This multicentre longitudinal study investigated nasotemporal retinal asymmetry as a geometric biomarker for monitoring myopia risk in children. A total of 2520 Chinese children (Beijing cohort: N = 49, 5–14 years old; Anyang cohort: N = 2471, 6–9 years old) underwent annual measurements over 2 years, including axial length (AL), central spherical equivalent (CSE) and peripheral AL (30° nasal, temporal, superior, inferior) in the Beijing cohort and horizontal meridian peripheral refractions (±15°, ±30°) in the Anyang cohort. Retinal morphology was quantified through the vertex radius of curvature, asphericity and areas under the horizontal nasal and temporal retinal curve (AUHRCn and AUHRCt, respectively). Nasotemporal retinal asymmetry was defined as AUHRCt/n. Vertical asymmetry was defined as superior peripheral AL/inferior peripheral AL. Participants from the Anyang cohort were stratified into persistent myopia (myopic at baseline), newly developed myopia (myopia onset during follow-up) and persistent non-myopia (remained non-myopic over 2 years). In the Beijing cohort, the temporal-to-nasal AL ratio was the only factor significantly associated with myopic progression (ΔAL: r = −0.36, p = 0.01; ΔCSE: r = 0.37, p = 0.01). Validating this, in the Anyang cohort, decreasing AUHRCn preceded myopia onset, followed by progressive temporal steepening. Linear regression identified baseline AUHRCt/n as an independent negative predictor of myopic progression (β = 2.90, p = 0.03). A model incorporating baseline AUHRCt/n improved the prediction of progression risk (integrated discrimination improvement (IDI) = 3.74

Non-orthogonal lenses, in which the principal meridians of the cylinder surfaces are not perpendicular to each other, can be used to improve vision in the condition of irregular astigmatism. A procedure is developed that allows raytracing and image-quality analysis with such lenses. A non-orthogonal surface was developed as a user-defined surface in the programme Ansys Zemax OpticStudio using a bi-cubic meridional mapping function. The function consists of two third-order polynomial sub-functions, each for mapping the actual ‘on surface’ meridian to an effective meridian that determines the meridional curvature for the two sectors of meridians bounded by the principal meridians. Equations were derived for partial derivatives across the surface, as Zemax requires these for raytracing through a user-defined surface. Examples are shown of tangential and pupil power maps for a thin orthogonal (conventional) +5.00 DS/+2.00 DC × 180 lens and for a non-orthogonal +5.00 DS/+2.00 DC (60) × 180 lens. The orthogonal lens has principal meridians 180° and 90° while the non-orthogonal lens has principal meridians 180° and 60°. For the orthogonal lens, both maps show regular changes in power with meridional angle, and the sagittal power map is rotated by 90° relative to the tangential power map. For the non-orthogonal lens, the sagittal power pattern shows sharp changes in power. The non-orthogonal surfaces were replicated using the ‘grid sag’ surface of Zemax, and the user-defined surface was verified. Surface fitting using Zernike polynomials returned only a reasonable approximation to a non-orthogonal surface. A type of non-orthogonal optical surface based on two third-order polynomials is presented. Aspects of its geometrical optics properties were investigated, including confirming the non-orthogonality of its axes. This type of surface may have utility in the correction of irregular astigmatism, such as occurs in keratoconus.

Many new optical treatments have been developed recently to slow the progression of myopia. Most of these are based on theories of how myopia develops, such as poor accommodation, the type of peripheral refraction and image contrast (contrast modulation). Optically related treatments include spectacle lenses, contact lenses, orthokeratology, light therapies, more outdoor time, better interior lighting, indoor illumination, pharmacological intervention (through pupil and accommodation effects) and combination therapies. Current myopia-control spectacle lenses are described, including progressive addition, multisegment, annular cylinder, diffusion optics technology and concentric bifocals. Background is provided and a critical eye is passed over some of the designs. Short-term (12-month) efficacies for both axial length and myopia reduction in myopia-control spectacle wear, relative to single-vision lenses, are about 50

To determine how accommodation affects lens shape in myopic and non-myopic children. Participants included 76 non-myopic (spherical equivalent refraction (SER): 0.00 to +1.75 D) and 18 myopic children (SER = −3.50 to −0.75 D) aged 5−12 years. Anterior and posterior lens surface shapes were determined by image processing and ray tracing of IOLMaster 700-generated B-scan images (six meridians per scan) at 0, 3, 6 and 9 D accommodation demands, expressed as refractive power vectors (M, J0 and J45). For all children, anterior and posterior lens surface M and total lens power increased by means (±SD) of +0.45 ± 0.17, +0.23 ± 0.20 and +0.65 ± 0.32 D per dioptre of accommodation demand, respectively, with a shift towards a more equiconvex shape with increasing accommodation. J0 and J45 did not change significantly during accommodation (for anterior surface, p = 0.68 and 0.48, respectively; for posterior surface, p = 0.47 and 0.88, respectively). Myopic lenses had significantly lower anterior and posterior surface M and total lens power than non-myopic lenses (p < 0.05), but no significant differences were observed in astigmatic vectors except for anterior lens surface J0. There were no interactions between accommodation demand and refractive error for any lens parameters (all p ≥ 0.13). Myopic children have flatter lens surfaces than non-myopic children. Lens surface shape changes with accommodation are similar between myopic and non-myopic children.

