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To ascertain the theoretical impact of optical design variations of the intraocular lens (IOL) on the accuracy of IOL power formulas based on a single lens constant using a thick lens eye model. This impact was also simulated before and after optimization. We modeled 70 thick-lens pseudophakic eyes implanted with IOLs of symmetrical optical design and power comprised between 0.50 D and 35 D in 0.5-step increments. Modifications of the shape factor resulting in variations in the anterior and posterior radii of an IOL were made, keeping the central thickness and paraxial powers static. Geometry data from three IOL models were also used. Corresponding postoperative spherical equivalent (SE) were computed for different IOL powers and assimilated to a prediction error of the formula due to the sole change in optical design alone. Formula accuracy was studied before and after zeroization on a uniform and non-uniform realistic IOL power distribution. The impact of the incremental change in optic design variability depended on the IOL power. Design modifications theoretically induce an increase in the standard deviation (SD), Mean Absolute Error (MAE), and Root Mean Square (RMS) of the error. The values of these parameters reduce dramatically after zeroization. While the variations in optical design can affect refractive outcomes, especially in short eyes, the zeroization of the mean error theoretically reduces the impact of the IOL’s design and power on the accuracy of IOL power calculation.

An innovative intraocular lens (IOL), the CM-T Flex IOL, was used to correct surgical aphakia without disturbing a functioning filtering bleb. A 66-year-old man presented with aphakia in the left eye. Cataract extraction and trabeculectomy was performed in the left eye 2 years previously elsewhere. Corrected distance visual acuity (CDVA) in the left eye was 6/18, and, on examination, it showed a filtering bleb that encroached on the limbus and superior cornea. The cornea was clear with a deep anterior chamber. Retinal examination was normal. Disc cupping was noted with a cup-to-disc ratio of 0.8. Refractive correction was performed by implanting the CM-T Flex IOL. This IOL has a unique design that eliminates the need for maneuvering the IOL haptics extraocularly. It entails a simple grasp, exteriorize, and release technique that anchors the IOL firmly to the scleral bed. At 6 months, CDVA in the left eye was 6/9 with a stable, centered IOL.

The diffraction efficiency of conventional diffractive lenses is typically analyzed using the complex Fourier series expansion coefficients. While conventional diffractive lenses typically target high diffraction efficiency in a single diffractive order, applications such as multifocal intraocular lenses seek high diffraction efficiency in multiple diffractive orders. Here, the complex Fourier series technique is generalized to handle these multifocal lenses, and applied to a novel trifocal intraocular lens design.

Biometric measurement of the anterior segment is of great importance for the ophthalmology, human eye modeling, contact lens fitting, intraocular lens design, etc. This paper serves as a comprehensive review on the historical development and basic principles of the technologies for measuring the geometric profiles of the anterior segment. Both the advantages and drawbacks of the current technologies are illustrated. For in vivo measurement of the anterior segment, there are two main challenges that need to be addressed to achieve high speed, fine resolution, and large range imaging. One is the motion artefacts caused by the inevitable and random human eye movement. The other is the serious multiple scattering effects in intraocular turbid media. The future research perspectives are also outlined in this paper.

We investigated whether eyes with keratoconic corneal tomography pattern could benefit more from aberration correction with custom intraocular lenses (IOLs) than normal cataractous eyes despite the effect of misalignment on the correction of aberrations. Custom IOLs (cIOLs) were calculated for twelve normal and twelve keratoconic eyes using personalized numerical ray tracing models. The Stiles-Crawford weighted root-mean-square spot-size (wRMS) at the virtual fovea was evaluated for cIOLs and aberration-neutral IOLs (nIOLs) in a simulated clinical study with 500 virtual IOL implantations per eye and per IOL. IOL misalignment (decentration, tilt, rotation) and pupillary ectopia (4.5 mm iris aperture) were varied upon each virtual implantation. The nIOLs achieved average wRMS of 16.4 ± 4.3 μm for normal, and 92.7 ± 34.4 μm for keratoconic eyes (mean ± standard deviation). The cIOLs reduced the average wRMS to 10.3 ± 5.8 μm for normal, and 28.5 ± 18.6 μm for keratoconic eyes. The cIOLs produced smaller wRMS than nIOLs in most virtual implantations (86.7% for normal and 99.4% for keratoconic eyes). IOL misalignment resulted in larger wRMS variations in the keratoconus group than in the normal group. Custom freeform IOL-optics-design may become a promising option for the correction of advanced aberrations in eyes with non-progressive keratoconic corneal tomography pattern.

