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Qvision Research and Evidence Department

Goal: The Qvision Research and Evidence Department was born in 2015 with the main aim of improving our knowledge about vision sciences. With a more focused activity in Anterior Segment Surgery the department works for improving their results and to increase the current evidence in Opthalmology Medical Devices

Date: 1 January 2015

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Manuel Rodriguez-Vallejo
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The aim of this study was to assess the stability and differences between objective (O-Rx) and subjective (S-Rx) refraction for the assessment of the prediction error (PE). A secondary aim was to report the results of a monofocal intraocular lens (IOL). 100 subjects were included for whom S-Rx and O-Rx were obtained for all visits, and for visual performance, posterior capsular opacification incidence and Nd:YAG rates at 12 months. Either S-Rx and O-Rx showed a hyperopic shift from 1 to 6 months (p < 0.05) and stabilization after 6 months. S-Rx was related with the axial length (rho = −0.29, p = 0.007), obtaining a major tendency towards hyperopia in short eyes implanted with high-power IOLs. O-Rx showed a myopic shift in comparison to S-Rx (p < 0.05). This resulted in a decrease of the number of eyes in ±0.50 D and ±1.00 D from 79 to 67% and from 94 to 90%, respectively. The median (interquartile range) uncorrected and corrected visual acuities were 0.1 (0.29) and 0 (0.12) logMAR, respectively, and seven eyes required Nd:YAG capsulotomy at 12 months. Some caution should be taken in PE studies in which O-Rx is used or S-Rx is measured in a 1-month follow-up. Constant optimization should be conducted for this IOL after S-Rx stabilization.
Manuel Rodriguez-Vallejo
added a research item
To evaluate the prediction error (PE) obtained in Phacoemulsification (Phaco) or Femtosecond (Femto) surgeries without considering posterior corneal astigmatism correction (non-PCA) versus the correction based on Abulafia-Koch + Medicontur (AK) and Barrett calculators in toric intraocular lens (IOL) power calculation. 58 right eyes were retrospectively retrieved from our database. Two groups formed by 28 and 30 eyes depending on the surgery type, Phaco or Femto respectively, were defined. Astigmatism PE were evaluated considering the approach used for calculation of the implanted IOL power (AK) versus the estimation of PEs in non-PCA and Barrett formula. A doubly-multivariate analysis was conducted to assess the differences between-surgery types, within-methods of calculation, and interaction. Mean centroid PE was significantly different between non-PCA, AK and Barrett approaches (p < 0.0005), and neither differences (p < 0.239) nor interaction (p = 0.672) between Phaco or Femto were found. Post-hoc univariate analysis showed a higher PE for the x-component of the non-PCA method versus AK (0.15 D, p < 0.0005) and non-PCA versus Barrett (0.18 D, p < 0.0005), though no differences were found between AK and Barrett (0.03 D, p = 0.93). Against-the-rule under-correction and with-the-rule overcorrection were found in both arms when PCA was not considered. Both calculators provide comparable clinical results.
Manuel Rodriguez-Vallejo
added a research item
1) Background: To evaluate the efficacy at 6 years postoperative after the implantation of a trifocal intraocular lens (IOL) AT Lisa Tri 839MP. The secondary objective was to evaluate the contrast sensitivity defocus curve (CSDC), light distortion analysis (LDA), and patient reported outcomes (PROs). (2) Methods: Sixty-two subjects participated in phone call interviews to collect data regarding a visual function questionnaire (VF-14), a patient reported spectacle independence questionnaire (PRSIQ), and questions related to satisfaction and decision to be implanted with the same IOL. Thirty-seven of these subjects were consecutively invited to a study visit for measurement of their visual acuity (VA), CSDC, and LDA. (3) Results: The mean monocular distance corrected VA was −0.05, 0.08, and 0.05 logMAR at far and distances of 67 cm and 40 cm, respectively. These VAs were significantly superior to those reported in previous literature (p < 0.05). The total area under the CSDC was 2.29 logCS/m −1 and the light distortion index 18.82%. The mean VF-14 score was 94.73, with 19.4% of subjects requiring spectacles occasionally for near distances, and 88.9% considering the decision of being operated again; (4) Conclusions: Long-term AT LISA Tri 839MP IOL efficacy results were equal or better than those reported 12 months postoperatively in previous studies. The spectacle independence and satisfaction rates were comparable to those reported in short-term studies.
