Evaluation of Lag of Accommodation with Full-Field Diffusion Optics Technology™ (DOT) Contrast Management Spectacle Lenses in Emmetropic Children

Asiya Jabeen,1 Doerte Luensmann,1 Jill Woods,1 Jennifer S Hill,2 Lyndon Jones1 1Centre for Ocular Research & Education (CORE), School of Optometry & Vision Science, University of Waterloo, Waterloo, ON, Canada; 2SightGlass Vision, Inc, Palo Alto, CA, USACorrespondence: Asiya Jabeen, Centre for Ocular Research & Education (CORE), School of Optometry & Vision Science, University of Waterloo, Waterloo, ON, Canada, Tel +1 519-888-5467, Ext. 36210, Fax +1 519-888-4303, Email [email protected]: To evaluate the impact on the lag of accommodation (LOA) in emmetropic children after short-term wear of full-field Diffusion Optics TechnologyTM (DOT) spectacle lenses, designed to modulate retinal contrast to control myopia progression.Patients and Methods: This was a single-visit, prospective, randomized, subject-masked study of emmetropes (ametropes ± 1.00D or less in each meridian) with no history of myopia control treatment. Unaided logMAR visual acuity was measured, and ocular dominance was determined using the sighting method. In a randomized order, participants wore plano full-field contrast management (DOT) spectacles (no clear central aperture) or control spectacles (standard single vision spectacle lenses). Each participant was given 5 minutes for adaptation to the respective lenses before open field autorefraction measurements were taken at 6 meters and 40 cm. Ten measurements were taken for each eye. Data were evaluated from the right eye and the dominant eye separately.Results: A total of 30 participants (20 females and 10 males) with a mean age of 10.4 ± 2.8 (7 to 17) years completed the study. There was no significant difference in right eye mean LOA with contrast management spectacles 0.57 ± 0.39D versus control spectacles 0.62 ± 0.34D; Wilcoxon test, p = 0.37. For dominant eyes, LOA values were 0.60 ± 0.40D and 0.68 ± 0.33D with contrast management spectacles and control spectacles, respectively (p = 0.14). Additionally, no significant difference was observed in mean LOA between males and females or between age groups (7– 11 years vs 12– 17 years) for either right or dominant eyes with contrast management or control spectacles (all p > 0.05).Conclusion: Full-field contrast management spectacle lenses had no significant effect on LOA compared to standard single vision spectacle lenses, indicating no differential impact on accommodative response over the short period of lens wear tested.Keywords: myopia, children, accommodation, contrast, spectacles, Diffusion Optics Technology, DOT, contrast management optic

Profiling biometric changes during disaccommodation in emmetropes and myopes

Se ha observado que, debido a la imposibilidad de relajar la acomodación rápidamente, se produce un cambio miópico de corta duración, inmediatamente después de una actividad en visión próxima. Este fenómeno se conoce como miopía transitoria inducida tras una tarea en visión próxima y se especula que el desenfoque retiniano temporal producido, podría tener un papel importante en el desarrollo o progresión de la miopía. El objetivo de este trabajo se ha centrado en el estudio de los cambios ópticos y biométricos que se producen durante una demanda acomodativa y tras la finalización de la misma. Para ello se han obtenido medidas en una muestra 29 sujetos jóvenes (rango=19-39 años), de los cuales 14 eran miopes y 15 paraemétropes. Las medidas se realizaron con un biómetro basado en la reflectometría óptica de baja coherencia que ha permitido determinar las dimensiones de longitud axial (LA), espesor del cristalino (EC) y profundidad de la cámara antrior (PCA). Así mismo se han obtenido medidas de la respuesta acomodativa dinámica mediante un autorefractómetro de campo abierto. Los resultados muestran que la diferencia entre los valores de la profundidad de la cámara anterior sin presencia de ningún estímulo acomodativo y durante una demanda acomodativa de +4,50D tienen una correlación significativa (p=0,04) con la longitud axial. Además se ha observado que la relajación de la acomodación es ligeramente más lenta en los miopes

Entwurf und Erzeugung neuartiger diffraktiver Optiken durch die Mikrostrukturierung von Kontaktlinsenoberflächen

