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This study investigates the use of progressives with mental verbs in courtroom talk and shows a range of subjective meanings which are not delivered by the simple form. Looking at the data from a British libel trial, it explores patterned co-occurrences with first-person subjects vs. second- and third-person subjects, revealing both emphatic, polite and interpretative uses of the analyzed items. In addition, context-sensitivity and speaker status (judge vs. other participants) are shown to be significant factors affecting both the choice of verbs and their interactional configurations. The findings reveal not only well-established uses of "progressive statives" (wonder and think) but also less conventional ones which convey intensity and expressivity (e.g., understand, remember and want). It is also revealed that the use of progressives with mental verbs differs from the deployment of progressives with communication verbs. In both groups of verbs, however, the interpretative meaning is common. In sum, the study situates progressives with mental verbs among stancetaking resources which speakers employ to share their thoughts, wishes and desires, and to position themselves against other interactants and their propositions. [ABSTRACT FROM AUTHOR]

The progressive addition lens (PAL) is a spectacle lens design with progressive refractive power changes across the lens surface to provide sharp vision at different viewing distances for patients with reduced accommodative strength. It has gained in popularity not just for presbyopic patients, but also patients with occupational (office, driving, or digital device) and therapeutic (e.g., myopia control) needs. However, despite the increasing prevalence of astigmatism in adults > 40 years old who rely on PAL correction, no metric is available to reflect the optical variation in PALs with astigmatic prescriptions. Based on recent studies, four novel optical metrics sensitive to variation of refractive power across the lens surface of PALs have been developed. These metrics were used to compare the optical performance of PALs of various prescriptions, designs, and manufacturers. For each lens, the refractive power profile was first measured with a Moire-deflectometry-based instrument.The data was then exported and analyzed using a two-dimensional error map for each of the four metrics. The results revealed significant impacts of astigmatic prescription, providing evidence for the usefulness of these metrics in quantifying the optical performance of PALs for patients with astigmatic prescriptions. [ABSTRACT FROM AUTHOR]

Progressive addition lenses introduce distortions in the peripheral visual field that alter both form and motion perception. Here we seek to understand how our peripheral visual field adapts to complex distortions. The adaptation was induced across the visual field by geometrically skewed image sequences, and aftereffects were measured via changes in perception of the double-drift illusion. The double-drift or curveball stimulus contains both local and object motion. Therefore, the aftereffects induced by geometrical distortions might be indicative of how this adaptation interacts with the local and object motion signals. In the absence of the local motion components, the adaptation to skewness modified the perceived trajectory of object motion in the opposite direction of the adaptation stimulus skew. This effect demonstrates that the environment can also tune perceived object trajectories. Testing with the full double-drift stimulus, adaptation to a skew in the opposite direction to the local motion component induced a change in perception, reducing the illusion magnitude (when the stimulus was presented on the right side of the screen. A non-statistically significant shift, when stimuli were on the left side). However, adaptation to the other orientation resulted in no change in the strength of the double-drift illusion (for both stimuli locations). Thus, it seems that the adaptor's orientation and the motion statistics of the stimulus jointly define the perception of the measured aftereffect. In conclusion, not only size, contrast or drifting speed affects the double-drift illusion, but also adaptation to image distortions. [ABSTRACT FROM AUTHOR]

Abstract We analyzed the effect of modified mono-vision prescription on the occupational progressive addition lenses (OPALs) in presbyopia for indoor use as a method to solve the inconvenience caused by the decrease in the intermediate and the near distances' vision when the PALs worn. To analyze the effect, 37 subjects (57.22 ± 5.18 years) were selected who were wearing PALs and had working hours over 6 h per day on average at intermediate and near distances. Entire tests were carried out with regard to three cases: subjects wearing PALs, occupational progressive addition lenses (OPALs), and prescription for modified mono-vision of OPALs. In order to compare visual performance of three cases, our study evaluated corrected visual acuity and subjective satisfaction at far, intermediate and near distances, stereo-acuity and phoria at far and near distances. The results showed that the prescription of modified mono-vision of OPALs could be useful when applied to the clinical practices for prescribing presbyopic correction. [ABSTRACT FROM AUTHOR]

To precisely measure the whole-surface characterization of freeform progressive addition lenses (PALs), considering the multi-optical-axis conditions is becoming particularly important. Spherical power and astigmatism (cylinder) measurements for freeform PALs, using a Hartmann–Shack wavefront sensor (HSWFS) are proposed herein. Conversion formulas for the optical performance results were provided as HSWFS Zernike polynomial expansions. For each selected zone, the studied PALs were placed and tilted to simulate the multi-optical-axis conditions. The results of two tested PALs were analyzed using MATLAB programs and represented as contour plots of the spherical equivalent and cylinder of the whole-surface. The proposed experimental setup can provide a high accuracy as well as a possibility of choosing 12 lines and positions of 193 measurement zones on the entire surface. This approach to PAL analysis is potentially an efficient and useful method to objectively evaluate the optical performances, in which the full lens surface is defined and expressed as the contour plots of power in different regions (i.e., the distance region, progressive region, and near region) of the lens for regions of interest. [ABSTRACT FROM AUTHOR]

