PubMed Health⌕ Search

Biomedical subjects

R L Yolton

Publications and source records attributed to R L Yolton.

At least 19 recordsLinked to original sources
PubMed1998

Use of the Taylor Visagraph II system to evaluate eye movements made during reading.

BACKGROUND: The Taylor Visagraph II is a relatively new device designed to evaluate eye movements made during reading. It uses goggles with infrared optics to detect the eye movements and computer software to determine the number of fixations, regressions, and other characteristics of the eye movements. The system also calculates several scores, including a school-grade equivalent for the reader. METHODS: Fifty first-year optometry students served as subjects. Each read five standard Taylor Level 10 (College) paragraphs during each of two sessions while eye movements were assessed by the Visagraph II. RESULTS: The Visagraph II operated correctly for 498 of the 500 trials; operator error caused two malfunctions. Significant differences were found between scores from the first paragraph read and subsequent paragraphs. Nonlinear relationships were found between most of the variables, especially those that involved grade levels and spans of recognition. Also of interest was the wide range of reading eye-movement skills; several of the optometry students appeared to have skills that placed them at below fourth grade level. CONCLUSIONS: The Visagraph II performed properly over a large number of trials and produced data that seemed to be reliable indicators of reading skills. Paragraph-to-paragraph variations in mean scores suggest caution in interpretation of small changes in performance across paragraphs and the need for at least one practice trial before usable data are obtained.

Adult↗
PubMed1998

The Drug Evaluation Classification Program: using ocular and other signs to detect drug intoxication.

BACKGROUND: A systematic approach to determining drug intoxication has been developed for use by police officers. By considering specific physiological signs, trained officers can detect the effects of seven major drug types. METHODS: Officers follow a 12-step testing sequence and evaluate signs such as pupil sizes and responses, eye movements, heart rate, body temperature, mental timing, and balance. A matrix is then used to compare that subject's signs to those that would be produced by the seven types of drugs. If a pattern match is found, the officer concludes that the subject is under the influence of a drug and specifies the drug type. RESULTS: Several field and laboratory validation studies have been conducted using these procedures. In general, officers were 70% to 90% accurate in determining intoxication status and drug classification, but poly-drug use and drug rebound effects can sometimes cause problems in interpretation. CONCLUSION: Ocular and other physiological signs can be used to detect drug intoxication and classify the type of drug taken. Knowledge of the procedures used in the Drug Recognition Program can enable optometrists to serve as consultants to the police and as expert witnesses in cases involving the use of ocular signs that indicate illicit drug use.

Body Temperature↗
PubMed1997

Use of the Ober2 Model B-1200 system for analysis of eye movements made during reading.

BACKGROUND: The Ober2 Model B-1200 system uses infrared reflections to record and analyze eye movements made during reading. The system's ability to analyze data from normal subjects and the reliability of the data produced by subjects who read standard paragraphs were investigated. METHODS: Forty-two optometry students and 20 junior high school students, all self-assessed normal readers, read five different Taylor test paragraphs during each of two sessions. Ober2 Model B-1200 analysis was attempted for each paragraph; when analysis was successful, grade-equivalent scores based on fixations, span of recognition, regressions, fixation duration, and reading rate were determined. RESULTS: The Ober2 Model B-1200 system was unsuccessful in analyzing data from 30% of the paragraph presentations; manual calibration procedures allowed no additional data analysis. Using mean grade-equivalent data from 16 optometry student subjects for whom all 10 paragraphs could be analyzed, significant differences were found between results for two of the test paragraphs. Split-half inter-session reliability coefficients for grade-equivalent data ranged from 0.84 to 0.95. No intra-session learning or fatigue effects on reading data were found. CONCLUSIONS: Although the Ober2 Model B-1200 potentially can provide valuable information on eye movements made during reading, problems exist with respect to its ability to analyze data. The analysis failures significantly limited the value of this system.

Adolescent↗
PubMed1997

Meeting the vision care needs of aircraft pilots.

