Contribution and Compensation Effects of Refracting Components to Ocular Aberrations in Keratoconus.

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.

Off-axis imagery through two multi-segment lenses for myopia treatment.

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.

Retinal shadows of multisegment lenses in fundus imaging.

Purpose: 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.

Methods: 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.

Retinal reconstruction from peripheral biometry.

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.

Diversity of Peripheral Refraction Patterns-Have These Been Oversimplified?

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.

Oblique effects with multisegment spectacle lenses: 2. Ray tracing to determine power corrections.

Purpose: 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.

Methods: Modelling and ray tracing were carried out with lenses of -4 D distance power and, to a lesser extent, +0.

Oblique effects with multisegment spectacle lenses: 1. Images of a point object.

Introduction: 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.

The role of the epithelium in intraocular lens and corneal power calculation.

Purpose: To investigate the influence of the corneal epithelium on corneal power, particularly in special cases such as post-refractive surgery and keratoconus.

Methods: A retrospective observational study. Measurement data were obtained from a high-resolution anterior segment analyser (CSO MS-39).

Fine Motor Skills, Reading Speed, and Self-Reported Quality of Life in Adults With Amblyopia and/or Strabismus.

Purpose: The purpose of this study was to assess fine motor skills and reading proficiency in adults with amblyopia and/or strabismus, and to determine how these relate to clinical measures of vision and self-reported vision-related quality of life.

Methods: Fine motor skills (Manual dexterity - Bruininks-Oseretsky Test of Motor Proficiency [BOT-2]) and reading performance (International Reading Speed Texts [IReST]) were assessed in 23 adults with non-strabismic amblyopia, 20 with non-amblyopic strabismus, 52 with both amblyopia and strabismus, and 19 with normal visual development. Visual acuity and binocular function score (BFS), obtained from stereoacuity and presence/absence of suppression, were also determined.

Four-Year Longitudinal Investigation of the Relationship Between Myopia and Retinal Shape in Chinese Children: The Anyang Childhood Eye Study.

Purpose: To investigate the longitudinal relationship between myopia and retinal shape in Chinese children.

Methods: A total of 2471 seven-year-old Chinese children were measured for axial length, anterior corneal radius of curvature, anterior chamber depth, lens thickness, central spherical equivalent, and peripheral refractions along the horizontal meridian (±15°, ±30°) under cycloplegia. Retinal shape was fitted using vertex radius of curvature, asphericity, and an offset.

Accommodating version of a schematic eye for emmetropia and myopia.

Aim: To develop an accommodating, wide-angle, schematic eye for emmetropia and myopia in which spectacle refraction and accommodation level are input parameters.

Method: The schematic eye is based on an earlier unaccommodated refraction-dependent eye for myopia developed by Atchison in 2006. This has a parabolic gradient index lens and parameters derived from biometric and optical measurements on young adults.

Optics of spectacle lenses intended to treat myopia progression.

This is a review of the optics of various spectacle lenses that have been used in myopia control over the last 60 years, with emphasis on approximately the last 15 years.Myopia has become an increasing health problem worldwide, particularly in some East Asian countries. This has led to many attempts to slow its progression in children and reduce its endpoint value.

Risk Factors for Corneal Monochromatic Aberrations and Implications for Multifocal and Extended Depth-of-Focus Intraocular Lens Implantation.

Purpose: To discuss factors influencing corneal aberrations that might influence the optical quality after intraocular lens (IOL) implantation.

Methods: PubMed and Scopus were the main resources used to search the medical literature. An extensive search was performed to identify relevant articles concerning factors influencing the level of corneal aberrations as of August 27, 2023.

Measurement of in vivo lens shapes using IOLMaster 700 B-scan images: Comparison with phakometry.

Purpose: This study compared in vivo crystalline lens shape measurements using B-scan images from the IOLMaster 700 with phakometry.

Methods: Twenty-four young adult participants underwent IOLMaster 700 and phakometry measurements under cycloplegia (1% cyclopentolate). The IOLMaster 700 generated B-scan images along six meridians in 30° increments, which were analysed using custom MATLAB software to determine lens surface radii of curvature.

Change in refractive errors with changes in IOL parameters.