Background: Some intracranial aneurysms treated by stent-assisted coiling (SAC) with incomplete occlusion undergo progressive occlusion (PO) during follow-up period. We analyzed the predictors for the occurrence of PO. Methods: Among 74 cerebral aneurysms treated by SAC using the Enterprise or Neuroform stents from 2010 to 2015, we included 43 aneurysms with occlusion grade of neck remnant (NR, n = 36) or residual aneurysm (RA, n = 7) at the post-procedure. We defined PO as improvement in occlusion grade from RA to NR, or from NR or RA to complete occlusion on angiographic follow-up imaging at 6 months after the procedure. We analyzed the independent predictors for PO using a multivariate logistic regression model and receiver operating characteristic (ROC) curve analysis. Results: Forty-three aneurysms were analyzed, with mean volume embolization ratio of 30.3 ± 6.7%. Twenty aneurysms (47%) achieved PO. Univariate analysis found that the median neck diameter of the aneurysms was smaller in aneurysms with PO than others. Multivariate logistic regression analysis also found that the odds ratio of neck diameter of the aneurysm for PO was 0.44 (95% CI, 0.19-0.82, p < 0.01). Moreover, ROC curve analysis for PO found that the optimal cut-off value of the neck diameter was 5.5 mm, with a sensitivity of 95%, specificity of 57% ( p < 0.01). Conclusions: Incompletely occluded aneurysms with a neck diameter of 5.5 mm or less might be more likely to develop PO within 6 months after SAC by using Enterprise or Neuroform stents. [ABSTRACT FROM AUTHOR]

Background: Adult hemophagocytic lymphohistiocytosis is a secondary immunopathologic phenomenon, mainly secondary to malignancy, infection, or autoimmune disorders. The performance of diagnostic criteria, studied in the pediatric population, is yet to be validated in the adult population. Some of the criteria include cytopenias and organomegaly that are inherent features to malignant processes, thus making the diagnosis of hemophagocytic lymphohistiocytosis a challenge in patients with cancer.Case Presentation: We describe the case of a 54-year-old white man with history of metastatic maxillary sinus adenoid cystic carcinoma who had severe liver injury and cytopenias with progressive clinical deterioration. We performed an evaluation, by flow cytometry, of the expression of surface markers in his natural killer cells that revealed remarkable abnormalities. His syndrome eventually fulfilled criteria for hemophagocytic lymphohistiocytosis and he received therapy with steroids with interval clinical improvement. Unfortunately, he refused further cytotoxic treatment and died 2 weeks later.Conclusions: The conventional criteria for the diagnosis of hemophagocytic lymphohistiocytosis are suboptimal for adult patients with cancer resulting in delays in diagnosis and timely initiation of treatment. The diagnostic criteria have to be re-evaluated in patients with cancer; novel, easily available, and accurate diagnostic methods are needed. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a novel concept of liquid-actuated aspheric lens (LAL) with a built-in aspheric polydimethylsiloxane lens (APL) to enable the design of compact optical systems with varifocal microscopic imaging. The varifocal lens module consists of a sandwiched structures such as 3d printed syringe pump functionally serves as liquid controller. Other key components include two acrylic cylinders, a rigid separator, a APL/membrane composite (APLMC) embedded PDMS membrane. In functional operation, the fluidic controller was driven to control the pressure difference and ALPMC deformation. The focal length can be changed through the pressure difference. This is achieved by the adjustment of volume change of injected liquid such that a widely tunable focal length. The proposed LAL can transform to 3 modes: microscopic mode (APLMC only), convex-concave mode and biconcave mode. It is noticeable that LAL in the operation of microscopic mode is tunable in focus via the actuation of APLMC (focal length is from 4.3 to 2.3 mm and magnification 50X) and can rival the images quality of commercial microscopes. A new lab-on-phone device is economically feasible and functionally versatile to offer a great potential in the point of care applications. [ABSTRACT FROM AUTHOR]

Purpose Non-uniform magnification (distortion) and dioptric blur are two major undesired optical defects affecting vision when looking through progressive addition lenses ( PALs) and studying them is potentially very valuable for PAL design. The major purpose of this paper is to analyse the relationship between dioptric power and magnification and, additionally, to evaluate the expected values of distortion and dioptric blur typically present in PALs. This has not been carefully and rigorously analysed to date. Methods We computed the local dioptric and magnification matrices (using a two-ray differential method) for different gaze directions in an archetypical model of a PAL. We used four different maps: scalar magnification and anamorphic distortion, to describe magnification, and mean power and astigmatism, to describe dioptric power. Results There is a good correlation between scalar magnification and mean power on the one hand, and anamorphic distortion and astigmatism on the other hand. Changes of 1 D in mean power are associated with variations in scalar magnification of around 3%. Also, 3% of anamorphic distortion is associated with increasing astigmatism up to 1 D. The directions of maximal power and maximal magnification are quite similar, though not equal (differences up to ± 1.5°). These directions strongly change from close to isotropic at the intermediate corridor to around 45° of oblique inclination for a few degrees of horizontal eye rotation. In typical PALs the level of distortion, which is unavoidably present when dioptric blurring appears, is small for usable vision zones (below 1 D of astigmatism). Conclusion The combined analysis of dioptric power and magnification in PALs helps to understand their limitations as a visual aid. On the one hand, the potentials of including distortion magnitude as a target in the metric function being optimised in the PAL design are reduced; on the other hand, it seems worthwhile to explore adding the degradation orientation as an additional target. [ABSTRACT FROM AUTHOR]

