Intraocular Lens Models Research Articles

Evaluation of Physiological Responses at the Anterior Surface of Two (Hydrophobic Acrylic) Intraocular Lens Models

Evaluation of Physiological Responses at the Anterior Surface of Two (Hydrophobic Acrylic) Intraocular Lens Models

Impact of Primary Calcification in Segmented Refractive Bifocal Intraocular Lenses on Optical Performance Including Straylight.

To describe and analyze the impact of calcification on the optical quality of segmented refractive bifocal intraocular lenses (IOLs). Eight segmented refractive bifocal IOLs made of hydrophilic acrylic were explanted from 8 patients due to opacification (and one opacified IOL that was not explanted) and analyzed in a cross-sectional study with laboratory analysis. Nine cases comprised three IOL models: LS-313 MF30 (5 cases), LS-312 MF30 (3 cases), and LS-313 MF15 (1 case). Material analysis with scanning and transmission electron microscopy confirmed IOL calcification. Measurements of modulation transfer function (MTF) and straylight permitted assessment of the IOL optical quality. Values were compared to a control lens. Except for one case of Nd:YAG (neodymium:yttrium-aluminum-garnet) capsulotomy, there was no secondary surgical procedure in the patients' histories. Eight of nine patients reported deteriorated visual quality, ultimately requiring IOL exchange. Material evaluation revealed fine granules of a calcium phosphate. Despite calcification, all but one lens still showed two distinct foci on the MTF measurements. Straylight values were higher than in a cataractous lens (33.1 deg2/sr) in all cases, with an average value of 170.1 ± 71.5 deg2/sr. Optical quality assessment showed that IOL calcification had a small effect on the MTF of segmented refractive bifocal lenses but a large impact on the straylight levels. Accordingly, in the clinical case, straylight levels were elevated. [J Refract Surg. 2020;36(1):20-27.].

Phacosurgery features in keratoconus

The review summarizes the results of surgical treatment of cataracts in patients with keratoconus. The major challenges of phacosurgery in keratoconus are associated with intraocular lens (IOL) power calculation, choice of the most appropriate IOL model and additional interventions required to stabilize keratectasia and reduce corneal irregularity.

Validation of Mahajan's formula for scaling ocular higher-order aberrations by pupil size.

Purpose:Zernike polynomials for describing ocular higher order aberrations are affected by pupil aperture. The current study aimed to validate Mahajan’s formula for scaling Zernike polynomials by pupil size.Methods:Higher order aberrations for 3 intraocular lens models (AcrySof IQ IOL SN60WF, Technis ZA9003, Adapt Advanced Optics) were measured using the Zywave aberrometer and a purpose-built physical model eye. Zernike coefficients were mathematically scaled from a 5 mm to a 3 mm pupil diameter (5:3 mm), from a 5 mm to a 2 mm pupil diameter (5:2 mm), and from a 3 mm to a 2 mm pupil diameter (3:2 mm). Agreement between the scaled coefficients and the measured coefficients at the same pupil aperture was assessed using the Bland–Altman method in R statistical software.Results:No statistically significant mean difference (MD) occurred between the scaled and measured Zernike coefficients for 21 of 23 analyses after Holm-Bonferroni correction (P > 0.05). Mean differences between the scaled and measured Zernike coefficients were clinically insignificant for all aberrations up to the fourth order, and within 0.10 μm. Oblique secondary astigmatism (Z−24) was significantly different in the 5:3 mm comparison (MD = - 0.04 μm, P < 0.01). Horizontal coma (Z13) was significantly different in the 3:2 mm comparison (MD = - 0.07 μm, P = 0.03). There were borderline statistical differences in both vertical (Z−13) and horizontal coma (Z13) in the 5:3 mm comparison (MD = 0.02 μm, - 0.09 μm, P = 0.05, 0.05, respectively).Conclusion:A formula for the scaling of higher order aberrations by pupil size is validated as accurate. Pupil scaling enables accurate comparison of individual higher order aberrations in clinical research for situations involving different pupil sizes.

