IOL Design Research Articles

Clinical validation of an adaptive optics visual simulator (VAO), a new instrument for the clinic

Purpose: To validate in the clinic the Adaptive Optics Visual Simulator VAO (Voptica SL, Murcia, Spain).Setting: Laboratory of Clinical Optics, University of Murcia, Spain.Methods: Adaptive optics visual simulators have been widely used in research laboratories for various applications within the visual sciences, however, their use in clinical practice has been limited. Recently, an Adaptive Optics Visual Simulator (VAO, Voptica S.L) has been commercially introduced as a medical device for clinical use. VAO combines optical measurements and visual testing within the same compact instrument. It incorporates a Hartmann‐Shack wave‐front sensor to measure objective refraction and aberrations, together with a spatial light modulator capable of correcting or inducing any optical profile while performing visual testing. In seventy‐six eyes from 38 subjects, subjective refraction (SR) was measured using VAO and trial frame as a gold standard (GS). The agreement of spherical equivalent (M) and cross cylinders (J0 and J45) between SR with VAO and with the GS was estimated using different statistic parameters: 95% confidence limits (CL), Student's t‐test or Wilcoxon Rank Sum and Pearson correlation coefficient (r).Results: There was a strong correlation (r ranged between 0.88 and 0.99) for subjective refraction (M, J0, J45) between GS and VAO and there were not statistically significant differences (p > 0.05). The 95% CL of M, J0 and J45 were ±0.58, ±0.14 and ±0.14 D respectively. In addition to the subjective refraction, the visual acuity was also validated comparing BCVA values from GS with those from VAO, a high correlation (ρ = 0.73) was found for BCVA between both methods. Individual differences in BCVA between both methods were around or below 1 line since 95% CI was ±0.10 LogMAR.Conclusions: Our findings suggest that VAO, the new instrument for vision analysis based on adaptive optics, provides measurements that are comparable to those of the gold standard technique in healthy eyes with 73.7% of the spherical equivalent (M) differences between them within ±0.25 D and 68.4% for BCVA within ±0.05 LogMAR. Thus, subjective refraction found with VAO can be used for prescribing, as a baseline to simulate any optical profile and to customize the selection of the ablation and the IOL design in refractive surgery.

EDOF intraocular lens design: shift in image plane vs object vergence

BackgroundTo compare 2 different design scenarios of EDOF-IOLs inserted in the Liou-Brennan schematic model eye using raytracing simulation as a function of pupil size.MethodsTwo EDOF IOL designs were created and optimized for the Liou-Brennan schematic model eye using Zemax ray tracing software. Each lens was optimized to achieve a maximum Strehl ratio for intermediate and far vision. In the first scenario, the object was located at infinity (O1), and the image plane was positioned at far focus (I1) and intermediate focus (I2) to emulate far and intermediate distance vision, respectively. In the second scenario, the image plane was fixed at I1 according to the first scenario. The object plane was set to infinity (O1) for far-distance vision and then shifted closer to the eye (O2) to reproduce the corresponding intermediate vision. The performance of both IOLs was simulated for the following 3 test conditions as a function of pupil size: a) O1 to I1, b) O1 to I2, and c) O2 to I1. To evaluate the imaging performance, we used the Strehl ratio, the root-mean-square (rms) of the spot radius, and the spherical aberration of the wavefront for various pupil sizes.ResultsEvaluating the imaging performance of the IOLs shows that the imaging performance of the IOLs is essentially identical for object/image at O1/I1. Designed IOLs perform dissimilarly to each other in near-vision scenarios, and the simulations confirm that there is a slight difference in their optical performance.ConclusionOur simulation study recommends considering the difference between object shift and image plane shift in design and test conditions to achieve more accurate pseudoaccommodation after cataract surgery.