ABSTRACT Model polypropylene and polypropylene/low molecular weight modifier systems with identical crystalline structure but of different physical state of noncrystalline regions were analyzed. The deformation of reference material was accompanied by a cavitation phenomenon while the deformation of the polypropylene/modifier systems occurred in non-cavitating manner. Based on X-ray and PALS measurements the observed change of the intensity of the cavitation phenomenon during the deformation of the analyzed systems was explained. Additionally, the change of interlamellar distance (induced by introducing the modifier molecules and uniaxial stretching) was correlated with the change of average size of the free volume pores of the amorphous phase-this analysis was performed based on experimental data and theoretical estimations. It was proven that the presence of modifier reduce significantly the average size of free volume pores in relation to the system with similar interlamellar distance. Finally, the method enabling specifying the effective content of the modifier in interlamellar regions based on PALS measurements and the observed change of the value of long period was presented. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 531-543 [ABSTRACT FROM AUTHOR]

A freeform progressive addition lens (PAL) provides a good solution to correct presbyopia and prevent juvenile myopia by distributing pupils' optical powers of distance zone, near zone, and intermediate zone and is more widely adopted in the present optometric study. However, there is still a lack of a single-optical-axis system for the design of a PAL. This paper focuses on the research for an approach for designing a freeform PAL. A multioptical-axis system based on real viewing conditions using the eyes is employed for the representation of the freeform surface. We filled small pupils in the intermediate zone as a progressive corridor and the distance-and near-vision portions were defined as the standard spherical surfaces delimited by quadratic curves. Three freeform PALs with a spherical surface as the front side and a freeform surface as the backside were designed. We demonstrate the fabrication and measurement technologies for the PAL surface using computer numerical control machine tools from Schneider Smart and a Visionix VM-2000 Lens Power Mapper. Surface power and astigmatic values were obtained. Preliminary results showed that the approach for the design and fabrication is helpful to advance the design procedure optimization and mass production of PALs in optometry. [ABSTRACT FROM AUTHOR]

Background This study intended to measure the near and far points of clear vision as a function of the inclination of the line of sight with comfortable head posture. Measurements with different lenses for presbyopic correction were made to suggest comfortable positions of the monitor for computer work. Method An 'inclined optometer' was built, including a concave mirror to shift a visual target of constant angular size from near to infinity (proposed by Reiner). The optometer could be inclined vertically from horizontal to 50 degrees downward to vary the inclination of the line of sight. Measurements were made with a comfortable head position adjusted on a headrest. Results The near and far points were plotted both in the unit one/metre as a function of eye inclination (optometric diagram) and also as positions from the eyes in workspace co-ordinates (workplace diagram). First, individual examples of plots of the vertical zones of clear vision at the workplace are shown. Second, the group mean data of 22 observers with newly prescribed lenses showed that the vertical zones of clear vision for general purpose progressive addition lenses (PALs) reach infinity and are flatter, while computer vision PALs lead to more steep vertical zones ending at intermediate distances. Third, the mean results of three samples from our laboratory were compared with respect to general purpose PALs, which are most frequently used by presbyopic people. Conclusions The diagrams of the vertical zones of clear vision for different spectacles provide information on the ergonomic vertical position of computer monitors for clear vision with a comfortable head position. The grand mean of general purpose PALs suggests that the upper edge of the monitor should be at least approximately 15 cm below eye level at a typical viewing distance of approximately 75 cm. Higher monitor positions are possible with computer vision PALs. [ABSTRACT FROM AUTHOR]

Background Two types of progressive addition lenses ( PALs) were compared in an office field study: 1. General purpose PALs with continuous clear vision between infinity and near reading distances and 2. Computer vision PALs with a wider zone of clear vision at the monitor and in near vision but no clear distance vision. Methods Twenty-three presbyopic participants wore each type of lens for two weeks in a double-masked four-week quasi-experimental procedure that included an adaptation phase (Weeks 1 and 2) and a test phase (Weeks 3 and 4). Questionnaires on visual and musculoskeletal conditions as well as preferences regarding the type of lenses were administered. After eight more weeks of free use of the spectacles, the preferences were assessed again. The ergonomic conditions were analysed from photographs. Results Head inclination when looking at the monitor was significantly lower by 2.3 degrees with the computer vision PALs than with the general purpose PALs. Vision at the monitor was judged significantly better with computer PALs, while distance vision was judged better with general purpose PALs; however, the reported advantage of computer vision PALs differed in extent between participants. Accordingly, 61 per cent of the participants preferred the computer vision PALs, when asked without information about lens design. After full information about lens characteristics and additional eight weeks of free spectacle use, 44 per cent preferred the computer vision PALs. Conclusion On average, computer vision PALs were rated significantly better with respect to vision at the monitor during the experimental part of the study. In the final forced-choice ratings, approximately half of the participants preferred either the computer vision PAL or the general purpose PAL. Individual factors seem to play a role in this preference and in the rated advantage of computer vision PALs. [ABSTRACT FROM AUTHOR]

Background: Multifocal glasses (bifocals, trifocals, and progressives) increase the risk of falling in elderly people, but how they do so is unclear. To explain why glasses with progressive addition lenses increase the risk of falls and whether this can be attributed to false projection, this study aimed to 1) map the prismatic displacement of a progressive lens, and 2) test whether this displacement impaired reaction time and accuracy. Methods: The reaction times of healthy ⩾75-year-olds (31 participants) were measured when grasping for a bar and touching a black line. Participants performed each test twice, wearing their progressives and new, matched single vision (distance) glasses in random order. The line and bar targets were positioned according to the maximum and minimum prismatic displacement effect through the progressive lens, mapped using a focimeter. Results: Progressive spectacle lenses have large areas of prismatic displacement in the central visual axis and edges. Reaction time was faster for progressives compared with single vision glasses with a centrally-placed horizontal grab bar (mean difference 101 ms, P=0.011 [repeated measures analysis]) and a horizontal black line placed 300 mm below center (mean difference 80 ms, P=0.007). There was no difference in accuracy between the two types of glasses. Conclusion: Older people appear to adapt to the false projection of progressives in the central visual axis. This adaptation means that swapping to new glasses or a large change in prescription may lead to a fall. Frequently updating glasses may be more beneficial. [ABSTRACT FROM AUTHOR]