Manuel Rodriguez-Vallejo
added a research item
Introduction Positive dysphotopsia (PD) is a topic of great interest in intraocular lens (IOL) field. Several approaches have been developed from the physics, psychophysics and psychometry fields to measure PD. However, the complexity of characterizing this phenomenon and the lack of standardization have resulted in a considerable bias between studies that avoid its inclusion in systematic reviews and meta-analysis. Areas Covered The purposes of this review were first to suggest a definition and classification of PD that minimize the bias between studies that use different questions to rate PD prevalence. Second, to describe the limitations found in psychophysical studies. Finally, to identify the associations between photic phenomena (PP) and the design of monofocal and multifocal IOLs. A non-systematic literature review was conducted from the last 30 years. Expert Opinion PD can be defined as any bothering bright artifact perceived by patients along or around direct bright lights or reflected over objects located in the visual field. If the patient is not bothered by the artifact, the term PP should be used instead. Psychophysical approaches measure PP and not PD. Whereas LED approaches are preferable, these really measure Light Disturbance because the classification of PP cannot be differentiated.
Manuel Rodriguez-Vallejo
added a research item
Purpose: To evaluate the incidence of central islands after 6-month follow-up of Small Incision Lenticule Extraction (SMILE) and to assess their role in safety and accuracy. Methods: Analysis of the preoperative and postoperative corneal tomography, best spectacle refraction and corrected distance visual acuity of 82 subjects that underwent SMILE. Incidence of central islands was assessed through total corneal spherical aberration (SA) over 4 mm of central diameter and the SA was compared between two groups with and without safety loss (CDVA difference ≥0.1 logMAR from preoperative). The cut-off value for detecting the risk of postoperative central island development was calculated. The influence in accuracy was calculated through magnitude of error of the spherical equivalent and astigmatism, both for spectacle refraction at corneal plane (SE-Rx and AST-Rx) and for total corneal refractive power at 3 mm (SE-TCRP3 and AST-TCRP3). Results: Five from 82 eyes resulted in a loss of safety, obtaining significant differences in SA, both preoperatively (p = .01) and postoperatively (p = .007) after stratification by safety loss. A preoperatively cut-off value ≤0.012 μm of SA predicted the appearance of central islands with sensitivity of 100% and specificity of 75%. Despite postoperative SA being related to the preoperative spherical equivalent, for both SE-Rx and SE-TCRP3, this tendency disappeared after readjusting results according to a nomogram. Conclusions: Central islands in SMILE, despite being a rare adverse event, can affect the safety of the procedure and are related to preoperative central steepness, not corrected by the spherical lenticule, which is clearly visible postoperatively.
Manuel Rodriguez-Vallejo
added a research item
Concerns regarding the article by Hoffer & Savini: (1) reporting the formula for the implanted intraocularlens (IOL) and clinical trials, (2) the 6-m standard is not in agreement with international standards and (3) how should discretization of PE be performed for calculating cumulative percentages?
Manuel Rodriguez-Vallejo
added a research item
PURPOSE: To evaluate the distribution of pupil size in patients implanted with multifocal intraocular lenses (IOLs) and to assess the variations according to age. METHODS: A total of 168 eyes that had implantation of several multifocal IOLs and were measured at the 3-month follow-up visit were included in the analysis. The Keratograph 5M (Oculus Optikgeräte) was used to measure the photopic and mesopic pupil size, as well as the average between both (average pupil size). Eyes were stratified in four groups by age: 50 years or younger, 51 to 60 years, 61 to 70 years, and older than 70 years. RESULTS: Considering the total sample, 84.5% and 95.8% of eyes had a photopic pupil size of 3 and 3.5 mm or less, respectively. The mesopic pupil size was greater than 4.5 mm in 39.3% and greater than 5 mm in 16.7% of eyes. The average pupil size was 3.5 and 4 mm or less in 54.2% and 85.1% of eyes, respectively. Mesopic pupil size resulted in a steeper decrease with age than photopic pupil size: 0.028 versus 0.015 mm/year, respectively. Statistically significant differences were found among the four age groups (P < .0005). No significant mean differences were found between multifocal IOL models for photopic pupil size, mesopic pupil size, or average pupil size (P > .05). CONCLUSIONS: Eyes implanted with multifocal IOLs had a photopic pupil size of 3.5 mm or less and mesopic pupil size of 5 mm or less. Mesopic and photopic pupil size decreased 0.28 and 0.15 mm per decade, respectively. This information can help surgeons to understand the general functioning of multifocal IOLs whose performance varies with pupil size.