BACKGROUND: Of the approximately 640,000 currently active civilian aircraft pilots in the United States, many receive their vision care from optometrists. This report reviews the vision requirements for pilots and describes the results of surveys designed to determine whether the vision care needs of pilots are being fully met by optometrists. METHODS: Surveys were sent to 100 optometrists and 120 pilots in the Seattle, Washington area. The optometrists' surveys included questions regarding knowledge of licensing regulations and differences in examinations for pilots and nonpilots. The pilots' surveys asked about vision care examinations, experiences, and expectations. RESULTS: The majority of pilots recognized the need for complete vision examinations, beyond those provided as part of their flight physicals. Their most commonly reported needs were for evaluation of any medical problems, obtaining correct lens powers, sunglass tints, and for information on vision enhancement. Results of the survey also indicated that optometrists were relatively unfamiliar with Federal Aviation Administration (FAA) regulations and with the forms needed to report examination results to the FAA. CONCLUSIONS: Many of the optometrists surveyed knew little about FAA regulations, test procedures, or required eye examinations. By becoming more familiar with basic information regarding these regulations and the demands of aircraft operation, optometrists can enhance their ability to provide complete vision care services for their pilot patients.

Aerospace Medicine↗
PubMed1997

OPTX 20/20 and Press-On Optics bifocal segments: an evaluation.

BACKGROUND: OPTX 20/20 and Press-On Optics removable bifocal segments were evaluated in three areas: optical quality, effects on vision, and stability under simulated environmental conditions. METHODS: To evaluate optical quality, sphere, cylinder, and spherical equivalent powers were measured in center and peripheral portions of 10 segments, with powers ranging from +1.00 to +2.50 D. RESULTS: Twelve of 20 OPTX 20/20 segments and six of 20 Press-On Optics +1.00 and +1.50 D segments failed to pass ANSI Z80.1 standards because of unwanted cylinder powers. With regard to vision, +2.00 D OPTX 20/20 segments provided a 1 Snellen line advantage in near acuity, as compared with the Press-On Optics segments. contrast sensitivity for low- and mid-spatial frequencies was not significantly different for segments of the two types. CONCLUSION: For higher powers, the optical characteristics of the OPTX 20/20 segments are better and provide better visual acuity. For lower powers, distortion and small amounts of unwanted cylinder reduce the optical quality of the OPTX 20/20 segments. Both segment types retained adhesion to CR-39 carriers equally well and should be satisfactory for their designated purposes of providing temporary and removable adds for occasional use.

Adult↗
PubMed1996

Myopia associated with hyperbaric oxygen therapy.

BACKGROUND: Hyperbaric oxygen therapy (HBOT) involves exposing patients to elevated oxygen pressures and concentrations for the treatment of soft tissue degenerative diseases. As side effects, some patients experience cataract development and/or a significant increase in myopia. SUBJECTS: Eight subjects participated in this project. All were receiving HBOT for health problems. METHODS: For all subjects, acuities and refractive error corrections were measured before and after HBOT sessions at the beginning, midpoint, and end of therapy. For four subjects, A-scan ultrasound and corneal curvature measurements were also made before and after selected HBOT sessions. In addition, susceptibility to free radical damage and indicators of actual damage were measured by blood analyses. During the first half of HBOT therapy, four subjects took placebo tablets; during the second half, antioxidant supplements were given. RESULTS: No subject showed significant acuity or refractive error changes produced by single HBOT sessions. Two of the 8 subjects showed significant increases in myopia over the 20 session course of HBOT. No corresponding changes were found in the ultrasound, corneal curvature, or blood analysis data. DISCUSSION: Theoretically, the increases in myopia could have been caused by lenticular refractive index changes resulting from oxidative damage to lens proteins. However, the biochemical assays used in this project did not predict which subjects were susceptible to increased myopia, nor did they demonstrate elevated levels of free radical activity in a subject who did experience an increase in myopia.

Adult↗
PubMed1996

Personal defense sprays: effects and management of exposure.

