer. Resultados Se encontraron 1.293 publicaciones con 11.730 citaciones generadas en la red, siendo el año 2019 el de mayor número de publicaciones. La publicación más citada es «European multicenter study of the AcrySof ReSTOR apodized diffractive intraocular lens», de Kohnen et al., publicada en el año 2006. Mediante la función Clustering se encontraron cuatro grupos sobre distintas áreas de investigación en este campo, tales como: calidad visual, diseños de LIO, aberraciones oculares o curvas de desenfoque. Conclusiones La red de citaciones muestra un análisis exhaustivo y objetivo de los principales trabajos sobre los distintos diseños y clases de LIO multifocales (AU)

Background and objective The implantation of multifocal intraocular lens (IOL) has increased in recent years, allowing patients to achieve good quality vision at all distances, independence from use of glasses, and consequently, an increase in quality of life. The main purpose of this study was to analyse the links between publications and authors via citation networks, as well to as identify the different research areas and determine the most cited publications. Material and methods The publication search was performed through the Web of Science database, using the terms «Multifocal intraocular lens», «Bifocal intraocular lens», «Trifocal intraocular lens», «Diffractive intraocular lens», «Refractive intraocular lens», «Accommodative intraocular lens» and «Extended depth of focus intraocular lens», for a time interval from 1989 to August 2020. The software used to analyse the publications was the Citation Network Explorer. Results A total of 1293 publications were found, with 11730 citations generated in the network, and 2019 had the highest number of publications of any year. The most cited publication was «European multicenter study of the AcrySof ReSTOR apodized diffractive intraocular lens» by Kohnen et al., published in 2006. Four groups about different research areas in this field were found using the Clustering functionality: visual quality, IOL designs, ocular aberrations, or defocus curves. Conclusions The citation network offers an objective and comprehensive analysis of the main articles on the different designs and classes of multifocal IOL (AU)

Lentes intraoculares fáquicas: recientes avances e innovaciones / Phakic intraocular lenses: Recent advances and innovations

Las lentes intraoculares fáquicas (LIOf) son la opción de primera elección en la corrección de ametropías elevadas y en los casos en los que la superficie ocular o la córnea no son idóneas para realizar técnicas queratorrefractivas. Esta revisión pretende actualizar y detallar el estado actual de los seis modelos de LIOf disponibles en Europa, precisar la ampliación de sus indicaciones y describir las innovaciones de diseño que se han dado en los últimos años. Estas han consistido en las LIOf de cámara posterior, en habilitar un micropuerto central para mejorar la circulación del humor acuoso, y en disponer de mayores diámetros de zona óptica, así como de ópticas multifocales para compensar la presbicia. Se constatan los excelentes resultados de seguridad y eficacia que se obtienen, recordando la importancia de la educación de los pacientes para asegurarlas a medio-largo plazo. Finalmente revisamos las indicaciones especiales de LIOf, así como la bilensectomía, procedimiento que eventualmente requerirán una mayoría de pacientes con LIOf a medida que desarrollen cataratas por la edad

Phakic intraocular lenses (pIOL) are recommended when counselling refractive surgery candidates presenting with high ametropia or ocular surface and/or corneal conditions that contraindicate corneal refractive surgery. This review aims to present the state-of-the-art regarding pIOL models currently available in Europe, addressing their newer indications and recent design innovations. These include, in the case of posterior chamber pIOLs, the addition of a central hole to improve aqueous humour circulation, the availability of larger optical zones, and multifocal optics for the compensation of presbyopia. The review also highlights their good safety and efficacy results, as well as the role of patient education to ensure adequate outcomes in the medium-long term. The indications of pIOLs in special situations, as well as bi-lensectomy, a procedure that most pIOL patients may eventually require as they age and develop cataracts, are also addressed

Characterization of optical performance with defocusing curve: Analysis of two refractive intraocular lens models with high and medium addition / Caracterización del comportamiento óptico mediante curva de desenfoque: análisis de dos modelos de lentes intraoculares refractivas con adición alta y media

PURPOSE: To characterize the optical performance of two models of refractive bifocal intraocular lenses, with medium and high addition, using defocus curves. METHODS: 20 eyes from 20 subjects were included in this study. 10 eyes underwent caratact surgery with an implant of a medium addition refractive bifocal intraocular lens (IOL) (Lentis LS-313 MF20) and the other 10 eyes underwent cataract surgery with an implant of a high addition refractive bifocal IOL (Lentis LS-313 MF30). Six weeks after surgery, subjective refraction and defocus curve were made. RESULTS: Mean final residual refraction in spherical equivalent was +0.10 ± 0.07 D in the LS-313MF30 group and +0.12 ± 0.10 D in the LS-313MF20 group. Defocus curve showed a different optical performance in intermediate/near distance depending on the IOL model. The medium addition IOL provided good visual acuity (VA) at far and intermediate distance up to 50 cms, and the high addition IOL provided better VA in near distance up to 25 cms. CONCLUSIONS: The high addition intraocular lens provides better visual acuity in the spatial range from infinity to the point close to 25 cm. The medium addition intraocular lens provides excellent visual acuity in far and intermediate vision. The defocus curve seems to be a valid and reproducible tool for evaluating the optical behavior of multifocal sector refractive lenses