Manuel Rodriguez-Vallejo
added a research item
Purpose: To evaluate the agreement between subjective high and low contrast visual acuity (VA) and predicted values from double-pass system measurements in healthy candidates to laser refractive surgery. Methods: Ninety-two eyes measured during the preoperative screening to laser refractive surgery were included in this retrospective analysis. High contrast subjective visual acuity (HCVA) and low contrasts at 20% (LCVA20) and 9% (LCVA9) were compared with the predicted VA obtained with a commercial double-pass system (OQAS) at the same levels of contrast, 100% (OV100), 20% (OV20), and 9% (OV9). The agreement was evaluated with Bland-Altman analysis computing the limits of agreement (LoAs) and the correlations with the spearman rho. Results: An underestimation of VA was obtained with the double-pass system for the highest contrast. Differences between predictive and subjective measurements were statistically significant for 100% contrast (− 0.08 logMAR, p < 0.0005), but not for 20%(− 0.03 logMAR, p = 0.07) and 9%(− 0.02 logMAR, p = 0.9) of contrasts. The LoAs increased with the decrease of contrast from 0.29 with 100% to 0.39 logMAR with 9% of contrast. A weak correlation was obtained between subjective and predicted VA (rho ≤ 0.33) that was only significant for 100% (p = 0.001) and 20% (p = 0.004) contrasts. Conclusion: Mean differences between methods were reasonably small so mean results obtained for predicted VA in OQAS studies can be considered as reliable, at least in healthy subjects and for low contrast. However, limits of agreement were considerably poor which means that OQAS cannot replace individual subjective measurements of VA in clinical practice.
Manuel Rodriguez-Vallejo
added a research item
Purpose/Aim to assess, following the standards, the results of safety, efficacy and predictability for a trifocal intraocular lens and to evaluate contrast sensitivity and visual acuity defocus curve. Materials and Methods 50 subjects operated on cataract surgery or refractive lens exchange with a trifocal intraocular lens have been recruited for the study. The monocular uncorrected visual acuity (VA) at far, intermediate (67 cm) and near (40 cm) distances in addition to corrected VA at far and near distances was evaluated at 1 week, 1 month and 3 months after surgery. Postoperative refraction, binocular contrast sensitivity function (CSF) and binocular defocus curves were also collected at the 3 months follow-up visit. Results Mean uncorrected VA was 0.10, 0.07 and 0.05 logMAR at far, intermediate and near distances. Corrected distance VA at far and near distances was 0.04 and 0.02 logMAR. 90% and 100% achieved a spherical equivalent in ±0.50 D and ±1.00 D, respectively. CSF was above normal range for 12 and 18 cycles per degree (cpd) in all the conditions, inside the normal range in 1.5, 3 and 6 cpd and only decreased below normal range for 1.5 and 3 cpd in mesopic vision without glare. Conclusions The procedure achieved a safety, efficacy and predictability similar to those reported by previous studies. The CSF was generally enhanced after the procedure in comparison to those reported in non-operated subjects above 60 years old. Previous studies might underestimate the effective distance of the intermediate and near foci.
