Progressive Lenses Research Articles

Progressive power lenses - part 7

In the seventh part of our comprehensive series discussing progressive spectacle lens design, Professor Mo Jalie looks at the fitting of the lenses

Fabrication of freeform progressive addition lenses using a self-developed long stroke fast tool servo

A long stroke fast tool servo (LFTS) system with a maximum stroke range of ±4 mm based on the voice coil actuator was developed and integrated on a diamond turning machine (DTM) for the fabrication of freeform progressive addition lenses (PALs). The LFTS utilized a three-ring cascade control system for the motion trajectory control of a diamond tool. The numerical control codes of the tool path were transferred from the 3D surface data with freeform features. The complete process chain from tool path generation and diamond machining to power measurement was experimentally demonstrated. The obtained surface form accuracy was 6.7 μm (rms), and the measured power of the PAL agreed well with the theoretical design indicating the desirable processing capability of LFTS for the customized freeform spectacle optics.

Peripheral refraction with different designs of progressive soft contact lenses in myopes

Aim: The purpose of this study was to compare the changes in relative peripheral refractive error produced by two different designs of progressive soft contact lenses in myopic schoolchildren. Methods: Twenty-seven myopic schoolchildren age between 13 to 15 years were included in this study. The measurements of central and peripheral refraction were made using a Grand-Seiko WR-5100K open-field autorefractometer without correction (baseline), and two different designs of progressive contact lenses (PCLs) (Multistage from SEED & Proclear from Cooper Vision) with an addition power of +1.50 D. Refractive power was measured at center and at eccentricities between 35º temporal to 35º nasal visual field (in 5º steps). Results: Both PCLs showed a reduction in hyperopic defocus at periphery. However, this reduction was only significant for the Multistage PCL (p= 0.015), (Proclear PCL p= 0.830). Conclusion: Multistage PCLs showed greater reduction in peripheral retinal hyperopic defocus among myopic schoolchildren in comparison to Proclear PCLs.

Progressive power lenses: part 6

In the sixth part of our comprehensive series discussing progressive spectacle lens design, Professor Mo Jalie looks at degressive designs

Efficacy of 1% atropine eye drops in retarding progressive axial myopia in Indian eyes.

Purpose:The aim of this study is to assess the efficacy of 1% atropine eye drops for the retardation of progressive axial myopia in Indian eyes.Methods:This prospective interventional cohort study included children aged 5–16 years. Both the eyes of myopic children with progressive increase of ≥−0.5D sphere/year with the best-corrected vision of ≥6/6 were treated with once a day application of 1% atropine eye drops and progressive addition photogray lenses. The progression of myopia after 1-year follow-up was analyzed.Results:Sixty eyes of thirty myopes were included in the study. The mean age was 10 years and 15 were girls. The mean baseline sphere was −5.2D (−2.5D–−13D). Mean duration of follow-up was 23 months (12–36 months). The baseline rate of progression was reduced from −0.6D/year (range −0.5D/year to −3D/year) to −0.2D/year (range 0D/year to −1.5D/year) after atropine therapy. Seventeen patients (57%) had to use the atropine in the daytime to reach the target progression of <−0.5D/year. There was no difference between the efficacy of atropine drops in the boys and girls (P = 0.6). The efficacy of atropine drops did not have a correlation with the age of the patients or the magnitude of baseline myopia (Pearson's r = 0).Conclusion:1% atropine eye drops was well tolerated and efficacious for the retardation of progressive myopia in Indian eyes. Effectiveness was better with daytime application. Further studies are necessary to assess the role of 1% atropine in the rapid progressors and patients poorly responding to low-dose atropine.

基于拉普拉斯方程的渐进多焦点眼用镜片轮廓线优化设计

基于拉普拉斯方程的渐进多焦点眼用镜片轮廓线优化设计

Survey on Improperly Fitting after Prescription of Progressive Additional Lens

Survey on Improperly Fitting after Prescription of Progressive Additional Lens

渐进多焦点镜片表面初始矢高模型的设计

渐进多焦点镜片表面初始矢高模型的设计

누진다초점 렌즈 착용의 자각적 만족감에 미치는 요인

누진다초점 렌즈 착용의 자각적 만족감에 미치는 요인

Use of coordinate measuring machine to measure circular aperture complex optical surface

Abstract The measurement of complex surface with form accuracy up to micrometers is of critical importance in the field of precision manufacturing and measuring. In this paper, a systematical measuring method based on coordinate measuring machine (CMM) was proposed for the circular aperture complex optical surface. By proposed method, concentric-circles discretized by equally spaced angle were chosen to obtain the sampling points, and the spline interpolation method for probe radius compensation was considered, then the compensated data points were fitted to measured surface using Zernike polynomials. Furthermore, a simulation of toric surface was studied to analyze surface construction error. Under specific parameter condition of discretization angle of 15°, step length of 1 mm and fitting terms of Zernike polynomials 66, the PV form error was 0.1596 μm and RMS was 0.0292 μm. The simulation results show that the proposed fitting method can meet the requirement of inspection accuracy at the micron level. Finally, a progressive addition lens complex surface was measured by a MQ686 CMM to verify the feasibility of the proposed method.

Progressive power lenses - part 5

In part five of this eight-part series, Professor Mo Jalie continues his discussion of the development of progressive lenses with a look at sixth and seventh generation designs.

Peripheral refraction with different designs of progressive soft contact lenses in myopes.