OBJETIVO: Caracterizar el comportamiento óptico de dos modelos de lentes intraoculares bifocales refractivas, con adición media y alta, utilizando curvas de desenfoque. MÉTODOS: Se incluyó en este estudio a 20 ojos de 20 sujetos: 10 ojos sometidos a cirugía de cataratas con implante de lentes intraoculares (LIO) bifocales refractivas con adición media (Lentis LS-313 MF20), y los 10 ojos restantes sometidos a cirugía de cataratas con implante de LIO bifocales refractivas de adición alta (Lentis LS-313 MF30). Transcurridas seis semanas de la cirugía, se realizó refracción subjetiva y curva de desenfoque. RESULTADOS: La refracción residual final media en el equivalente esférico fue de +0,1 ± 0,07 D en el grupo LS-313MF30, y de +0,12 ± 0,1 D en el grupo LS-313MF20. La curva de desenfoque mostró un comportamiento óptico diferente en la distancia intermedia/de cerca, dependiendo del modelo de LIO. La LIO de adición media aportó buena agudeza visual (AV) en la distancia de lejos e intermedia, de hasta 50 cm, y la LIO de adición alta aportó mejor AV en la distancia de cerca de hasta 25 cm. CONCLUSIONES: Las lentes intraoculares de adición alta aportan mejor agudeza visual en el rango espacial comprendido entre el infinito y el punto próximo a 25 centímetros. Las lentes intraoculares de adición media aportan una agudeza visual excelente en la visión de lejos e intermedia. La curva de desenfoque parece ser una herramienta válida y reproducible para evaluar el comportamiento óptico de las lentes refractivas multifocales

Patient selection to optimize near vision performance with a low-addition trifocal lens / Selección del paciente para optimizar el rendimiento visual en visión próxima con una lente trifocal de baja adición

PURPOSE: To assess the impact of ocular biometric variables on the visual performance achieved with a low addition trifocal intraocular lens (MIOL). METHODS: Retrospective observational study including 34 eyes. Preoperative measured variables included mean corneal power (Km), corneal regular astigmatism (RA), anterior chamber depth (ACD), axial length (AXL), total irregular astigmatism (IA), spherical aberration (SA) and distance from pupil center to vertex normal (mi). Same variables were retrieved from the three month visit follow-up in addition to the actual lens position (ALP), the calculated effective addition (EA), the IOL centration from vertex normal (d), and the visual acuity defocus curve. The area under the defocus curve was computed along the total curve (TAUC) and ranges for far (FAUC), intermediate (IAUC) and near vision (NAUC). The sample was split in two groups of 17 eyes with TAUCs above and below the mean, and the differences among groups for different ocular parameters were assessed. RESULTS: The group of eyes above TAUC of 2.03 logMAR*m-1 showed significantly lower Km and greater AXL and SA. Km was negatively correlated with TAUC and NAUC. NAUC was negatively correlated with IA and positively with d. A multiple lineal regression model including Km, d, and IA predicted NAUC (r-square = 34%). No significant differences between IA and SA were found between preoperative and postoperative values but mi significantly decreased after surgery. CONCLUSIONS: The mean corneal power, irregular astigmatism, and centration from vertex normal should be considered for optimizing the near visual performance with this MIOL

OBJETIVO: Valorar el impacto de las variables biométricas oculares sobre el rendimiento visual con una lente intraocular trifocal de baja adición (MIOL). MÉTODOS: Estudio observacional retrospectivo que incluyó 34 ojos. Las variables preoperatorias medidas incluyeron potencia corneal media (Km), astigmatismo regular corneal (AR), profundidad de la cámara anterior (ACD), longitud axial (AXL), astigmatismo irregular total (AI), aberración esférica (AE) y distancia entre el centro de la pupila y el vértice normal (mi). Algunas variables se obtuvieron de la visita de seguimiento a los tres meses, a las que se añadieron la posición real de la lente (ALP), la adición efectiva (AE), el centrado de las LIO desde el vértice normal (d), y la curva de desenfoque de agudeza visual. El área bajo la curva de desenfoque se calculó a lo largo de la curva total (TAUC) así como los rangos para visión de lejos (FAUC), intermedia (IAUC) y de cerca (NAUC). La muestra se dividió en dos grupos de 17 ojos con TAUCs por encima y por debajo de la media, valorándose las diferencias entre los grupos para los diferentes parámetros oculares. RESULTADOS: El grupo de ojos con un valor por encima de TAUC igual a 2,03 logMAR*m-1 reflejó un menor Km y valores mayores de AXL y AE. Km se correlacionó negativamente con TAUC y NAUC. NAUC se correlacionó negativamente con AI, y positivamente con d. Un modelo de regresión lineal múltiple incluyendo Km, d, y AI realizó la predicción de NAUC (R2 = 34%). No se encontraron diferencias significativas entre AI y AE entre los valores preoperatorios y postoperatorios, aunque mi disminuyó significativamente tras la cirugía. CONCLUSIONES: La potencia corneal media, el astigmatismo irregular y el centrado desde el vértice normal deberían considerarse para optimizar el desempeño visual de cerca con MIOL

Avoiding misinterpretations of Kappa angle for clinical research studies with Pentacam / Evitar malas interpretaciones del ángulo de Kappa para estudios de investigación clínica con Pentacam

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