Professor of Optometry and Vision Science
School of Optometry
Psychophysical basis for clinical tests in acuity, perimetry, and color vision. The visual stimulus and photometry. Visual receptors. Psychophysical method and visual threshold. Light sensitivity. Contrast sensitivity. Light and dark adaptation. Temporal and spatial properties of visual function. Color vision and abnormalities. Changes with age and disease. Visual illusion. Basis for advanced diagnostic procedures.
Introduction to sensory aspects of light and color vision, including psycho-physical methods, spectral response of the eye, mechanisms of sensitivity control, dark adaptation, color discrimination, and mechanisms of normal and defective color vision.
Supervising students during examination of patients in a primary care setting. Diagnosis, prognosis, treatment, patient management, and follow-up in Low Vision Clinic.
Cortical adaptation and plasticity in response to vision loss
Research in our lab focuses on the understanding of how the visual system works in people with normal vision, as well as in people with uncorrectable subnormal vision (visual impairment). Uncorrectable sub-normal vision can occur as a result of an eye disease (e.g., age-related macular degeneration, the leading cause of visual impairment in the US for people over the age of 65), or even in the absence of an eye disease (amblyopia, or “lazy eye”).
In our lab, we combine various non-invasive techniques to study vision of people with normal or impaired vision. These techniques include standard (e.g., signal detection theory) and more contemporary psychophysical methods (e.g., reversed-correlation method), retinal imaging using Scanning Laser Ophthalmoscope combined with psychophysical tasks, and functional magnetic brain imaging (fMRI).
The ultimate goals of our research program are to understand the various limiting factors on visual performance in people with visual impairment, and to devise methods, devices or rehabilitative strategies to improve the functional vision of these people, thereby improving their quality of life.
Chung STL, Mansfield JS, Legge GE (1998). Psychophysics of reading. XVIII. The effect of print size on reading speed in normal peripheral vision. Vision Research 38: 2949–2962.
Legge GE, Mansfield JS, Chung STL (2001). Psychophysics of reading. XX. Linking letter recognition to reading speed in central and peripheral vision. Vision Research, 41: 725–743.
Chung STL, Levi DM, Legge GE (2001). Spatial-frequency and contrast properties of crowding. Vision Research, 41: 1833–1850.
Chung STL (2002). The effect of letter spacing on reading speed in central and peripheral vision. Investigative Ophthalmology & Visual Science 43: 1270–1276.
Chung STL, Legge GE, Tjan BS (2002). Spatial-frequency characteristics of letter identification in central and peripheral vision. Vision Research, 42: 2137–2152.
Chung STL (2007). Learning to identify crowded letters: Does it improve reading speed? Vision Research, 47: 3150–3159.
Chung STL, Legge GE (2009). Precision of position signals for letters. Vision Research, 49: 1948–1960.
Chung STL (2011). Improving reading speed for people with central vision loss through perceptual learning. Investigative Ophthalmology & Visual Science, 52: 1164–1170.
Bernard JB, Chung STL (2011). The dependence of letter crowding on flanker complexity and target-flanker similarity. Journal of Vision, 11(8):1, 1–16.
Chung STL, Li RW, Levi DM (2012). Learning to identify near-acuity letters, either with or without flankers, results in improved letter size and spacing limits in adults with amblyopia. PLoS One, 7(4): e35829.
Chung STL (2013). The Glenn A. Fry Award Lecture 2012: Plasticity of the visual system following central vision loss. Optometry & Vision Science, 90: 520–529.
Coates DR, Chin JM, Chung STL (2013). Factors affecting crowded acuity: Eccentricity and contrast. Optometry & Vision Science, 90: 628–638.
Chung STL (2013). Cortical reorganization following long-term adaptation to retinal lesions in humans. Journal of Neuroscience, 33: 18080–18086.
Kumar G, Chung STL (2014). Characteristics of fixational eye movements in people with macular disease. Investigative Ophthalmology & Visual Science, 55: 5125–5133.
Millin R, Arman AC, Chung STL, Tjan BS (2014). Visual crowding in V1. Cerebral Cortex, 24: 3107–3115.
Chung STL, Kumar G, Li RW, Levi DM (2015). Characteristics of fixational eye movements in amblyopia: limitations on fixation stability and acuity? Vision Research, 114: 87–99.
Chung STL, Legge GE (2016). Comparing the shape of the contrast sensitivity functions for normal and low vision. Investigative Ophthalmology & Visual Science, 57: 198–207.
Chung STL (2016). Spatio-temporal properties of letter crowding. Journal of Vision, 16(6):8, 1–20.
Coates DR, Chung STL (2016). Crowding in the S-cone pathway. Vision Research, 122: 81–92.
Bernard JB, Chung STL (2016). The role of external features in face recognition with central vision loss. Optometry & Vision Science, 93: 510–520.
Agaoglu MN, Ogmen H, Chung STL (2016). Unmasking saccadic uncrowding. Vision Research, 127: 152–164.
Legge GE, Chung STL (2016). Low vision and plasticity: Implications for rehabilitation. Annual Review of Vision Science, 2: 321–343.
Agaoglu MN, Chung STL (2016). Can (Should) theories of crowding be unified? Journal of Vision, 16(15):10, 1–22.
Wallace JM, Chung STL, Tjan BS (2017). Object crowding in age-related macular degeneration. Journal of Vision, in press.
Agaoglu MN, Chung STL (2017). Interaction between stimulus contrast and pre-saccadic crowding. Royal Society Open Science, in press.