Different from the traditional single or bifocal lens, freeform progressive addition lens (PAL) comprises of a far view zone, a near zone and a progressive zone between the far and near zones. Freeform PAL provides a good solution to correct presbyopia and other disorders of accommodation, which is more widely adopted in the present optometric applications. However, there is still a lack of a standard procedure for the design of a PAL. Besides, the traditional manufacturing of freeform PAL is usually done by the approaches of grinding and polishing one by one, which is not only expensive but also time-consuming. This paper presents the research of a new approach for design and manufacturing technology for freeform PAL by ultra-precision machining approach. Extended polynomial is employed for the representation of freeform surface, which is used for the optimization of optical performance by some commercial optical software such as Zemax. Ultra-precision machining technology based on single-point diamond turning with slow slide servo (3S) machining is used to produce the mould inserts for precision moulding of the freeform PAL. Machining mechanics of 3S is discussed. A freeform PAL with an aspherical surface as front side and a freeform surface as back side has been designed. The precision mould insert of the designed freeform PAL was produced by ultra-precision machining process, and a plastic freeform PAL made of polycarbonate was also produced by precision moulding. Preliminary results obtained show that the new approach for design and fabrication is helpful to advance the design procedure optimization and mass production of PAL in optometry. [ABSTRACT FROM AUTHOR]

Abstract: We propose a variational-difference method for designing the optical free form surface of progressive-addition lenses (PALs). The PAL, which has a front surface with three important zones including the far-view, near-view and intermediate zones, is often used to remedy presbyopia by distributing optical powers of the three zones progressively and smoothly. The problem for designing PALs could be viewed as a functional minimization problem. Compared with the existing literature which solved the problem by the B-spline finite element method, the essence of the proposed variational-difference numerical method lies in minimizing the functional directly by finite difference method and/or numerical quadratures rather than in approximating the solution of the corresponding Euler–Lagrange equation to the functional. It is very easily understood and implemented by optical engineers, and the numerical results indicate that it can produce satisfactory designs for optical engineers in several seconds. We believe that our method can be a powerful candidate tool for designing various specifications of PALs. [Copyright &y& Elsevier]

Progressive addition lenses (PALs) are engraved with permanent marks at standardized locations in order to guarantee correct centering and alignment throughout the manufacturing and mounting processes. Out of the production line, engraved marks provide useful information about the PAL as well as act as locator marks to re-ink again the removable marks. Even though those marks should be visible by simple visual inspection with the naked eye, engraving marks are often faint and weak, obscured by scratches, and partially occluded and difficult to recognize on tinted or antireflection-coated lenses. Here, we present an extremely simple optical device (named as wavefront holoscope) for visualization and characterization of permanent marks in PAL based on digital in-line holography. Essentially, a point source of coherent light illuminates the engraved mark placed just before a CCD camera that records a classical Gabor in-line hologram. The recorded hologram is then digitally processed to provide a set of high-contrast images of the engraved marks. Experimental results are presented showing the applicability of the proposed method as a new ophthalmic instrument for visualization and characterization of engraved marks in PALs. [ABSTRACT FROM AUTHOR]

Nonsurgical treatment options commonly prescribed for teenagers with high AC/A ratios are progressive lens spectacles, single vision lens spectacles, bifocal contact lenses, and monovision. The gold standard treatment for high AC/A ratios in patients with esotropia is bifocal spectacles, but they are not cosmetically acceptable for most teenagers. However, excellent binocularity is often sacrificed with the alternative treatment options. Quality of life surveys acknowledge that poor cosmesis can have a negative psychosocial impact on individuals. Therefore, it is often necessary for practitioners to strike a balance between good psychosocial health and best visual potential with treatment options other than bifocal spectacles. [ABSTRACT FROM AUTHOR]

Abstract: This work proposes a method for dioptric power mapping of progressive lenses through dual wavelength, low-coherence digital speckle pattern interferometry. Lens characterization finds several applications and is extremely useful in the fields of ophthalmology and astronomy, among others. The optical setup employs two red diode lasers which are conveniently aligned and tuned in order to generate a synthetic wavelength. The resulting speckle image formed onto a diffusive glass plate positioned behind the test lens appears covered of contour interference fringes describing the deformation on the light wavefront due to the analyzed lens. By employing phase stepping and phase unwrapping methods the wavefront phase was retrieved and then expressed in terms of a Zernike series. From this series, expressions for the dioptric power and astigmatic power were derived as a function of the x- and y-coordinates of the lens aperture. One spherical and two progressive lenses were measured. The experimental results presented a good agreement with those obtained through a commercial lensometer, showing the potentialities of the method. [Copyright &y& Elsevier]

Objective: Evaluate induced astigmatism in progressive addition lenses into deflectometer measurements. Methods: Eleven progressive addition lenses were included with power away from +1.00D and addition 2.00D. Induced astigmatism was assessed twelve points in the zone intermediate, with six on each side of the progressive corridor in deflectometer. Results: There are significant differences between the sums of induced astigmatism on each side of the corridor and in the general in progressive addition lenses studied, with coefficient of variation with strong dispersion (CV 10-13%). Conclusion: There is an important variation of the power of induced astigmatism in progressive addition lenses. [ABSTRACT FROM AUTHOR]

The article offers information on myopia progression in children and the methods of controlling the disease. It says that myopia may increase the risk of having retinal detachment, associated glaucoma, and serious visual impairment. It also mentions several methods of treating myopia which include the use of bifocal spectacles, progression addition lenses, and multifocal contact lenses.

