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Biomedical subjects

J L Keltner

Publications and source records attributed to J L Keltner.

At least 73 records · Page 4Linked to original sources
PubMed1981

Static and acuity profile perimetry at various adaptation levels.

Effects of target size, eccentricity and background luminance were determined for static and acuity profile perimetry in the central 30 degree radius of the visual field. Reductions in target size produced decreases in sensitivity for both functions, with acuity profiles (resolution sensitivity) being more affected than static profiles (detection sensitivity). At photopic background luminances, detection sensitivity was greatest at the fovea and progressively declined with increased eccentricity; lower background fovea. Resolution sensitivity for small targets (20/80 or less) exhibited a rapid decline with increasing eccentricity that was relatively independent of background luminance, whereas large targets (20/125 or greater) revealed findings similar to the detection sensitivity results. The relative contributions of rods and cones to threshold visual responses thus appear to depend on the type of visual task, target size, eccentricity, background luminance and their interactions. These data provide a comparison basis for future evaluations of patients with photoreceptor dysfunction.

Humans↗
PubMed1981

Computer analysis of visual field loss and optimization of automated perimetric test strategies.

Preliminary investigations of optimal target distribution patterns of automated perimetry were conducted. In the first study, frequency distributions of visual field defects were determined in glaucoma (260 scotomata) and optic nerve disease (110 scotomata) for approximately 30,000 visual field locations. The frequency distributions in glaucoma and optic nerve disease were different, and suggest guidelines for development of target distribution patterns to achieve optimal detection rates. The second study included computer simulation of 20 target distribution patterns currently used in manual and automated perimetry. Each distribution pattern was processed through the 370 glaucoma and optic nerve disease scotomata to assess detection performance. Both the density and distribution of target locations affected overall detection rates. In addition, some target configurations were more susceptible to false alarms than others. These data provide qualitative information for optimization of target distribution patterns in automated perimetry, and serve as a foundation for future quantitative studies.

Automation↗
PubMed1980

Abnormalities of the pupil and visual-evoked potential in quinine amblyopia.

Total blindness with a transient tonic pupillary response, denervation supersensitivity, and abnormal visual-evoked potentials developed in a 54-year-old man after the use of quinine sulfate for leg cramps. He later recovered normal visual acuity. A transient tonic pupillary response, denervation supersensitivity, and abnormal visual-evoked potentials in quinine toxicity, to our knowledge, have not been previously reported.

Blindness↗
PubMed1980

Automated suprathreshold static perimetry.

Automated (Fieldmaster) and manual kinetic perimetry were performed in 1,019 eyes with various visual disorders. tunder appropriate test conditions, automated Fieldmaster evaluations showed a 96.1% detection rate and a 4.7% false alarm rate for detection of visual field defects. Preliminary results for 168 eyes showed that sequential follow-up testing with the Fieldmaster correctly identified progression or regression of visual field loss in more than 94% (34 of 36) of the eyes with visual field changes. The Fieldmaster correctly determined no change in visual field characteristics for 99% (131 of 132) of the eyes with stable visual fields. These data indicate that the Fieldmaster is an excellent device for detecting visual field defects, and also has some capabilities for monitoring progression or regression of visual field loss.

Automation↗
PubMed1980

Mass visual field screening in a driving population.

With the cooperation of the California Department of Motor Vehicles and Synemed, Inc., visual field screening tests were administered to 1,027 eyes of driver's license applicants using the Fieldmaster Model 101-PR automated perimeter. Approximately 5% of the eyes tested demonstrated significant visual field loss. These results indicate that mass visual field screening in a driving population is feasible and may become a valuable technique for early detection of eye disease in large populations. It may also be an important factor in traffic safety.

Adolescent↗
PubMed1980

Comparative evaluation of the Autofield-I, CFA-120, and Fieldmaster Model 101-PR automated perimeters.

Clinical evaluations of the Autofield-I, CFA-120, and Fieldmaster Model 101-PR automated perimeters were performed in comparison with manual kinetic testing on the Goldmann perimeter. All the automated perimeters displayed similar high rates of detecting visual field defects, although their false-alarm (false-positive) rates were considerably different. The principal factors responsible for high-detection and low false-alarm rates are discussed.

Evaluation Studies as Topic↗
PubMed1979

Acuity profile perimetry: description of technique and preliminary clinical trials.

