Se discute un nuevo dispositivo láser servo - motorizado y un protocolo de investigación para vías visuales enfermedades terapias. El dispositivo láser de servo mecanizado propuesto puede ser utilizado para el potencial de la rehabilitación de pacientes con hemianopsia, cuadrantanopsia, escotoma y algunos tipos de daños corticales. El dispositivo utiliza una estructura semiesférico en el que el estímulo visual se mostrará en el interior, de acuerdo con una terapia de estímulos anterior diseñado por un oftalmólogo. El dispositivo utiliza un par de servomotores (con par = 1,5 kg), que controla la posición de los estímulos de láser para la terapia interna y otro par para la terapia externa. El uso de herramientas electrónicas tales como microcontroladores, junto con los materiales electrónicos diversos, combinados con interfaz basada en LabVIEW, un mecanismo de control está desarrollado para el nuevo dispositivo. El dispositivo propuesto es muy adecuado para ejecutar diversas terapias estímulos visuales. Planteamos los grandes principios de diseño, incluyendo las dimensiones físicas, análisis cinemático del dispositivo láser y el desarrollo de software correspondiente.
Palabras clave: Neuroplasticidad, robótica, terapias visuales, servomotor, dispositivo laser.
We discuss a novel servo-motorized laser device and a research protocol for visual pathways diseases therapies. The proposed servo-mechanized laser device can be used for potential rehabilitation of patients with hemianopia, quadrantanopia, scotoma and some types of cortical damages. The device uses a semi spherical structure where the visual stimulus will be shown inside, according to a previous stimuli therapy designed by an ophthalmologist or neurologist. The device uses a pair of servomotors (with torque=1.5kg), which controls the laser stimuli position for the internal therapy and another pair for external therapy. Using electronic tools such as microcontrollers along with miscellaneous electronic materials, combined with LabVIEW based interface, a control mechanism is developed for the new device. The proposed device is well suited to run various visual stimuli therapies. We outline the major design principles including the physical dimensions, laser device’s kinematical analysis and the corresponding software development.
Keywords:Neuroplasticity, Robotics, Visual Therapies, Servomotor, Laser device.
LESIONS occurred in front of optical chiasm can cause visual field lose in only one eye whereas lesions behind can cause visual field lose in both eyes, more or less congruent to each other [1]. The total destruction of any of the visual structures behind the optical chiasm in only one side causes contralateral homonymous hemianopia [1]. Hemianopia, as with other visual field defects, is a result of retrochiasmatic lesions of visual pathways, produced by different causes, predominantly by vascular malfunctions [2].
There are two major techniques to enhance and/or repair visual field homonymous defects. The first one is to teach the patient to explore his or her blind side by compensatory saccadic movements and the other is to enhance the visual field to stimulate the border between the visible and damaged visual side [3] using a computer program. The scanning with ocular movements has been reported as an efficient tactic by the previous studies, reporting visual field enlargement up to 35° [4]. There is strong evidence supporting the effectiveness of the border zone stimulation and a possible activation of the extrastriate pathways [6], [7]. Neuroplasticity is reported as a possible cause of this particular therapy method in humans [9] with delicate behavior measurement, as measured by functional magnetic resonance (fMRI) images and positron emission tomography (PET). It has been observed that reactivation in some areas at the occipital lobe [8] and also activation in concentration areas [6].
It has been proved that the nervous system is continuously remodeled by experience and learning in response to an activity [9]. Moreover, it is observed that such remodeling mechanisms grow as the axon and dendrites reestablish new synaptic connections. Clinical practice and research have shown the possibility of total or partial restitution of the lost functions observing restoration of the affected visual functions. In this paper, we detail a novel servo-mechanized laser device which can be used for such visual stimuli therapies.
The rest of the paper is organized as follows. Section
II outlines the design of the proposed device and Section III
details the associated control mechanism which can help
ophthalmologists and neurologists in using the device for
various therapies. Section IV concludes the paper.
A. Physical design
The device consists mainly of an acrylic semispherical
structure (Fig.1(I)) where visual stimuli will be
shown, according to a pre-designed therapy. Four servomotors
(I)
(II)
Fig.1. (I) Acrylic structure (inferior side) where the patient is enclosed to avoid external stimulus. (II) Chin rest, corresponding proportions and measurements.
LabVIEW has a friendly COM port interface to work [18] enabling the possibility to develop a complete control system in few time.
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[a]Carlos Ignacio Sarmiento is an Electronic Engineer at the Instituto Tecnológico de Ciudad Madero (ITCM), Mexico. He works as part-time clinical engineer and researcher in the Department of Bioengineering at the National Institute of Neurology and Neurosurgery “Manuel Velasco Suárez” in Mexico City. His research fields include robotics, neural engineering, brain-computer interfaces, neuroplasticity, neuro-ophthalmology, electronic design, bioinstrumentation biomechanics, mechatronics, medical mathematics and medical equipment repair.