The accommodative response of the human eye is predominantly driven by foveal vision, but reacts also to off-foveal stimuli. Here, we report on monocular accommodation measurements using parafoveal and perifoveal annular stimuli centered around the fovea and extending up to 8 & DEG; radial eccentricity for young emmetropic and myopic subjects. The stimuli were presented through a sequence of random defocus step changes induced by a pupil-conjugated tunable lens. A Hartmann-Shack wavefront sensor with an infrared beacon was used to measure real-time changes in ocular aberrations up to and including the fourth radial order across a 3 mm pupil at 20 Hz. Our findings show a significant reduction in accommodative response with increased radial eccentricity.

Multifocal contact lenses are increasingly popular interventions for controlling myopia. This study presents the short-termeffects of multifocal contact lenses on foveal and peripheral vision. TheMiSight contact lenses designed to inhibit myopia progression and the 1-Day Acuvue Moist contact lenses designed for presbyopia were investigated. The MiSight produced similar foveal results to spectacles despite the increased astigmatism and coma. The MiSight also reduced the low-contrast resolution acuity in the periphery, despite no clear change in relative peripheral refraction. When compared with spectacles, Acuvue Moist decreased accommodative response and reduced foveal high- and low-contrast resolution acuity, whereas peripheral thresholds were more similar to those of spectacles. The most likely treatment property for myopia control by theMiSight is the contrast reduction in the peripheral visual field and the changed accommodation.

The difference in peripheral retinal image quality between myopic and emmetropic eyes plays a major role in the design of the optical myopia interventions. Knowing this difference under accommodation can help to understand the limitations of the currently available optical solutions for myopia control. A newly developed dual-angle open-field sensor was used to assess the simultaneous foveal and peripheral (20 degrees nasal visual field) wavefront aberrations for five target vergences from -0.31 D to -4.0 D in six myopic and five emmetropic participants. With accommodation, the myopic eyes showed myopic shifts, and the emmetropic eyes showed no change in RPR. Furthermore, RPR calculated from simultaneous measurements showed lower infra-subject variability compared to the RPR calculated from peripheral measurements and target vergence. Other aberrations, as well as modulation transfer functions for natural pupils, were similar between the groups and the accommodation levels, foveally and peripherally. Results from viewing the same nearby target with and without spectacles by myopic participants suggest that the accommodative response is not the leading factor controlling the amplitude of accommodation microfluctuations.

We have developed a novel dual-angle open field wavefront sensor. This device captures real-time foveal and peripheral Zernike aberrations, while providing natural binocular viewing conditions for the subjects. The simultaneous data recording enables accurate analysis of changes in ocular optics with accommodation overcoming any uncertainties caused by accommodative lag or lead. The instrument will be used in myopia research to study central and peripheral ocular optics during near work and to investigate the effects of optical myopia control interventions. Proof of concept measurements, performed on an artificial eye model and on 3 volunteers, showed good repeatability with foveal-peripheral data synchronization of 65 msec or better. The deviations from subjective cycloplegic refractions were not more than 0.31 D. Furthermore, we tested the dual-angle wavefront sensor in two novel measurement schemes: (1) focusing on a close target, and (2) accommodation step change.

Purpose: Many myopia control interventions are designed to induce myopic relative peripheral refraction. However, myopes tend to show asymmetries in their sensitivity to defocus, seeing better with hypermetropic rather than myopic defocus. This study aims to determine the influence of chromatic aberrations (CA) and higher-order monochromatic aberrations (HOA) in the peripheral asymmetry to defocus. Methods: Peripheral (20° nasal visual field) low-contrast (10%) resolution acuity of nine subjects (four myopes, four emmetropes, one hypermetrope) was evaluated under induced myopic and hypermetropic defocus between ±5 D, under four conditions: (a) Peripheral Best Sphere and Cylinder (BSC) correction in white light; (b) Peripheral BSC correction + CA elimination (green light); (c) Peripheral BSC correction + HOA correction in white light; and (d) Peripheral BSC correction + CA elimination + HOA correction. No cycloplegia was used, and all measurements were repeated three times. Results: The slopes of the peripheral acuity as a function of positive and negative defocus differed, especially when the natural HOA and CA were present. This asymmetry was quantified as the average of the absolute sum of positive and negative defocus slopes for all subjects (AVS). The AVS was 0.081 and 0.063 logMAR/D for white and green light respectively, when the ocular HOA were present. With adaptive optics correction for HOA, the asymmetry reduced to 0.021 logMAR/D for white and 0.031 logMAR/D for green light, mainly because the sensitivity to hypermetropic defocus increased when HOA were corrected. Conclusion: The asymmetry was only slightly affected by the elimination of the CA of the eye, whereas adaptive optics correction for HOA reduced the asymmetry. The HOA mainly affected the sensitivity to hypermetropic defocus.

