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Biomedical subjects

K J Ciuffreda

Publications and source records attributed to K J Ciuffreda.

At least 127 records · Page 7Linked to original sources
PubMed1980

Lack of positive results of a physiologically based treatment of amblyopia.

Recent reports have described marked improvement of visual acuity in amblyopic eyes of young children following monocular exposure to square-wave gratings presented at a variety of spatial frequencies and orientations for as little as 7 minutes. We sought to confirm and expand on these investigations, with emphasis on single-session results. Sixteen juvenile and 11 adult amblyopes and 26 control subjects were used. Visual acuity was determined before and after a 7-minute stimulation period using an E-chart that controlled for contour interaction. The 50% visual acuity threshold corrected for guessing was computer calculated by probit analysis. Results show that frequency, range, and magnitude of changes (either increases or decreases) in visual acuity following stimulation were approximately the same (< +/- 10% Snell-Sterling) in both amblyopic and control groups. These findings suggest that brief exposure to the grating patterns had little if any beneficial effect on visual acuity in amblyopic eyes.

Adolescent↗
PubMed1980

Dynamic vergence eye movements in strabismus and amblyopia: symmetric vergence.

Dynamic vergence eye movements in response to step target displacements along the midline were measured by an infrared reflection technique in 11 patients having either intermittent strabismus, constants-strabismus amblyopia, or amblyopia without strabismus. We found the absence of normal disparity (fusional) vergence in all patients having strabismus and in some patients having amblyopia without strabismus. A characteristic response consisting of a binocular accommodative vergence component and an early binocular saccadic component was used to foveate the target of interest with the dominant eye. Vergence responses in our control subjects and patients with the nondominant eye occluded were similar to those recorded in our patients during binocular viewing. These results suggest that disparity information is not utilized by patients, probably as a result of long-term, ongoing suppression in the deviated or amblyopic eye. Accommodative vergence with the aid of an early foveating saccade was the primary mechanism for tracking targets in three-dimensional space.

Accommodation, Ocular↗
PubMed1980

Disparity vergence: a proposed name for a dominant component of binocular vergence eye movements.

A proposal to name the dominant aspect of vergence "disparity vergence" is put forward. Support for this proposal is gathered by briefly reviewing the components of vergence: (1) disparity vergence, the visual feedback control system for removing binocular disparity with an appropriate binocular convergence or divergence, (2) accommodative vergence, a synkinesis with accommodative motor control, (3) proximal vergence, and (4) tonic vergence. Sensory fusion is a higher level perceptual process aided by disparity vergence, and historically the term fusional vergence called attention to this relationship. However, it now appears to obscure the fact that disparity is the only direct stimulus to vergence.

Accommodation, Ocular↗
PubMed1980

Voluntary nystagmus: new findings and clinical implications.

Horizontal eye position was monitored during a variety of tracking tasks in three normal subjects capable of producing voluntary nystagmus. New findings included ability to superimpose voluntary nystagmus saccades on smooth movements during tracking of a target moving with constant acceleration, brief persistence of voluntary nystagmus, and transient occurrence of voluntary nystagmus, and transient occurrence of voluntary nystagmus-like movements and oscillopsia following an intense period of voluntary nystagmus-like movements and oscillopsia during marked convergence. Clinical implications of these new findings are discussed.

Electrophysiology↗
PubMed1979

Saccadic intrusions in strabismus.

Fixational eye movements were studied to determine the presence of and to quantify saccadic intrusions under monocular and binocular viewing conditions in subjects with intermittent strabismus, amblyopia without stabismus, or constant strabismus amblyopia. Saccadic intrusions were present under most test conditions in intermittent strabismus, were rarely observed in amblyopia without strabismus, and were prominent during monocular fixation with the amblyopic eye in constant strabismus anblyopia. This suggests that the presence of saccadic intrusions was related to strabismus and not amblyopia. There was no relationship between saccadic intrusion amplitude and visual acuity. Two possible mechanisms for producing intrusions are abnormally rapid regional visual adaptation and strabismus-induced fixation degradation.

Adolescent↗
PubMed1979

A versatile multi-input device to study the Pulfrich effect.

A versatile multi-input device based on an x-y recorder was designed for the study of the Pulfrich effect. Because the device provided constant velocity of the target, a rectangular Pulfrich effect was observed rather than the traditional elliptical effect. The instrument permits study of the response induced when the input is changed in a variety of ways.

Humans↗
PubMed1979

Objective assessment of accommodation orthoptics. I. Dynamic insufficiency.

Three young adult females with symptoms related to focusing difficulties at near were treated by standard orthoptic procedures, including jump focus, plus-and-minus lens flippers, and pencil pushups. Home training was done 20 minutes each day for 4 1/2--7 weeks. Objective measures of dynamic accommodation were made each week in our Neuro-optometry Clinic. Initially, these objective measures showed prolongations of time constants and latencies of accommodation. During treatment, the patients showed significant reductions in time constants and latencies that correlated well with elimination of subjective symptoms. Also, in all three patients, flipper rates increased and symptoms were either markedly diminished or no longer present at termination of therapy. These results clearly demonstrate that orthoptic treatment in our three adult patients resulted in objective improvement of accommodation function.

