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Biomedical subjects

V Giambalvo

Publications and source records attributed to V Giambalvo.

6 recordsLinked to original sources
PubMed1981

Biofeedback of accommodation to reduce functional myopia.

Functional myopia may be defined as the refractive condition of the eye due to spasm of the ciliary muscle. As a result of the ciliary muscle spasm, the crystalline lens becomes more convex, creating a myopic refractive condition. The normal increase and decrease in the refractive power of the crystalline lens is know as accommodation and is controlled by the autonomic nervous system innervation to the ciliary muscle. Previous studies have reported that voluntary control of accommodation is possible by biofeedback training (Cornsweet & Crane, 1973; Randle, 1970). The present research investigated the application of biofeedback control of accommodation to reduce functional myopia. A double-reversal, multiple-baseline design was used to conduct the experiment. The results revealed that the three adult male subjects achieved the preset criterion, a 1/2-diopter reduction from initial baseline to a subsequent baseline. Further analysis of the data revealed even greater changes between initial baseline and feedback periods. Although generalization to a nonexperimental environment was not trained, each subject showed a reduction in myopia and an increase in visual acuity. The results of the experiment clearly demonstrated that functional myopia is subject to voluntary control.

Accommodation, Ocular↗
PubMed1978

A method for localization of sources of human cerebral potentials evoked by sensory stimuli.

A method based on potential field theory is described for assessing the location and orientation of dipole generators of the human scalp-recorded sensory evoked potential (EP). The method assumes that the EP at a given moment is due to a single dipole source and that the head can be modeled by a homogeneous conductive sphere (brain) surrounded by inner (skull) and outer (scalp) shells of differing conductivity (three-sphere model). Solution for source location and orientation from the surface potential field is given for the case of a single homogeneous sphere (one-sphere model). It is then shown that a unique solution for the three-sphere model can be derived from the one-sphere solution. Solutions are obtained by application of an iterative procedure which minimizes the error between calculated and empirical potential fields. A test of the method is described in which the calculated location and orientation of a dipole was in good agreement with the known source of an early component of the human somatosensory EP.

Brain↗
PubMed1976

Neurological syndromes involving the visual system.

Because optometrists are the primary deliverers of eye care, their role in pathology detection is of primary importance. The neurological syndromes of the visual system have been reviewed and put into a chart format as an aid to the optometric clinician.

Eye Diseases↗
PubMed1976

The stimuli to accommodation in the optometric examination.

The study of the stimuli to accommodation has been a topic of particular interest to vision scientists for the past 40 years. Currently, as revealed by a review of the literature, there are 11 different stimuli to accommodation. While it is difficult enough to hold 10 stimuli constant to measure the effect of a single stimulus, stimulus control becomes an even bigger problem when we consider stimulus interactions. With 11 different stimuli there are 2,047 possible stimulus combinations. In the present paper, the authors discuss at length the relationship between stimulus control problems and clinical optometric routine.

Accommodation, Ocular↗