January 2021

  • Professor Vallabh Das, Benedict-Pitts Professor Chair, Department of Basic Sciences. Host: Arvind Chandna

    Oculomotor studies in non-human primates with strabismus

    Event Date:

    Abstract - Binocular alignment and binocular coordination of eye movements are necessary to direct both foveae at targets within 3D space. Unfortunately, individuals suffering from strabismus (ocular misalignment) never develop the necessary alignment and coordination of eye movements for binocular vision. Developmental loss of sensory or motor fusion leads to strabismus in nearly 5% of children making this disease a significant public health issue. In order to develop a better understanding of this disabling disease, we have been performing studies in non-human primate models for sensory strabismus previously induced by disrupting binocular vision through the use of prisms or occluders during the developmental critical period. An excellent feature of these NHP models is that they not only develop eye misalignment but also develop common eye movement disruptions associated with the human condition. We have identified widespread changes in many visual and oculomotor neural centers, specifically vergence related areas of the brain, leading to new insight on the development and maintenance of eye misalignment and other associated strabismus properties. Our most recent work has been focused on the superior colliculus to identify its role in determining the state of eye misalignment and also as a substrate that might be involved in fixation-switch behavior. In another direction of research into strabismus, we have explored the neural plasticity that accompanies the treatment of strabismus via surgical methods with the goal of understanding how plasticity might influence the success or failure of the surgical treatment. https://www.opt.uh.edu/faculty/VDas/

    Improving Zoom accessibility for people with hearing impairments People with hearing impairments often use lipreading and speechreading to improve speech comprehension. This approach is helpful but only works if the speaker’s face and mouth are clearly visible. For the benefit of people with hearing impairments on Zoom calls, please enable your device’s camera whenever you are speaking on Zoom, and face the camera while you speak. (Feel free to disable your camera when you aren’t speaking.)

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  • Zoom Brown Bag: Recovering information hidden behind the binocular scotoma in macular degeneration

    Zoom Brown Bag: Recovering information hidden behind the binocular scotoma in macular degeneration

    Event Date:

    Abstract - When macular degeneration affects the foveae bilaterally, it results in a binocular scotoma that compromises both high-acuity vision and eye movements. A preferred retinal locus (PRL) is eventually adopted for fixation and oculomotor reference, but individuals still struggle with daily-living tasks as they are often unaware of the location and extent of their scotoma. Current methods of detailed scotoma mapping are mainly monocular; very few methods offer the same level of precision for binocular scotoma. In this brown bag, I will present my work done at Smith-Kettlewell in the last two years as a postdoctoral fellow. First, I will present a new eyetracker-based method to map precisely the binocular scotoma. Second, I will present how we use this detailed map to investigate in a visual search task how saccades compensate for the scotoma, which obscures parts of the visual scene.

    Improving Zoom accessibility for people with hearing impairments People with hearing impairments often use lipreading and speechreading to improve speech comprehension. This approach is helpful but only works if the speaker’s face and mouth are clearly visible. For the benefit of people with hearing impairments on Zoom calls, please enable your device’s camera whenever you are speaking on Zoom, and face the camera while you speak. (Feel free to disable your camera when you aren’t speaking.)

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  •  The Mind‘s Eye, Open, and Closed

    Zoom Colloquium: The Mind‘s Eye, Open, and Closed

    Event Date:

    Abstract - "I used to be a hyperphant and had something like HSAM [Highly Superior Autobiographical Memory]. I had a stroke in 2017, which left me with memory impairment (including SDAM [Severely Deficient Autobiographical Memory]) and aphantasia. I noticed immediately that my memories were gone, and I knew something else was wrong, but it took a while to figure out that I’d lost my mind’s eye. It’s been devastating to me. I’ve lost my job, career, and my sense of identity.

    – Anonymous, shared with permission

    The person above has first-hand experience with two extremes of human imagination. Those with hyperphantasia have highly detailed and nearly photo-realistic visual imagery, while those with aphantasia are unable to visualize at all – they have a blind mind’s eye. In this talk, I will focus on such individual differences in visual imagery and how they might – or might not – relate to other cognitive functions.

    https://english.hi.is/staff/heidasi

    Improving Zoom accessibility for people with hearing impairments People with hearing impairments often use lipreading and speechreading to improve speech comprehension. This approach is helpful but only works if the speaker’s face and mouth are clearly visible. For the benefit of people with hearing impairments on Zoom calls, please enable your device’s camera whenever you are speaking on Zoom, and face the camera while you speak. (Feel free to disable your camera when you aren’t speaking.)

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  • Zoom Brown Bag: The eye of the beholder. Does visual input and function affect ocular growth?"

    Event Date:

    Abstract - The eye undergoes significant structural change following birth and through development—a process of ocular growth. Some of the control mechanisms implicated in this emmetropization process are visual input, optical defocus on retina, accommodation, and feedback. Ocular growth is closely related to oculomotor and visual development. Though visual and oculomotor development are extensively investigated, normal and disordered ocular growth during childhood is less studied. Such information would make an important contribution towards an integrated understanding of visual development and informed management of childhood conditions such as refractive errors, amblyopia, cataract, and glaucoma.

    We performed a prospective, cross-sectional study of 332 typically developing infants and young children to measure ocular growth in each eye (corneal thickness, lens thickness, axial length. etc.). With this large data set, we were able to create normal growth curves for each of the variables, which can now be compared to ocular growth in different ocular conditions. We next examined ocular growth in the setting of visual deprivation by measuring eyes with pediatric unilateral and bilateral cataracts before and after surgery. We have discovered trends that suggest altered ocular growth when cataracts are present, and after removal of the cataracts, these trends differ between unilateral and bilateral deprivation.

    We are now at the stage of brainstorming about and speculating on the significance of these findings. Why would eyes with cataracts be shorter? Why are there differential effects between unilateral and bilateral cataracts after surgery? Can the data we have serve as a model for amblyopia and other pediatric ophthalmic conditions? Where do we go next with this research? Questions that we hope will engender a discussion…...

    https://www.ski.org/users/arvind-chandna https://www.ski.org/users/spencer-harris https://www.ski.org/users/saeideh-ghahghaei

    Improving Zoom accessibility for people with hearing impairments People with hearing impairments often use lipreading and speechreading to improve speech comprehension. This approach is helpful but only works if the speaker’s face and mouth are clearly visible. For the benefit of people with hearing impairments on Zoom calls, please enable your device’s camera whenever you are speaking on Zoom, and face the camera while you speak. (Feel free to disable your camera when you aren’t speaking.)

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