Purpose To use ray-tracing analysis and simulated retinal illumination profiles to design an intraocular lens (IOL) that prevents or reduces negative dysphotopsia after cataract surgery. Setting Mayo Clinic, Rochester, Minnesota, and Simpson Optics LLC, Arlington, Texas, USA. Design Experimental study. Methods Ray-tracing software was used to simulate peripheral retina illumination from an extended light source for a pseudophakic eye with a biconvex high refractive index IOL. Ray intensities were adjusted to include the effects of the surface reflections and the energy reduction caused by pupil obliquity at high incident angles. The results were compared with similar optical modeling of a modified IOL design with a concave region on the peripheral posterior surface. Results For a standard biconvex high refractive index IOL, simulated retina illumination profiles showed an area of nonilluminated peripheral nasal retina at a relative visual angle of approximately 85 degrees to 93 degrees. Using a modified IOL optic with a peripheral concave posterior surface, ray-tracing diagrams showed that peripheral input rays were redirected anteriorly into the nonilluminated dark area of the peripheral retina. Simulated retina illumination images confirmed that the redirected input rays improved illumination to the peripheral retina, including the dark area. Conclusions Optical modeling showed that the new IOL design provides more uniform illumination of the peripheral nasal retina and specifically illuminates the dark region of the nasal retina associated with negative dysphotopsia. This modified IOL design could prevent or reduce negative dysphotopsia after cataract surgery.

PURPOSE: To compare visual outcomes, rotational stability, and centration in a randomized controlled trial in patients undergoing cataract surgery who were bilaterally implanted with two different trifocal intraocular lenses (IOLs) with a similar optical zone but different haptic shape. METHODS: Twenty-one patients (42 eyes) with cataract and less than 1.50 D of corneal astigmatism underwent implantation of one FineVision/MicoF IOL in one eye and one POD FineVision IOL in the contralateral eye (PhysIOL, Liège, Belgium) at IOA Madrid Innova Ocular, Madrid, Spain. IOL allocation was random. Outcome measures, all evaluated 3 months postoperatively, included monocular and binocular uncorrected distance (UDVA), corrected distance (CDVA), distance-corrected intermediate (DCIVA), and near (DCNVA) visual acuity (at 80, 40, and 25 cm) under photopic conditions, refraction, IOL centration, haptic rotation, dysphotopsia, objective quality of vision and aberration quantification, patient satisfaction, and spectacle independence. RESULTS: Three months postoperatively, mean monocular UDVA, CDVA, DCIVA, and DCNVA (40 cm) under photopic conditions were 0.04 ± 0.07, 0.01 ± 0.04, 0.15 ± 0.11, and 0.16 ± 0.08 logMAR for the eyes implanted with the POD FineVision IOL and 0.03 ± 0.05, 0.01 ± 0.02, 0.17 ± 0.12, and 0.14 ± 0.08 logMAR for those receiving the FineVision/MicroF IOL. Moreover, the POD FineVision IOL showed similar centration ( P > .05) and better rotational stability ( P < .05) than the FineVision/MicroF IOL. Regarding halos, there was a minimal but statistically significant difference, obtaining better results with FineVision/MicroF. Full spectacle independence was reported by all patients. CONCLUSIONS: This study revealed similar visual outcomes for both trifocal IOLs under test (POD FineVision and FineVision/MicroF). However, the POD FineVision IOL showed better rotational stability, as afforded by its design. [ J Refract Surg . 2016;32(6):394–402.]

Aim: To evaluate the outcomes after bilateral implantation of a new trifocal intraocular lens (IOL).Materials and Methods: The study included patients with visually significant cataract that underwent bilateral implantation of the Acriva Trinova Sinusoidal Trifocal IOL. The preoperative corrected distance visual acuity (CDVA) and postoperative uncorrected distance visual acuity (UDVA), CDVA, uncorrected intermediate (UIVA) and near visual acuities (UNVA) along with manifest refractions were assessed at 1 month and 6 months after cataract surgery. The defocus curve and contrast sensitivity (CS) were evaluated at the 6th month visit. Patient satisfaction and incidence of dysphotopic symptoms were assessed. Results: The study enrolled a total of 60 eyes of 30 patients, 10 males and 20 females aged 61.78± 8.73 years (range, 45 to 78 years). 90% of the patients (n: 27) achieved a binocular UIVA of 0.1 LogMAR or better at the 6-month visit while, 96.7% (n:29) patients had a binocular UNVA of 0.1 LogMAR or better in the same postoperative visit. The CS results were within the the range of normality at 6 months post-surgery. 6.7% of patients reported marked halo around light sources and 3.3% reported glare that interferes with nighttime driving. 96.6% of the patients reported spectacle independence for all distances and rated their visual function and quality satisfactory at all distances. Conclusion: Bilateral implantation of the Acriva Trinova Sinusoidal Trifocal IOL seems to provide effective restoration of visual function at all distances after cataract surgery in the majority of patients. Contrast sensitivity results and low incidence of dysphotopic phenomena might be associated with high patient satisfaction.

