Erin M. Harvey - US grants

DESCRIPTION: (Applicant's Abstract) Evidence from the scientific literature indicates that uncorrected astigmatism during childhood is associated with three types of amblyopia: (1) a difference in best-corrected acuity and contrast sensitivity for orthogonal gratings (meridional amblyopia or MA), (2) a difference in best-corrected acuity for orthogonally-oriented vernier acuity stimuli (also termed MA), and (3) a deficit in best-corrected recognition (letter) acuity. These data suggest the presence of a sensitive period for the development of astigmatism-related amblyopia. However, only limited information is available concerning factors that influence the development and treatment of astigmatism-related amblyopia. The lack of research regarding astigmatism-related amblyopia is most likely due to the low prevalence of astigmatism in most populations of children. However, a high prevalence of large amounts of astigmatism and astigmatism-related amblyopia has been documented in members of the Tohono O'Odham grade-school children are not currently wearing eyeglass correction. The presence of this large sample of uncorrected highly astigmatic children provides a unique opportunity for the study of the development and treatment of astigmatism-related amblyopia. The goals of the present study are: (1) to characterize vision deficits associated with astigmatism-related amblyopia (through measurements of grating acuity, vernier acuity, recognition acuity, and contrast sensitivity), (2) to identify factors influencing the development of astigmatism-related amblyopia (e.g., factors such as amount and type of astigmatism), and (3) to determine age-specific effects of glasses intervention on astigmatism-related amblyopia. The proposed study will provide valuable clinical information regarding the development and treatment of astigmatism-related amblyopia. In addition, it will provide a valuable public health service to members of the Tohono O'Odham.

DESCRIPTION (provided by applicant): The visual experience of the uncorrected astigmat provides a unique natural experiment on the effect of chronic blur on visual development. Studies of Tohono O'odham children, 30 to 40% of whom have visually significant astigmatism, provide a unique opportunity for investigation of the effects of astigmatism. The first aim of the proposed research is to determine factors associated with spectacle wearing compliance in Tohono O'odham children, which will provide essential information for the development of future strategies to increase treatment compliance. The second aim is to determine the effect of uncorrected astigmatism on both uncorrected and corrected performance of complex and everyday visual tasks (global perception of form and motion, visual motor integration, reading), and will provide insight into how astigmatism impacts everyday functioning and whether it affects the development of the ability to perform these tasks when the child is wearing best correction. The third aim is to examine the relation between the visual experience of uncorrected astigmatic children, taking into account task-specific accommodative patterns, and the specific patterns of best-corrected visual deficits that result. These data will allow us to better understand the complex relation between visual experience and visual development. Aims 2 and 3 will also provide valuable clinical information regarding the amount of uncorrected astigmatism necessary to significantly disrupt visual performance and the amount of astigmatism necessary to disrupt normal development of visual capabilities necessary to perform simple, complex, and everyday visual tasks. The final aim is to study the stability of astigmatism in Tohono O'odham children over time, and to determine the anatomical origins of their astigmatism. The research will examine long-term change in astigmatism in over 2,000 school-age children. In addition, measurements of the posterior cornea will provide fundamental data on the origin of the internal astigmatism that often compensates for external (anterior) corneal astigmatism. RELEVANCE (See Instructions): This research will will generate important clinical information to aid in the development of guidelines for treatment and prevention of astigmatism-related amblyopia, will further our basic understanding of the influence of visual experience on visual development, and will provide the first analysis of the anatomic origins of internal astigmatism in this population.

DESCRIPTION (provided by applicant): The visual experience of the uncorrected astigmat provides a unique natural experiment on the effect of chronic blur on visual development. Studies of Tohono O'odham children, 30 to 40% of whom have visually significant astigmatism, provide a unique opportunity for investigation of the effects of astigmatism. The first aim is to study the stability of astigmatism in Tohono O'odham children over time, and to determine the anatomical origins of their astigmatism. Measurements of the posterior cornea will provide fundamental data on the origin of the internal astigmatism that often compensates for external (anterior) corneal astigmatism. The second aim is to determine how astigmats perform in the everyday complex visual environment. Specifically, we will examine the relation between astigmatic refractive error and (a) compliance with spectacle correction, (b) accommodation patterns, and (c) performance of complex perceptual tasks. By examining the influence of social, refractive, visual performance, and accommodation factors on compliance, we will provide a uniquely broad analysis of barriers to compliance, will provide essential information for development of strategies to increase treatment compliance in this population, and may identify barriers to compliance that are relevant to astigmats in general. Measures of accommodation under various task demand conditions will allow us to better understand how astigmats compensate for the unique persistent blur introduced by astigmatism, and will allow us to better understand how these strategies impact visual development. Finally, data on how astigmatism influences performance on tasks that require visual motor integration, reading fluency, and global perception of form and motion will provide valuable insight into how astigmatism impacts everyday functioning. In summary, access to this unique population of high astigmats introduces a valuable opportunity to conduct novel studies to further our understanding of the long-term stability and anatomic origins of astigmatism and to explore the effects of astigmatism on functioning in a complex visual environment. RELEVANCE: This research will provide the first analysis of the anatomic origins of astigmatism in this population, generate important clinical information for development of guidelines for treatment and prevention of astigmatism-related amblyopia, and will further our understanding of the influence of astigmatism on visual functioning. Results will benefit astigmatic Tohono O'odham children and astigmatic children in general.

PROJECT SUMMARY The benefits of early spectacle treatment for moderate refractive error in asymptomatic toddlers are not known. AAPOS spectacle prescribing guidelines for children less than 3 years of age are based on consensus and clinical experience because ?there are no scientifically rigorous published data for guidance?. The United States Preventive Services Task Force concluded in 2017 that there is insufficient evidence to assess the balance of benefits of vision screening for children less than 3 years of age because data on the benefits of spectacle correction for refractive error in toddlers are lacking. The SPEC Trial addresses these important gaps in the literature with a focus on assessing the developmental and visual benefits of spectacle treatment for astigmatism in toddlers, and the factors associated with spectacle treatment compliance in this age group. SPEC is a prospective trial to determine if prescribing and providing spectacle correction for astigmatic toddlers (at 12 to < 24 months or 24 to < 36 months of age) meeting current consensus based prescribing guidelines result in better developmental and visual outcome compared to astigmatic children who are prescribed and provided spectacles at age 36 to < 40 months. Developmental outcomes will be measured using the Bayley Scales of Infant and Toddler Development, 3rd Edition. Visual acuity outcome will be measured using the Amblyopia Treatment Study HOTV Protocol. Spectacle treatment compliance will be measured using a wearable sensor attached to the spectacles. The results of the SPEC Trial will have important implications for screening and treatment of young astigmatic children. This study will generate evidence to inform parents, pediatricians, and eye care providers if prescribing spectacles for astigmatic toddlers will have a beneficial effect on their global development, and will allow clinicians to make evidence-based, rather than consensus-based, recommendations regarding treatment of astigmatism in toddlers. The SPEC Trial is also unique in that it includes objective measures of spectacle treatment compliance, and will provide much needed data on factors associated with spectacle treatment compliance in toddlers.