In dieser Arbeit werden die Möglichkeiten zur Herstellung von diffraktiven optischen Elementen, Fresnelsche Zonenplatten und Photonensieben auf Kontaktlinsenoberflächen zum Ausgleich von Sehfehlern des menschlichen Auges untersucht. Dabei wird beschrieben, inwieweit sich die Elektronenstrahllithographie zur Applikation dieser Optiken auf entsprechende Trägermedien eignet. Da formstabile Kontaktlinsen eine besonders gute und sichere Anwendung am menschlichen Auge ermöglichen, wurden diese als Testmedien verwendet. Ein fundamental neuer Ansatz ist, die von Kipp et al entwickelte Photonensiebtechnologie für die Anwendung als Korrektionssystem nutzbar zu machen. Da sich die Technik bei der Fokussierung von Röntgenstrahlung als optisch überlegen herausgestellt hat, liegt der Gedanke nahe, dass dies auch unter normalen Bedingungen im polychromatischen Tageslicht der Fall ist. Diese Arbeit verbindet die Anwendung von Dünnfilm- und Lithographietechniken mit der Berechnung neuer physikalisch-optischer Zonenplatten- und Photonensiebtechnologie im Zusammenspiel mit physiologisch-optischen Parametern des menschlichen Auges und somit die Gebiete Materialwissenschaft, Physik und Optometrie. Die Anwendung der Elektronenstrahllithographie zur Erzeugung diffraktiver optischer Elemente auf Kontaktlinsen stellt ein Novum dar. In dieser Arbeit wird untersucht, inwieweit sich das Verfahren zur Fertigung individueller Kontaktlinsen eignet. Dazu werden die verschiedenen Anwendungsbereiche definiert und die erforderliche Genauigkeit der optischen Elemente zum Ausgleich menschlicher Sehfehler definiert. Die vorliegende Arbeit gliedert sich in drei große Teile. Im ersten Teil werden die anatomischen und physiologischen Zusammenhänge des komplexen visuellen Systems betrachtet. Der zweite Teil befasst sich mit den physikalisch-optischen Ableitungen von Korrektionsmitteln und fertigungstechnischen Besonderheiten der Elektronenstrahllithographie. Der dritte Teil ist der Kernteil der Arbeit und befasst sich mit Berechnungen diffraktiver optischer Elemente, der experimentellen Fertigung dieser auf flachen Substraten und formstabilen Kontaktlinsen mittels Elektronenstrahllithographie, sowie der Bewertung der optischen Eigenschaften der somit erzeugten optischen Systeme. Zur Berechnung werden realistische Daten und Anforderungen des menschlichen Sehsystems verwendet. Die experimentelle Fertigung diffraktiver optischer Elemente, insbesondere die Schreibfeldgröße, wurde maßgeblich durch die technische Ausstattung zur Durchführung der Elektronenstrahllithographie bestimmt. Daher wurde die Berechnung der Größe und optischen Parameter der applizierten Zonenplatten- und Photonensiebstrukturen diesen Gegebenheiten angepasst. Geeignete Beschichtungsmaterialien wurden in Form von Chrom, für flache Substrate, und Gold, für Kontaktlinsen, angewendet. Einige fertigungstechnische Probleme, wie die Oberflächenaufladung der Kontaktlinsen, mussten überwunden werden. Zur Aufnahme der Kontaktlinsen wurde ein spezieller Probenhalter konstruiert und eingesetzt. Alternativ werden ebenfalls die UV-Lithographie und die Applikation von Lack mittels Tampondruck als Verfahren zur Erzeugung diffraktiver optischer Elemente auf ihre Eignung hin betrachtet. Abgeschlossen wird diese Arbeit mit der Diskussion der Ergebnisse und dem Ausblick für eine Anwendung der Elektronenstrahllithographie zur Herstellung von Muttermasken für die vergleichsweise schnelle und preisgünstige Herstellung von multifokalen formstabilen Kontaktlinsen im Pressschmelzverfahren und Weichlinsen im Cast-Moulding Verfahren, bzw. mit der Light-Stream-Technologie

Accommodation effects on peripheral ocular biometry

The effect of near work on the biometric properties of the eye, including the eye’s length and the thickness of the posterior vascular layer were investigated. Short-sighted eyes had greater increases in length and greater thinning of the vascular layer when focused on close objects than did normally-sighted eyes. These changes occurred across the horizontal meridian of the eye and were greatest at the posterior pole. These ocular effects of focusing may partly explain the influence of close work on development of short-sightedness