Phacoemulsification technique with intraocular lens implantation has been a common treatment for cataract patients. With rising demand among the public, new technologies for lens design have emerged to minimize intraocular aberrations, improving visual quality to the largest extent. This paper systematically reviews the development of materials applied in lens manufacturing, the different categories of intraocular lenses, and respective design principles. The advantages and potential drawbacks of intraocular lenses are illustrated in the paper, and prospective research to improve the design are presented in the end.

Purpose: To analyze biometry data and corneal astigmatism in cataract candidates from Yazd. Methods: The corneal thickness, anterior chamber depth and keratometry measurements of anteroposterior width were measured using the IOL Master system. Ocular biometric data were collected and analyzed in the year 2015. Results: The study comprised of 2000 patients' cataract candidates with a mean age of 66.79 ± 10.72 years (range 28 to 100 years). No significant differences were found between these variables for mean ± SDs of age and gender (p

PURPOSE To present the results of longitudinal chromatic aberration measurements on two groups of pseudophakic eyes in comparison to healthy eyes. METHODS The longitudinal chromatic aberration of the eye, defined as chromatic difference of refraction with disabled accommodation, was measured with the use of a visual refractometer with a custom-designed target illuminator consisting of a narrow-band RGB diode (blue λb = 470 ± 15 nm; green λg = 525 ± 18 nm; red λr = 660 ± 10 nm). The measurements were performed on nine eyes implanted with AcrySof IQ SN60WF, 14 eyes implanted with AcrySof SA60AT, and 10 phakic eyes under cycloplegia. RESULTS The mean values of the longitudinal chromatic aberration between 470 and 660 nm for the control group was 1.12 ± 0.14 D. For SA60AT group, it was 1.45 ± 0.42 D whereas for SN60WF it was 1.17 ± 0.52 D. The statistical test showed significant difference between SA60AT and the control group (p << 0.05) and no significant difference between SN60WF and the control groups (p = 0.64). CONCLUSIONS The study showed that the longitudinal chromatic aberration in vivo can be easily and reliably estimated with an adapted visual refractometer. The two groups of pseudophakic eyes measured in this study showed different values of chromatic aberration. Its magnitude for SA60AT group was significantly larger than for the control group whereas for SN60WF the difference was not significant. The optical material used for intraocular lens design may have significant influence on the magnitude of the chromatic aberration of the pseudophakic eye, and therefore on its optical and visual performance in polychromatic light.

Recent advances in cataract surgery have increased the safety and efficacy of this common procedure. Cataract surgery has evolved from ‘couching’ with sub-optimal results to phacoemulsification with excellent results. Introduction of the femtosecond laser into cataract surgery may further the safety and predictability of this procedure. In addition, innovations in intraocular lens material have enabled the surgery to be done through a small incision with quicker recovery and more predictable refractive outcome. New intraocular lens design technologies have helped patients minimize their need for glasses at most distances. Further, invention of ophthalmic viscosurgical devices reduced the risk of endothelial decompensation and corneal edema. These innovations have transformed the goal of cataract surgery from purely visual rehabilitation to a refractive procedure as well.