MT6 Global Systematic Review on the Incidence of Nd:Yag Laser Capsulotomy Post-Cataract Surgery in Eyes Implanted with the Clareon Intraocular Lens (IOL) Implanted Eyes

The improvements in surgical technique has made cataract surgery an increasingly safe procedure, posterior capsule opacification (PCO), however, remains the most common complication post-cataract surgery. PCO development has been associated with IOL design, IOL biomaterial, and other factors. Nd:YAG laser capsulotomy is used to treat clinically significant PCO.

Advanced Optical Wavefront Technologies to Improve Patient Quality of Vision and Meet Clinical Requests

Adaptive optics (AO) is employed for the continuous measurement and correction of ocular aberrations. Human eye refractive errors (lower-order aberrations such as myopia and astigmatism) are corrected with contact lenses and excimer laser surgery. Under twilight vision conditions, when the pupil of the human eye dilates to 5-7 mm in diameter, higher-order aberrations affect the visual acuity. The combined use of wavefront (WF) technology and AO systems allows the pre-operative evaluation of refractive surgical procedures to compensate for the higher-order optical aberrations of the human eye, guiding the surgeon in choosing the procedure parameters. Here, we report a brief history of AO, starting from the description of the Shack-Hartmann method, which allowed the first in vivo measurement of the eye's wave aberration, the wavefront sensing technologies (WSTs), and their principles. Then, the limitations of the ocular wavefront ascribed to the IOL polymeric materials and design, as well as future perspectives on improving patient vision quality and meeting clinical requests, are described.

Update on Biometry and Lens Calculation - A Review of the Basic Principles and New Developments.

These days, accurate calculation of artificial lenses is an important aspect of patient management. In addition to the classic theoretical optical formulae there are a number of new approaches, most of which are available as online calculators. This review aims to explain the background of artificial lens calculation and provide an update on study results based on the latest calculation approaches. Today, optical biometry provides the computational basis for theoretical optical formulae, ray tracing, and also empirical approaches using artificial intelligence. Manufacturer information on IOL design and IOL power recorded as part of quality control could improve calculations, especially for higher IOL powers. With modern measurement data, there is further potential for improvement in the determination of the axial length to the retinal pigment epithelium and by adopting a sum-of-segment approach. With the available data, the cornea can be assumed to be a thick lens. The Kane formula, the EVO 2.0 formula, the Castrop formula, the PEARL-DGS, formula and the OKULIX calculation software provide consistently good results for artificial lens calculations. Excellent refractive results can be achieved using these tools, with approximately 80% having an absolute prediction error within 0.50 dpt, at least in highly selected study populations. The Barrett Universal II formula also produces excellent results in the normal and long axial length range. For eyes with short axial lengths, the use of Barrett Universal II should be reconsidered; in this case, one of the methods mentioned above is preferable. Second Eye Refinement can also be considered in this patient population, in conjunction with established classic third generation formulae.

Predicting the biomechanical stability of IOLs inside the postcataract capsular bag with a finite element model

Background and Objectives: Although cataract surgery is a safe operation in developed countries, there is still room for improvement in terms of patient satisfaction. One of the key issues is assessing the biomechanical stability of the IOL within the capsular bag to avoid refractive errors that lead to a second surgery. For that purpose, a numerical model was developed to predict IOL position inside the capsular bag in the short- and long-term. Methods: A finite element model containing the implanted IOL, the postcataract capsular bag, the zonules, and a portion of the ciliary body was designed. The C-loop hydrophobic LUCIA IOL was used to validate the numerical model and two more worldwide IOL designs were tested: the double C-loop hydrophobic POD FT IOL and the plate hydrophilic AT LISA IOL. To analyze the biomechanical stability in the long-term, the effect of the fusion footprint, which occurs days following cataract surgery, was simulated. Moreover, several scenarios were analyzed: the size and location of the capsulorexhis, the capsular bag diameter, the initial geometry of the capsular bag, and the material properties of the bag. Results: The biomechanical stability of the LUCIA IOL was simulated and successfully compared with the in vitro results. The plate AT LISA design deformed the capsular bag diameter up to 11.0 mm against 10.5 mm for the other designs. This design presented higher axial displacement and lower rotation, 0.19 mm and 0.2∘, than the C-loop design, 0.09 mm and 0.9∘. Conclusions: All optomechanical biomarkers were optimal, assuring good optical performance of the three IOLs under investigation. Our findings showed that the capsulorexhis size influences the stiffness of the capsular bag; however, the shape in the anterior and posterior curvature surfaces of the bag barely affect. The results also suggested that the IOL is prone to mechanical perturbations with the fusion footprint, but they were not high enough to produce a significant refractive error. The proposed model could be a breakthrough in the selection of haptic design according to patient criteria.

