Binocular alignment must be maintained in the horizontal, vertical and torsional planes to ensure binocular sensory fusion. Normal development ensures binocular alignment during fixation and binocular coordination during eye movements. Unfortunately, abnormal visual experience during development usually leads to ocular misalignment (strabismus). In fact, various studies have reported the incidence of strabismus to be about 2-5% of the infant population. Data from strabismic humans and from strabismic monkeys in our laboratory have shown that ocular misalignment is accompanied by a lack of conjugate eye movements. Though strabismus is most often associated with a horizontal misalignment, often a combined horizontal, vertical and torsional misalignment is observed. Along with the static horizontal, vertical and torsional misalignment, there appears to be substantial dynamic cross-talk between the principal eye movement planes. In the clinical literature these apparent cross-axis interactions are usually described as 'A' and 'V' patterns of strabismus. Unfortunately, there is a lack of understanding of the neural or mechanical bases for these cross-axis movements, the putative relationship or lack thereof to the neural control of horizontal, vertical or torsional eye movements and the relationship to the etiology of the strabismus. Competing hypotheses include static malpositioning of extraocular muscle pulleys, sideslip of extraocular muscles and muscle pulleys, torsional control of eye movements gone awry leading to apparent muscle dysfunction and finally simply unexplained overaction/underaction of individual extraocular muscles. The goal of our studies is to clarify static and dynamic properties of cross-axis movements and examine its source in animals with a sensory induced strabismus. Our approach will include structural imaging of extraocular muscle to determine role of muscle pulleys; behavioral experiments to examine control of torsion and Listing's laws; neurophysiological experiments to examine the role of motor and pre-motor structures in the brain and biomechanical modeling of extraocular musculature to simulate experimental data. Completion of our studies will be of benefit to the understanding and treatment of certain types of strabismus.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY015312-02
Application #
6843152
Study Section
Special Emphasis Panel (ZEY1-VSN (04))
Program Officer
Hunter, Chyren
Project Start
2004-02-01
Project End
2007-01-31
Budget Start
2005-02-01
Budget End
2006-01-31
Support Year
2
Fiscal Year
2005
Total Cost
$360,240
Indirect Cost
Name
Emory University
Department
Neurology
Type
Schools of Medicine
DUNS #
066469933
City
Atlanta
State
GA
Country
United States
Zip Code
30322
Joshi, Anand C; Agaoglu, Mehmet N; Das, Vallabh E (2017) Comparison of Naso-temporal Asymmetry During Monocular Smooth Pursuit, Optokinetic Nystagmus, and Ocular Following Response in Strabismic Monkeys. Strabismus 25:47-55
Upadhyaya, Suraj; Meng, Hui; Das, Vallabh E (2017) Electrical stimulation of superior colliculus affects strabismus angle in monkey models for strabismus. J Neurophysiol 117:1281-1292
Das, Vallabh E (2016) Strabismus and the Oculomotor System: Insights from Macaque Models. Annu Rev Vis Sci 2:37-59
Pirdankar, Onkar H; Das, Vallabh E (2016) Influence of Target Parameters on Fixation Stability in Normal and Strabismic Monkeys. Invest Ophthalmol Vis Sci 57:1087-95
Agaoglu, Sevda; Agaoglu, Mehmet N; Das, Vallabh E (2015) Motion Information via the Nonfixating Eye Can Drive Optokinetic Nystagmus in Strabismus. Invest Ophthalmol Vis Sci 56:6423-32
Agaoglu, Mehmet N; LeSage, Stephanie K; Joshi, Anand C et al. (2014) Spatial patterns of fixation-switch behavior in strabismic monkeys. Invest Ophthalmol Vis Sci 55:1259-68
Joshi, Anand C; Das, Vallabh E (2013) Muscimol inactivation of caudal fastigial nucleus and posterior interposed nucleus in monkeys with strabismus. J Neurophysiol 110:1882-91
Das, Vallabh E (2012) Responses of cells in the midbrain near-response area in monkeys with strabismus. Invest Ophthalmol Vis Sci 53:3858-64
Ono, Seiji; Das, Vallabh E; Mustari, Michael J (2012) Conjugate adaptation of smooth pursuit during monocular viewing in strabismic monkeys with exotropia. Invest Ophthalmol Vis Sci 53:2038-45
Das, Vallabh E (2011) Cells in the supraoculomotor area in monkeys with strabismus show activity related to the strabismus angle. Ann N Y Acad Sci 1233:85-90

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