Purpose To assess the rotation and centration stability of the new design features of a 1-piece aspheric hydrophobic acrylic intraocular lens (IOL). Setting National Eye Hospital, Cairo, Egypt. Design Randomized clinical trial. Methods Patients in this study had implantation of a 1-piece Tecnis 1 ZCB00 IOL or a 3-piece Sensar AR40e IOL. Decentration and rotation were recorded immediately postoperatively, and 2 to 3 days and 8 weeks postoperatively. This was done using 2 slitlamp eyepieces and referring to constant corneal landmarks (ie, the limbus and the phaco incision). Results Thirty-two 1-piece IOLs and 30 3-piece IOLs were implanted. Although the 1-piece IOLs moved toward the corneal center more than the 3-piece IOLs between 3 days and 8 weeks postoperatively ( P =.054), the difference was not statistically significant between 0 day and 3 days or during the entire follow-up ( P =.546 and P =.367, respectively). There were no statistically significant differences in the horizontal or vertical components of this movement between the 2 groups ( P =.883 and P =.636, respectively). The mean rotation was 2.5 degrees ± 9.1 (SD) in the 1-piece IOL group and 0 ± 6.5 degrees in the 3-piece IOL group, with no statistically significant difference between the groups ( P =.521). Conclusion The new 1-piece design showed relatively good centration and stability in the horizontal, vertical, and rotational aspects. Financial Disclosure Drs. Roshdy, Riad, Morkos, Hassouna, and Wahba receive travel support from Abbott Medical Optics, Inc., Santa Ana, California, USA; Drs. Riad, Morkos, and Hassouna have equipment provided by Abbott Medical Optics, Inc., and Alcon Laboratories, Inc., Fort Worth, Texas, USA. No author has a financial or proprietary interest in any material or method mentioned.

12 págs.; 13 figs., Purpose To evaluate visual and perceptual performance for different orientations of a rotationally asymmetric bifocal intraocular lens (IOL) (M-Plus) simulated optically using a simultaneous vision simulator. Setting Instituto de Optica, Madrid, Spain. Design Prospective observational study. Methods Perceptual quality and decimal high-contrast visual acuity (HCVA) was measured under cycloplegia for 8 orientations of the asymmetric bifocal IOL phase pattern at far, intermediate, and near distances simulated with a simultaneous vision simulator using face images and tumbling E targets. The preferred orientation at each distance was calculated as the centroid of the data for 8 orientations. The visual Strehl value was calculated using the subjects' ocular aberrations and multifocal pattern at each orientation. Optical predictions were obtained by implementing a differential visual Strehl values–based ideal observer model. Results The study comprised 20 subjects (aged 21 to 62 years). Horizontal orientation (near segment at 0 or 180 degrees ± 45 [SD]) was preferred by 14 subjects and by 13 subjects at far and near distances, respectively; 8 subjects showed strong orientation preferences. The mean difference in preferred orientation between far and near was 27 ± 22 degrees. No significant differences in HCVA were observed. Optical predictions correlated strongly and significantly with measurements (far r = 0.71, near r = 0.62; P < .0001). The mean difference between measurement and simulation in the preferred orientation was 28 ± 29 degrees at far and 36 ± 28 degrees at near. Conclusions The perception varied for different orientations of an asymmetric bifocal IOL design tested using a simultaneous vision simulator. Optimum orientation was driven by interactions of the design with the eye's optical aberrations. Financial Disclosure None of the authors has a financial or proprietary interest in any material or method mentioned. Q 2016 ASCRS and ESCRS, Funding provided by the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007- 2013)/ERC Grant Agreement number 294099 (Dr. Marcos), Spanish Government grant FIS2011-264605 and FIS2014-56643-R (Dr. Marcos), the 7th Framework Programme of the European Community through the Marie Curie Initial Training Network OpAL (OpAL is an Initial Training Network funded by the European Commission under the Seventh Framework Programme), (PITN-GA-2010- 264605, Dr. Radhakrishnan), and Oculentis GmBH, Germany.

Accurate eye models representing the anatomic and optical behavior of the real human eye are essential for the design and development of implantable intraocular lenses (IOLs) for cataract surgery. The correct prediction of the IOL's dioptric power is of high importance, as a wrongly chosen IOL dioptric power outpaces every other known aberration in loss of visual acuity. An introduction into eye modeling is given encompassing biometric data acquisition, 4 modeling paradigms (population based-and personalized eye modeling, models for IOL power calculation and discrete, physical eye models) and the description of some modeling procedures. Finally, field tracing simulations of a trifocal diffractive IOL in different eye models (Navarro model, Liou-Brennan model and ISO eye model) are compared. It is concluded that the ISO eye model will have to be substituted by a more realistic model in cases where the addition value of a multifocal IOL is to be obtained correctly by measurements.

Posterior capsule opacification (PCO) remains the most common long-term complication after cataract surgery. Many studies have attempted to identify factors that influence the development of PCO. The aim of this systematic review based on Cochrane methodology was to summarize the effects of intraocular lens (IOL) geometry, including modifications of the IOL optic (especially optic edge design) and haptics, on the development of PCO. Twenty-six prospective randomized controlled trials with a follow-up of at least 12 months were included. In 5 of 7 studies, visual acuity was better in sharp-edged IOLs than in round-edged IOL. The PCO score was significantly lower with sharp-edged IOLs but did not differ significantly between 1-piece and 3-piece open-loop IOLs. Because of the significant difference in the PCO score, sharp-edged IOL optics should be preferred to round-edged IOL optics.

