Of age, the infant begins to integrate fixation with grasping At 3 months of age, the infant maintains fixation in allįields of gaze and reestablishes fixation instantly after interruption. The eyes follow a light or a bright objectįor a few degrees, but once fixation is interrupted, reestablishment The development of the fixation reflex is first manifest when the full-term Of the New Orleans Academy of Ophthalmology, p 94. (Parks MM: Sensory adaptations in strabismus. Object of regard is projected along the visual line and imaged on the fovea. Lobe, the vestibular pathways, and the auditory and pain pathways.įig. Muscles over the voluntary oculogyric pathways of the frontal It may be interrupted by disturbing innervations arriving at the extraocular It is an involuntary reflex mediated through the optomotor pathways, but Regard by a complex visuomotor reflex designed to steer the fixation line this The best visual acuity is obtained and maintained for the object of Theįixation line (visual axis) is a line drawn between the fixation pointĪnd the fovea ( Fig. The fixation point is the spatial location of the object of regard. Results in maximal perception of contour, known as best visual acuity. Power for contrast sensation, projection of images onto this area
Since the fovea possesses the highest resolving TheĬontrast sensation results in the perception of shape, size, and relative Produced between stimulated and unstimulated photoreceptors. The contour of each image is determined by the contrast Waves emanating from objects in the visual field form miniaturized The basis for the contoured image that projects onto the retina. Of light sources and comprising a patterned spatial stimulus-is To an infinite number of light waves emanating from a multitude Penetrating light waves, the characteristic of the light wave angle-applied Since the refracting surfaces of the eye exert a constant effect on all That each localization is away from center is equal to the number ofĭegrees the stimulated neuroepithelial element is displaced from the Receptor localizes inferior to center, and so on. Localizes objects in space to the temporal side of center, a superior Zero directional value, and the image projected here is perceived asĬentered in the visual field. The direction the light wave was traveling in reference to This is the basis for spatially identifying Has the innate ability to register the specific angle formed by the The angle of the light waves entering the eye is the characteristic of the stimulus that determines which retinal neuroepithelial Sensation providing varied color perception. Of varied sensations related to the wavelength of the light stimulus, each The cones in photopic vision, however, respond with a multitude Wavelength, the sensation of the rods is unvaried, and they perceive Only by the cones of the retina and not by the rods. The length of the light waves is a characteristic within the visible spectrum that can be sorted out Volume of light waves that enters the eye per unit of surface area. The intensity of the stimulus is graded according to the Ranging from weak to strong, providing perception of a dim or a bright
Intensity of the light stimulus is the characteristic that creates a light sensation Sensation, providing the perception of a flickering or sustained light. Vision lack of any of the three results in no vision.įour separate characteristics of the light stimulus are identifiable: frequencyĪnd duration, intensity, the length of the light waves, and theĪngle of the light waves entering the eye.įrequency and duration of the light stimulus are characteristics that evoke the on-off light ThisĬhain reaction of light, sensation, and perception results in Interpretation of the light sensation is the perception process. Light creates a sensation in the retinas that is transmitted to theĬortex. Is the visible spectrum portion of electromagnetic waves. Stimulus, (2) sensation, and (3) perception. There are three requisites for vision: (1) light Monocular vision itself is a complex phenomenon, but binocular vision isĮven more complex.