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Biomedical subjects

W G Bachman

Publications and source records attributed to W G Bachman.

16 recordsLinked to original sources
PubMed1999

Comparison between anti-reflection-coated and uncoated spectacle lenses for presbyopic highway patrol troopers.

BACKGROUND: The use of anti-reflection coatings (AR) for spectacle lenses is steadily increasing. These ultra-thin coatings reduce reflections in lenses, increasing light transmittance about 8% (from 91% to 99%). Patient reports of crisper detail and brighter environment indicate that this perceived increase in visual function would probably be of benefit to many, including highway patrolmen who must make daily judgments on the basis of fine visual detail. METHODS: Nineteen presbyopic Missouri State Highway Patrolmen (MSHP) participated in this crossover study. Subjects randomly wore Varilux Comfort progressive addition lenses in CR-39 that were uncoated or AR-coated. The AR coating was Crizal. Subjects wore each lens for 1 month, then compared the lenses directly for 1 week. Data were collected for lens scoring (both general and job specific) and lens preferences. RESULTS: The AR-coated lens was found to be significantly better in most categories. Reduction in glare and reflections during the day, night, indoors, and in the patrol vehicle--as well as improvement in overall night vision--were highly significant. Eighty-nine percent of the subjects chose the Crizal-coated lenses as their overall preferred lens. CONCLUSIONS: The results of this study appear to demonstrate a noticeable subjective preference for AR-coated lenses when used by a group engaged in a visually demanding occupation.

Adult↗
PubMed1996

The continuing impact of treatment of eye disease on optometric practice in Missouri.

BACKGROUND: This study is a follow-up to a study performed in 1991 to determine the continuing impact of the use by optometrists in Missouri of therapeutic agents (TPA) to treat eye diseases. METHODS: Sixty-four percent of the Missouri optometrists certified to use therapeutic pharmaceutical agents responded to a 1995 questionnaire. RESULTS: More than 90 percent of those responding prescribe all categories of topical agents, while oral agents are used at lower percentages. Almost two-thirds of optometrists are registered with the Drug Enforcement Administration to prescribe controlled substances. The median number of therapeutic prescriptions written per year was 240, an increase of 67 percent from the previous study. More than half of the respondents now receive in-office detailing by drug company representatives. A small percent of optometrists have hospital clinical privileges and about one-fourth have privileges in nursing homes. CONCLUSIONS: The percentage of TPA-certified optometrists residing and practicing in Missouri has risen from one-half to slightly more than three-fourths of practitioners in a 4-year time period. This increase, coupled with the demonstrated increase in therapeutic prescriptions written, enhanced exposure to in-office detailing, and recent amendment of the optometry law to include the management of glaucoma bodes well for the delivery of primary eye care to citizens of the state.

Drug Prescriptions↗
PubMed1995

Visual characteristics of Missouri State Highway Patrol troopers.

BACKGROUND: The Missouri State Highway Patrol (MSHP) had 902 troopers on duty at the time of this study. The purpose of this study was to determine, for the first time, the visual characteristics of this group. METHODS: All 902 troopers were requested to be screened during early 1993 at their local MSHP troop headquarters. Vision screening was done by Department of Motor Vehicle Personnel using Keystone/Mast DVS II Driver Vision Screeners. The results, along with current prescriptions obtained from their eye care practitioners, were mailed to the author. RESULTS: A 94 percent response rate was achieved. The group's mean age was 38.7 years and most (98 percent) were male. Forty-seven percent wear an optical correction either some or all of the time and these were evenly divided between single vision and multifocal corrections. Seventy-four percent of eyes had uncorrected distance acuity of 20/20 increasing to 94 percent of eyes with 20/20 when corrections were worn. CONCLUSIONS: The results of this study will be used as a basis to update MSHP vision standards for acquisition and retention of troopers.

Adult↗
PubMed1994

Enhanced vision screening of highway patrol applicants.

BACKGROUND: The Missouri State Highway Patrol (MSHP) required that its vision standards be updated in order to comply with the Americans with Disabilities Act (ADA). This act prohibits employers from using qualification standards to screen out people with disabilities, including vision, unless they are job-related and necessary. METHODS: Since 1992 the author and a team of optometry students have screened all MSHP applicants using the American Optometric Association (AOA)'s Vision Standards for Police Officers with the addition of grating contrast sensitivity. RESULTS: The mean age of this group was 24.8 years and most (87%) were male. Thirty percent wore spectacles, contact lenses, or had refractive modification. Ninety-seven percent of the applicants were able to pass all aspects of the enhanced vision screening. CONCLUSION: The initiation of optometric screening to ensure that all future troopers meet the recommended vision standards for police officers should ensure uniformity of these standards for the MSHP.