In this research, we firstly design the phakic intraocular lens (PIOL) based on individual eye model with optical design software ZEMAX. The individual PIOL is designed to correct the defocus and astigmatism, and then we compare the PIOL power calculated from the individual eye model with that from the experiential formula. Close values of PIOL power are obtained between the individual eye model and the formula, but the suggested method has more accuracy with more functions. The impact of PIOL decentration on human eye is evaluated, including rotation decentration, flat axis decentration, steep axis decentration and axial movement of PIOL, which is impossible with traditional method. To control the PIOL decentration errors, we give the limit values of PIOL decentration for the specific eye in this study.

PURPOSE: The aim of this study was to design and evaluate in the laboratory a new intraocular lena (IOL) intended to provide superior octtlar optical quality by reducing spherical aberration. METHODS: Corneal topography measurements were performed on 71 cataract patients using an Orbscan I. The measured corneal surface shapes were used to determine the wavefront aberration of each cornea. A model cornea was then designed to reproduce the measured average spherical aberration. This model cornea was used to design IOLs having a fixed amount of negative spherical aberration that partially compensates for the average positive spherical aberration of the cornea. Theoretical and physical eye models were used to assess the expected improvement in optical quality of an eye implanted with this lens. RESULTS: Measurements of optical quality provided evidence that if this modified prolate IOL was centered within 0.4 mm and tilted less than 7 degrees, it would exceed the optical performance of a conventional spherical IOL. This improvement occurred without an apparent loss in depth of focus. CONCLUSION: A new IOL with a prolate anterior surface, designed to partially compensate for the average spherical aberration of the cornea, is intended to improve the ocular optical quality of Pseudophakie patients. [J Refract Surg 2002;18: 683-691]

Purpose To assess the potential for reflected glare images from commonly used intraocular lens (IOL) materials and designs. Setting Mayo Clinic, Rochester, Minnesota, USA. Methods The interaction of reflected light rays from 3 commonly used IOLs (Bausch & Lomb LI61U and P359UV; Alcon AcrySof® MA60BM) with different optic designs (equi-biconvex: 10.0 and 15.0 mm anterior radius of curvature; unequal biconvex: 32.0 mm anterior radius of curvature) and optic materials (silicone, poly[methyl methacrylate], and acrylic) were examined in an eye model using the Zemax optical design program. The potential of each IOL model to produce subjective glare was determined from the size of the defocused reflected glare image at the retina. Results The unequal biconvex design concentrated reflected light on a retinal area that was 60-fold smaller than that of the equi-biconvex design. Increasing the refractive index of the IOL material from 1.43 (silicone) to 1.55 (acrylic) increased the amount of reflected light 5-fold. Compared to an equi-biconvex design composed of a lower refractive index material, the unequal biconvex design with a higher refractive index material increased the relative intensity of reflected light at the retina 300-fold, and for eyes with low corneal power the intensity increased 3500-fold. Similarly, for external glare apparent to an outside observer, the intensity of reflected light increased 400-fold and for low corneal power it increased 6000-fold. Conclusion An unequal biconvex IOL design (32.0 mm anterior radius of curvature) composed of a higher refractive index material increased the potential for postoperative glare and external reflections.

Purpose: To find the conditions that prevent posterior capsule opacification through in vitro analysis of the relationship between intraocular lens (IOL) optic configuration and lens epithelial cell (LEC) migration. Setting: Division of Morphogenesis, Department of Developmental Biology, National Institute for Basic Biology, Okazaki, Japan. Methods: In a preliminary experiment, we measured the size of the capsular bag of rabbits at 8, 16, 20, and 26 weeks of age. The size of a 20-week-old capsular bag was the same size as the capsular bag in senescent Japanese eyes. We isolated the capsular bags in 20- and 8-week-old rabbits. The bags along with a biconvex (BC), convex-piano (CP), or no IOL (C) were cultured, and the eyes were divided into one of six groups (8W-C, 8W-BC, 8W-CP, 20W-C, 20W-BC and 20W-CP), each including six specimens. Results: Two specimens in the 8W-CP group completely blocked LEC migration at the optic edge. All specimens in the 20W-CP group and one in the 20W-BC group showed cell aggregation along the optic edge. None of the other specimens in the BC and C groups blocked migration or showed cell aggregation. Conclusions: In the rabbit-model study, the convex-piano lens was superior to the biconvex lens in inhibiting migration of LECs. A firm contact between the IOL and the posterior capsule blocked the migration.