基于我国人眼数据的人工晶体模型及其三维打印技术研究

基于我国人眼数据的人工晶体模型及其三维打印技术研究

Influence of models of hydrophobic acrylic intraocular lenses on the development of posterior lens capsule opacifications (preliminary results)

To compare the influence of three models of hydrophobic acrylic IOLs on the development of PCO within one year after phaco surgery. The study included 72 patients (91 eyes) who were followed up for 12 months after implantation of one of three models of posterior chamber hydrophobic acrylic IOLs: MIOL-2 (Reper-NN, Russia, 24 eyes, 1st group), SA60AT and US60MP (Alcon, USA, 41 and 26 eyes, 2nd and 3rd groups, respectively). Posterior capsule images were taken and then processed with the EPCO 2000 (Evaluation of Posterior Capsular Opacification) software. The area of posterior capsule adjacent to the center of IOL's optic of 4.0 mm in diameter was estimated. PCO score was calculated as the weighted sum of opacification areas multiplied by the degree (from 0 to 4). Within 1 year of the follow-up, mean visual acuity was at least 1.0 (20/20). Significant PCO progression was observed as early as 3 months after surgery. Despite that, opacification density in all three groups at every follow-up visit did not exceed grade 2; maximal PCO score (0.0315, median) was seen 12 month after surgery in the 1st group. At the same time, differences in PCO score between the groups were not significant. Nd:YAG laser posterior capsulotomy was performed only in one patient from the 1st group 12 month after surgery. Difference in the percentage of clear posterior capsules was significant only 12 month after surgery between the 1st and 3rd groups (p=0.024). All three models of hydrophobic acrylic IOLs showed comparably high vision outcomess during 12 months of the follow-up with somewhat better PCO score and percentage of clear posterior capsules in eyes with US60MP.

Model of the light sword intraocular lens: in-vitro comparative studies.

This work presents the first models of light sword intraocular lenses (LS IOLs) with angularly modulated optical power. We performed an experimental, comparative study with multifocal and extended depth of focus intraocular lenses, which are available on the market. The measurements conducted in an original optical bench were utilised for an analysis of point spread functions, elongated foci, modulation transfer functions and the areas defined by them. The LS IOL models perform homogeneous imaging in the whole range of designed defocus. The proposed concept of extended depth of focus seems to be promising for the development of presbyopia-correcting intraocular lenses capable of regaining fully functional vision.

Scanning electron microscopy study of different one-piece foldable acrylic intraocular lenses after injection through microincisional cataract surgery cartridges.

To evaluate possible surface alterations of different models of one-piece foldable acrylic intraocular lenses (IOLs) after folding and ejecting process through 2.2-mm microincisional cataract surgery (MICS) cartridges. In this experimental laboratory study, the following IOLs were studied: Johnson&Johnson PCB00, HOYA iSert 251, Alcon AcrySof IQ SN60WF, Bausch&Lomb enVISTA MX-60. A total of 80 IOLs were analyzed. Twenty intraocular lenses of each type were studied: ten with a power of + 21 D ± 1 and ten with a power of + 28 D ± 1. IOLs were injected through a dedicated 2.2-mm MICS cartridge into a 50-mL vial containing 10mL of deionized water. After rinsing and metallization process, scanning electron microscopy images were acquired. All IOLs presented high-quality construction biomaterials. Some IOLs showed superficial scratches and tears on the optic surface, mainly positioned according to the direction of the stress induced by the folding process. In other cases, small superficial tears were seen in a more peripheral position. All lenses showed excellent surface quality. After folding and injection process some superficial scratches and tears of the IOL optic were detected in some models. Further studies are needed to assess the possible effects of those superficial damages on the optical quality of the IOLs.

Automated extraction of ophthalmic surgery outcomes from the electronic health record

