Design Of Progressive Addition Lenses Research Articles

An objective measurement approach to quantify the perceived distortions of spectacle lenses

The eye’s natural aging influences our ability to focus on close objects. Without optical correction, all adults will suffer from blurry close vision starting in their 40s. In effect, different optical corrections are necessary for near and far vision. Current state-of-the-art glasses offer a gradual change of correction across the field of view for any distance—using Progressive Addition Lenses (PALs). However, an inevitable side effect of PALs is geometric distortion, which causes the swim effect, a phenomenon of unstable perception of the environment leading to discomfort for many wearers. Unfortunately, little is known about the relationship between lens distortions and their perceptual effects, that is, between the complex physical distortions on the one hand and their subjective severity on the other. We show that perceived distortion can be measured as a psychophysical scaling function using a VR experiment with accurately simulated PAL distortions. Despite the multi-dimensional space of physical distortions, the measured perception is well represented as a 1D scaling function; distortions are perceived less with negative far correction, suggesting an advantage for short-sighted people. Beyond that, our results successfully demonstrate that psychophysical scaling with ordinal embedding methods can investigate complex perceptual phenomena like lens distortions that affect geometry, stereo, and motion perception. Our approach provides a new perspective on lens design based on modeling visual processing that could be applied beyond distortions. We anticipate that future PAL designs could be improved using our method to minimize subjectively discomforting distortions rather than merely optimizing physical parameters.

Theoretical performance of progressive addition lenses with poorly measured individual parameters.

The aim of this paper was to present a theoretical study of how poorly measured individual parameters affect the optical performance of progressive addition lenses (PALs). Modern progressive lenses can be prescribed based on parameters such as vertex distance, pantoscopic and wrap angles. These parameters can be measured from the lens wearer using specific devices; however, not all of them can be measured with the same precision, and the impact of measurement errors on the lens performance is still unknown. Data from 1900 patients were used to simulate the performance of four PAL designs with different degrees of complexity: perfect individual design, individual design with induced errors in the individual parameters, optimised design and conventional/basic design. For each patient and design, a quality metric was calculated to describe the optical performance of the lens. The design having the best performance was the perfect individual design, followed by the individual design with induced errors, the optimised design and finally the conventional/basic design. Individual designs with measurement errors have better optical performance than lenses with less complexity, such as the optimised or conventional designs. This knowledge is useful for the eye care professional to make informed choices when dispensing these lenses.

Design of Progressive Addition Lenses Based on Conic Parametric Equations

Design of Progressive Addition Lenses Based on Conic Parametric Equations

Design of Progressive Addition Lens Based on Weight Function Optimization

Design of Progressive Addition Lens Based on Weight Function Optimization

Optimal Design of Progressive Addition Lenses Based on Aspherical Formula

Optimal Design of Progressive Addition Lenses Based on Aspherical Formula

누진굴절력렌즈 디자인에 고려할 누진대 패턴의 제안

누진굴절력렌즈 디자인에 고려할 누진대 패턴의 제안

权重函数对渐进镜片设计的影响

权重函数对渐进镜片设计的影响

How free-form technology improves progressive addition lens design

How free-form technology improves progressive addition lens design

Simple approach to the generalized Minkwitz theorem.

The Minkwitz theorem plays an important role in the design of progressive addition lenses. Recently, this theorem has been generalized by Esser etal. [J. Opt. Soc. Am. A34, 441 (2017)10.1364/JOSAA.34.000441JOAOD60740-3232] to non-umbilic lines under the assumption of a symmetric surface. We present a simplified derivation and generalize their findings to arbitrary but sufficiently smooth surfaces.

Peripheral Design of Progressive Addition Lenses and the Lag of Accommodation in Myopes.

Insufficient accommodative response is assumed to result in myopia progression. We have investigated if the accommodative lag in myopes is different between a single vision lens (SVL) and the progressive addition lens PAL 2, clinically trialled for its ability to reduce progression of myopia, and if there exist differences in accommodative lag between PAL 2 and other PALs with the same addition power (+1.50 D). The influence of spherical SVL and four different designs of PALs that differ in the near zone width (PAL 1) or that have different signs and magnitude of horizontal gradients of mean power adjacent to their near vision zones (PAL 3 and PAL 4) on the accommodative response was investigated for different near viewing distances (40, 33, and 25 cm) in 31 subjects, aged 18 to 25 years. The SVL correction resulted in insufficient accommodative response for the near object viewing distances tested. PAL 2 did significantly reduce accommodative lag for all near object distances tested. The PAL design with a more negative horizontal mean power gradient (PAL 4) provided a lower lag of accommodation when compared with PAL 2 at the shortest object distance of 25 cm (P = 0.03) and was able to reduce the lag of accommodation to a level below the depth of focus for the higher near working distances tested. Designs of PAL with more negative horizontal mean power gradients are the most effective in lowering the lag of accommodation in myopes. This could make them good test candidates for myopia control applications.