Clinical Performance of Extended Depth of Focus (EDOF) Intraocular Lenses - A Retrospective Comparative Study of Mini Well Ready and Symfony.

PurposeExtended depth of focus intraocular (EDOF) IOLs form a bridge between single- and multifocal IOL design. This study aimed to compare clinical outcomes obtained after implanting two different optical designs of EDOF IOLs: the Mini Well Ready (SIFI Medtech, Catania, Italy) and Tecnis Symfony (Abbott Laboratories, Illinois, USA).MethodsThe retrospective observational study included 61 patients (122 eyes) who underwent bilateral implantation of the Mini Well Ready IOL (32 patients) or the Tecnis Symfony IOL (29 patients). The following preoperative and postoperative parameters were evaluated: spherical equivalent, anterior astigmatism, pupil size, monocular and binocular uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA), monocular and binocular uncorrected intermediate visual acuity (UIVA) and distance-corrected intermediate visual acuity (DCIVA), monocular and binocular uncorrected near visual acuity (UNVA) and distance-corrected near visual acuity (DCNVA). In the 6 months postoperative period, defocus curve, contrast sensitivity, photopic phenomena, and posterior capsule opacification were assessed.ResultsThe patients receiving the Tecnis Symfony had slightly better monocular and binocular UDVA and CDVA than with the Mini Well Ready IOL, the differences were not statistically significant. Whereas the UIVA, DCIVA, UNVA, DCNVA, UNVA and DCNVA values were higher in the Mini Well Ready group, the differences were not significant. There were no significant between-group differences regarding the defocus curve for the vast majority of tested vergences. Dysphotopsias postoperatively were assessed at 6 months.ConclusionPatients receiving both the Mini Well Ready and Symfony IOLs had excellent visual acuity outcomes and spectacle independence.

In Vitro Chromatic Performance of Three Presbyopia-Correcting Intraocular Lenses with Different Optical Designs.

Most of the new premium models of intraocular lenses for presbyopia correction use diffractive optics in their optical design. The presence of multiple foci and the difference of the diffractive efficiency for different wavelengths have a great impact in the lens optical performance. In this context, there is a limited information available for clinicians to understand the optical principles that differentiate each design and their potential influence on clinical outcomes. Optical bench studies with polychromatic light are necessary to solve this limitation. In this work, a custom made optical bench was employed to assess with polychromatic light the through the focus optical quality of three different IOL designs: trifocal, EDOF effect; and enhanced monofocal. By using different and complimentary approaches: images of the USAF test, axial PSFs and TF-MTFs, each design revealed its intrinsic features, which were not previously reported for these IOLs models in a comparative way. It was found that the chromatic aberration plays a very important role in the performance of each IOL. Our results could help clinicians to understand the optical principle of each lens and also provide useful information for choosing the lens that best suits the needs of the individual patient.

POSB18 A Syliterature Review of the Clinical Evidence on ND:YAG Laser Capsulotomy Incidence Post-Cataract Surgery in Eyes Implanted with the Clareon Intra-Ocular LENS (IOL) Implanted Eyes

Posterior capsular opacification (PCO) is the most common complication post-cataract surgery, and its development is associated with the IOL material and design, and other factors. Clinically significant PCO is treated by Nd:YAG laser capsulotomy. The Clareon hydrophobic acrylic IOL is a new single-piece IOL, first launched in Europe in 2017. The purpose of this literature review was to collate and report Nd:YAG capsulotomy incidence post-cataract surgery in patients implanted with the Clareon IOL.

