Research Areas 



Traumatic brain injury (TBI) is a leading cause of death and disability among children and young adults in the United States. Each year an estimated 1.5 million Americans sustain a TBI, which disrupts the normal function of the brain. People who have had strokes have a high morbidity of oculomotor disorders and unique problems of visual neglect. Due to this, they have problems with visually fixating on the person speaking to them. They may eat only from one side of their plate or pay less attention to one side when grooming, for example, shaving or applying makeup. A wheelchair user may repeatedly bump into walls and objects on the neglected side, and an affected individual may omit or misread individual words when reading text on one side of the page. It is critical to determine whether residual deficits following an apparent recovery on standard tests relate to ongoing symptoms and how much they impact activities of daily living. These neglect conditions are often overlooked in clinics because, in many cases, the visual fields of these patients register as normal. Diagnosing these neglects early and treating them with a proper rehabilitation plan of visual training will help to improve the quality of life for affected individuals. My research has shown that, with a battery of tests, visual neglect could be detected in stroke patients even when visual field measures are normal. It also shows the importance of screening for visual neglect in stroke patients in hospitals and rehabilitation centers.


Shrestha G, Upadhyaya S, Sharma A, Gajurel B. Ocular–visual defect and visual neglect in stroke patients – A report from Kathmandu, Nepal. Journal of Optometry. 2012 January 01; 5(1):43-49.




Strabismus is a developmental disorder present in up to 5% of all infants around the world. These individuals suffer from an inability to perceive depth throughout their lives. Besides obvious cosmetic issues, strabismus can be associated with reading problems, eye-strain, headache, and other oculomotor deficits. Developmental strabismus is often treated at the level of extraocular muscles, and most surgeries result in over-corrections, under-correction, or multiple operations due to the reoccurrence of strabismus. This is because developmental strabismus is not only a muscle problem but also a brain problem. In order to fully understand the neural mechanism of strabismus, it is essential to identify brain areas that are involved in it. Only when the disease is fully understood can a better approach for treatment be devised. I have examined the role of the brain, particularly the superior colliculus, in strabismus and, for the first time, have shown that the superior colliculus is involved in maintaining a steady state of eye misalignment. This gives researchers and clinicians a deeper understanding of the neurophysiology of strabismus.


Upadhyaya S, Meng H, Das VE. Electrical stimulation of superior colliculus affects strabismus angle in monkey models for strabismus. J Neurophysiol. 2017 Mar ;117(3):1281-1292. PubMed PMID: 28031397; PubMed Central PMCID: PMC5349331.



The human eye is never steady even when fixating on a stationary target. In conditions such as strabismus, amblyopia, age-related macular degeneration, diabetic retinopathy, and other neurological disorders, fixation stability is poor. Fixational eye movements can be broadly categorized into quick flicks of eye movements and slow eye movements. Although fixation instability is often the hallmark of many visual system pathologies, it was not previously known how components of fixational eye movements are related to fixation instability. I have examined the contribution of fixational saccades toward fixation instability in strabismus monkeys. This study, for the first time, has shown that the relationship between overall fixation instability and fixational saccade amplitude is nonlinear and exhibits a saturation of fixational saccade amplitude. This opens the possibility of training to control fixational saccades leading to improvement in fixation stability in central and peripheral pathologies as a potential avenue for treatment.


Upadhyaya S, Pullela M, Ramachandran S, Adade S, Joshi AC, Das VE. Fixational Saccades and Their Relation to Fixation Instability in Strabismic Monkeys. Invest Ophthalmol Vis Sci. 2017 Nov 1;58(13):5743-5753. PubMed PMID: 29114840; PubMed Central PMCID: PMC5678548.