Personalized Progressive Addition Lenses: Correlation between Performance and Design.

A continuous set of personalized designs (design space) for progressive addition lenses (PALs) is investigated. The main goals are (1) to study how the subjects' perception of a personalized design depends on its position in the design space and (2) to compare the performance of personalized PALs to a conventional PAL with a fixed design. In a double-blind study, 51 subjects compared Rodenstock Impression FreeSign 3, which is a family of PALs with a continuously controllable personalized design, and Rodenstock Progressiv Life Free, which is a conventional PAL with a single fixed design. The positions and sizes of viewing zones and the softness of gradients of mean power and astigmatism of personalized lenses were customized to individual viewing preferences. These designs were represented as points in a design space comprising a continuum of PAL designs. Subjective ratings and experimental measurements were used to study viewing zone widths, blur gradient smoothness, amount of distortion, the feeling of safety during motion, and overall wearing comfort. (1) Far viewing zone width (experiments and ratings), near viewing zone width (experiments), blur gradient smoothness, and the amount of distortion (ratings) were significantly dependent on the position of the personalized lens design in the design space. This was consistent with the structure of the design space. (2) 82% of the subjects chose personalized lenses as their favorite. Most subjects reported higher wearing comfort and tolerability with personalized lenses than with conventional lenses. The designs of the tested personalized lenses were perceived by the subjects as intended. This is a prerequisite to the successful customization of PALs to individual wearing preferences. Possible reasons for the preference of the tested personalized lenses are the optimization with respect to individual wearing conditions and the personalization.

Hyperbolic tangential function-based progressive addition lens design.

The diopter distribution is key to the successful design of a progressive addition lens. A hyperbolic tangential function is then introduced to describe well the desired diopter distribution on the lens. Simulation and fabrication show that the astigmia on the whole surface is very close to the addition, exhibiting superior performance than that of currently used high-order polynomials and cosine functions. Our investigations found that once the diopter distribution design is reasonable, both the direct and indirect methods of constructing a progressive addition lens can give consistent results. With this function we are able to effectively control the design of critical areas, the position, sizes of far-view and near-view zones, as well as the channel of the lens. This study would provide an efficient way to customize different progressive lenses not only for presbyopia, but also for anti-fatigue, office progressive usages, etc.

Progressive lens design by discrete shape modelling techniques

The free-form technologies, recently introduced in the manufacturing process of ophthalmic lenses, allow the production of high performance and custom progressive addition lenses (PALs). In this work a method for the parametric design and analysis of PAL, based on discrete shape modelling, is proposed. Both the optical (e.g. power and addition) and the geometrical (e.g. inset, corridor length, amplitude of the distance and near vision area) parameters have been taken into account. In addition the method developed for the analysis of surface optical properties, especially with regard to the astigmatic surface power, has proved an essential tool for the analysis of results. Moreover the exchange data formats for the CNC manufacturing process were described. The influence of different parameters on the optical properties are analyzed and discussed. In this context a key role on the resultant optical properties of the designed PAL is covered by the distribution of the curves in the intermediate area and by the curvature equation along the corridor. Surface power and astigmatic surface power show similar behaviour to other commercial progressive additional lens but, moreover, the designer can specify the distribution of astigmatism in the intermediate region. Compared to the methods proposed in literature, this one shows more opportunities in the design parameters definition and allows highly customized lens, designed on the main habits of the wearer. Finally the method was applied to the manufacturing process of glass mould for PAL and the results of optical parameters measurements are proposed.