A 3½-year-old, female (spayed) working black Labrador Retriever was referred to the Unit of Comparative Ophthalmology at the Animal Health Trust after a penetrating lead gunshot injury to the right eye. Clinical examination revealed penetrating injuries to the right cornea, left lateral canthus, and left forelimb. Radiography revealed the presence of multiple metallic foreign bodies in the head and one in the left forelimb. B-mode ocular ultrasonography confirmed the presence of an intraocular metallic foreign body within the posterior tunics of the right eye. Medical treatment of the right eye over a period of 1 month resulted in a comfortable, visual eye. Long-term follow-up over 4½ years revealed a slow deterioration in vision because of progressive lens opacification and the presence of a localized area of chorioretinopathy. [ABSTRACT FROM AUTHOR]

Discrepancies exist in optometric education, practice and regulation across the Asia-Pacific region and the competence of optometric practitioners in adopting new lens technologies may vary widely. Over the past 10 years, a continuing professional development program, Varilux Academy Asia-Pacific (VAAP), was implemented and conducted in countries across the Asia-Pacific region to improve practitioners' understanding of optometric fitting principles, with special emphasis on progressive addition lenses (PAL). The aim was to demonstrate the effectiveness of VAAP and to compare the competence of practitioners across the Asia-Pacific region in new lens fitting technologies. From 2002 to 2008, all VAAP participants from 12 countries across Asia-Pacific were invited to complete a pre- and a post-program competency test and a post-program survey. A total of 5658 practitioners were trained, and 69.9 per cent (n = 3,957) of participants completed the pre- and post-program competency test; 80.9 per cent (n = 4,580) of participants completed the post-program survey. There was a significant improvement in competency after VAAP (mean change = 19.4 per cent ± 3.3, p < 0.01). Before VAAP was conducted the mean competency score was significantly lower in developing countries compared with developed countries (mean score of developed countries = 50.6 ± 10.3, mean score of developing countries = 45.0 ± 7.8, p < 0.05). After VAAP, these differences were not significant. Confidence in fitting PAL improved by 27.1 per cent. Most participants (91.6 per cent) intended to fit more PAL and 96.8 per cent of participants rated the program as excellent or good. Our findings highlight the need for further continuing education of practitioners across the Asia-Pacific region. The results of the training course indicate that, across Asia-Pacific, continuing education courses in ophthalmic optics and dispensing encompassing modern lens design and best practice fitting principles are warranted. [ABSTRACT FROM AUTHOR]

In this article, the materials used for glass (mineral) and plastic (organic) spectacle lenses and the properties of monofocal, bifocal, trifocal and multifocal spectacle lenses are investigated. On the other hand, the new generation personalized lenses, which were produced by freeform technology and customized high resolution (HD) wavefront-guided spectacle lenses and ongoing glass research studies are also discussed. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to simulate the retinal image of the eye with progressive addition lens (PAL), correction (without cylindrical component) and investigate its quality. The optical design and analysis software was used in simulation. The topographical data of the front surface of PAL were taken from the scanning profilometry. Also the coordinates of the points of the distant and near power measurements were taken from topographical measurements. The back surface was assumed to be spherical with a radius of curvature matched so that the optical power of PAL meets the data given by the manufacturer. In order to describe the retinal image quality, various metrics were calculated in comparison to the eye without correction. [ABSTRACT FROM AUTHOR]

Aims: To describe the clinical profiles and results of surgical and non-surgical interventions in a large cohort of patients with strabismus associated with chronic progressive external ophthalmoplegia (CPEO). Methods: A retrospective case note review was conducted of all patients with a clinical diagnosis of CPEO referred to our institution’s strabismus department in the United Kingdom between 1990 and 2008. Results: The total number of patients in this series was 28 (12 male, 16 female). The main presenting symptoms were diplopia (14) or cosmetically objectionable strabismus (11). Three had symptoms unrelated to strabismus and were excluded from further analysis. The most common strabismus findings were large angle exotropias (mean 47 prism diopters), half of which had associated vertical deviations. Strabismus management consisted of prisms (3), occlusion (3), botulinum toxin (7), and surgery (8). Two patients were offered surgery but were deemed unfit for general anesthesia, and a further 2 declined surgery or defaulted follow-up. Three had no active treatment for strabismus. The most effective procedure for exotropia was maximal, bilateral lateral rectus recessions (8 mm or 17 mm from the limbus) with medial rectus resections (7 mm) using adjustable sutures. Patients who had less than maximal horizontal muscle surgery were inevitably undercorrected, even in the early postoperative period. Long-term stability of measurements was rarely achieved, with either progressive increase in the angle of exotropia, or with new onset vertical deviations. Conclusions: In selected patients with CPEO and exotropia, maximal bilateral surgery significantly improves ocular alignment and may relieve symptoms of diplopia, but due to the progressive nature of the disease, strabismus often recurs. Toxin can be invaluable in maintaining a satisfactory ocular alignment in patients with residual or progressive exotropias, who have undergone maximal horizontal rectus muscle surgery or multiple previous strabismus procedures. [ABSTRACT FROM AUTHOR]