Retinal characteristics of myopic eyes in a semi-rural UK population

All levels of myopia are associated with an increased risk of ocular diseases such as glaucoma, and retinal detachment. The prevalence of myopia is increasing at an alarming rate across the globe so an increase in ocular morbidity would be expected unless action is taken. The studies in this thesis were carried out to investigate how the retina, and optic nerve head change in appearance at different levels of myopia. Identification of signs indicating future progression would allow targeting of interventions to minimise the ultimate degree of myopia. This thesis describes four community-based studies investigating retinal appearance in myopic eyes. A mixture of retrospective cross-sectional and longitudinal assessments using previously obtained digital fundus images are presented, along with a prospective cross-sectional study of the peripheral retina. The participants had myopia ≤-0.50 D and were mainly of white European ethnicity. Crescent width was found to increase with both age and level of myopia. Those with inferior-temporally located crescents had the highest levels of myopia. Tilted discs were associated with higher levels of myopia and smaller optic discs. Upon longitudinal assessment of disc measures, the optic cup measures, and crescent width were found to increase. Peripheral retinal lesions were observed in 27 % of eyes. Pigmentary degeneration was the most frequently observed and was associated with increasing age and the widest crescents. White without pressure was found in 5.8 % of eyes and was associated with a higher magnitude of myopia. Static retinal vessel analysis showed no significant relationships between retinal vessel calibre summary measures and myopia, age, or optic nerve head measures. The position of the myopic crescent is a possible predictor of future myopic progression. Further longitudinal study is needed to investigate this. The vertical disc diameter remained constant justifying the use of the quotient of the maximum crescent width to vertical disc diameter to determine crescent width change without the need for magnification correction

Diseño, estudio y validación de una lente de contacto de gradiente de potencia para controlar la miopía = Design, study and validation of a radial refractive gradient contact lens for myopia control

Myopia is the main cause of vision loss worlwide, with associated ocular pathology risks related to myopia amount. Therefore, interventions directed towards limiting or preventing the progression of myopia are of high importance to reduce the risk of potential eye disease and blindness. Research in animals has shown that the emmetropization process and ocular growth are image dependent, is a local eye phenomenon and the fovea is not essential. Specifically, the periphery, in isolation, can mediate the normal development of refraction and when an image conflict between the fovea and the periphery occurs, the later dominates eye development. Recent clinical trials conducted with multifocal lenses and orthokeratology have shown that their optical induced changes including the one on peripheral image shell reduce eye growth. In this sense, the main objective was to determine if a contact lens designed to produce myopic peripheral defocus may slow down myopia progression. This thesis describes 6 main studies, and is the result of efforts to design, patent and validate the experimental optical lens, as well as to undertake two longitudinal trials. The first chapter includes a description of the process to design and patent the lens. This unique and innovative design has an optical, single, progressive and continuous zone with an addition of 1.5 D preset at 30° from central axis. Designed using the Atchison eye model, this lens obtained a triple "A" Spanish patent under the number: ES 2406381B1. An initial pilot study of ten subjects was conducted to assess the soft and gas permeable materials (GP) peripheral refractive changes, as well as subjective and objective changes in the optical axis. In view of the results, the addition was increased to 2 D and two studies on 52 and 59 subjects were conducted to measure changes in the peripheral refraction (PR), optical aberrations, contrast sensitivity (CS), visual acuity and accommodative Lag. The GP material resulted in a myopic shift of the peripheral image beyond 10 degrees of eccentricity at nasal and temporal visual field, enough to place the focus in front of the peripheral retina in most of the evaluated myopic patients. With the hydrophilic material, the relative peripheral refraction showed significant changes in the spherical equivalent from 30th to 15th nasal temporal and 30 degrees. There was also a significant increase in higher order aberrations, a loss of contrast sensitivity and a decrease in the accommodative lag. All these aspects had been suggested in the literature as contributing elements to slow down myopia. A longitudinal study to investigate the effects of experimental GP lens material suffered a great loss of follow-up and only one case was finally analyzed. However, due to the trial design of intra-subject crossover study, we could compare the eye wearing the experimental lens in each of the two periods of eight months with its contralateral. Since myopia increased less with experimental GP lens, this suggests a high potential to be evaluated in a longitudinal future study. Moreover, after two years of a longitudinal experimental soft lenses study it was showed a control effect of 43% on refractive outcome and a 27% less in axial length increase compared with a group with monofocal glasses. In addition, the experimental group displayed no differences with an orthokeratology control group. This work represents the first controlled clinical trial that provides information on the progression of myopia 12 months before entering into a myopia control study, compares the efficacy of two different contact lenses treatments and shows a comprehensive view of the potential causes of myopia control by analyzing PR, ocular aberrations and lag of accomodation. In the light of the results, the new experimental lenses showed a promising effect in myopia control, and other potential designs based on the knowledge provided in this thesis may increase their effectiveness.La miopía es el principal problema de visión en el mundo, con riesgos asociados cuanto mayor es su magnitud. Por ello, resultan de gran importancia las intervenciones que puedan limitar o prevenir la progresión de la miopía, disminuyendo los riesgos de patologías oculares y potencial ceguera. Las investigaciones en primates han mostrado que el proceso de crecimiento ocular es dependiente de la imagen, actúa localmente en el ojo y que la fóvea no es esencial. En concreto, la periferia, de modo aislado, puede mediar el desarrollo normal de la refracción y cuando hay un conflicto entre las señales visuales de la fóvea y la periferia, estas últimas dominan sobre las centrales en el desarrollo ocular. Estudios recientes, con lentes de ortoqueratología y multifocales, han mostrado que su óptica, que incluye el movimiento de adelantamiento de la imagen periférica, reduce el crecimiento del ojo. En este sentido, el principal objetivo fue determinar si un lente de contacto diseñado para producir desenfoque periférico miope podía ralentizar el avance de la miopía. Esta tesis, que describe 6 estudios principales, es el resultado de los esfuerzos para diseñar, patentar, validar la óptica de la lente experimental y realizar dos ensayos longitudinales. El primer capítulo incluye la descripción del proceso para diseñar y patentar la lente. Esta, de diseño innovador, dispone una zona óptica, única, progresiva y continua, con una adición prefijada en 1,5 D a 30º respecto al eje. Diseñada utilizando el modelo de ojo de Atchison, obtuvo una patente Española de triple "A" con el número: ES 2406381B1. Se condujo un estudio piloto inicial con diez sujetos para constatar su validez óptica y evaluar en materiales hidrofílicos y permeables a los gases (GP) los cambios refractivos periféricos inducidos, al igual que los ópticos. En función de los resultados, se condujeron dos estudios con 52 y 59 sujetos para medir los cambios en refracción periférica, aberraciones ópticas, sensibilidad al contraste (CS), agudeza visual y Lag acomodativo. El material GP resultó en un cambio miópico de la imagen periférica más allá de los 10 grados de excentricidad nasal y temporal del campo visual, suficientes para adelantar la imágen en la mayor parte de los miopes evaluados. Con lente blanda, la refracción relativa periférica mostró cambios significativos desde 30º nasal a 15º temporal y a 30º grados en el equivalente esférico. También hubo un aumento significativo de las aberraciones de alto orden, así como una disminución de la sensibilidad al contraste y del Lag acomodativo. Elementos contribuyentes a frenar la miopía. Los estudios longitudinales investigaron el efecto de control de la lente experimental. El grupo de lente GP sufrió una gran pérdida de seguimiento y sólo un caso fue finalmente analizado. Sin embargo, gracias al diseño del estudio intrasujeto cruzado, se pudo valorar que el ojo que llevaba la lente experimental, en cada uno de los dos periodos de que constaba el estudio, aumentó menos la miopía que en el contralateral. Sugiriendo un potencial a ser evaluado en un estudio longitudinal futuro. Adicionalmente, las lentes experimentales blandas, tras 2 años de estudio longitudinal frenaron un 43% y un 27% el incremento refractivo y axial respectivamente, en comparación con un grupo de gafas monofocales. Además, el grupo experimental no mostró diferencias respecto un grupo control de ortoqueratología. Este es el primer ensayo clínico controlado que proporciona información sobre la progresión de la miopía 12 meses antes de entrar en el estudio, se compara la eficacia de dos tratamientos con diferentes lentes de contacto y presenta una visión completa de las causas potenciales de control de la miopía mediante el análisis de la refracción periférica. Las lentes experimentales evidencian un efecto de control de la miopía prometedor. Otros potenciales diseños basados en el conocimiento proporcionado en este trabajo podrían incrementar su efectividad