Manuel Rodriguez-Vallejo
added a research item
Purpose: To identify the most sensitive visual performance metric for evaluating the pupil-dependency of a multifocal intraocular lens (MIOL) and to determine the pupil measurement method most correlated with such metric. Methods: Twenty-seven right eyes implanted with a MIOL were included in the analysis. Three pupil size measurements were obtained preoperatively and at 1 month after surgery with the Keratograph 5M system: photopic (PP), mesopic (MP), and the average from both (AP). Pupil was also measured with a rule (RP) under the same light conditions of postoperative visual performance measurements that included, corrected visual acuities (VA) at three distances (far, 67 cm and 40 cm), visual acuity (VADC) and contrast sensitivity defocus curves for optotype sizes of 0.3 logMAR (CSDC3) and 0.7 logMAR (CSDC7). Differences in visual performance were also analyzed for eyes with RP > 3 mm (Group A) and RP ⩽ 3 mm (Group B). Results: PP diameter decreased after surgery by 16% (p = 0.001), whereas MP (p = 0.013) and AP (p = 0.008) decreased by 10%. The best agreement with RP was obtained for AP. Group B showed a trend to better performance than Group A for all the included metrics (p > 0.05). From the three types of defocus curves, CSDC3 obtained generally highest statistical power for testing differences between groups. The strongest statistically significant correlations between pupil size and CSDC3 were obtained for RP and AP. Conclusion: The CSDC3 was the most sensitive metric to detect MIOL pupil-dependency. PR and AP were more correlated with CSDC3 than PP and MP.
Manuel Rodriguez-Vallejo
added a research item
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 (µ). 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 µ 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.
Manuel Rodriguez-Vallejo
added 18 research items
Sports are a very common activity practiced around the world, to such an extent that they are completely integrated into our daily lives. The main reason is because sports practice is good for our health, but sometimes can have some risks that must be taken into account. Particularly, eyes are an irreplaceable organ that could suffer an injury due to a sport, especially those in high risk sports. In this mini-review, we classify the sports according to the risk of eye injury, later we describe the most common injuries and how to prevent them, with the optimum solution depending on the characteristics of each sport.
Manuel Rodriguez-Vallejo
added a project goal
The Qvision Research and Evidence Department was born in 2015 with the main aim of improving our knowledge about vision sciences. With a more focused activity in Anterior Segment Surgery the department works for improving their results and to increase the current evidence in Opthalmology Medical Devices
 
Manuel Rodriguez-Vallejo
added a research item
Purpose: To evaluate the standard clinical outcomes, defocus curves, and satisfaction obtained with a new diffractive low addition trifocal intraocular lens (IOL). Methods: Thirty patients who were implanted with the Versario Multifocal 3F IOL (Valeant Med Sp.zo.o., Warsaw, Poland) were recruited for a prospective observational study at Qvision, Vithas Virgen del Mar Hospital, Almería, Spain. Variables for reporting standard outcomes were collected at the 1-month visit for monocular vision and the 3-month visit for binocular vision, including best spectacle refraction and corrected and uncorrected visual acuities at far, intermediate (67 cm), and near (40 cm) distances. In addition, monocular and binocular visual acuity defocus curves were measured and questionnaires for grading subjective visual quality, satisfaction, and visual function were supplied at the end of the follow-up. Results: Monocular corrected distance visual acuity decreased progressively from far (-0.05 logMAR) to near (0.25 logMAR) and improved approximately -0.1 logMAR along the defocus curve in binocular vision. The mean residual spherical equivalent (SE) was 0.15 ± 0.47 diopters (D), with 79% of eyes within ±0.50 D and 97% within ±1.00 D with the SRK/T formula. All of the visual function tasks improved after surgery, especially driving at night, which increased from 58 to 79 (P < .05). Of 27 patients, 84.4% were satisfied or very satisfied with their general vision. Conclusions: This new lens was similar in terms of visual performance and satisfaction to other trifocal IOLs. It can be classified as a trifocal extended depth of focus IOL because of the performance between extended depth of focus IOLs and medium-high addition trifocal IOLs. [J Refract Surg. 2019;35(4):214-221.].