We compared the effect of biconvex and convex-plano (posterior plano) intraocular lenses on posterior capsule opacification (PCO) following continuous curvilinear capsulorhexis (CCC) in 212 eyes. During the three years following surgery, the cumulative frequency of neodymium:YAG laser posterior capsulotomy, calculated with the Kaplan-Meier method, was significantly higher in patients in the biconvex group (32.5% by the third year) than in those in the convex-plano group (5.9% by the third year) (P < .05, Wilcoxon's test; P < .01, Cox-Mantel's test). Measured with the tracing method, the area within a 5 mm diameter central circle that developed Elschnig pearls was 2.93 +/- 4.91 mm2 in the biconvex group and 1.66 +/- 2.37 mm2 in the convex-plano group. In the study, PCO was less severe in the convex-plano group than in the biconvex group following CCC. These results are contrary to those reported previously in patients with can-opener capsulotomy.

Aim: To design an accommodating intraocular lens with extended accommodative range that can be adapted to current standard phacoemulsification and endocapsular implantation technique. Method: Ray tracing analysis and lens design; cadaver eye implantation. Results: Ray tracing analysis indicated that axial movement of an exaggerated converging anterior optic linked by spring loaded haptics to a compensatory static diverging posterior optic produced greater change in conjugation power of the eye compared to axial movement of a single optic lens. A dual optic one piece foldable silicone lens was constructed and implanted via a 4 mm corneal incision into the capsular bag of two cadaver eyes. Conclusion: A dual optic intraocular lens design can increase the optical effect of a given displacement and suggests improvements for accommodating intraocular lenses.

OBJECTIVE: To determine whether the anterior capsulotomy shape (capsulorhexis or envelope) or the IOL design (polyHEMA, one-piece PMMA open and closed loops, three-piece polypropylene and PMMA loops) influence the lens decentration after intercapsular cataract surgery. STUDY DESIGN: Retrospective study of postoperative results 18 months after surgery. SETTING: University Eye Clinic of Trieste, Italy. PATIENTS: 150 patients divided into two groups: in 75 cases anterior circular continuous capsulorhexis (CCC) was performed and in 75 cases the envelope technique was used. Only patients with uncomplicated eyes and absence of posterior capsular opacification were included. MAIN OUTCOME MEASURES: Degree of IOL decentration was measured by projecting a slide of the anterior segment of the eye, taken after maximum dilatation, and calculating the distance between the circles formed by the corneoscleral limbus and the edge of the IOL. RESULTS: Including all IOLs, mean decentration was 0.28 ± 0.21 mm in the capsulorhexis group and 0.55 ± 0.32 mm in the envelope group; the difference is statistically significant ( P

Purpose: To compare the incidence and severity of development of posterior capsule opacification (PCO) following implantation of square-edged polymethylmethacrylate (PMMA) or hydrophobic acrylic intraocular lenses (IOLs) following paediatric cataract surgery. Design: Prospective, consecutive, interventional, comparative, randomized and cross-sectional study of 40 eyes of 32 children aged between 4 and 12 years who underwent phacoemulsification and posterior chamber IOL implantation. Methods: The patients were randomized into two groups of 20 eyes each. Group 1 eyes received a square-edge hydrophobic acrylic IOL (Acrysof SA 60 AT, Alcon Surgical, Fort Worth, Texas), and Group 2 eyes received a square-edge single-piece PMMA lens (Aurolab SQ 3600 Aurolab IOL Division, Madurai, India) in the capsular bag. No eye underwent a primary posterior capsulotomy. The PCO density was evaluated on slitlamp retroillumination photographs by using POCOman software at 3, 6, 9 and 12 months post surgery. Results: The average percentage PCO on POCOman analysis was 51.23 for Group 1 and 49.49 for Group 2 (P = 0.09), and the average PCO severity grade was 1.34 in Group 1 and 1.12 in Group 2 (P = 0.08). Visual axis remained clear in 14 of 20 eyes with the acrylic lens as compared with 13 of 20 eyes with the PMMA lens. (P = 0.32). Conclusions: Square-edge PMMA IOLs offer a significant cost advantage over acrylic lenses at similar rates of PCO formation following paediatric cataract surgery, which is of significant value in developing countries.