Accommodation, Ocular↗
PubMed1979

Abnormal saccadic substitution during small-amplitude pursuit tracking in amblyopic eyes.

Small-amplitude, low-velocity, predictable triangular tracking was tested in patients having amblyopia without strabismus, intermittent strabismus, or constant strabismus amblyopia by means of a photoelectric eye-movement recording technique. In the majority of amblyopic patients, abnormal saccadic substitution was found; that is, abnormally large saccades rather than small-amplitude smooth movements were used by the amblyopic eye to follow a spot stimulus that moved horizontally with low to high frequencies. Pursuit for the same range of stimuli was normal for binocular tracking and for monocular tracking with the dominant eye, pointing to a sensory rather than motor basis for the defect. This abnormal saccadic substitution response appeared to be related to the presence of amblyopia rather than strabismus. Several possible mechanisms responsible for causing this unusual response are discussed, including impairment of direction sense over small central regions of the amblyopic eye.

Adolescent↗
PubMed1979

Fixational eye movements in amblyopia and strabismus.

Horizontal eye position was monitored using a photoelectric method during monocular and binocular fixation in four patients having amblyopia without strabismus, thirteen patients having constant strabismus with amblyopia, and five patients having intermittent strabismus. Four abnormalities of fixation were found: increased drift, saccadic intrusions, manifest nystagmus, and latent nystagmus. Increased drift was related to the presence of amblyopia, while saccadic intrusions and nystagmus were related to the presence of strabismus. Understanding dynamic aspects of oculomotor control can provide insight into clinical assessment of fixation in amblyopia and strabismus.

Adolescent↗
PubMed1979

Jerk nystagmus: some new findings.

Eye movements in a subject with jerk nystagmus were recorded during a variety of tracking tasks using a photoelectric method. New findings included ability to reduce nystagmus amplitude and frequency when instructed "to hold the eye steady" rather than "to fixate" in the presence of a visible target, changes in nystagmus characteristics and visual acuity as a function of head position which related to overall retinal-image motion, marked variability of nystagmus especially during reading, and necessity of a prolonged period of visual feedback for generation of nystagmus to approach a "steady-state" level. Clinical implications of these findings are discussed, including use of the "hold" command during ophthalmoscopy in patients with nystagmus.

Adult↗
PubMed1979

Different rates of functional recovery of eye movements during orthoptics treatment in an adult amblyope.

Although it is common clinical knowledge that oculomotor control appears to normalize during the course of successful orthoptics therapy for amblyopia, reports providing a quantitative analysis of eye movements during extended periods of treatment are lacking. We provide for the first time such a report in an adult amblyope. Aspects of eye movement control that tended to normalize with therapy include drift amplitude and velocity, duration and frequency of steady fixation, and pursuit gain. These results suggest that smooth pursuit control can be modified, even in an adult amblyope. Aspects of eye movement control that remained abnormal throughout therapy, in spite of normalization of visual acuity and centralization of fixation, include increased saccadic latencies, use of large saccades during small-amplitude pursuit tracking, and static overshooting. These results suggest that certain aspects of saccadic and pursuit control could either no longer be modified or would require longer periods for this to occur.

Adolescent↗
PubMed1978

Processing delays in amblyopic eyes: evidence from saccadic latencies.

Saccadic latencies were measured in amblyopes with constant strabismus, amblyopes without strabismus, and intermittent strabismics with or without amblyopia. Subjects tracked a small spot of light, either monocularly or binocularly, which moved with random horizontal step displacements of 0.25--8.5 deg over the central field. Increased saccadic latencies were observed in the amblyopic eyes of 6 of 11 subjects, with or without strabismus; saccadic latencies were similar in each eye of 2 subjects having intermittent strabismus without amblyopia. Amblyopia was a necessary condition for increased saccadic latencies and not strabismus. Evidence for normal motor control of eye movements in amblyopic subjects is as follows: normal saccadic durations in the amblyopic eyes, normal saccadic-latency distribution curves for binocular tracking and monocular tracking with the nonamblyopic eyes, and synchronous movements of the 2 eyes. Our results are interpreted in terms of a processing delay in the sensory pathways leading from the central region of the amblyopic eye to the centers involved in saccadic initiation.

Amblyopia↗
PubMed1978

Increased saccadic latencies in amblyopic eyes.

Increased saccadic latencies were measured in the amblyopic eyes of subjects having amblyopia without strabismus, constant strabismus amblyopia, and intermittent strabismus. The subjects tracked a small, bright spot of light moving with random, horizontal step displacements of 0.25 to 8.5 degrees over the central retina. Normal saccadic latencies were generally found during monocular tracking with the nonamblyopic eye as well as during binocular tracking. Studies of eye-hand reaction time in amblyopic eyes have shown delays to occur over the central retina; our new finding establishes this for saccadic initiation. Normal trajectories found for all tracking saccades, normal saccadic latencies measured when the nonamblyopic eye was utilized for tracking, and synchronous movement of the eyes under all test conditions point to a sensory rather than motor basis underlying these delays. Our results are interpreted in terms of a processing delay in the sensory pathways leading from the central region of the amblyopic eye to those centers involved in saccadic initiation.

Adolescent↗