Manuel Rodriguez-Vallejo
added 2 research items
Purpose: To evaluate surgically induced astigmatism as computed by means of either simulated keratometry (KSIM) or total corneal refractive power (TCRP) after temporal incisions. Methods: Prospective observational study including 36 right eyes undergoing cataract surgery. Astigmatism was measured preoperatively during the 3-month follow-up period using Pentacam. Surgically induced astigmatism was computed considering anterior corneal surface astigmatism at 3 mm with KSIM and considering both corneal surfaces with TCRP from 1 to 8 mm (TCRP3 for 3 mm). The eyes under study were divided into two balanced groups: LOW with KSIM astigmatism <0.90 D and HIGH with KSIM astigmatism ≥0.90 D. Resulting surgically induced astigmatism values were compared across groups and measuring techniques by means of flattening, steepening, and torque analysis. Results: Mean surgically induced astigmatism was higher in the HIGH group (0.31 D @ 102°) than in the LOW group (0.04 D @ 16°). The temporal incision resulted in a steepening in the HIGH group of 0.15 D @ 90°, as estimated with KSIM, versus 0.28 D @ 90° with TCRP3, but no significant differences were found for the steepening in the LOW group or for the torque in either group. Differences between KSIM- and TCRP3-based surgically induced astigmatism values were negligible in LOW group. Conclusion: Surgically induced astigmatism was considerably higher in the high-astigmatism group and its value was underestimated with the KSIM approach. Eyes having low astigmatism should not be included for computing the surgically induced astigmatism because steepening would be underestimated.
Purpose/Aim: To evaluate the impact of ocular parameters on the visual performance achieved with the multifocal intraocular lens (IOL) Bi-Flex M 677MY. Materials and Methods: 26 subjects were included in the current study. Several physiological variables were retrieved from the 3-month follow-up visit, including pupil diameter and distance from pupil center to the vertex normal of the anterior cornea (µ). These variables were also obtained in the preoperative visit. Binocular and monocular visual acuity defocus curves were measured at 1 and 3 months after surgery, respectively. The area under the monocular defocus curve was computed along the total curve (TAUC, +1.00 to −4.00 D) and for the ranges of far (FAUC, +0.50 to −0.50 D), intermediate (IAUC, - 1.00 to −1.50 D) and near vision (NAUC, −2.00 to −4.00 D). Correlations between these areas and the postoperative physiological variables were assessed. Results: The mean µ was reduced from 0.21 mm to 0.10 mm after surgery, as well as pupil diameters, either photopic (−7.4%) and mesopic (−8.1%) (p < 0.05). The mean AUCs were 2.08 ± 0.74 for TAUC, 0.57 ± 0.17 for FAUC, 0.16 ± 0.09 for IAUC and 0.81 ± 0.29 for NAUC. Significant correlations were found between NAUC and Km (r = −0.39, p = 0.05) as well as between IAUC and temporal decentration of the lens from vertex normal (ρ = −0.41, p = 0.04). Conclusions: The performance at near with the IOL evaluated improved in eyes with less corneal power. On the other hand, a slight temporal IOL decentration from vertex normal also improved intermediate visual acuity. The binocular defocus curve was similar to other trifocal IOLs.
Manuel Rodriguez-Vallejo
added a research item
Dysfunctional lens syndrome (DLS) is a term coined to describe the natural aging changes in the crystalline lens. Different alterations in the refractive properties and transparency of the lens are produced during the development of presbyopia and cataract, such as changes in internal high order aberrations or an increase in ocular forward scattering, with a potentially significant impact on clinical measures, including visual acuity and contrast sensitivity. Objective technologies have emerged to solve the limits of current methods for the grading of the lens aging, which have been linked to the DLS term. However, there is still not a gold standard or evidence-based clinical guidelines around these new technologies despite multiple research studies have correlated their results with conventional methods such as visual acuity or the lens opacification system (LOCS), with more scientific background around the ocular scattering index (OSI) and Scheimpflug densitometry. In either case, DLS is not a new evidence-based concept that leads to new knowledge about crystalline lens aging but it is a nomenclature change of two existing terms, presbyopia and cataracts. erefore, this term should be used with caution in the scientific peer-reviewed literature.