Progressive Addition Lens Measurement by Point Diffraction Interferometry

Design a device for accurate measurements of local optical properties of progressive addition lenses (PALs). A point diffraction interferometer has been adapted to measure local prescriptions of PALs. The most basic configuration of the interferometer for the measurement of PALs showed in this work presents high dynamic range and accuracy as well as the possibility of choosing the number and position of measurement points. Measurements are taken within a region of interest within a radius of about 0.4 to 1.5 mm. Different PAL designs are measured by the method proposed here and compared with results by a last generation commercial lens mapper. With the point diffraction interferometer we also compared several PAL designs in order to analyze their properties in the progression zone. The device is compact, robust, and fairly accurate, and the operational principle is very simple. By direct measurements it provides the local dioptric power, i.e., the second order wavefront properties, of the lens for selected regions of interest. The position and area can be chosen by the user. The only mobile part of the setup allows for the selection of the measurement points without any additional prismatic correction or movement of the PAL.

Non-surgical interventions for convergence insufficiency.

Convergence insufficiency is a common eye muscle co-ordination problem in which the eyes have a strong tendency to drift outward (exophoria) when reading or doing close work. Symptoms may include eye strain, headaches, double vision, print moving on the page, frequent loss of place when reading, inability to concentrate, and short attention span. To systematically assess and synthesize evidence from randomized controlled trials (RCTs) on the effectiveness of non-surgical interventions for convergence insufficiency. We searched The Cochrane Library, MEDLINE, EMBASE, Science Citation Index, the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com) and ClinicalTrials.gov (www.clinicaltrials.gov ) on 7 October 2010. We manually searched reference lists and optometric journals. We included RCTs examining any form of non-surgical intervention against placebo, no treatment, sham treatment, or each other. Two authors independently assessed eligibility, risk of bias, and extracted data. We performed meta-analyses when appropriate. We included six trials (three in children, three in adults) with a total of 475 participants. We graded four trials at low risk of bias.Evidence from one trial (graded at low risk of bias) suggests that base-in prism reading glasses was no more effective than placebo reading glasses in improving clinical signs or symptoms in children.Evidence from one trial (graded at high risk of bias) suggests that base-in prism glasses using a progressive addition lens design was more effective than progressive addition lens alone in decreasing symptoms in adults. At three weeks of therapy, the mean difference in Convergence Insufficiency Symptoms Survey (CISS) score was -10.24 points (95% confidence interval (CI) -15.45 to -5.03).Evidence from two trials (graded at low risk of bias) suggests that outpatient (or office-based as used in the US) vision therapy/orthoptics was more effective than home-based convergence exercises (or pencil push-ups as used in the US) in children. At 12 weeks of therapy, the mean difference in change in near point of convergence, positive fusional vergence, and CISS score from baseline was 3.99 cm (95% CI 2.11 to 5.86), 13.13 diopters (95% CI 9.91 to 16.35), and 9.86 points (95% CI 6.70 to 13.02), respectively.In a young adult population, evidence from one trial (graded at low risk of bias) suggests outpatient vision therapy/orthoptics was more effective than home-based convergence exercises in improving positive fusional vergence at near (7.7 diopters, 95% CI 0.82 to 14.58), but not the other outcomes.Evidence from one trial (graded at low risk of bias) comparing four interventions, also suggests that outpatient vision therapy/orthoptics was more effective than home-based computer vision therapy/orthoptics in children. At 12 weeks, the mean difference in change in near point of convergence, positive fusional vergence, and CISS score from baseline was 2.90 cm (95% CI 0.96 to 4.84), 7.70 diopters (95% CI 3.94 to 11.46), and 8.80 points (95% CI 5.26 to 12.34), respectively. Evidence was less consistent for other pair-wise comparisons. Current research suggests that outpatient vision therapy/orthoptics is more effective than home-based convergence exercises or home-based computer vision therapy/orthoptics for children. In adult population, evidence of the effectiveness of various non-surgical interventions is less consistent.

Experimental procedure for measuring and comparing head–neck–trunk posture and movements caused by different progressive addition lens designs

This study demonstrates that appropriate measurement procedures can detect differences in head movement in a near reading task when using three different progressive addition lenses (PALs). The movements were measured using an anatomical reference system with a biomechanical rationale. This reference system was capable of representing rotations for comparing head flexion relative to trunk, head flexion relative to neck, head rotation relative to trunk and trunk flexion. The subject sample comprised 31 volunteers and three PAL designs with different viewing zones were selected. Significant differences were found between the lenses for three of the seven movement parameters examined. The differences occurred for both vertical and horizontal head movements and could be attributed to aspects of the PAL design. The measurement of the complete kinematic trunk–neck–head chain improved the number of differences that were found over those in previous studies. Statement of Relevance: The study proposes a methodology based on a biomechanical rationale able to differentiate head–neck–trunk posture and movements caused by different progressive addition lens designs with minimum invasiveness. This methodology could also be applied to analyse the ergonomics of other devices that restrict the user's field of view, such as helmets, personal protective equipment or helmet-mounted displays for pilots. This analysis will allow designers to optimise designs offering higher comfort and performance.