BACKGROUND: Most personal defense sprays contain o-chlorobenzylidene malononitrile (CS), w-chloroacetophenone (CN), oleoresin capsicum (OC), or a combination of these ingredients as the active agent. They are designed to incapacitate by causing acute ocular irritation, lacrimation, conjunctivitis, blepharospasm, and mild to moderate respiratory distress. METHODS: To assess the ocular effects of sprays containing OC as the active agent. Snellen visual acuities and anterior segment appearances of 22 police officers were determined before and after spray exposure. To assess the effects of OC spray contamination on soft contact lenses, four brands of lenses were sprayed and cleaned twice with an alcohol-based cleaner. Gas chromatography was used to search for residual OC in the lenses. RESULTS: All officers experienced intense blepharospasm, lacrimation, conjunctivitis, and incapacitation as the result of spray exposure. Acute effects lasted about 5 to 10 min, with relatively complete recovery occurring in about 30 to 60 min. All had significant conjunctivitis, and some had water-drop-shaped corneal defects that stained with fluorescein. These defects resolved within 24 hours without treatment. OC residue was found to be present in the soft lenses that had been sprayed and cleaned twice. CONCLUSIONS: Optometrists can manage uncomplicated spray exposure patients by directing at-home irrigation with water, and following up with an in-office examination. Soft lenses contaminated by OC spray should be discarded.

Aerosols↗
PubMed1995

The dizzy patient: a review of etiology, differential diagnosis, and management.

BACKGROUND: Dizziness is a lay term used to describe a variety of sensations. Unfortunately, the term "dizziness" does not have a precise medical definition, and additional information is typically required to further define the patient's problem. METHODS: When dizziness is a presenting complaint, distinctions must be made between vertigo (a sense of false movement), near-syncope (a feeling of impending faint), disequilibrium (loss of balance), and ill-defined lightheadedness (an inability to concentrate or focus the mind). Possible causes of dizziness include conflicts between visual and vestibular information, vascular problems, adverse reactions to medication, psychological difficulties, systemic disease, and the effects of aging. RESULTS: Dizziness is a symptom of a physiological or psychological illness, and therefore management is typically directed toward treatment of the underlying illness. In some cases the cause of the dizziness cannot be found, however, or is untreatable. In these cases, management is directed toward symptom reduction. CONCLUSIONS: Dizziness is a relatively common problem that arises from a variety of causes. In many cases, optometrists can participate in the diagnosis and management of patients with complaints of dizziness.

Diagnosis, Differential↗
PubMed1995

Second opinion: a computer expert system designed to aid in the determination of spectacle lens prescriptions.

BACKGROUND: Expert systems (ESs) are computer programs that simulate the decision-making ability of human experts. In this project, an ES was developed that used optometric data and decision rules to determine spectacle lens prescription powers. METHODS: Decision rules derived from clinical experience and standard references were provided to a commercially available shell program to create an ES called Second Opinion. The ES determined spherical, cylindrical, and add powers designed to provide maximum acuity consistent with a high probability of patient acceptance. CONCLUSIONS: Second Opinion demonstrates how a computer program can be used to analyze optometric data and offer suggestions regarding lens prescriptions.

Adult↗
PubMed1994

The effects of gender and birth control pill use on spontaneous blink rates.

BACKGROUND: Two major reference works suggest that men and women blink spontaneously at different rates, but they disagree with regard to which gender blinks faster. METHODS: Spontaneous blink rates of 59 males and 86 females, 44 of whom were taking birth control (BC) pills, were measured for 5 consecutive minutes. Schirmer test results and tear break-up times (TBUTs) were also obtained. RESULTS: Females taking BC pills blinked at a mean rate of 19.6 times per minute, females not taking birth control pills blinked 14.9 times per minute, and males blinked 14.5 times per minute. There were very large differences between blink rates for individuals in each of the groups. No strong associations were found between spontaneous blink rates and a history of contact lens use, tear break-up time, Schirmer test results, temperature or humidity in the examination room, subject age, or menstrual cycle phase. CONCLUSIONS: The 32 percent increase in mean blink rate for females taking BC pills suggests that the pills affect at least one of the mechanisms that control spontaneous blinking, but it is unclear how they accomplish this.

Adult↗
PubMed1994

Demonstration of a neural network expert system for recognition of glaucomatous visual field changes.