Aim: The purpose of this study was to compare the changes in relative peripheral refractive error produced by two different designs of progressive soft contact lenses in myopic schoolchildren. Methods: Twenty-seven myopic schoolchildren age between 13 to 15 years were included in this study. The measurements of central and peripheral refraction were made using a Grand-Seiko WR-5100K open-field autorefractometer without correction (baseline), and two different designs of progressive contact lenses (PCLs) (Multistage from SEED & Proclear from Cooper Vision) with an addition power of +1.50 D. Refractive power was measured at center and at eccentricities between 35º temporal to 35º nasal visual field (in 5º steps). Results: Both PCLs showed a reduction in hyperopic defocus at periphery. However, this reduction was only significant for the Multistage PCL (p= 0.015), (Proclear PCL p= 0.830). Conclusion: Multistage PCLs showed greater reduction in peripheral retinal hyperopic defocus among myopic schoolchildren in comparison to Proclear PCLs.

Progressive power lenses - part 3

In part three of this six-part series, Professor Mo Jalie continues his discussion of the development of progressive lenses from the second to the fourth generation designs.

Specific eye-head coordination enhances vision in progressive lens wearers.

In uncorrected vision all combinations of eye and head positions are visually equivalent; thus, there is no need for a specific modification of eye-head coordination in young healthy observers. In contrast, the quality of visual input indeed strongly depends on eye position in the majority of healthy elderly drivers, namely in progressive additional lens (PALs) wearers. For a given distance, only specific combinations of eye and head position provide clear vision in a progressive lens wearer. However, although head movements are an integral part of gaze behavior, it is not known if eye-head coordination takes part in the enhancement of visual input in healthy individuals. In the current study we determined changes in eye-head coordination in progressive lens wearers in challenging tasks with high cognitive load, in the situation of driving. During a real-world drive on an urban round track in Stuttgart, gaze movements and head movements were measured in 17 PAL wearers and eye-head coordination was compared to 27 controls with unrestricted vision. Head movement behavior, specific to progressive lens wearers, was determined in head gain and temporal properties of head movements. Furthermore, vertical eye-head coordination was consistent only among PAL wearers. The observed differences in eye-head coordination clearly demonstrate a contribution of head movements in the enhancement of visual input in the healthy human visual system.

Aspherics in spectacle lenses

Abstract A review of the use of aspherics in the last decades, understood in a broad sense as encompassing single-vision lenses with conicoid surfaces and free-form and progressive addition lenses (PALs) as well, is provided. The appearance of conicoid surfaces to correct aphakia and later to provide thinner and more aesthetically appealing plus lenses and the introduction of PALs and free-form surfaces have shaped the advances in spectacle lenses in the last three decades. This document basically considers the main target optical aberrations, the idiosyncrasy of single lenses for correction of refractive errors and the restrictions and particularities of PAL design and their links to science vision and perception.

The Case for Lens Treatments in the Control of Myopia Progression

ABSTRACT Myopia is on the rise in the United States and around the world, and with its progression comes increasing risk of a wide variety of associated vision-threatening conditions. Fortunately, several evidence-based treatments for myopia control are currently available and show promise. Basic research on the visual control of eye growth and the development of refractive state is being successfully translated to clinical studies on lens and drug treatments, and patients are already benefiting. Evidence-based practice is transforming the clinical care for myopia from correction to treatment. In this commentary on the role of lens treatments for myopia control from the 15th International Myopia Conference, the author considers bifocals, progressive addition lenses, multifocal contact lenses, and orthokeratology to make the case that lens treatments, particularly using multifocal contact lenses, are effective for myopia control and should be considered as a first-line treatment. A number of areas for further research and treatment optimization are also identified.

Progressive power lenses - part 2

In the second of a six-part series, Professor Mo Jalie explains the design of modern progressive power lenses.

Progressive power lenses - part 1

In the first of a four part series, Professor Mo Jalie explains the design of modern progressive power lenses.

The relationship between dioptric power and magnification in progressive addition lenses.

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. 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. 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). 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.

A Novel Marking Reader for Progressive Addition Lenses Based on Gabor Holography.

Progressive addition lenses (PALs) are marked with permanent engraved marks (PEMs) at standardized locations. Permanent engraved marks are very useful through the manufacturing and mounting processes, act as locator marks to re-ink the removable marks, and contain useful information about the PAL. However, PEMs are often faint and weak, obscured by scratches, partially occluded, and difficult to recognize on tinted lenses or with antireflection or scratch-resistant coatings. The aim of this article is to present a new generation of portable marking reader based on an extremely simplified concept for visualization and identification of PEMs in PALs. Permanent engraved marks on different PALs are visualized using classical Gabor holography as underlying principle. Gabor holography allows phase sample visualization with adjustable magnification and can be implemented in either classical or digital versions. Here, visual Gabor holography is used to provide a magnified defocused image of the PEMs onto a translucent visualization screen where the PEM is clearly identified. Different types of PALs (conventional, personalized, old and scratched, sunglasses, etc.) have been tested to visualize PEMs with the proposed marking reader. The PEMs are visible in every case, and variable magnification factor can be achieved simply moving up and down the PAL in the instrument. In addition, a second illumination wavelength is also tested, showing the applicability of this novel marking reader for different illuminations. A new concept of marking reader ophthalmic instrument has been presented and validated in the laboratory. The configuration involves only a commercial-grade laser diode and a visualization screen for PEM identification. The instrument is portable, economic, and easy to use, and it can be used for identifying patient's current PAL model and for marking removable PALs again or finding test points regardless of the age of the PAL, its scratches, tints, or coatings.