A novel double-pass instrument and its data analysis method for the measurement of central and peripheral refraction is presented and validated in a group of healthy subjects. The instrument acquires in-vivo, non-cycloplegic, double-pass, through-focus images of the eye’s central and peripheral point-spread function (PSF) using an infrared laser source, a tunable lens and a CMOS camera. The through-focus images were analyzed to determine defocus and astigmatism at 0° and 30° visual field. These values were compared to those obtained with a lab-based Hartmann-Shack wavefront sensor. The two instruments provided data showing good correlation at both eccentricities, particularly in the estimation of defocus.

This study compares the effects on peripheral vision and image quality of four myopia control interventions: a) Perifocal spectacles/ArtOptica, b) Stellest spectacles/Essilor), c) MiyoSmart spectacles/Hoya and d) MiSight contact lenses/CooperVision. Five subjects participated with habitual or no correction as reference. Three techniques were used: 1) Hartmann-Shack sensors for wavefront errors, 2) double-pass imaging system for point-spread-functions (PSF), and 3) peripheral acuity evaluation. The results show that multiple evaluation methods are needed to fully quantify the optical effects of these myopia control interventions. Perifocal was found to make the relative peripheral refraction (RPR) more myopic in all subjects and to interact with the natural optical errors of the eye, hence showing larger variations in the effect on peripheral vision. MiSight had a smaller effect on RPR, but large effect on peripheral vision. Stellest and MiyoSmart also showed small effects on RPR but had broader double-pass PSFs for all participants, indicating reduced retinal contrast. Reduction in peripheral retinal contrast might thereby play a role in slowing myopia progression even when the peripheral refraction does not turn more myopic.

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 rapid rise in myopia prevalence has caused an urgent need for effectivemyopia control interventions. This thesis investigates the role of theperipheral optics of the human eye in myopia progression. It was initiallybelieved that the axial elongation of the myopic eye is caused only by thedefocus signals presented to the central retina. However, studies on animals have proven that ocular growth can be regulated by optical factors beyondthe fovea. A common hypothesis nowadays is that peripheral image quality is an important factor for eye growth regulation also in humans. The detection of the sign of defocus by the retina is essential for the control of both accommodation and eye growth. Therefore, the aim of this thesis is to map out visual cues to myopia development by evaluating peripheral vision. Additionally, effective optical properties of multifocal contact lensesfor myopia control have been investigated.

Peripheral vision was evaluated by adaptive psychophysical routines inorder to find properties in the peripheral image quality that might be used by the eye to detect the sign of defocus. We have shown that peripheral high-contrast detection acuity and contrast sensitivity can be improved by correction of higher-order aberrations and eliminating chromatic aberrations.The measurements proved that asymmetries in peripheral vision under myopic and hypermetropic defocus are mainly due to the monochromatic and not the chromatic aberrations of the eye. Moreover, we found that relative peripheral refraction did not change with increasing accommodationfor emmetropes, whereas for myopes a myopic shift was observed.However, in spite of these differences, the two groups showed similar peripheral modulation transfer functions. When subjects were accommodating to an off-axis target, the accommodation amplitude declined and the accommodation response time increased with eccentricity. Finally, we evaluated optical quality and vision with the MiSight multifocal contact lens for myopia control. We believe that the effective optical properties of this lens are the larger peripheral blur and the more asymmetric point spread function,due to the additional astigmatism and coma, and that this leads to the larger accommodative response shown by some of the subjects.

Den snabbt ökande förekomsten av myopi (närsynthet) har skapat ett akutbehov av effektiva behandlingar. Denna avhandling undersöker vilken rollögats perifera optik har för myopiprogression. Tidigare trodde man att detvar felfokuseringen i bilden på den centrala delen av näthinnan som leddetill den ökade axiala längden i det myopa ögat. Studier på djur har dockvisat att ögats tillväxt kan styras av optiska signaler utanför fovea (mittenav gula fläcken). En vanlig hypotes idag är att den perifera bildkvaliténär en viktig faktor för tillväxtreglering även i mänskliga ögon. Näthinnansförmåga att avgöra vilket tecken felfokuseringen har är fundamental för attkunna kontrollera både ögats tillväxt och dess ackommodation. Målsättningen med denna avhandling är därför att kartlägga de visuella ledtrådarnaför myopiutveckling genom att utvärdera vår perifera syn. Dessutom har deeffektiva egenskaperna hos myopikontrollerande multifokala kontaktlinserundersökts.Perifer syn utvärderades med adaptiva psykofysiska rutiner för att hittaegenskaper i den perifera bildkvalitén som ögat skulle kunna använda föratt avgöra tecknet på felfokuseringen. Vi har visat att perifer högkontrastdetektion och kontrastkänslighet kan förbättras genom att korrigera högre ordningarnas aberrationer och eliminera kromatiska aberrationer. Mätningarna bevisar att asymmetrier i perifer syn mellan negativ och positivdefokus främst beror på ögats monokoromatiska aberrationer och inte påde kromatiska. Dessutom har vi sett att den relativa perifera refraktioneninte förändras för rättsynta, men att den blir mer negativ med ackommodationen för närsynta. Trots denna skillnad uppvisar dock de två gruppernalikartad perifer modulationsöverföringsfunktion. Vid ackommodation tillobjekt utanför optiska axeln minskade ackommodationsamplituden samtidigt som responstiden ökade med ökad excentrisitet. Slutligen utvärderade vi synen med multifokala kontaktlinser, MiSight som utformats för attbromsa närsynthet, och vi tror att de effektiva egenskaperna hos denna linsär att den ger: större perifer suddighet, mer asymmetrisk punktspridningsfunktion på grund av extra astigmatism och koma, samt stimulerar till ökadackommodativ respons hos vissa av försökspersonerna.

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.

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.

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.