Structural and functional aspects of myopia in young adults. An investigation of nearwork-induced transient myopia and accommodation in relation to refractive stability.

This thesis has investigated nearwork-induced transient myopia and accommodation responses in relation to refractive stability, multichromatic stimuli and orthokeratology. Five individual studies have been carried out. Initially an investigation into the temporal and dioptric aspects of nearwork-induced transient myopia was undertaken, suggesting that increased task duration does not increase the level, or slow the regression of post-task NITM, however an increase in the dioptric demand of the task does. In the second study, a longitudinal myopia progression study, these findings were related to short term myopia progression. The third investigation demonstrates the feasibility of measuring the biometric correlates of nearwork-induced transient myopia using a low coherence reflectometry device (LenStar, Haag Streit Koeniz, Switzerland). Fourthly, a comparison of the differences between static and dynamic accommodative responses, microfluctuations and nearwork-induced transient myopia produced when viewing a black/white target as oppose to a red/blue target has suggested the possibility of four accommodative responses to this multichromatic stimulus. Further investigation will be necessary to investigate if any of these response types are related to myopia progression. 2 The final study investigates the effect of two different designs of orthokeratology contact lenses (C5 and polynomial) on visual function. It appears to be the case that although the polynomial lens design has a larger refractive effect than the C5 lens it reduces both high and low contrast corrected visual acuity to a greater extent. The higher the baseline mean spherical equivalent refractive error the larger the detrimental effect.College of Optometrist