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Avery H Weiss, James O. Phillips, Russ Saneto, John P Kelly; Chronic Progressive External Ophthalmoplegia (CPOE) in Childhood: A Disorder of Supranuclear Bioenergetics. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2169.
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The purpose of this study was to characterize the conjugate eye movements of children with chronic progressive external ophthalmoplegia (CPOE) due to a mitochondrial disorder.
Eye alignment and conjugate eye movements of 9 children (4.0-15.5yrs) with deletions or mutations of mitochondrial or nuclear DNA were measured using binocular infrared VOG (Sensorimotoric Instruments). The VOG recordings and target position data for saccades, smooth pursuits, horizontal OKN (hOKN) were exported and analyzed offline using customized analysis programs.
Saccades were variably normometric, hypometric, or limited to glissades or a pulse and transient step of eye position. Saccades fell below the main sequence for larger target steps. Smooth pursuit of a point target drifted sinusoidally at peak velocities of 10, 20 and 30 deg/s was characterized by initial epochs of high gain pursuit followed by progressive decreases in gain and variable increases in catch-up saccades. OKN responses to large field gratings of low spatial frequency drifting velocities of 15 deg/s 30 deg/s and 45 deg/s were well below the 95% confidence intervals of age-similar controls.
The pulse step mismatch of targeted saccades specifically implicates pre-motor burst neurons owing to their high firing rate and critical dependency on oxidative metabolism. Staircase hypometric saccades and glissades represent compensatory strategies for acquiring targets when bio-energetic resources are limited. Reduced gains for smooth pursuit and hOKN are consistent with the sustained and cumulative depletion of bio-energetics over an extended neural circuitry including the cerebellum.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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