To evaluate posterior capsule opacification (PCO) and the impact of different intraocular lens (IOL) models on PCO characteristics using optical coherence tomography (OCT).Eighty-three eyes with PCO (fibrosis or pearl type) and 32 pseudophakic eyes without PCO were included. Horizontal 3.0 mm long OCT scans of the posterior capsule were obtained. Measurements and means of the peak posterior capsule intensity (PCI) and posterior capsule thickness (PCT) (distance between 2 spikes at posterior capsule) at 3 scan points were recorded. The PCI and PCT were compared with best corrected visual acuity (BCVA) and IOL data.The PCT was high for IOLs with a rounded edge (P = .001) and with poly(methyl methacrylate) (PMMA) IOLs (P.001). If the IOL optic was concave-convex, the PCT was higher than if the optic was biconvex (P = .001). The PCT of hydrophilic acrylic IOLs was higher than of hydrophobic acrylic IOLs (P = .04). Multivariate analysis of PCT showed that PMMA was the only factor statistically associated with PCT (P = .02). The worse logMAR BCVA correlated significantly with a higher PCT value (P.001) but not with PCI (P = .42). An IOL size of 12.5 mm was related to fibrosis-type PCO (odds ratio, 3.14; P = .04).The PCT was most affected by IOL characteristics. Poly(methyl methacrylate) IOLs and IOLs with rounded edges were associated with higher PCT. Hydrophilic acrylic IOLs were associated with greater PCT than hydrophobic IOLs. Posterior capsule thickness was a factor in decreased BCVA.

Background For more than half a century, intraocular lenses have been used effectively to correct vision after cataract extraction. New developments in intraocular lens design have led to the creation of lenses that may have a significant role in the restoration of accommodation as well. Purpose Accommodative lens technology is constantly evolving. Many different lens designs are currently under development. It is important for optometrists to be familiar with this technology and the various lenses being developed, as accommodative intraocular lenses stand to become the mainstay for cataract surgery, as well as for the surgical treatment of presbyopia. Method The literature is reviewed in order to summarize the developments in accommodative lens technology.

Modern cataract surgery is constantly evolving and improving in terms of lens material and design. Researchers and physicians strive to obtain better refractive correction with smaller wound size and minimizing host cell response to limit the proliferation of lens epithelial cells leading to opacification of the lens capsule. Intraocular lens material varies in water content, refractive index, and tensile strength. Intraocular lens design has undergone revisions to prohibit lens epithelial cell migration and reflection of internal and external light. The evolution of intraocular lens and extracapsular cataract surgery has lead to faster postoperative recovery and better visual outcomes.

Purpose: To evaluate patients who had implantation of an acrylic intraocular lens (IOL) and reported edge glare that did not lessen with time. Setting: Hawthorn Eye Clinic, Kew, Victoria, Australia. Method: This retrospective study comprised patients who had uneventful phacoemulsification and then reported glare that did not abate after 12 months. Results: Five patients (7 of 322 eyes; 2.2%) who received an AcrySof® MA30BA IOL with a 5.5 mm optic and 1 patient (1 of 221 eyes; 0.5%) who received an AcrySof MA60BM IOL with a 6.0 mm optic reported permanent edge glare. Extensive retinal and neurological evaluations in 2 patients showed no deficits in 1 and an abnormal photopic red electroretinogram in the other. Pilocarpine 1% was used in 3 patients and gave no relief of symptoms. Two patients (3 eyes) had IOL explantation with complete resolution of glare symptoms. There was no statistical significance between the 2 types of IOLs. Conclusion: Sharp-edged IOL designs can cause permanent intractable glare.

We evaluated intraocular lens (IOL) decentration resulting from asymmetric capsular shrinkage. In 19 eyes of 10 white rabbits, a D-shaped incision was made in the anterior capsule and one of three IOL types implanted in the capsular bag: three-piece with polypropylene haptics, one-piece all-poly(methyl methacrylate) (PMMA), or compressible disk. Eight weeks later, eyes were enucleated for assessment of IOL decentration. Mean decentration was 0.75 mm for three-piece IOLs, 0.46 mm for one-piece IOLs, and 0.30 mm for compressible-disk lenses. Decentration was significantly less in eyes with compressible-disk lenses than in those with three-piece IOLs. Although decentration was less with the compressible-disk lens, the lens is not commonly used because of the large incision and special insertion technique required. If an open-loop IOL is to be used in eyes at risk for asymmetric capsular shrinkage, our results indicate that an all-PMMA onepiece IOL would be preferable to a three-piece lens with a polypropylene haptic.