Evaluation of a Novel Zonular Tension Restoring Accommodating Silicone IOL Design: Pilocarpine and Cyclopentolate-Induced Effect 20 Months after Implantation.

Purpose To investigate a novel zonular-stress restoring accommodating 1-piece silicone IOL. Setting. Angeles City, Philippines. Design Prospective randomized bilateral study. Methods Each patient received a study IOL (ActaLens™, Emmetrope, La Canada, CA) in one eye and a control IOL (CrystaLens® AO, B&L, USA, or an AcrySof IQ®, Alcon, USA) in the contralateral eye to allow for intraindividual comparison. At the 20-month follow-up, two measurement days were set to measure all eyes before and after instilling 2% pilocarpine on the first day and 1% cyclopentolate on the second measurement day using an optical biometry device (Lenstar, Haag-Streit AG, Switzerland), respectively. PCO was graded by two examiners independently at the slit lamp. Results In total, 16 eyes of 8 patients were included. In the study group and the control group, the pilocarpine-induced ACD shift was 0.32 mm (SD: 0.12) (p=0.014) and 0.04 mm (SD: 0.16) (p=0.854), respectively. In the study group and the control group, the mean cyclopentolate-induced ACD shift was 0.14 (SD: 0.06) (p=0.014) and 0.03 mm (SD: 0.03) (p=0.181), respectively. PCO and Nd : YAG rates were higher in the study group, but differences were not found to be significant (AcrySof vs. ActaLens p=0.100 and CrystaLens vs. ActaLens p=0.174). Conclusion The investigated IOL is a novel concept for an accommodating IOL, and results showed a moderate pilocarpine-induced forward shift of the IOL 20 months following implantation. For all patients, the investigated IOL seems to have a higher PCO rate compared to standard monofocal IOLs.

Refractive Lens Exchange Candidate Selection

Refractive lens exchange (RLE) is a popular procedure in presbyopic patients who desire the full range of vision. Advances in IOL designs can allow patients to achieve distance, intermediate, and near vision without the need for glasses. Seeing a smart phone or computer without correction is a significant lifestyle benefit. Patient satisfaction has been very high with both multifocal and extended depth of focus implants. Candidates for RLE may have any refractive error and are usually presbyopic and desire the full range of vision. Presbyopic low hyperopes are very motivated, as they never wore distance glasses when they were younger, started with readers in their early 40s, and now need glasses for both distance and near activities. Most hyperopic, myopic, and astigmatic refractive errors can be treated with a RLE. Patients should have a normal cornea, macula, optic nerve, and peripheral retina. Diagnostic testing should demonstrate a normal corneal topography without evidence of irregular astigmatism. CE Notification: This article is available as a COPE accredited CE course. You may take this course for 1-hour credit. Read the article and take the qualifying test to earn your credit. Click here to Enroll (https://www.crojournal.com/refractive-lens-exchange-candidate-selection)

Reply.

