Posts Tagged saccades
Background. Humans use voluntary eye movements to actively gather visual information during many activities of daily living, such as driving, walking, and preparing meals. Most stroke survivors have difficulties performing these functional motor tasks, and we recently demonstrated that stroke survivors who require many saccades (rapid eye movements) to plan reaching movements exhibit poor motor performance. However, the nature of this relationship remains unclear.
Objective. Here we investigate if saccades interfere with speed and smoothness of reaching movements in stroke survivors, and if excessive saccades are associated with difficulties performing functional tasks.
Methods. We used a robotic device and eye tracking to examine reaching and saccades in stroke survivors and age-matched controls who performed the Trail Making Test, a visuomotor task that uses organized patterns of saccades to plan reaching movements. We also used the Stroke Impact Scale to examine difficulties performing functional tasks.
Results. Compared with controls, stroke survivors made many saccades during ongoing reaching movements, and most of these saccades closely preceded transient decreases in reaching speed. We also found that the number of saccades that stroke survivors made during ongoing reaching movements was strongly associated with slower reaching speed, decreased reaching smoothness, and greater difficulty performing functional tasks.
Conclusions. Our findings indicate that poststroke interference between eye and limb movements may contribute to difficulties performing functional tasks. This suggests that interventions aimed at treating impaired organization of eye movements may improve functional recovery after stroke.
[Project] Optimal Interventions for Treatment of Visual Deficits in Individuals with an Acquired Brain Injury
Approximately one-third of the human brain controls visual anatomy or transmits and registers visual information (Kapoor & Ciuffreda, 2002). Because of this, acquired brain injuries ABI can frequently cause visual impairment.
Following an ABI, it is important for visual deficits to be taken into account and addressed during occupational therapy evaluation and treatment. Although considered a primary sense for obtaining information, vision is often ignored or overlooked in rehabilitation programs. Vision screens should be conducted and collaborations and referrals to a neuro-optometrists made. There is a lack of research regarding the benefits of visual interventions with individuals that are more than two years post-injury.
The project looked at benefits of addressing visual deficits in individuals who have experienced a ABI and are five years or more post-injury. A vison program was established at a day enrichment center for individuals’ years postinjury. Vision programs were established in collaboration with a neuro optometrist and performed at an inpatient brain injury rehabilitation center.
Two different case studies and a pilot study detail the benefits of a comprehensive vison program in individuals who have experienced a traumatic brain injury. A pilot study was conducted to monitor the benefits of development of a program to address visual deficits effecting reading with individuals more than five years post-brain injury. There is potential for ocular motor deficits such as pursuits and saccades to improve with continued training and for improvements in visual deficits to improve performance in activities of daily living
[ARTICLE] Eye movements during saccadic and fixation tasks in patients with hemianopia – Full Text PDF
Objectives The aim was to quantify oculomotor performance in hemianopic patients and in healthy controls during saccadic and fixation tasks, and to detect potential spontaneous adaptive mechanisms in the patients.
Methods Eye movements were recorded in 33 hemianopic patients (15 right, 18 left, disease duration 0.2-29 years) and 14 healthy subjects by Scanning Laser Ophthalmoscope allowing determination of the absolute fovea position relative to the stimulus without calibration. Landing accuracy of saccades was determined for 5° saccades, indicated by the number of dysmetric saccades (DS), and fixation stability (FS) after landing. Furthermore, during continuous fixation of a central cross, FS and distribution of fixational eye movements (FEM) were measured. Size of macular sparing was determined using custom microperimetry software (stimulus grid 0.5°).
Results Landing accuracy was decreased, indicated by significantly more DS (hypo- and hypermetric) to the blind side compared with the seeing side. Their number was more increased in macular sparing <4°. DS were not correlated with age and disease duration.. FS after landing was lower after saccades to the blind side. Distribution of FEM during continuous fixation was asymmetrically shifted to the blind side, especially in macular sparing <4°.
Conclusions Number of DS was not correlated with disease duration indicating insufficient spontaneous long-term adaptation. Increased number of DS and decreased FS after landing in patients with small or absent macular sparing stresses the importance of intact parafoveal vision. Asymmetric FEM during continuous fixation indicate an advantageous adaptive mechanism to shift the visual field border towards the hemianopic side.