Purpose: To develop a nomogram for improving the accuracy of intraocular lens (IOL) power calculation at the time of cataract surgery based on the manifest refraction spherical equivalent (MRSE) change produced by laser in situ keratomileusis (LASIK). Setting: University-based clinical practice, Jules Stein Eye Institute, Los Angeles, California, USA. Methods: This was a retrospective review of the records of consecutive patients who had cataract surgery after LASIK. Spherical equivalent refractive data before and after LASIK and cataract surgery were recorded. The differences between the targeted postoperative refractive errors after cataract surgery and the achieved refractive errors were plotted against the LASIK-induced MRSE change, yielding postoperative refractive errors to target during IOL power calculation to achieve emmetropia. Results: Thirty-two eyes of 23 patients were identified; 25 eyes had myopic LASIK and 7, hyperopic LASIK. Regression analysis yielded the following polynomial relationship: target postoperative refractive error (D) to achieve emmetropia during IOL power calculation = −0.018(MRSE Change)2 + 0.192(MRSE Change) − 0.062. The outcomes in 97% of eyes fell within ±1.00 D of the value predicted by this formula. Conclusions: A 2nd-order polynomial relationship was found between LASIK-induced MRSE change and the MRSE error after cataract surgery. From this equation, a simple adjustment nomogram was generated and put into a look-up table format. The formula and nomogram should improve IOL power calculation accuracy in post-LASIK eyes when the MRSE change is known. [Copyright &y& Elsevier]

Purpose: To determine the accuracy of intraocular lens (IOL) power calculations in eyes with high myopia and to suggest adjusted constants for these cases. Setting: Centre for Ophthalmology, Eberhard-Karls-University, Tuebingen, Germany. Methods: Patients with high myopia having phacoemulsification with implantation of an AcrySof MA60MA IOL (power range +5.00 to −5.00 diopters [D]) were evaluated. Optical biometry (IOLMaster) and IOL calculations were performed before and after IOL implantation. Because of different optic principal planes of negative-diopter and positive-diopter IOLs, separate constants were calculated for these groups. Results: Fifty eyes (32 patients) were evaluated. Thirty eyes (mean AL 31.15 mm ± 1.69 [SD]) had implantation of a positive-diopter IOL (mean power +3.10 ± 1.50 D) and 18 eyes (mean AL 33.20 ± 2.25 mm), a negative-diopter IOL (mean power −3.20 ± 1.70 D). Postoperatively, the mean spherical equivalent was −1.42 ± 1.33 D and −0.41 ± 1.81 D, respectively. The difference in optimized constants between positive- and negative-diopter IOLs was significant for all formulas. Power calculation with the SRK II formula showed a wide range of deviation of postoperative refraction from target refraction. Calculation with the Haigis, SRK/T, Holladay 1, and Hoffer Q formulas showed a mean deviation of 0.00 D with an SD of 0.88, 0.92, 1.03, and 1.15, respectively. Conclusions: Results indicate that the SRK II formula cannot be recommended for IOL power calculation in highly myopic patients. With optimized constants, the SRK/T, Haigis, Hoffer Q, and Holladay 1 formulas produced small deviation of postoperative refraction from target refraction. [Copyright &y& Elsevier]

Studies which have examined the effect of bifocals or progressive addition lenses on the progression of myopia in children with different nearpoint phoria levels are reviewed. There is limited effect on myopia progression in children with exophouria or orthophoria. For children with esophoria, the number of subjects in various studies were often too small to achieve statistical significance. However, a reduction in the rate of progression with plus adds in esophoria can be recognized by comparing the results of multiple studies. A small previously unpublished prospective study, where rates of myopia progression is also presented. This study found that the difference in mean rates for esophoric plus add wearers who had their nearpoint phoria shifted out of esophoria with the add (-0.32D/yr) and single vision lens group subjects with esophoria at near (-0.49D/yr) was almost statistically significant (p=0.052). Implications of the literature reviewed and of the additional prospective data are discussed. Reduction in progression rates may be more likely in nearpoint esophoria when the phoria is shifted into exophoria with the add. Future studies to control myopia with plus adds should consider the use of individually prescribed add powers rather than providing all plus add group subjects with the same add power. [ABSTRACT FROM AUTHOR]

Purpose: To determine the accuracy of the Holladay 2, Hoffer Q, SRK/T, and Haigis intraocular lens (IOL) power calculation formulas in high myopic and high hyperopic refractive lens exchange (RLE) with hydrophobic acrylic foldable IOLs. Setting: Department of Ophthalmology, Johann Wolfgang Goethe University, Frankfurt am Main, Germany. Methods: Preoperatively, axial length (AL) was measured by partial coherence interferometry with the IOLMaster. The RLE was performed by phacoemulsification with posterior chamber IOL implantation in the capsular bag. Optimization of the lens constants for each IOL type was done separately for eyes with a positive lens and eyes with a negative lens. Prediction error (predicted refraction − postoperative refraction) and mean absolute error were back-calculated for the Holladay 2, Hoffer Q, SRK/T, and Haigis formulas. Results: Sixty-three eyes (44 myopic, AL ≥26.0 mm; 19 hyperopic, AL ≤22.0 mm) were included. In myopic and hyperopic RLE, all 4 formulas had an overall good performance. In myopic RLE, the Haigis formula performed better. Conclusion: In myopic and hyperopic RLE, optimization of lens constants improved the accuracy of IOL power calculation. [Copyright &y& Elsevier]