ObjectiveComprehensive analysis of ophthalmic surgical outcomes is often restricted by limited methodologies for efficiently and accurately extracting clinical information from electronic health record (EHR) systems because much is in free-text form. This study aims to utilize advanced methods to automate extraction of clinical concepts from the EHR free text to study visual acuity (VA), intraocular pressure (IOP), and medication outcomes of cataract and glaucoma surgeries. MethodsPatients who underwent cataract or glaucoma surgery at an academic medical center between 2009 and 2018 were identified by Current Procedural Terminology codes. Rule-based algorithms were developed and used on EHR clinical narrative text to extract intraocular lens (IOL) power and implant type, as well as to create a surgery laterality classifier. MedEx (version 1.3.7) was used on free-text clinical notes to extract information on eye medications and compared to information from medication orders. Random samples of free-text notes were reviewed by two independent masked annotators to assess inter-annotator agreement on outcome variable classification and accuracy of classifiers. VA and IOP were available from semi-structured fields. ResultsThis study cohort included 6347 unique patients, with 8550 stand-alone cataract surgeries, 451 combined cataract/glaucoma surgeries, and 961 glaucoma surgeries without concurrent cataract surgery. The rule-based laterality classifier achieved 100% accuracy compared to manual review of a sample of operative notes by independent masked annotators. For cataract surgery alone, glaucoma surgery alone, or combined cataract/glaucoma surgeries, our automated extraction algorithm achieved 99–100% accuracy compared to manual annotation of samples of notes from each group, including IOL model and IOL power for cataract surgeries, and glaucoma implant for glaucoma surgeries. For glaucoma medications, there was 90.7% inter-annotator agreement. After adjudication, 85.0% of medications identified by MedEx determined to be correct. Determination of surgical laterality enabled evaluation of pre- and postoperative VA and IOP for operative eyes. ConclusionThis text-processing pipeline can accurately capture surgical laterality and implant model usage from free-text operative notes of cataract and glaucoma surgeries, enabling extraction of clinical outcomes including visual acuities, intraocular pressure, and medications from the EHR system. Use of this approach with EHRs to assess ophthalmic surgical outcomes can benefit research groups interested in studying the safety and clinical efficacies of different surgical approaches.

5 year incidence of YAG capsulotomy and PCO after cataract surgery with single-piece monofocal intraocular lenses: a real-world evidence study of 20,763 eyes

ObjectivesTo evaluate the 3- and 5-year incidence of posterior capsule opacification (PCO) and neodymium-doped yttrium aluminium garnet (Nd:YAG) capsulotomy in patients following cataract surgery, comparing results for different single-piece acrylic hydrophilic and hydrophobic monofocal intraocular lens (IOL) models and other patient factors.Patients and methodsElectronic medical record data collected from seven United Kingdom (UK) National Health Service (NHS) ophthalmology clinics for routine, age-related (≥65 years) cataract surgeries that implanted single-piece acrylic monofocal IOLs during 2010–2013 were used to calculate 3- and 5-year incidence of Nd:YAG and PCO. IOL models of Alcon Acrysof, AMO Tecnis, Bausch & Lomb (B & L) Akreos, LenStec Softec, and Rayner Flex were analyzed. Pairwise comparisons were conducted between AcrySof IOLs and other IOLs using Bonferroni adjustment for multiplicity. Multivariate analyses were conducted adjusting for known confounders.ResultsThe incidence of Nd:YAG capsulotomy ranged between 2.4–12.6% at 3 years and 5.8–19.3% at 5 years post-cataract surgery. Similarly, the incidence of PCO ranged between 4.7–18.6% at 3 years and 7.1–22.6% at 5 years. When comparing all of the single-piece IOLs, AcrySof demonstrated the lowest incidence rates for both PCO and Nd:YAG (P < 0.001 for each comparison). From adjusted logistic regression analysis, AcrySof were associated with lower 3- and 5-year odds of Nd:YAG and PCO incidence.ConclusionsFollowing cataract surgery with single-piece monofocal IOLs different incidence rates of PCO were observed with different IOLs. AcrySof IOLs were associated with significantly lower incidence of PCO requiring Nd:YAG treatment over periods of 3 and 5 years.

Multifocal Intraocular Lenses Implantation in Presbyopia Correction. Literature Review

Reduced dependence on glasses is an increasingly common expectation among those who want to take advantage of new surgical opportunities, especially for patients who lead an active lifestyle. Currently, due to the increase in the duration of active life in people over 40, there is a need for effective correction of presbyopia. Multifocal intraocular lenses are increasingly used in the treatment of presbyopia. After implantation of multifocal intraocular lenses most patients have no need for spectacle or contact vision. However, complications can affect the patient’s quality of life and level of satisfaction. The most common complications of multifocal correction are blurred vision and the presence of optical phenomena (“halo” and “glare”), associated with residual ametropia, clouding of the posterior capsule, large pupil size, anomalies of the wave front, dry eye and lens decentration. The main reasons for this are the failure to attempt to neuroadapt a patient, the dislocation of the lens, the residual refractive error and the clouding of the lens. The review presents the main features of various models of multifocal intraocular lenses, their implantation techniques, associated complications and methods for their correction. The development of multifocal correction of presbyopia and ametropia seems to be a promising direction in ophthalmic surgery.