Acuity profile perimetry is a technique that allows visual acuity properties to be rapidly measured at any location in the visual field. This report describes our initial clinical trials with acuity profile perimetry, as performed in combination with standard static perimetry. Preliminary results from patients with cataracts, amblyopia, and central serous retinopathy show, in general, a much greater deficit for acuity profiles than for static sensitivity profiles. In contrast, patients with optic neuritis or other optic neuropathies display approximately equivalent losses for static and acuity profiles. The recovery process in optic neuritis is also about equal for the two functions. Our initial findings suggest that acuity profile perimetry may be a valuable differential diagnostic test, particularly for cases in which optic nerve disease is suspected.

Adult↗
PubMed1979

Virus-simulating structures in the optic nerve head in Creutzfeldt-Jakob disease.

A 68-year-old man was treated for and died of Creutzfeldt-Jakob disease. At autopsy we found multiple virus-like particles in the optic nerve head, but saw no similar structures in the cornea. Although these particles were morphologically similar to those previously reported in brain, we believe that they are not virions but unrelated cellular structures. We speculate that the causative agents may be naked membrane bound nucleic acids rather than true viruses. We found no optic atrophy or other specific pathologic changes in the eyes; severe occipital cortical degeneration was responsible for the patient's visual loss.

Aged↗
PubMed1979

Comparison of photographic techniques and films used in stereophotogrammetry of the optic disk.

We compared photogrammetric measurements of optic cup volume, area, and depth made from two types of stereophotography and two types of film to determine their effect on the precision of the measurements. We found that measurements from simultaneous stereophotography (Donaldson stereoscopic fundus camera) had a smaller range of values and a smaller mean percent error than measurements from consecutive stereophotography (Zeiss Fundus Flash II camera). However, a Student's t-test for related measures showed no significant difference. The measurements from Kodachrome 25 film and Kodak Photomicrography film varied in range and mean percent error without a pattern. The Student's t-test for related measures showed no significant difference.

Evaluation Studies as Topic↗
PubMed1979

Suprathreshold static perimetry in glaucoma and other optic nerve disease.

Comparisons between automated suprathreshold static perimetry and manual kinetic perimetry were performed for 226 eyes with glaucoma or ocular hypertension, and 147 eyes with other optic nerve disease. Both techniques produced similar high detection rates for glaucomatous visual field defects, whereas suprathreshold static perimetry performed significantly better than kinetic testing in optic nerve disease other than glaucoma. It is concluded that automated suprathreshold static perimetry is an excellent quantitative screening technique for detecting visual field defects.

Glaucoma↗
PubMed1979

A regional course to update the practicing specialist.

Four medical centers collaborated in the development of a course in ophthalmology to present new information and skills to the practicing specialist who is not associated with a medical center. The course is presented in 8 two-day sessions, scheduled Friday and Saturday, four times a year, on a two-year cycle. Thus, the participant loses only four days a year from his practice. This course differs from most of the postgraduate courses currently being offered in that it is designed to update basic specialty knowledge and skills systematically to improve health care delivery.

Education, Medical, Continuing↗
PubMed1979

Photogrammetry of the optic disc in glaucoma and ocular hypertension with simultaneous stereo photography.

Stereophotogrammetric evaluations of the optic cup were performed for normal, ocular hypertensive, and glaucomatous eyes. Average volume, area, and depth measurements were progressively larger from normal to ocular hypertensive to glaucomatous eyes, although the distributions of individual values exhibited considerable overlap among the three groups. Similar results were obtained for volume, area, and depth asymmetry between each pair of eyes. None of these measurements was able to distinguish accurately between normal and glaucomatous optic cups. However, normal eyes showed a high correlation (r = +0.85) between area and depth of the optic cup, whereas this area/depth relationship was reduced in ocular hypertensives (r = +0.63) and completely broke down for glaucomatous eyes (r = +0.04). Approximately 89% of the glaucomatous eyes and 47% of the ocular hypertensive eyes were beyond the range of normal area/depth correlation values. These findings represent an improvement over most previous attempts to quantitatively differentiate between normal and glaucomatous eyes on the basis of optic disc measurements alone, and support the hypothesis that optic disc damage usually precedes visual field loss in glaucoma. With further technical refinements such as computer image processing, stereophotogrammetry of the optic cup may become a valuable differential diagnostic technique for glaucoma.

Glaucoma↗