We present a systematic assessment of peripheral refractive errors in pseudophakic eyes. Optical bench measurements were performed using a physical eye model to characterize the peripheral cylinder of eight different intraocular lens (IOL) models of approximate power 20 D, covering different IOL types (monofocal, enhanced monofocal, extended depth of focus, bifocal, trifocal) and technologies (refractive, diffractive, wavefront-shaping) from several manufacturers. In addition, optical simulations were done for average and personalized pseudophakic eye models. Peripheral cylinder at 20° visual field was similar for all IOLs (range -2.24 to -2.87 D). Simulations in average eye models further showed the peripheral cylinder to be independent of pupil size, retinal radius of curvature (ROC), and IOL technology (-2.31 to -2.62 D across all conditions). Peripheral blur parameter (range 1.24 to 2.03 D across all conditions) showed small variations with IOL technology and ROC but negligible change with different pupil sizes. For simulations with personalized eye models, the peripheral cylinder and blur showed small variation across different IOL technologies.

To provide a more sophisticated explanation of the optics involved when retinal ‘shadows’ are seen in scanning laser ophthalmoscopic images during the wear of multisegment and diffusion optic spectacle lenses. Images were recorded with a system that uses a scanning broad line fundus imaging principle in participants with undilated pupils wearing a multisegment spectacle lens. The live infra-red preview display of the system was also acquired during image recording. Ray-tracing and image simulations were performed, assuming a Maxwellian illumination system in which a source was refracted first through a lens and then through a model of a multisegment spectacle lens focused onto the pupil of an eye model and hence to the retina. A detector surface was positioned slightly in front of the retina to record the irradiation distribution. The light source was varied from 0.1 μm to 1.8 mm in diameter to investigate the effect of light source size on retinal irradiation distribution. The retinal shadow pattern was visible on the live infra-red preview display, as reported previously. However, the recorded images of the retina do not exhibit the same shadow pattern. The simulations predict that the circular shadows corresponding to lenslet positions become progressively less discernible with increasing light source size. An explanation is provided for the shadows on retinal images due to multisegment lenses, which may be observable under certain illumination conditions.

To investigate the influence of the corneal epithelium on corneal power, particularly in special cases such as post-refractive surgery and keratoconus. A retrospective observational study. Measurement data were obtained from a high-resolution anterior segment analyser (CSO MS-39). Corneal curvature and power data, as well as surface height data, were organised in a cylindrical coordinate system. Calculations considered one, two and three refractive surfaces, examining the role of epithelial thickness and stromal curvature. The effect of the epithelium on corneal power was minimal (<0.1 D) in normal corneas, but it was considerable in keratoconus and post-refractive surgery cases, with differences up to 0.9 D. The effect decreased for larger measurement zones. Incorporating epithelial thickness and stromal curvature into corneal power calculations is a crucial next step in accurate corneal power and intraocular lens calculation in eyes with previous refractive surgery or keratoconus. This study highlights the need for advanced diagnostic and calculation methods in complex cases.

The field of visual and physiological optics is undergoing continuous significant advancements, driven by a deeper understanding of the human visual system and the development of cutting-edge optical technologies. This Roadmap, authored by leading experts, delves into critical areas such as corneal biomechanical properties, keratoconus, and advancements in corneal imaging and elastography. It explores the intricate structure-function relationship within the eye lens, offering new perspectives through lens models and ray tracing techniques. The document also covers advancements in retinal imaging, highlighting the current state and future directions, and the role of adaptive optics in evaluating retinal structure and function in both healthy and diseased eyes. Furthermore, it addresses the modeling of ocular surfaces using different mathematical functions and examines the factors affecting peripheral image quality in the human eye, emphasizing the importance of these aspects in visual performance. Additional topics include schematic and functional models of the human eye, the impact of optical and chromatic aberrations, and the design of contact, and intraocular lenses. Finally, the Roadmap addresses the intersection of neurosciences with vision health, presenting a comprehensive overview of current research and future trends aimed at improving visual health and optical performance. Ultimately, this Roadmap aims to serve as a valuable resource for ophthalmologists, optometrists, vision scientists, and engineers dedicated to advancing the field of visual and physiological optics.