Surface properties of commercially available hydrophobic acrylic intraocular lenses: Comparative study

To analyze and compare the surface properties of commercially available hydrophobic acrylic intraocular lenses (IOLs). Eye Clinic, University of Trieste, Italy. Experimental study. The following 6 single-piece hydrophobic acrylic IOL models with the same dioptric power were studied and compared: Clareon SY60WF, Tecnis PCB00, enVista MX60, CT Lucia 601P, Vivinex iSert XY1, and iSert 251. Topography of the IOL surface was analyzed using atomic force microscopy (AFM). Surface contact angle measurements using the sessile drop method were performed to assess IOL wettability. The AFM analysis showed that the Vivinex iSert XY1 IOL and Clareon SY60WF IOL had the lowest surface roughness (P<.05); there was no statistically significant difference in surface roughness between the those 2 IOL models (P>.05). Surface contact angle measurements showed that the iSert 251 IOL had the highest hydrophobicity. The CT Lucia 601P IOLhad the lowest contact angle of all IOL models. The AFM analysis and surface contact angle measurements of all IOLs tested showed that the Vivinex iSert XY1 IOL and Clareon SY60WF IOL had the best topographic features. The smoother, more regular surface of these new IOL models might reduce cell adhesion and therefore lower the incidence of posterior capsule opacification.

Use of low-vault posterior chamber collagen copolymer phakic intraocular lenses for the correction of myopia: a 3-year follow-up.

Phakic intraocular lens (pIOL) models have indicated an association between cataract formation and inadequate vaulting. In this study, the efficacy and safety of low-vault posterior chamber pIOLs in the correction of myopia were examined over 3years. From 316 patients undergoing surgery, 14 eyes with a low vault (≤ 150μm) were examined from 14 patients. After implanting the Visian Implantable Collamer pIOL for the correction of myopia (moderate and high), the pIOL vault, endothelial cell loss, uncorrected distance visual acuity (UDVA), corrected DVA (CDVA), and detrimental events were examined over 3years. Based on the findings, the mean spherical equivalent reduced from - 8.15 ± 3.29 before surgery to - 1.02 ± 0.75 diopters 3years after the surgery. In terms of visual outcomes, the mean UDVA (Log MAR) significantly increased from 0.95 ± 037 to 0.27 ± 0.28, and the mean CDVA also increased from 0.99 ± 0.11 to 0.06 ± 0.08 (P < 0.05). The mean indices of safety and efficacy were respectively 1.075 and 0.748. The eyes lost not more than two visual acuity lines. Based on the findings, 82% achieved 0.80 or better CDVA, while the total endothelial cell loss was 7.96% during 3years. Overall, vision-threatening conditions were not reported. The introduced pIOL can be considered a safe and efficient method for myopia at moderate to high levels.

Versatile optical setup customized to verify the quality of spherical and aspheric intraocular lenses.

This paper proposes a customized and versatile optical setup to evaluate the optical performance of different commercially available intraocular lenses (IOLs). The setup was used to measure the wavefront error induced by different IOL models, verifying and analyzing the magnitude of low- and high-order aberrations induced by currently available IOLs. Independent analyses included non-toric spherical and aspheric IOLs from three different manufacturers. Three different dioptric powers were tested: 15, 20, and 25 D from each model. Dioptric power, induced cylinder, and spherical aberration were measured in each tested lens. All lenses had dioptric power within the tolerated margin of error. Induced cylinder was also within the current standards and clinically irrelevant. Spherical aberration varied according to the analyzed dioptric power and to the IOL model. We reported on the importance of the plane where the spherical aberration is reported, IOL or cornea. All analyzed IOLs were within current standards for the dioptric power and induced cylinder. Spherical IOLs had higher spherical aberration measured at the IOL plane.

Refractive Outcomes after Pars Plana Vitrectomy and Scleral Fixated Intraocular Lens with Gore-Tex Suture