Progressive addition lens design and the short of stature

Traditional progressive addition lens (PAL) design, which places the distance vision correction in the upper half of the lens,1,2 may pose a specific challenge for the short of stature. Given that ...

Effectiveness of Base in Prism for Presbyopes with Convergence Insufficiency

Although the treatment of symptomatic convergence insufficiency (CI) with base-in (BI) prism in adults has a strong theoretical foundation, there have been very few studies addressing its efficacy. The purpose of this study was to investigate whether the application of BI prism, using a novel progressive addition lens design which incorporates BI prism in the near portion only, could help alleviate the symptoms in presbyopes with CI. A total of 29 symptomatic CI subjects aged 45 to 68 years were examined. All subjects took the CI Symptom Survey V-15 (CISS) and scored >or=16 points. Each subject was assigned two pairs of progressive addition glasses made by the same manufacturer in a randomized sequence, one with BI prism and one with the same lens prescription but no prism (placebo). Subjects wore each pair of glasses for 3 weeks and completed the CISS at the end of the 3rd week. Symptom level measured with CISS was the major outcome measure. The mean (standard deviation) CISS score was 30.21 (9.30) at baseline and decreased to 13.38 (9.44) with the BI-prism glasses, vs. 23.62 (10.76) with the placebo glasses. There were significant differences between the baseline survey score and the score with the BI-prism glasses (p < 0.0001) and between the score with placebo glasses and the one with BI-prism glasses (p = 0.001). The progressive addition glasses with BI-prism were found to be effective in alleviating symptoms of presbyopes with symptomatic CI.

Paraxial Optics of Astigmatic Systems: Relations Between the Wavefront and the Ray Picture Approaches

The paraxial propagation of astigmatic wavefronts through astigmatic optical systems can be described by the augmented step-along method (ASAM). Its equivalence to the linear ray optics approach is considered in detail. The ASAM is exploited to derive paraxial ray paths through a general coaxial astigmatic system. Starting from the information inherent in the ASAM all 2x2 submatrices rendering the general 4x4 transference of linear optics can be generated. This proves the complete equivalence of both approaches. Additionally, we show that the symplectic relations are automatically obeyed in the ASAM. The ASAM offers a complete alternative to describe the paraxial optics of astigmatic optical systems. According to the ASAM, an optical system is fully characterized by the back vertex vergence and the angular magnification matrix. Hence, a complete description of the paraxial optics of an eye should not only report the state of refraction but the angular magnification matrix as well, although it is not yet very common. The magnification matrix might be important in cases of anisometropia or the design of progressive addition lenses. Yet, a simple clinical procedure to determine the angular magnification matrix is missing.

Progressive addition lenses—measurements and ratings

Background This study is a followup to a previous study in which the optics of several progressive addition lens (PALs) designs were measured and analyzed. The objective was to provide information about various PAL designs to enable eye care practitioners to select designs based on the particular viewing requirements of the patient. Methods The optical properties of 12 lenses of the same power for each of 23 different PAL designs were measured with a Rotlex Class Plus lens analyzer. Lenses were ordered through optical laboratories and specified to be plano with a +2.00 diopters add. Measurements were normalized to plano at the manufacturer-assigned location for the distance power to eliminate laboratory tolerance errors. The magnitude of unwanted astigmatism and the widths and areas of the distance, intermediate, and near viewing zones were calculated from the measured data according to the same criteria used in a previous study. Results The optical characteristics of the different PAL designs were significantly different from one another. The differences were significant in terms of the sizes and widths of the viewing zones, the amount of unwanted astigmatism, and the minimum fitting height. Ratings of the distance, intermediate, and near viewing areas were calculated for each PAL design based on the widths and sizes of those zones. Ratings for unwanted astigmatism and recommended minimum fitting heights were also determined. Ratings based on combinations of viewing zone ratings are also reported. Conclusions The ratings are intended to be used to select a PAL design that matches the particular visual needs of the patient and to evaluate the success and performance of currently worn PALs. Reasoning and task analyses suggest that these differences can be used to select a PAL design to meet the individual visual needs of the patient; clinical trials studies are required to test this hypothesis.