We thank Dr. Galvis and team for the attentive reading of our study on defocus curves. In our study, we compared the visual performance of 4 presbyopia-correcting IOLs and found that the 4 IOLs provided patients with equally good corrected distance visual acuity (CDVA). The extended depth-of-focus IOL demonstrated a slightly better intermediate CDVA, however a worse near CDVA than the other IOLs, with only the panfocal IOL presenting a better intermediate VA at 50 cm. We agree that the patients' uncorrected vergence is 0.25 D for an object at 4 m distance. In our study, the manifest refraction was performed with Early Treatment Diabetic Retinopathy Study charts at 4 m distance, and the defocus curves were performed with the values of this manifest refraction. Thus, the vergence of 0.25 D of measuring VA at 4 m was already included in the manifest refraction used for defocus curve measurement, and consequently, the 4 m distance of the defocus curve can be seen as the reciprocal of the diopters used for measurement. The same defocus curve testing was used for all IOLs, allowing a relative comparison of the differences between the IOLs. Other published studies on the visual performance of IOLs, including that of Gundersen and Potvin, used the same methods to test VA and defocus curves.1–3 One of the main purposes of defocus curves is that they allow the comparison of the visual performance of IOLs with different designs, not just the simulation of visual performance in daily life. We agree that binocular measurements reflect more real-world viewing because of the presence of retinal disparity cues in addition to blur. However, the monocular defocus curve approach is suitable to compare the visual performance of various IOL designs. Because the main aim of our study was to compare the visual performance of presbyopia-correcting IOLs, the monocular defocus curve was the method of choice. The testing of positive IOLs in defocus curves is traditionally performed to compare the vision of preoperated patients with that of postoperated patients.4 We included positive defocus testing to allow the comparison of other published studies that had tested with an overcorrection of +1.00 to −4.00 D.2,3 We agree with the authors that positive IOL-simulated defocus testing takes some additional time; however, in our study, only 3 additional lens powers per eye were tested up to +1.50 D vs 8 lens powers for the myopic side up to −4.00 D.5 Thus, the impact on additional test time was rather low. In addition, defocus curves for both positive and negative IOLs have an important advantage in that they allow an understanding of how well residual refractive errors are tolerated by IOL designs and if the VA reduces monotonically as a function of defocus on this side. In our study, there were no differences between IOLs identified, with all IOLs showing a similar drop of VA as a function of induced positive IOLs. In conclusion, we agree that the relationship between lens vergence and distance defocus is essential for interpreting the resultant defocus curves as performed in our study.

Comparison of wavefront aberrations in eyes with multifocal and monofocal iols before and after Nd:YAG laser capsulotomy for posterior capsule opacification.

The aim of this study was to compare wavefront aberrations before and after Nd:YAG capsulotomy in multifocal intraocular lens (MfIOL) and monofocal (MoIOL) pseudophakic eyes with posterior capsule opacification (PCO). Wavefront aberrations were measured using a ARK-10000 topographer before and after Nd:YAG capsulotomy in eyes that underwent MfIOL or MoIOL implantation and developed PCO. Total and higher-order aberrations (HOAs) values were evaluated as root mean square (RMS). The study included 64 eyes with MfIOLs (64 patients) and 72 with MoIOLs (72 patients) that developed PCO. Total RMS values before and 1month after Nd:YAG capsulotomy were 0.863 ± 0.27 and 0.504 ± 0.24 in the MFIOL group and 0.862 ± 0.31 and 0.466 ± 0.26 in the MoIOL group, respectively. Total RMS values did not differ significantly between the groups before (p = 0.914) or 1month after Nd:YAG laser capsulotomy (p = 0.357), but decreased significantly after Nd:YAG capsulotomy compared to baseline in both the MfIOL (p = 0.027) and MoIOL (p = 0.012) groups. HOA values before and 1month after Nd:YAG capsulotomy were 0.546 ± 0.23 and 0.364 ± 0.19 in the MfIOL group and 0.500 ± 0.21 and 0.346 ± 0.18 in the MoIOL group, respectively. HOA values did not differ significantly before (p = 0.828) or after Nd:YAG capsulotomy (p = 0.111), while both groups showed significant reduction in HOAs after Nd:YAG capsulotomy (MfIOL: p = 0.021, MoIOL: p = 0.027). Nd:YAG capsulotomy reduces total and HOAs to the same extent in eyes with both MfIOLs and MoIOLs, with no significant impact of the IOL design.

Intra Ocular Lens Technology - A Review of Journey from Its Inception

Aim: To understand the advancement and development in Intraocular lens.
 Introduction: Now a day cataract surgery is the most commonly performed surgical procedure in the world. Removing the opaque, cataractous lens and replacing it with an artificial lens to achieve near to normal visual acuity post operatively is not only accepted but by and large a mandatory norm.
 Findings: The lenses used for the purpose are called Intra Ocular Lens. Ridley’s brilliance has improved the lives of many millions of people. The gradual improvement in IOL design, first in making flexible lenses, then the ever-improving optical outcomes have meant that vision after cataract surgery has never been better – in the developed world.
 Conclusion: We have come a long way in terms of IOL design, but many people with cataracts in rural areas of the developing world, need help to catch up.