To evaluate refractive outcomes after combined pars plana vitrectomy (PPV) and scleral fixation of an intraocular lens (IOL) using Gore-Tex suture. Retrospective cohort study. Fifty-five eyes from 53 patients who underwent PPV with a Gore-Tex sutured IOL from June 2013 through December2017. Patients who underwent combined PPV and scleral fixation of an IOL with Gore-Tex suture were identified. All eyes underwent scleral fixation of either an Akreos A060 or enVista MX60 IOL and were fixated either 2 mm or 3 mm posterior to the limbus. Postoperative manifest refractions were performed at least 3 months after surgery and were compared with preoperative predicted target refraction based on in-the-bag IOL calculations. Subgroup analyses based on sclerotomy placement and IOL models were performed. Postoperative manifest refraction and difference with sclerotomy placement and IOL model. The mean postoperative spherical equivalent (SEQ) was -0.99±1.00 diopters (D). The mean difference in SEQ (ΔSEQ) from preoperative predicted target was -0.64±1.00 D. The IOL was fixated 2 mm posterior to the limbus in 14 eyes and 3 mm in 41 eyes. Within these 2 subgroups, the mean postoperative SEQ was -1.53±1.35 D for fixation 2 mm posterior to the limbus and -0.82±0.83 D for fixation 3 mm posterior to the limbus (P= 0.09). The mean ΔSEQ was -0.43±0.71 D for fixation 3 mm posterior to the limbus and -1.35±1.32 D for fixation 2 mm posterior to the limbus (P= 0.03). The mean amount of surgically induced astigmatism in the overall cohort was 0.77±0.65 D. The mean ΔSEQ and induced astigmatism were similar between IOL models. After combined PPV and Gore-Tex-sutured IOL implantation, mean postoperative refractive outcomes were more myopic when the IOL was fixated 2 mm from the limbus compared with 3 mm from the limbus. No significant difference was found between IOL models. Based on these results, future implant power calculations may be adjusted to approximate preoperative target refraction more accurately.

Large-scale opacification of a hydrophilic/hydrophobic intraocular lens.

To determine the prevalence and risk factors related to the opacification of the LS-502-1 intraocular lens. Cross-sectional study including patients submitted to cataract surgery between January 2010 and March 2012, with implantation of the LS-502-1 intraocular lens. Past medical history was registered and a complete ophthalmologic evaluation, that included best-corrected visual acuity, slit-lamp examination and fundoscopy, was performed. Anterior segment photographs were taken whenever intraocular lens opacification was present. One hundred and sixty-nine eyes of 154 patients were included, mean age 78.5 ± 7.9 years. The average follow-up after intraocular lens implantation was 65.6 ± 10.0 months. Intraocular lens opacification was seen in 53.3% (n = 90) and presented as one of four different patterns: peripheral (15.6%, n = 14), central (4.4%, n = 4), diffuse (71.1%, n = 64) and superficial white deposits (8.9%, n = 8). There was no statistically significant association with systemic or ophthalmic conditions. In patients with bilateral implantation, intraocular lens opacification in one eye was significantly related to intraocular lens opacification in the fellow eye. A significant variability in opacification was found across intraocular lens serial numbers: the odds ratio for opacification in intraocular lens with serial number beginning with 200003 was 6.0 when comparing with the remaining lenses. The opacification prevalence of the LS-502-1 intraocular lens was 53.3%, which is the highest ever described for any intraocular lens model. Our results suggest that this occurrence is secondary to an interaction between unknown patient variables and problems related to intraocular lens manufacturing and storage procedures.

Evaluation of intraocular lens mechanical stability

To compare mechanical characteristics and stability of Clareon CNA0T0 intraocular lens (IOL) with 4 currently marketed monofocal IOLs and to evaluate axial displacement and simulated dioptric power shift using a range of compression diameters. Alcon Laboratories, Inc., Fort Worth, Texas, USA. Experimental study. Clareon CNA0T0, AcrySof SN60WF, enVista MX60, Tecnis ZCB00, and Vivinex iSert XY1 IOLs (10 per group) were assessed using standardized methods for axial displacement, optic decentration, and optic tilt per the International Organization for Standardization ISO11979-3. Axial displacement was also measured over a range of compression diameters (9.0 to 11.0mm). At 10.0mm compression, the mean axial displacement for the CNA0T0 IOL (0.02mm±0.01 [SD]) was significantly lower than for the MX60, ZCB00, and XY1 IOLs (P<.005). At all compression diameters, the CNA0T0 and SN60WF IOLs had the lowest levels of axial displacement and corresponding simulated dioptric power shift at the corneal plane versus other IOL models. At 10.0mm compression, the mean optic decentration was within ±0.06mm for all models, and there were no significant differences between the CNA0T0 IOL and other IOLs. At 10.0mm compression, the mean optic tilt was no greater than 1.2 degrees for all IOL models evaluated; however, the mean optic tilt for the CNA0T0 IOL was significantly lower than for the MX60 IOL (P<.005). The CNA0T0 and SN60WF IOLs showed the lowest levels of axial displacement and corresponding simulated dioptric power shift over all tested compression diameters, indicating they might provide the most consistent refractive outcomes.