This study considered two questions associated with intraocular lens (IOL) power and refraction: (1) Given a refraction with a particular IOL in the eye, what will be the refraction for the IOL or another IOL if located differently with regard to tilt or anterior-posterior position? (2) For a target refraction, what is the power of another IOL if located differently with regard to tilt or position? A thin lens technique was developed to address these questions. For the first question, light was traced through the initial correcting spectacle lens to the cornea, refracted at the cornea, transferred to the position of the initial IOL, refracted at this IOL, transferred to the position of a new IOL (which may be the same IOL but with a different position and/or tilt), refracted backwards through the new IOL, transferred to the cornea and refracted out of the eye to give a new correcting spectacle lens power. For the second question, light was traced through the initial correcting spectacle lens to the cornea, refracted at the cornea, transferred to the position of the initial IOL, refracted at the initial IOL and transferred to the position of a new IOL.

Vision screening using the Acuidrive device.

Clinical Relevance: Understanding devices used for vision screening, including their potential utilisation and validity, will facilitate proper utilisation of this technology.

Background: The Acuidrive is a self-illuminated, hand-held, visual acuity screening device intended for use in policing, with visual acuity assessed roadside to identify drivers who may not meet vision standards for driving. The target is presented binocularly at 24 cm, and +4.

Refractive errors occurring with tilt of intraocular lenses.

A thin lens technique was developed to determine how the effective powers of toric monofocal intraocular lenses (IOLs) are influenced by tilt and the refractive errors associated with the tilt. A series of steps determined the effective power of the cornea at the IOL, the IOL power, the effective power of the tilted IOL, the correction required at the front of the eye and the power of an IOL that would compensate for the tilt. The correction was determined by starting at the ideal reduced image vergence at the IOL, backwards raytracing to obtain a reduced image vergence at the cornea, and subtracting the cornea power from this reduced image vergence.

Retinal shadows produced by myopia control spectacles.

Purpose: To analyse ocular coherence tomography (OCT) images of the retinal shadows caused by defocus and diffusion optics spectacles.

Methods: One eye was fitted successively with the Hoya Defocus Incorporated Multiple Segments (DIMS) spectacle lens, two variations of the +3.50 D peripheral add spectacle (DEFOCUS) and the low-contrast dot lens (Diffusion Optics Multiple Segments, DOMS); each at a vertex distance of 12 mm.

Determining specified intraocular lens powers when silicone oil is to be used in the vitreous chamber.

Purpose: To apply a theoretical approach to determining how specified intraocular lens (IOL) powers should change when vitreous oil substitution is combined with IOL implantation.

Setting: University laboratory, private Ophthalmological practice.

Design: Theoretical raytracing.

Effects of induced aniseikonia on binocular visual acuity.

Clinical Relevance: Binocular visual acuity is an important index of functional performance. Optometrists need to know how binocular visual acuity is affected by aniseikonia, and whether reduced binocular visual acuity is a marker for aniseikonia.

Background: Aniseikonia, the perception of unequal image sizes between the eyes, can occur spontaneously or can be induced after different types of eye surgery, or trauma.

Effect of multifocal spectacle lenses on accommodative errors over time: Possible implications for myopia control.

The study purpose was to improve understanding of how multifocal spectacle lenses affect accommodative errors and whether this changes over time. Fifty-two myopes aged 18 to 27 years were allocated randomly to one of two progressive addition lens (PAL) types with 1.50 D additions and different horizontal power gradients across the near-periphery boundary.

Do Anisometropic Eyes Have Steeper Retinas Than Their Isometropic Counterparts?

Significance: Our findings suggest that retinal shapes of the eyes of anisometropes are not different from that of the eyes of isometropes with the same refractions.

Purpose: We investigated ( a ) intereye differences in relative peripheral eye lengths between isometropes and anisometropes and ( b ) if the retinal shape is different between isometropic and anisometropic eyes with the same central refraction.

Methods: Central and peripheral eye lengths were determined along the horizontal meridian in 10° intervals out to ±30° using a noncontact biometer in 28 isometropes and 16 anisometropes.

Technical notes on peripheral refraction, peripheral eye length and retinal shape determination.

Purpose: To give an overview of the misconceptions and potential artefacts associated with measuring peripheral refractive error and eye length, the use of these measures to determine the retinal shape and their links to myopia development. Several issues were identified: the relationship between peripheral refractive error and myopia development, inferring the retinal shape from peripheral refraction or eye length patterns, artefacts and accuracy when measuring peripheral eye length using an optical biometer.

Methods: A theory was developed to investigate the influence of artefacts in measuring peripheral eye length and on using peripheral eye length to make inferences about retinal shape.

Central and peripheral choroidal thickness and eye length changes during accommodation.

Purpose: Eye length increases during accommodation, both on-axis and in the periphery. The aim of this study was to determine whether the peripheral choroid thins with accommodation and to determine the relationship with eye length changes measured at the same location.

Methods: Subjects included 53 young adults in good ocular and general health, with 19 emmetropes and 34 myopes.