Manuel Rodriguez-Vallejo
added a research item
Purpose: To assess the surgically induced astigmatism with femtosecond laser-assisted and manual temporal clear corneal incisions and to evaluate the performance of a model for prediction of the surgically induced astigmatism based on the preoperative corneal astigmatism. Methods: Clinical data of 104 right eyes and 104 left eyes undergoing cataract surgery, 52 with manual incisions and 52 with femtosecond laser-assisted incisions in each eye group, were extracted and revised retrospectively. In all cases, manual incisions were 2.2 mm width and femtosecond incisions were 2.5 mm width, both at temporal location. A predictive model of the surgically induced astigmatism was obtained by means of simple linear regression analyses. Results: Mean surgically induced astigmatisms for right eyes were 0.14D@65° (manual) and 0.24D@92° (femtosecond) (p > 0.05) and for left eyes, 0.15D@101° (manual) and 0.19D@104° (femtosecond) (p > 0.05). The orthogonal components of the surgically induced astigmatism (XSIA, YSIA) were significantly correlated (p < 0.05) with the preoperative orthogonal components of corneal astigmatism (Xpreop, Ypreop) (r = −0.29 for X and r = −0.1 for Y). The preoperative astigmatism explained 8% of the variability of the XSIA and 3% of the variability of YSIA. The postoperative corneal astigmatism prediction was not improved by the surgically induced astigmatism obtained from the model in comparison with the simple vector subtraction of the mean surgically induced astigmatism. Conclusion: Temporal incisions induce similar astigmatism either for manual or for femtosecond procedures. This can be clinically negligible for being considered for toric intraocular lens calculation due to the great standard deviation in comparison with the mean. The usefulness of the prediction model should be confirmed in patients with high preoperative corneal astigmatism.
Manuel Rodriguez-Vallejo
added a research item
Citation: Fernández J, Rodríguez-Vallejo M, Martínez J, Tauste A, Piñero DP. Above-average defocus curves in photopic and mesopic vision with multifocal intraocular lenses after laser assisted in situ keratomileusis. Int J Ophthalmol (Oftalmar) and Vithas Virgen del Carmen (Qvision) hospitals in Spain. I write to describe a case in which the visual acuity defocus curves (VADC) and contrast sensitivity defocus curves (CSDC) in photopic and mesopic vision after the implantation of a multifocal diffractive trifocal intraocular lens (IOL) are above average values in normal eyes. We discuss potential causes for this unexpected positive outcome. Patients operated on with laser refractive surgery (LRS) in the past will develop with age presbyopia or age-related cataract. Possibly, these patients will desire to maintain their spectacle independence [1]. It is well known that LRS modifies the corneal shape and induces positive spherical aberration (SA) after myopic treatments and negative SA after hyperopic treatments [2]. For this reason, the use of some types of multifocal intraocular lenses (MIOLs) in such cases is controversial as these implants generate light scattering and deteriorate the optical quality of the eye. Indeed, poorer ocular optical quality is expected at far vision with MIOLs implanted in eyes with non-treated corneas compared to monofocal IOLs, with the potential of leading to some complaints, such as contrast sensitivity (CS) loss, glare, and halos [3]. Therefore, the visual performance with MIOLs may decrease even more after laser assisted in situ keratomileusis (LASIK), especially in mesopic conditions with low contrast tests [4]. However, the combination of the modified corneal shape after LRS and the specific optics of the MIOL may also generate an aberrometric compensation, allowing the patient to achieve visual acuities above 20/20 at far and near distances in mesopic conditions without a significant reduction of CS. A 48-year-old man that had been treated with LASIK five years ago for the correction of around 5 diopters (D) of myopia attended to our clinic seeking for surgical solution for his presbyopia. Refractive error was (-0.75) (-0.50) @80° in the right eye (RE) and (-1.75) (-0.50) @120° in the left eye (LE), with corrected distance visual acuity of-0.1 logMAR in both eyes. The near addition was +1.50 D. We used the Cataract Pre-op modulus of the Pentacam system (Oculus Optikgeräte, Wetzlar, Germany) for screening and IOL selection according to the four steps proposed by Maeda [5]. The corneal irregular Multifocal intraocular lens after refractive surgery Figure 1 Contrast sensitivity function measured under photopic and mesopic conditions with (CSPg and CSMg) and without glare (CSP and CSM) The grey area represents the range of normality defined for post-LASIK patients without MIOLs implanted.