Multisegment (MS) spectacles are intended to slow myopia progression by modifying images falling on the peripheral retina. Some published optical treatments of these lenses assume normal incidence of light at the surfaces, but images falling on the peripheral retina are usually associated with oblique ray pencils. Here, we model representative images of point objects produced by the Hoya MiyoSmart MS spectacle lens when oblique ray pencils are used. Various imaging aspects of the MS lens alone and in combination with a suitable accommodating eye model for a 4D myope were evaluated using the Optical Design program Ansys Zemax OpticStudio. Configurations studied included object points at vergences of zero and –4 D, with the objects being either on the lens axis or at a field angle of about 30°. The effect on foveal vision of rotating the axis of the eye with respect to that of the lens was also considered. Images of point objects were described in terms of spot diagrams and fast Fourier transform point-spread functions. Symmetry and overall optical quality of images decreased with the obliquity of the ray pencils, due to the increased off-axis aberrations of the lens and the eye. Images of near object points were strongly affected by the level of accommodation: optimal retinal image quality occurred when accommodation brought the carrier lens focus close to the retina, rather than that of the lenslets. Attempts to understand why MS lenses slow myopia progression need to consider the way in which through-focus retinal image quality changes with obliquity of the ray pencils across the visual field and the possible effects of ocular accommodation.

We used modeling to investigate the imaging characteristics of two multi-segment spectacle lenses intended to treat myopia progression. Determinations were made for the peripheral field, when the eye looks through the lens center, and for foveal vision, when the eye rotates and looks through the lens surround, including the segments. Power corrections were derived across the field and across the pupil, and image quality was determined through spot diagrams and point-spread functions. Optics were characterized by high corrections, particularly in the periphery, including considerable astigmatism and large variations across the pupil. As with another lens studied previously, obliquity of light incidence produced greater aberrations than would occur at normal incidence.

Multisegment (MS) spectacle lenses, providing a distance correction with a clear central area and by having an array of small, positively powered lenslets in the periphery of the front surface, have proved effective in slowing childhood myopia progression. Debate continues as to whether their mechanism of action is due to through-focus effects or to the image contrast changes due to the inclusion of the lenslets. This study explores the second possibility by modelling the performance of a combined MS lens-eye optical system in terms of its modulation transfer function (MTF) under various conditions. The optical design program Ansys Zemax OpticsStudio was used to determine distance MTFs for the combination of either a single-vision or a Hoya MiyoSmart MS lens with a 4 D myopic eye model. Conditions included axial and peripheral objects with co-axial lens and eye, and rotating the eye away from the lens axis to observe objects through the lenslet-covered region of the lens. Visual resolution under each condition was estimated. Observing objects through the lenslet array lowered modulation transfer in comparison with that given by the single-vision lens, especially as spatial frequency increased. In peripheral observation at a field angle of approximately 32.5 degrees, imagery was poor. Foveal image quality was better with axial viewing through the clear MS lens centre than when the eye was rotated by approximately 30 degrees. Optimal visual resolution during MS lens wear is achieved when fixating through the clear, central area of the lens. Under these circumstances, objects at 20–50 degrees from fixation are seen through the lenslet-covered region of the carrier which produces a low-pass spatial frequency filtering effect. Here, visual resolution is limited to a few cycles per degree so that any growth control mechanism must rely on low spatial frequency information.

This study presents a method for retinal reconstruction using peripheral biometry. The incident beam is presumed to be directed toward the center of curvature of the anterior cornea, reaching the retina with minimal deviation. A significant advancement is demonstrated by extending previous approaches to three dimensions and effectively capturing the complexity of astigmatic corneal surfaces. The method was evaluated in Zemax using Navarro's eye model featuring a retina of 12 mm radius, across various levels of accommodation ranging from 0 to 8 D, and a visual field angle between 25 and 25°. The method's reliability diminishes for field angles ≥ 35°. Validation was carried out using 500 synthetically generated eyes, and the method's performance was also assessed with an ellipsoidal retina. The findings revealed that spherical equivalent differences were consistently under 0.25 D at 25° for both types of retinas. Overall, these results demonstrate the method's effectiveness, offering a promising new tool for retinal reconstruction.

