Acknowledgement to: Capturing the Moment When Fusion is Lost in - PowerPoint PPT Presentation

In Flagrante Delicto: Acknowledgement to: Capturing the Moment When Fusion is Lost in Strabismus • NATIONAL EYE INSTITUTE • Research to Prevent Blindness • Alcon Research Institute • That Man May See • Wayne and Gladys Valley Foundation • Jewish Guild for the Blind (No Financial Disclosures or Conflict of Interest) Jonathan C. Horton, UCSF http://vision.ucsf.edu/hortonlab Economides JR, Adams DL, Horton JC, Perception via the deviated eye in strabismus. J. Neuroscience , 32:10286-10295, 2012. Adams DL, Economides JR, Sincich LC, Horton JC, Cortical metabolic activity matches the pattern of visual suppression in strabismus. J. Neuroscience , 33:3752-3759, 2013. Economides JR, Adams DL, Horton JC, Eye choice for target acquisition in alternating strabismus. J. Neuroscience, 34:14578-14588, 2014. Economides, J.R., Adams, D.L., Horton, J.C., Variability of ocular deviation in strabismus. JAMA Ophthalmology , 34:63-69, 2016. Economides, J.R., Adams, D.L., Horton, J.C., Normal correspondence of tectal maps for saccadic eye movements in strabismus. J. Neurophysiology , 2016 Economides, J.R., Adams, D.L., Horton, J.C., Capturing the moment of fusion loss in intermittent exotropia. Ophthalmology , 2017. 1

Spontaneous Right XT Spontaneous Left XT Left Eye Fixation Right Eye Fixation 2

Velocity of Spontaneous & Shutter-Induced XT are Correlated Spontaneous r = 0.91 Shutter Velocity of Spontaneous XT & Amplitude are Correlated Blue Cross, Blue Target Red Cross, Red Target r = 0.81 3

Conclusions Target Undershoot in Exotropes (n = 16) • In alternating exotropia the deviated eye is unstable, with a standard deviation in horizontal position of ± 2.4° . • Even the fixating eye is slightly unsteady, compared with controls. • The outwards eye movement that occurs spontaneously is extremely similar to the outwards eye movement induced by occlusion. • Therefore, once fusion is broken and the eye begins to move outwards, visual feedback plays no role. • The peak velocity of the outwards eye movement is correlated with the amplitude of the exotropia. • Although intermittent exotropia is often blamed on excess divergence tone, in fact, adducting saccades are less accurate than abducting saccades. • We have not yet solved the chicken or egg problem. 18% 12% 4