Expert systems (ESs) are computer programs designed to make decisions in a manner similar to the way human experts make them. There are many forms of ESs, ranging from those that are given specific If-Then rules to those that are capable of deriving their own rules. Some ESs use neural network simulations to analyze patterns of data. In this project, a commercially available neural network shell program was used to demonstrate the development of an ES capable of analyzing the visual field loss patterns produced by glaucoma. Potential applications of ESs for the diagnosis of glaucoma are discussed.

Decision Making, Computer-Assisted↗
PubMed1994

Comparison of Irlen scotopic sensitivity syndrome test results to academic and visual performance data.

UNLABELLED: Irlen has defined a condition called Scotopic Sensitivity Syndrome (SSS) that is associated with reading problems. According to Irlen, SSS can be treated by the use of colored filters, but there is disagreement about the existence of SSS and the efficacy of colored filter therapy. METHODS: Thirty-nine children participated in the study: 24 were academically normal, nine had specific reading problems, and six had problems in multiple academic areas. SSS levels and preferred overlay colors were determined. Optometric test data were also available for each subject. RESULTS: No significant relationships were found between academic classification and degree of SSS. There were also no significant relationships between preferred overlay color and any other variables. There was, however, a significant tendency for subjects with higher SSS levels to be candidates for vision therapy and to derive greater benefit from the colored overlays. CONCLUSIONS: Many questions about the use of colored filters for the treatment of reading problems remain unanswered. Among these are questions dealing with whether the M-pathway anomalies found in some dyslexics are also present to a lesser degree in other cases of reading disabilities, and how colored filters could re-balance the M- and P-pathways. Is it the color of the filter itself that is critical, or is it the change in luminance or contrast produced by the filter that seems to make it easier for some subjects to read? More research will be needed to answer these questions.

Child↗
PubMed1994

The optometry game: enhancing test selection and lens prescribing skills by use of computer simulations.

The Optometry Game is a computer simulation developed to aid students in practicing test selection and lens prescription skills. Features of the simulation include a game format, digitally reproduced voices and patient pictures, and the ability of the user to customize the game for a variety of applications. Twenty optometry students evaluated the game by playing a variety of simulated patients and found it to be potentially useful in various classroom learning environments.

Computer Simulation↗
PubMed1993

Evaluation of dietary antioxidant levels and supplementation with ICAPS-Plus and Ocuvite.

BACKGROUND: Oxidative damage caused by free radicals has been implicated in the development of age-related macular degeneration (ARMD). Recent studies suggest that antioxidant vitamins and minerals can be useful for the management and/or prevention of this condition. METHODS: To assess the normal dietary intake of the antioxidants, 28 healthy subjects 55 years of age and over completed a diet survey. Then two over-the-counter (OTC) nutritional supplements that make claims about the antioxidant nutrients they contain (ICAPS-Plus and Ocuvite) were evaluated with respect to their ability to raise blood levels of two important antioxidant nutrients: zinc and beta-carotene. RESULTS: Based on the diet survey, 26 of the 28 subjects were found to have deficient intakes; zinc and selenium were the most commonly deficient nutrients. Following a 2-week administration period, both ICAPS-Plus and Ocuvite significantly raised mean serum zinc levels 24.7 percent and 18 percent respectively; ICAPS-Plus significantly raised mean beta-carotene levels by 21.4 percent, but Ocuvite did not change the mean level significantly. CONCLUSIONS: Based on the probable relationship between antioxidant levels and diseases such as ARMD, these results suggest that OTC supplements might be useful for selected patients.

Aged↗
PubMed1993

Free radicals and antioxidant supplementation: a review of their roles in age-related macular degeneration.

BACKGROUND: Age-related macular degeneration (ARMD) is a major cause of blindness in the elderly. Unfortunately, no proven form of treatment is currently available for the dry, atrophic form of ARMD seen in more than 90 percent of patients with this condition. METHODS: A recent theory suggests that ARMD is associated with damage to the retina caused by free radicals. If this is correct, it is possible that the damage could be prevented or moderated by supplementing the diet with specific antioxidant vitamins and minerals that enhance the body's natural defenses against free radicals. RESULTS AND CONCLUSION: This paper reviews the literature regarding the pathogenesis of ARMD and presents a rationale for its management or prevention by the use of supplemental vitamins and minerals.

Antioxidants↗