Resveratrol Inhibits Wound Healing and Lens Fibrosis: A Putative Candidate for Posterior Capsule Opacification Prevention.

Posterior capsule opacification (PCO) is a common complication of cataract surgery. In addition to improved surgical methods and IOL designs, it is likely additional agents will be needed to improve patient outcomes. Presently no pharmacological agent is in clinical use to prevent PCO. Here we investigate the putative ability of resveratrol (RESV), a naturally occurring polyphenol, as a therapeutic agent. The human lens epithelial cell line FHL124, a human lens capsular bag model, and central anterior epithelium were used as experimental systems. Standard culture was in 5% fetal calf serum Eagle's minimum essential medium; 10 ng/mL transforming growth factor-β2 (TGFβ2) was used to induce fibrotic changes. A scratch wound assay was used to measure cell migration and the patch assay was used to assess matrix contraction by FHL124 cells. Protein expression was assessed by immunocytochemistry and Western blot and gene expression by quantitative RT-PCR. In capsular bags, cell growth across the posterior lens capsule, capsular wrinkling, and epithelial-to-mesenchymal transition were determined by image analysis. In FHL124 cells, addition of 30 μM RESV significantly impeded cell migration in a wound-healing assay. RESV significantly inhibited TGFβ2-induced expression of the myofibroblast marker alpha-smooth muscle actin (α-SMA) at both the message and protein levels, as well as significantly inhibiting matrix contraction induced by TGFβ2. In human capsular bags, 30 μM RESV significantly inhibited cell growth. TGFβ2-induced α-SMA expression and capsular wrinkling were also significantly inhibited by RESV treatment. RESV significantly suppressed expression of TGFβ2-induced genes associated with fibrotic disease, including matrix metalloproteinase-2 in FHL124 cells, capsular bags, and central anterior epithelium. RESV can counter PCO-related physiological events in two human lens model systems. RESV therefore has the potential to be used as a candidate agent for the prevention of PCO, which in turn could benefit millions of cataract patients.

PMD24 - ASSOCIATION BETWEEN IOL DESIGN AND INCIDENCE OF PCO AND ND:YAG CAPSULOTOMY: A RETROSPECTIVE REAL WORLD EVIDENCE STUDY IN THE UK

Patients post-cataract surgery may experience abnormal proliferation of lens epithelial cells on the posterior capsule (posterior capsule opacification, PCO). Neodymium-doped yttrium aluminium garnet (Nd:YAG) laser capsulotomy is considered a safe surgical treatment for PCO, but could occasionally lead to further complications. Existing studies have reported numerous factors influencing PCO incidence including IOL material and design. In this study, real-world incidence of both PCO and Nd:YAG in the 5 years post-cataract surgery were assessed in a large UK population, including their association with IOL material. Patients (≥65 years) undergoing cataract surgery with ‘in-the-bag’ placement of acrylic monofocal single-piece IOLs between 2010-2013 were included. Data were collected from Electronic Medical records (EMR) from 7 UK NHS Ophthalmic clinics; only IOL models used in at least 500 procedures were included. The analysis focused on the association between the IOL model and the risk of PCO and Nd:YAG. Incidence proportion of PCO and Nd:YAG at 5 years from cataract surgery was calculated for each IOL model. Pairwise comparisons were conducted between AcrySof IOLs and other IOLs using Bonferroni adjustment for multiplicity. Multivariate analyses were also conducted adjusting for known confounders. Incidence proportion of Nd:YAG at 5 years post-cataract surgery was 5.8% for AcrySof (CI 5.2%-6.4%, n=5,342); this was significantly lower than Tecnis (8.5%, CI 7.8%-9.2%, n=5,609), B&L (15.2%, CI 14.3%-16.0%, n=6,847) and Lenstec (19.3%, CI 17.9%-20.8%, n=2,964) (all P values <0.001). AcrySof IOLs also had significantly lower incidence proportion of PCO compared with the other IOLs. This real world evidence study demonstrated that hydrophobic single-piece AcrySof IOLs are associated with a significantly lower incidence of Nd:YAG capsulotomy and PCO post cataract surgery, at a long-term follow-up of five years.