Purpose: To evaluate the accuracy of corneal power measurements by the Pentacam Scheimpflug system for intraocular lens (IOL) power calculation. Setting: Studio Oculistico d''Azeglio, Bologna, Italy. Methods: Consecutive patients having phacoemulsification and in-the-bag IOL implantation were prospectively studied. Intraocular lens power was calculated by entering 3 combinations of data into the Hoffer Q formula: (1) corneal power measurements by corneal topography (simulated keratometry) and axial length (AL) measurements by Ultrascan ultrasound (US) immersion biometry; (2) Scheimpflug corneal power measurements (simulated keratometry) and US AL measurements; (3) corneal power and AL measurements by partial coherence interferometry (PCI) (IOLMaster). The prediction error was calculated as the difference between the predicted and the measured refraction 1 month postoperatively. Results: Forty-one eyes were evaluated. The mean arithmetic error was zero for all combinations of measurements due to constant optimization. The mean absolute error (MAE) of the Scheimpflug–US combination was good (0.44 diopters [D] ± 0.30 [SD]) but significantly higher than the topography–US combination and PCI (0.33 ± 0.29 D and 0.33 ± 0.23 D, respectively) (P = .043). The percentage of eyes with an MAE of 0.75 D or greater was higher with the Scheimpflug–US combination (7 eyes, 17%) than with the corneal topography–US combination (2 eyes, 4.8%) or PCI (3 eyes, 7.3%). Conclusion: Corneal power measurements with the Pentacam Scheimpflug system should be used in IOL power calculation formulas with caution because the accuracy is good but is not as high as with standard measurement methods. [Copyright &y& Elsevier]

Purpose: To study from a theoretical viewpoint the effects in cases of extreme myopia of the different axial length (AL) behavior of current intraocular lens (IOL) calculation formulas and the problems caused by changes in lens geometry in the transition from plus to minus lenses. Setting: University Eye Hospital, Wuerzburg, Germany. Methods: A comparison of the thick-lens and thin-lens approach was made with allowance for the role of IOL constants and exemplified in model calculations based on design data of the MA60MA IOL in the power range from +5.0 to −5.0 diopters. Ray tracing was used to define model eyes for the MA60MA IOL, and the IOL constants producing the correct lens powers with the Haigis formula were determined. Results: An equation was derived linking lens geometry represented by the positions of the principal planes with the effective thin-lens position and thus with the respective IOL constants. Because IOL geometry changes considerably at the transition from plus to minus powers, a corresponding change is obtained in the necessary IOL constants. If no allowance is made for this effect, refractive errors increasing with AL will be associated with minus-power IOLs. Conclusion: Plus IOLs and minus IOLs have to be characterized by different sets of IOL constants. [Copyright &y& Elsevier]

Abstract: A 70-year-old woman with a history of diabetes mellitus and arterial hypertension presented with bilateral abduction deficits consistent with bilateral sixth nerve paresis. A diagnostic evaluation including magnetic resonance imaging and lumbar puncture was unrevealing. The bilateral sixth nerve paresis spontaneously resolved suggesting ischemic or microvascular disease as the underlying etiology. [Copyright &y& Elsevier]

Background: The aim of this trial was to compare the effectiveness of two generations of progressive lenses for presbyopia. Methods: A multicenter cross-over randomized controlled trial performed in a primary care setting (5 optical dispensaries) was planned. Two categories of progressive lenses were compared: 1) a new-generation lens (i.e., VARILUX PANAMIC ORMA CRIZAL), which is expensive but a supposed improvement in comfort, and 2) an older-generation lens (i.e., VARILUX CONFORT ORMA CRIZAL), which is less expensive and is considered the reference lens. Patients were randomized to wear one generation of progressive lens for 4 weeks, then cross over to wear the other lens for 4 weeks, without knowing the sequence of lenses. Inclusion criteria were 1) age 43-60 years; 2) outpatients already wearing progressive lenses and referred to an optician ophthalmologist for optical correction prescription within the last 6 months; 3) receiving a correction of ≤3 dioptres in cases of associated myopia, hyperopia or astigmatism; 4) understanding and speaking French and able to answer a questionnaire; and 5) giving written consent to participate in the study. The primary outcome was patient preference for one progressive lens at week 8. Secondary outcomes were subjective measures of bifocal visual performance, including a) near visual acuity, b) visual field, c) kinetic visual skills, d) visual adaptability, e) visual comfort, and f) rapidity of adaptation. Results: 127 patients were randomized to one of the lens groups. Two patients withdrew prematurely; 98.4% and 97.6% patients who wore the new versus older lenses, respectively, wore their progressive lenses every day during the 4-week period 1 and period 2. The number of participants in each of 5 centres varied from 16 (12.6%) to 35 (27.6%). 57.9% patients preferred the new-generation lenses, 36.5% the older-generation lenses, and 5.6% had no preference (p = 0.01). The two groups did not differ in any of the measures of bifocal visual performance except near visual acuity. Conclusion: Patients with presbyopia had slightly higher preference for the new-generation than older-generation lens, with no difference in lens groups for most of the visual outcomes assessed. Trial Registration: ClinicalTrials.gov NCT00635115 [ABSTRACT FROM AUTHOR]

The article discusses the development of multifocals and other high power lenses. In multifocals, the higher the power, the more precise fitting measurements had to be. It stresses that the pupillary distance (PD) had to be measured monocularly and very accurately. Early high power lenses include full field spheric glass, where lenses of these glasses were all steep-front base-curve lenses without any asphericity; the spheric lenticular round lenses; spheric lenticular oval lenses; and, aspheric lenses. It credited an ophthalmologist from Florida for opening a new era of excellence and opportunity for the industry and aphakic patients. The ophthalmologist designed a lens that had concentric circles of asphericity starting from the center of the lens.