Part 1 of the study investigated image quality associated with oblique incidence of light on a multisegment lens (Hoya MiyoSmart) intended to treat myopia development. Part 2 investigates power corrections associated with oblique incidence. Modelling and ray tracing were carried out with lenses of −4 D distance power and, to a lesser extent, +0.25 D. Ray tracing simulations were done for the lens by itself, an eye model by itself and the combination. These simulations were for the static situation of peripheral vision when the eye looks through the lens centre and for central (foveal) vision when the eye rotates to look at objects away from the lens optical axis. The outcome was power correction of the optics, that is, the difference between the nominal power of the distance correction provided by the carrier lens under specific conditions and the actual power. This was determined across the field to about 45° and across the pupil for certain field angles. Most investigations were performed for distance vision, but some were for near objects with an accommodating version of the model eye. Ignoring intended multisegment effects, the quality of optics associated with peripheral vision was poor. There was considerable astigmatism (cylinder) across the field and high variation in astigmatism across the pupil. The added effects of the lens and eye were similar to those of their combination. For the accommodated eye model with an object at 250 mm, results were similar to those obtained with the unaccommodated model viewing a distant object. For foveal vision with the rotating eye, optics were relatively good with lower levels of astigmatism than for peripheral vision. The results of Part 1, finding considerable effects of the obliquity of incidence associated with peripheral vision and with foveal vision for the rotating eye, were supported by the power corrections.

Purpose:To describe patterns of peripheral refraction based on spherical equivalent refraction and on tangential and sagittal refractions, and to assess the association of peripheral refraction patterns with different central refractions. Methods:Peripheral refraction data from 737 individuals (14.7 ± 5.1 years old) were analyzed. Peripheral refraction was determined along the horizontal field at ±30° eccentricity using an open-field autorefractor in 89 hyperopes, 276 emmetropes, and 372 myopes. Values were converted into spherical equivalent refraction and into tangential and sagittal refractions. Nine different peripheral refraction patterns (A-I) were described based on spherical equivalent refraction, and 81 patterns were described based on tangential and sagittal refractions. Results:Using spherical equivalent refraction, all nine possible peripheral refraction patterns (A-I) were represented. Type I (relative peripheral myopia in nasal and temporal retinas) was seen in 40% of hyperopes, in 32% of emmetropes, and in 8% of myopes. Type A (relative peripheral hyperopia in nasal and temporal retinas) was seen in 20% of myopes and in ≤1% of hyperopes and emmetropes. No pattern was unique to any refractive group. Using tangential and sagittal refractions, 47 out of 81 possible patterns were represented. The three refractive groups shared 19 patterns in common. Hyperopes, emmetropes, and myopes had two, six, and eleven unique patterns, respectively. Conclusions:Many types of peripheral refraction patterns were observed, and these may provide insights into the complexities of eye growth and myopiogenesis. Tangential and sagittal refractions should be considered to understand peripheral refraction rather than spherical equivalent refraction alone.

Purpose:The purpose of this study was to determine the (i) contributions of refracting components to ocular aberrations and (ii) compensation effects exhibited by these components in keratoconus. Methods:Right eyes of 14 keratoconus and 20 control participants were analyzed using 5 mm pupils. Ocular aberrations were measured with a Hartmann-Shack aberrometer. Corneas were imaged with a Scheimpflug tomographer. Three-dimensional models of the total cornea and anterior cornea were created. Raytracing included correct object-image conjugates and corneal decentration relative to the aberrometer pupillary center to determine the total corneal and anterior corneal aberrations. Posterior corneal and lenticular aberrations were computed. Compensation effects (%) were calculated: 100 (anterior corneal-total corneal aberration)/anterior corneal aberration, and 100 (total corneal-ocular aberration)/total corneal aberration. Results:Considering coefficients for the total cornea with absolute values >0.05 µm, for both corneal surfaces, keratoconus had higher magnitudes than controls for C(2,-2), C(3,-3), C(3,-1), C(4,-2), total root mean square (RMS), higher-order RMS (HORMS), and J45. Both surfaces' RMS aberrations were approximately 2 to 5 times higher in keratoconus than in controls. Anterior corneal RMS aberrations were approximately 5 times (keratoconus) and approximately 3 to 4 times (controls) higher than those of the posterior cornea. Posterior corneal compensations for anterior corneal aberrations were higher in keratoconus than in controls for C(3,-3) (21%, decompensation of -14%), C(3,-1) (21%, -33%), C(4,-2) (27%, -10%), C(4,+2) (22%, 10%), HORMS (20%, 2%), and J0 (68%, 66%), as were lenticular compensations for total corneal aberrations for C(2,-2) (40%, -64%), C(2,+2) (70%, 60%), total RMS (21%, 20%), and J0 (642%, -55%). Conclusions:Keratoconic eyes exhibited higher anterior and posterior corneal aberrations than control eyes. The posterior cornea and lens compensated partly for the anterior cornea and total cornea, respectively, with greater percentage compensations in keratoconus.

This study compared in vivo crystalline lens shape measurements using B-scan images from the IOLMaster 700 with phakometry. Twenty-four young adult participants underwent IOLMaster 700 and phakometry measurements under cycloplegia (1