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Biomedical subjects

M R O'Neal

Publications and source records attributed to M R O'Neal.

8 recordsLinked to original sources
PubMed1990

Survey of spectacle wear and refractive error prevalence in USAF pilots and navigators.

A retrospective survey of 5000 active aircrew records was performed at 12 United States Air Force (USAF) bases to obtain information about the prevalence of spectacle wear and refractive error. The data revealed that 27.4% of pilots and 51.5% of navigators/weapons systems operators (Nav/WSO) required spectacles when flying. Of the spectacle-wearing pilots, 12.4% required bifocals. Myopia was the predominant refractive error and a relatively large percentage of aircrew members had astigmatism of 0.75 D or more, e.g., 33.1% of pilots. At the time of entry into the USAF, refractive error data were clustered around emmetropia with a definite skew toward hyperopia.

Adult↗
PubMed1987

Refractive error change at the United States Air Force Academy--class of 1985.

A retrospective study was conducted at the United States Air-Force Academy (USAFA) to determine the incidence and change in refractive error over a 2.5-year period between the entrance and third academic year physical examinations. For all 994 eyes (497 cadets aged 17 to 21 years) at entrance, there were 37.3% hyperopes, 18.5% emmetropes, and 44.2% myopes of -0.25 D or more, by spherical equivalent (SPEQ). A significant (p less than 0.001) mean SPEQ change of -0.18 D, -0.21 D, and -0.57 D occurred for the hyperopic, emmetropic, and myopic eyes, respectively, over this period. A myopic change of -0.25 D or more was seen in 47.7%, 41.3%, and 74.0% of the hyperopic, emmetropic, and myopic eyes, respectively, with a clinically significant myopic shift of -0.50 D or greater seen in 21.3%, 25.0%, and 55.1% of these refractive error types, respectively. Myopia progression was derived separately from those eyes showing any amount of myopic shift (greater than or equal to -0.12 D), and was -0.42 D, -0.52 D, and -0.75 D for the hyperopic, emmetropic, and myopic eyes, respectively. There was a higher incidence and rate of myopia increase in the higher refractive errors, whether hyperopic or myopic. These findings suggest that 17- to 21-year-olds are not as safe from a myopic change as thought previously, particularly during an intensive educational program.

Adolescent↗
PubMed1987

Introduction to the Kaufman Assessment Battery for Children (K-ABC) for pediatric neuroclinicians.

This article introduces the neuroclinician to the Kaufman Assessment Battery for Children (K-ABC), a new test of intelligence and achievement with a strong theoretical base supported by diverse cognitive and neuropsychological research. The K-ABC global scales and their subtests are described in some detail, followed by a discussion of the neuropsychological relevance of the K-ABC subtests. The article also provides discussions of research in the following areas: psychometric properties of the K-ABC and a comparison to the Wechsler scales; interpretation and remediation of sequential-simultaneous processing differences; the value of the K-ABC in the assessment of minority children; and controversy surrounding the K-ABC.

Achievement↗
PubMed1986

Topical review of the WISC-R for pediatric neuroclinicians.

This article will familiarize neuroclinicians with the WISC-R and with the results of countless research studies on this popular test of the intelligence of children and adolescents. In addition to a description of the WISC-R and its subtests, and a discussion of the WISC-R from a historical context, the article reviews research in the following areas: relationship of the WISC-R to Wechsler's preschool and adult scales; interpretation of verbal-performance IQ differences; clinical implications of scatter; relationship of an IQ score to present and future functioning; and comparison of IQs on the WISC-R with scores on other tests for children and adolescents.

Adolescent↗
PubMed1986

Decreased endothelial pump function with aging.

Endothelial function may be affected by the endothelial cell loss and increased variability in cell shape and size (polymegathism) that accompany normal aging. Endothelial function can be evaluated by monitoring corneal hydration recovery following hypoxic stress. The authors compared corneal recovery and endothelial morphology between a group of younger (mean = 26.7 yr) and older (means = 65.7 yr) subjects with normal corneas. Edema (60 microns) was induced with hydrogel lenses worn with the eyes closed. Following lens removal, the decrease in corneal thickness was monitored for 4 hr with one eye open while the contralateral eye remained closed. For both age groups, corneal recovery followed a non-linear time course. The open eye required 2.5 hr and 3.0 hr to return to baseline for the younger and older age groups, respectively. Recovery during eye closure took 3.5 hr to reach the normal closed eye level for the younger subjects and was not complete at 4 hr for the older subjects. Recovery rates were significantly slower for the older vs younger subjects during the first 2 hr of closed eye recovery, 10.5 vs 15.0 microns/hr, and for the initial 1 hr of open eye recovery, 26.5 vs 35.6 microns/hr. For both age groups combined, the rate of recovery was negatively correlated with the coefficient of variation in cell area, r = -0.62 and -0.69 (P less than 0.01), for both closed and open eye recovery, respectively. When each morphological characteristic was isolated, the only significant correlation found was between the coefficient of variation in cell area and the rate of recovery during eye closure, r = -0.66 (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

In vivo assessment of mechanisms controlling corneal hydration.

The endothelial pump and evaporation components of corneal recovery were studied in the in vivo human cornea by inducing corneal swelling with the use of hypoxia and monitoring the subsequent decrease in corneal thickness. Corneal recovery follows a nonlinear time course with the rate of recovery decreasing as the cornea thins. Following 60 micron of induced edema, recovery with the eyes open required an average of 2.5 hr to reach baseline corneal thickness, while recovery with the eyes closed took an average of 4.0 hr to reach the normal physiologic corneal swelling (17 micron). Our analysis indicates that for open eye recovery from 60 micron of swelling, the endothelial pump provides 20%, while the osmotic thinning caused by tear evaporation contributes 80% of recovery. During recovery, the rate of water evaporation from the anterior corneal surface remained relatively steady at 2.5 microliter/cm2 X hr. Comparison of measured vs calculated recovery rates during recovery with the eyes closed suggests that the endothelial pump functions at one speed and that the "pump-leak" theory of corneal hydration control is applicable for the human cornea.

Adult↗