I denna avhandling används vågfrontsanalys för att studera ögats perifera optik med betoning på dess betydelse för utvecklingen av närsynthet (myopi). Syftet är att hitta egenskaper i den perifera bildkvalitén som skulle kunna användas av ögat för att reglera dess tillväxt. Avhandlingsarbetet består av följande delar: • Litteraturgenomgång och analys av populationsdata på det oackommoderade ögats perifera optik över det horisontella synfältet (artikel B). Denna översiktsartikel beskriver en metod för att analysera perifer vågfrontsdata och presentera sammanställd data för olika grupper: (a) populationsmedelvärden, (b) närsynta och (c) rättsynta. • Utveckling av en ny typ av vågfrontssensor med öppet synfält och dubbla kanaler (artikel D). Detta instrument möjliggör tidsupplösta och simultana mätningar av de centrala och perifera vågfrontsfelen i realtid med ett öppet binokulärt synfält. • Undersökning av den optiska kvalitén i närsynta och rättsynta ögon vid olika ackommodationsnivåer (artikel F). Det unika i detta arbete är att ögats ackommodationstillstånd följs i realtid vilket ger utökade möjligheter till noggrann analys av både dynamik och medelvärden hos den centrala och perifera optiska kvalitén. • Användning av vågfrontsanalys för att klargöra optikens betydelse för olika perifera synkvalitéer, så som synskärpa och kontrastkänslighet (artikel A, C, E). Resultaten av dessa studier visar på fördelen med binokulärt synfält och simultana centrala mätningar när perifera aberrationer undersöks vid ackommodation. Den relativa perifera refraktionen blir mer negativ med ökande ackommodation för de närsynta ögonen, medan förändringarna i de rättsynta ögonen är små. Den totala perifera optiska kvalitén var dock likartad för både närsynta och rättsynta och varierade knappt mellan avlägsna och närliggande objekt. Mätningarna indikerar även att ögats ackommodationsnivå inte är den huvudsakliga orsaken till storleken på mikrofluktuationer i ackommodationen. Oberoende av centralt brytningsfel, visade det sig att perifer lågkontrastsyn förbättras med korrektion av monokromatiska aberrationer, men att effekten av kromatiska aberrationer är försumbar. Slutligen visar studierna att multifokala kontaktlinser som utformats för att bromsa närsynthet, MiSight® , försämrar synfunktionen både vad gäller ackommodation och perifer lågkontrastresolution.

This thesis is dedicated to implementing wavefront analysis for studying the peripheral optics of the human eye with an emphasis on its relation to myopia. The aim is to find properties in the peripheral image quality. The work consists of the following main parts: • Literature review and analysis of population data on ocular aberrations of the relaxed eye over the horizontal visual field (Paper B). This paper recommends a method for the peripheral wavefront analysis and presents data for different groups of people: (a) population average, (b) myopic, and (c) emmetropic subjects. • Development of a novel, dual-angle, open field wavefront sensor (Paper D). The device enables recording of real-time, simultaneous fovealperipheral wavefront measurements, while providing a binocular open field of view. • Studying optical quality for myopic and emmetropic subjects under different accommodation demands (Paper F). The novelty of this work is the real-time accommodation state tracking, allowing a more accurate data analysis of both the dynamic and the average foveal and peripheral optical quality. • Using wavefront analysis to understand the contribution of optics to different aspects of peripheral human vision, such as resolution acuity and contrast sensitivity (Papers A, C, E). The results obtained in this work show the benefit of binocular viewing and real-time foveal measurements when studying peripheral aberrations under accommodation. With increasing accommodation, the relative peripheral refraction of myopic eyes becomes more negative, while the changes for the emmetropic eyes are small. However, the total peripheral optical quality proved to be similar between myopic and emmetropic subjects and varied little between distant and near objects. The results also suggest that the accommodative response is not the leading factor defining the magnitude of the microfluctuations in accommodation. Peripheral low contrast vision, irrespective of the foveal refractive error, is demonstrated to improve when monochromatic aberrations are corrected, while the effects of chromatic aberrations are negligible. Finally, the myopia control MiSight® multifocal contact lenses are shown to reduce vision performance in accommodation as well as in peripheral low-contrast resolution.

Peripheral image quality influences several aspects of human vision. Apart from off-axis visual functions, the manipulation of peripheral optical errors is widely used in myopia control interventions. This, together with recent technological advancements enabling the measurement of peripheral errors, has inspired many studies concerning off-axis optical aberrations. However, direct comparison between these studies is often not straightforward. To enable between-study comparisons and to summarise the current state of knowledge, this review presents population data analysed using a consistent approach from 16 studies on peripheral ocular optical quality (in total over 2,400 eyes). The presented data include refractive errors and higher order monochromatic aberrations expressed as Zernike co-efficients (reported in a subset of the studies) over the horizontal visual field. Additionally, modulation transfer functions, describing the monochromatic image quality, are calculated using individual wavefront data from three studies. The analysed data show that optical errors increase with increasing eccentricity as expected from theoretical modelling. Compared to emmetropes, myopes tend to have more hypermetropic relative peripheral refraction over the horizontal field and worse image quality in the near-periphery of the nasal visual field. The modulation transfer functions depend considerably on pupil shape (for angles larger than 30 degrees) and to some extent, the number of Zernike terms included. Moreover, modulation transfer functions calculated from the average Zernike co-efficients of a cohort are artificially inflated compared to the average of individual modulation transfer functions from the same cohort. The data collated in this review are important for the design of ocular corrections and the development and assessment of optical eye models.

Correction and manipulation of peripheral refractive errors are indispensable for people with central vision loss and in optical interventions for myopia control. This study investigates further enhancements of peripheral vision by compensating for monochromatic higher-order aberrations (with an adaptive optics system) and chromatic aberrations (with a narrowband green filter, 550 nm) in the 20 degrees nasal visual field. Both high-contrast detection cutoff and contrast sensitivity improved with optical correction. This improvement was most evident for gratings oriented perpendicular to the meridian due to asymmetric optical errors. When the natural monochromatic higher-order aberrations are large, resolution of 10% contrast oblique gratings can also be improved with correction of these errors. Though peripheral vision is mainly limited by refractive errors and neural factors, higher-order aberration correction beyond conventional refractive errors can still improve peripheral vision under certain circumstances.