Virtiol - Simulation of Quality of Vision with Multifocal and Edof Intraocular Lenses.

This was an experimental study involving atotal of 20 volunteers with artephakia (35 eyes). Each volunteer rated 5 types of IOLs, 4 presbyopia-correcting IOLs - WIOL-CF, Tecnis Symphony ZXR00, Acrysof IQ PanOptix TFNT00, M-flex 630 F, and as areference lens, we used the monofocal IOL Acrysof SA60AT. The corrected distance visual acuity (CDVA), distance corrected intermediated visual acuity (DCIVA) and distance corrected near visual acuity (DCNVA) were measured. Additionally, volunteers evaluated the quality of vision under normal or changed lighting conditions, and ranked IOL on scale from 1 to 5. The CDVA evaluated using the VirtIOL device was very good for all tested IOLs (0.04-0.09 log MAR) with minimum differences. However, CDVA without simulator (-0.01 logMAR) was statistically significantly better in all cases. DCIVA was also very similar in each of the investigated IOLs, surprisingly even with monofocal IOL (0.21-0.23 logMAR), without using simulator the DCIVA was statistically significantly worse (0.36 logMAR). The DCNVA was the best for PanOptix intraocular lens (0.22 logMAR); M-flex, Symphony and WIOL-CF lenses had comparable results (0.31-0.34 logMAR). Again, surprisingly similar results were obtained with the use of monofocal IOL (0.36 ± 0.14). Subjective perception of vision through the IOLs was best rated for the monofocal control IOL, whereas Symphony, WIOL-CF and M-flex did not show any statistically significant difference either with or without glare. All tested IOLs were statistically significantly better if compared to PanOptix with or without glare. Simulation of vision through IOLs using VirtIOL simulator allows to compare different models of multifocal IOLs from the viewpoint of visual acuity and subjective perception. However, some caution should be exercised when evaluating the results, given that in our experiments, the monofocal IOL achieved relatively good results at near distance, which does not correspond to clinical experience. On the contrary, from the comparison of the results of CDVA without and with VirtIOL, it is obvious that visual acuity is slightly adversely affected by added optics.

In vitro and schematic model eye assessment of glare or positive dysphotopsia-type photic phenomena: Comparison of a new material IOL to other monofocal IOLs

To compare the glare-type photic phenomena for a new intraocular lens (IOL) to other monofocal IOLs, and to investigate how IOL design features might affect these phenomena. Alcon Laboratories, Inc., Fort Worth, Texas; John A Moran Eye Center, University of Utah, Salt Lake City, USA. Schematic model eye evaluation and invitro study. Five monofocal IOL models (Clareon CNA0T0, Tecnis ZCB00, enVista MX60, Eternity W-60, and Vivinex XY1) were used to evaluate glare or positive dysphotopsia-type phenomena. Optical simulations of incoming light were generated using nonsequential ray-tracing software based on a collimated light source for various off-axis angles of illumination. The simulation analyses were verified using a laboratory invitro bench-top glare measurement system. The Clareon and Vivinex IOLs produced focused off-axis images with negligible peripheral glare characteristics. The Tecnis and enVista IOLs produced dispersed images with additional glare characteristics at 45 degrees of off-axis illumination and higher. The Eternity IOL showed the highest edge-reflected glare characteristic, likely because of its straight optic edge geometry. The laboratory bench images and glare intensity profiles were consistent with the simulation data. Invitro and nonsequential ray-tracing evaluations showed that straight optic edges and peripheral nonimaging optic geometry might contribute to positive dysphotopsia. The IOL designs with optic edge curvature and full functional optics demonstrated the lowest level of glare-type photic phenomena. Only clinical studies can confirm whether the differences observed between the IOLs invitro are clinically significant.

Characterization of optical performance with defocusing curve: Analysis of two refractive intraocular lens models with high and medium addition

PurposeTo characterize the optical performance of two models of refractive bifocal intraocular lenses, with medium and high addition, using defocus curves. Methods20 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. ResultsMean final residual refraction in spherical equivalent was +0.10±0.07D in the LS-313MF30 group and +0.12±0.10D 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 50cms, and the high addition IOL provided better VA in near distance up to 25cms. ConclusionsThe high addition intraocular lens provides better visual acuity in the spatial range from infinity to the point close to 25cm. 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.