Visual acuity of pseudophakic patients predicted from in-vitro measurements of intraocular lenses with different design.

The optical quality of a set of IOLs (modeling set: one monofocal and two bifocals) was assessed through focus by the area under the modulation transfer function (MTFa) metric and related to the visual acuity (VA) defocus curves of pseudophakic patients implanted with said IOLs. A non-linear relationship between the MTFa and clinical VA was obtained with an asymptotic limit found to be the best VA achievable by the patients. Two mathematical fitting functions between clinical VA and MTFa were derived with high correlation coefficients (R2≥0.85). They were applied to the MTFa obtained from a different set of IOLs with advanced designs (trial set: one extended range of vision -ERV-, one trifocal ERV and one trifocal apodized) to predict VA versus defocus of patients implanted with these IOLs. Differences between the calculated VA and the clinical VA for both fitting models were within the standard deviation of the clinical measurements in the range of -3.00 D to 0.00 D defocus, thus proving the suitability of the MTFa metric to predict clinical VA performance of new IOL designs.

Clinical outcomes of a novel IOL design for Femtosecond laser assisted cataract surgery

Clinical outcomes of a novel IOL design for Femtosecond laser assisted cataract surgery

Dysphotopsia: a multifaceted optic phenomenon.

To summarize the literature on dysphotopsia, focusing on strategies for management and prevention. Clinical studies and ray-tracing diagrams have improved our understanding of the risk factors for positive and negative dysphotopsiae. Well known management and prevention strategies such as piggyback IOL, reverse optic capture, Nd:YAG capsulotomy, and IOL exchange are reviewed, as well as newer strategies such as the infertemporal approach to IOL implantation, 'in-the-bag nasal optic truncation' and new IOL design implantation, and new IOL design. Positive and negative dysphotopsiae are known to occur in a number of patients after cataract surgery. Although studying dysphotopsiae has provided many challenges given its subjective patient experience and its multifactorial cause, these same challenges have generated new theories and ideas regarding dysphotopsiae. A better understanding of the available methods for treatment and prevention can improve management of dysphotopsiae and patient satisfaction.

Evaluation of the anterior segment parameters after Nd: YAG laser Capsulotomy: Effect the design of intraocular lens Haptic.

Objective:To evaluate the changes in anterior segment parameters after neodymium–yttrium-aluminum-garnet (Nd:YAG) laser capsulotomy in 1-piece and 3-piece IOLs.Methods:In an institution, 65 eyes of 65 consecutive pseudophakic patients with posterior capsule opacification underwent Nd:YAG laser capsulotomy. The patients were divided into two groups according to the IOL type. Group-1 consisted of 35 subjects with 1-piece IOL and Group-2 consisted of 30 subjects with 3-piece IOL. Anterior segment parameters were measured with the Sirius rotating camera before, one week and one month after Nd:YAG laser capsulotomy.Results:Mean age was 72.3±5.2 years in 1-piece IOL and 72.3±6.8 years in 3-piece IOL. There were no statistically significant differences before capsulotomy for IOP, axial length, spherical equivalent, anterior chamber depth, central corneal thickness, anterior chamber angle and anterior chamber volume between two IOL groups. BCVA improved after capsulotomy in both groups (p=0.001). Both IOL groups had statistically significant myopic shift compared with the baseline values (P= 0.03 and P=0.01 resp.). Both IOL groups had statistically significant decrease in ACD, from baseline to the 1st week and 1st month (p=0.04 and 0.03 resp.).Conclusion:To achieve the highest percentage of refractive and anterior segment stability surgeons may prefer to implant the 1-piece IOL design.