The article highlights the ZEISS Optical Optimization & Management process used by Carl Zeiss Vision in developing GT2 lens in the U.S. The author stated that ZEISS has always relied on a sophisticated lens design process that delivers the most advanced progressive lenses available. He added that careful management of the overall global configuration of the lens design is the first stage of the ZEISS Optical Optimization & Management process. Moreover, the second stage of the process is an intensive, point-by-point refinement of the entire lens surface using computer raytracing and sophisticated optimization routines.

Although the Varilux type varifocal has been and still is very popular, research has been carried out on other methods of providing a progressive addition lens. This paper deals with the field of gradient-index optics. It includes a review of the literature related to the production of a gradient-index element and the theoretical analysis of concentric varifocals. A procedure is described to construct a varifocal lens, after that described by Wood in 1905, to produce lenses known as 'non-homogeneous cylinders' or 'pseudo-lenses'. The method is based on a diffusion process, taking place in half of the lens, and creates steps in the refractive index of the material. Experimental data are also given on the change of the spherical and cylindrical power, which indicate that the lens constructed is an optical system having a rotational symmetry in power, around a fixed point. [ABSTRACT FROM AUTHOR]

An instrument is described for the automatic measurement of lens power across the whole aperture of a varifocal lens. The apparatus is based on an electronic focimeter controlled by an external computer, which also positions the lens by two stepper motors. Methods of display of the data are discussed, and the repeatability of measurement is illustrated. [ABSTRACT FROM AUTHOR]

Numerous reasons have been cited for patient non-tolerance to Progressive Addition Lenses (PALs). This paper considers two presbyopic subject populations - those who successfully wore PALs (n = 20), and those who were non-tolerant to them (n = 18). The dispensing accuracy of the PALs worn by subjects was assessed and the surface quality of those lenses worn by unsuccessful patients studied. These factors do not account for any significant differences between the two groups, suggesting that other causes must separate the subject populations. [ABSTRACT FROM AUTHOR]

Analysis of 98 progressive addition lens (PAL) wearers was undertaken using both mailed questionnaires and by assessing patient records. Statistical analysis was undertaken to investigate the nature and dependant variables of a PAL population. The PAL patients were from the Aston University undergraduate optometric clinic. Social survey techniques, such as the use of personalized mail, first-class stamps, and follow-up letters, were employed to produce a high return rate for the questionnaire. The number of returned questionnaires reached 89.9 % of those originally sent which may be considered to be highly representative. The clinical survey showed the success rate for the undergraduate clinic to be either 85.7% or 80.6% depending upon the criterion for successful wear. [ABSTRACT FROM AUTHOR]

The article lists titles of abstracts of poster presentation at the 19th Asia Pacific Optometric Congress (APOC) Congress in Seoul, Korea on October 2-4, 2013 related to optometry including corneal indices in Down syndrome, effect of progressive lens, and role of ocular movement in reading.

Purpose: To study the application of intraoperative retinoscopy for intraocular lens (IOL) power calculation in combined cataract extraction and silicone oil removal. Settings: Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India. Methods: This study comprised patients with silicone oil–filled eyes and visually significant cataract who had combined cataract extraction by phacoemulsification and silicone oil removal by a standard method through the pars plana route. Retinoscopy was performed with a streak retinoscope, standard vertex distance of 13.0 mm, and distance of 50.0 cm. All eyes had in-the-bag implantation of a foldable IOL with an A-constant of 118.4. The IOL power was calculated using the Ianchulev formula as follows: R × 2.01449. Postoperative refraction was performed at 3 months, and the spherical equivalent was calculated. Results: Twelve eyes of 12 patients were evaluated. The mean emmetropic power calculated by intraoperative retinoscopy was 20.46 diopters (D) ± 3.4 (SD) (range 13.09 to 25.18 D) and the mean refractive error, −0.45 ± 0.63 D (range −1.00 to +1.00 D). The postoperative refractive error was within ±0.50 D in 4 eyes (33.3%) and within ±1.00 D in all eyes. Ten eyes (83.33%) had a postoperative refractive error in the range of 0.00 to −1.00 D using IOL power based on intraoperative retinoscopy. Conclusion: Intraoperative retinoscopy for IOL power calculation in combined cataract extraction and silicone oil removal gave satisfactory refractive outcomes, although further studies with more patients are required to confirm its usefulness and determine whether there are disadvantages. [Copyright &y& Elsevier]

The article examines the research which reveals that a piggyback contact lens fits for a keratoconus eye patient in Canada. It says that the piggyback system of fitting contact lenses has gained more popularity over the past few years. It consists of a rigid gas permeable (RGP) lens placed on top of a soft contact lens. Meanwhile, it elaborates several categories of patients who benefit from the piggyback system which includes those patients who are experiencing discomfort with their RGP contact lenses, patients with poor RGP centration, and patients who experience corneal compromise from contact lenses. It also offers information on which contact lenses to choose and discusses the aspects of fitting assessment.

An instrument is described for the assessment of varifocal lens surfaces based on a reflection technique. Results are also presented of measurements made on a series of lenses of the same design, illustrating some of the differences that exist between glass and plastics versions of the same lens. [ABSTRACT FROM AUTHOR]