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Biomedical subjects

K J Ciuffreda

Publications and source records attributed to K J Ciuffreda.

136 records · Page 8Linked to original sources
PubMed1977

A field expander for patients with retinitis pigmentosa: a clinical study.

An inexpensive, commercially available optical device was tested on 10 patients with retinitis pigmentosa to determine its value as a field expander for scanning and as an aid to mobility. Visual acuity and visual fields were measured with and without the expander, and the patients' subjective responses were monitored by a questionnaire that was administered at regular intervals during a 2- to 4-week period between test sessions. Six of the 10 subjects considered the device helpful in at least 1 important visual task and planned to continue using it.

Adult↗
PubMed1977

Neuro-optometry: an evolving specialty clinic.

Neuro-optometry is evolving as an optometric clinical specialty focusing on neurological dysfunctions of the visual system. Initially, we focused upon abnormalities of ocular movements, and our investigations have now broadened to include static and dynamic measurements of eye movements, accommodation, and the pupil. We feel the clinic serves three fundamental purposes: (1) to provide service to the patient, (2) to perform clinical research, and (3) to broaden the scope of the students' clinical experience. Operation of the clinic, technical methods of measurement, the testing protocol, and examples of interesting clinical recordings are described.

Accommodation, Ocular↗
PubMed1976

Eye movements during reading: case reports.

Since the time of Javal, it has been well established that normal reading eye movement patterns have 3 principal components: (1) small saccades that move the eyes from word to word, (2) large saccades that return the eyes to the beginning of the next line, and (3) fixation pauses between each saccade for information processing. We discuss the vision analysis results and show the quantitative reading eye movement records, measured with the infrared photoelectric method, of 5 patients examined in the Neuro-optometry Clinic. The reading records showed a wide variety of behavior: 1 patient performed normal reading movements, 1 "slow reader" manifested an excessive number of fixations as well as extended fixational durations, another "slow" reader only exhibited an excessive number of fixations, a patient with dyslexia performed backward reading movements, and 1 patient exhibited nystagmus superimposed upon the reading pattern.

Adult↗
PubMed1976

Dynamic and static violations of Hering's law of equal innervation.

Hering's Law of Equal Innervation treats the double eye as a single organ. Normal humans often execute saccadic eye movements that are dynamic violations of Hering's Law. These infractions are produced by differences in the neural controller signals sent to each eye and are exemplified by monocular movements, such as dynamic overshoot, glissades, and double saccades; these dynamic violations occur more frequently in fatigued subjects. In contrast to dynamic violations, static violations of Hering's Law are usually indicative of pathological conditions.

Aged↗
PubMed1975

Juvenile glaucoma - a case report.

A case report of incipient juvenile glaucoma is presented. Clinical data obtained during the optometric examination indicating possible glaucoma were confirmed by an ophthalmological evaluation. Early detection of glaucoma in the young adult may help prevent significant visual impairment and disability in his later years. Screening patients of all ages for glaucoma is recommended.

Adult↗
PubMed1975

Descartes' law of reciprocal innervation.

Reciprocal innervation plays a crucial role in the fine motor control exhibited in body movements and this is especially true for the precise ocular rotations demanded of the extrinsic muscles of the eye. Although Galen, in 157 AD, was knowledgeable in human anatomy and muscle function, it was Descarted, who in 1626 first conceived of model for the nervous system controller, of a muscular mechanism for movement of the extra-ocular plant, and of reciprocal innervation as the linking principle to provide for control of agonist and antagonist muscles. Bell, in 1826, and Sherrington in 1893, clearly demonstrated reciprocal innervation in their experimental animals. Additional qualitative neurophysiological evidence supporting the concept of reciprocal innervation has been provided by clinical case reports, by electromyographic recording from the extraocular muscles, and by monitoring single unit activity in the extraocular motor nuclei. Recently the applicatio of bioengineering concepts, such as time optimal control and quantitative models to elucidate the nature of the neural signals sent by the brain to command eye movements have further emphasized the importance of Descartes' "Law of Reciprocal Innervation."

Animals↗
PubMed1975

Understanding fluorescein contact lens photography: equipment and technique.

A basic consideration of the utilization of close-up photography in the ophthalmic health care field is discussed. These principles can be applied to fluorescein contact lens photography using a hand-held camera. The discussion is divided into two areas: basic theory and equipment is reviewed, and a description of the clinical technique is described.

Contact Lenses↗
PubMedDate not supplied

Fixational ocular motor control is plastic despite visual deprivation.

The aim of this study was to assess the plasticity of human voluntary fixational eye movement control in relation to visual experience/chronic visual deprivation. Twelve blind adults participated (self-reported vision < or = light perception in each eye; age range = 23-56 years; visual experience range = 0-28 years; blindness duration range = 6-55 years). Infrared-based recordings of horizontal eye movements were made before, during, and immediately after three 30-s periods of auditory ocular motor feedback, while participants were instructed to look straight ahead and keep their eyes as steady as possible. Percent change in horizontal displacement of the eye during and after feedback was compared with the no-feedback baseline. Eleven of the 12 individuals demonstrated feedback-mediated increase in eye stability, which improved as a function of visual experience. Improved eye stability was inversely related to duration of blindness. Clearly, blind adults can use nonvisual external feedback to stabilize gaze. Thus, the fixational subsystem can exhibit improved voluntary control despite chronic visual deprivation. Possible cortical and subcortical mechanisms are discussed.

Adult↗
PubMedDate not supplied

Differential retinal-defocus magnitude during eye growth provides the appropriate direction signal.

INTRODUCTION: The rate of ocular growth can be modified by the imposition of either plus or minus lenses before the eyes, which creates changes in retinal defocus. Several hypotheses with relatively complicated mechanisms have been proposed to explain these changes, but the underlying mechanism has remained elusive. MATERIAL AND METHODS: Our new analysis using schematic models, however, provides a relatively simple and logically-consistent explanation of how retinal defocus magnitude alone during ocular growth gives the requisite sign for an appropriate change in ocular growth rate. RESULTS: During a normal genetically-determined incremental increase in axial length, the presence of either an imposed plus or minus lens results in an increase or decrease, respectively, of the blur circle magnitude. Neuromodulators in the retina are proposed to regulate the sensitivity to retinal-image contrast by means of a local feedback mechanism, and the alteration in retinal-image contrast associated with the change in blur circle causes an increase or decrease, respectively, in the rate of release of neuromodulators as well as the rate of proteoglycan synthesis, the latter being associated with the structural integrity of the sclera. CONCLUSION: This provides the critical sign, as well as amplitude, information needed to modulate appropriately the rate of eye growth, to result in a decrease or increase, respectively, in the rate of ocular growth.

Accommodation, Ocular↗