In this study,which also provides an assessment of machine performance, IOL optimization of aspheric surfaces, using the conic constant factor, has been selected. Such surfaces are easily machined by most software-driven lathes, such as DAC 2- and 4-axis lathes, which were utilized for this study. Measuring tilt and decentration performances on the optimized aspheric lenses, it is shown that 'best shape' IOLs scan be produced using a broad range of lens designs. This promises to increase manufacturer and surgeon confidence in maximizing patients' visual acuity with better contrast sensitivity using aspheric designs.

The ophthalmic field, as much as any other, has come to expect regular, and occasionally spectacular, research developments. Eager eyes routinely scan the literature for reports of vision restored by a surgical innovation, preserved through medical intervention, or enhanced by a new contact lens or intraocular lens design. Through it all, the venerable spectacle lens quietly remains the mainstay of visual correction for most of the population. This book represents the author's latest summary of those improvements made to the more mundane but enduring conventional ophthalmic lens, while it continues in its previous role as an introduction to ophthalmic optics. As in the two earlier editions, the author has compiled an admirable list of currently available lenses. Maintaining the same format as before, this third printing is organized into 15 short, readable chapters. The majority of these are devoted to discussion of specific lens materials and design, such as "Plastic

A survey of the practice styles and preferences of 1986 ASCRS members was taken in the summer of 1986. A total of 4,042 surveys were mailed in June of 1986 and 1,184 were returned—a return rate of 29%. The responses were analyzed using D Base III. Response rate was 5% greater than for the 1985 survey. There was no financial incentive for return of the survey other than return postage paid for by the author. Three main profile areas were analyzed: age of the ophthalmologist; volume of cataract surgery per month, and geographic location. Areas of interest were surgery locations, surgical techniques, Nd:YAG laser application, intraocular lens design preferences, radial keratotomy, and advertising in ophthalmology. The influence of age of the ophthalmologist, cataract surgery volume, and geographic location were cross-analyzed for each question. The results were compared to the results of comparable questions in the 1985 survey. This report looks at each question and looks for variances from the national average, as well as for trends from the 1985 survey.

In a prospective randomized study, 25 New Zealand white rabbit eyes were implanted with four intraocular lens (IOL) designs. These included a one-piece modified J-loop IOL, a three-piece modified J-loop IOL, a rigid disc IOL, and an experimental compressible disc (CD) IOL. The CD IOL revealed the lowest mean posterior capsular opacification (PCO) of all IOLs tested (P less than .01). With all lenses tested, a positive correlation between PCO and decentration was found (R = 0.55, P less than .05). These results suggest that because of its design features (i.e., one-piece construction, biconvex optic, posterior angulation of the fixation element), the CD lens produces a mechanical barrier against lens epithelial cell migration and reduces the incidence of PCO.

Of 1170 eyes implanted with posterior chamber lenses between 1981 and 1986 and having intact capsules at surgery, 1015 were examined two years after surgery, 741 were examined three years after surgery, and 308 were examined five years after surgery. At three years the capsulotomy rate for epithelium was 25% for 263 'lasergap' lenses, 2.4% for 296 convex posterior lenses, 8.2% for 73 planoposterior lenses with angulated loops. The highly significant difference for lasergap design, whether ridged, meniscus, or bossed, is of immediate interest to surgeons concerned with minimising the need for secondary capsulotomy. The two-year follow-up of soft hydrogel lenses suggested that these lenses also do not significantly retard the ingrowth of epithelium.

Phacoemulsification was performed on both lenses of 24 rabbits. One eye received a lens implant with a convex-plano optic; the fellow eye received an implant with a convex-concave optic which separated the posterior surface of the implant from the posterior capsule by 0.2 mm, 0.3 mm, or 0.4 mm. A YAG laser capsulotomy was performed on all eyes immediately following surgery and an assessment of both microscopic and macroscopic YAG-induced lens damage was made. The meniscus optics with their capsule-implant separation showed significantly less YAG-induced damage than their convex-plano counterparts without this separation. Increasing the amount of capsuleimplant separation beyond 0.2 mm did not enhance the degree of protection from YAG-induced damage.

This manuscript reports on a closed-form solution determining the personalized required shape of a new intraocular lens able to remove spherical aberration and coma of a pseudophakic eye. The proposed analytical method, within the framework of the Seidel theory of third-order optical aberrations, considers corneal conicities, fourth-order aspheric surface of the intraocular optics, pupil-shift effect and ocular kappa angle.