Adult↗
PubMed1994

Preteaching developmentally delayed preschoolers to aid vision screening.

Early identification and treatment of vision problems is a key element in learning. For preschool children already identified with developmental delay, vision screening and visual correction are particularly essential. Participants drawn from a public Special School District were 105 preschoolers ages 3 to 5 years identified as having developmental delay. Examples included autism, Down syndrome, physical handicap, or cognitive impairment. A partnership was created between the public preschool and the University Schools of Nursing and Optometry to implement vision screening. Teachers/teacher assistants were asked to characterize the children before and after preteaching and after vision screening. Using a semantic differential scale of bipolar descriptors, planned comparisons within a repeated measures MANOVA were statistically significant for all pairs before teaching vs. the mean of after teaching/after screening (p = 0.027) but not statistically significant for after teaching vs. after vision screening (p = 1.000). Results of this preliminary study suggest preteaching could be an important part of a successful vision screening partnership in that 102 (97%) of developmentally delayed children successfully completed screening for vision problems.

Child, Preschool↗
PubMed1994

The effect of the M43 and M17 protective masks on stereoacuity.

The purpose of this study was to evaluate the effects of the M17 and M43 protective masks on stereoacuity. Twelve subjects were tested on the Keystone diagnostic series stereopsis test at nearpoint and the Howard-Dolman apparatus at 40 cm and 6 m. Stereopsis was evaluated without a mask and with the M43 and M17 masks. Stereoacuity was decreased at near point with both masks and was not significantly affected at the 6-m distance.

Adult↗
PubMed1994

Compromises in the visual field with the M43 aviation mask.

This study evaluated peripheral vision through the M43 protective mask currently worn by aviators in the AH-64 Apache helicopter. A Humphrey Visual Field Analyzer was used to measure the sensitivity of a subject's visual field with and without the mask. The results were analyzed using Dicon's Fieldview software. The monocular visual field was reduced for each eye when wearing the mask, especially superiorly and nasally. The overall size of the visual field was not reduced when both eyes were open; however, the quality of the visual field was reduced. The area of binocular vision (central binocular vision fusion field subserving stereopsis) was restricted to the central 30 degrees.

Adult↗
PubMed1993

The impact of treatment of eye disease on optometric practice in Missouri.

This study attempts to determine the impact of the legal authorization to treat eye diseases on the practice of optometry in Missouri. Seventy-two percent of the therapeutic pharmaceutical agent (TPA) certified optometrists practicing in the state responded to a questionnaire in 1991. A majority of those responding prescribed every category of TPA except oral anti-histaminic agents. More than two-thirds have received registration numbers to prescribe controlled substances. The median number of therapeutic prescriptions written per year was 144. Disturbingly, most of the practitioners have never been visited in their offices by a drug company representative. Some have hospital privileges and only about one-fourth of the respondents have nursing home privileges.

Eye Diseases↗
PubMed1993

Comparison between "readables" aspheric spectacle lenses and conventional spherical spectacle lenses for overcorrection of presbyopic single-vision contact lens wearers.

Binocular spectacle overcorrection for near with "Readables" progressive-addition lenses and with lenses having spherical surfaces were compared by 36 successful presbyopic wearers of single-vision contact lenses. The two forms of near correction were each worn by these subjects for 3 weeks in a randomized cross-over study and were also directly compared for 1 week in which both overcorrections were available. "Readables" spectacle correction was significantly better than the conventional overcorrection in four of the five patient response categories studied (visual comfort, close vision, intermediate vision, and function without removal) and was not significantly different in one of the five categories (ability to adapt). When asked to choose between the two near corrections, 81 percent of the subjects (29 of 36) preferred their "Readables" spectacles. It appears that "Readables" spectacle lenses offer a viable alternative to single-vision lenses when used for near correction of presbyopic patients wearing single-vision contact lenses for distance correction.

Adult↗
PubMed1992

Computer-specific spectacle lens design preference of presbyopic operators.

Twenty-nine presbyopic subjects who spent at least 20 hours a week at a video display terminal compared a progressive addition lens designed for this function, with another commonly prescribed task-specific lens. Each of the paired lens types was worn for 4 weeks and then compared directly for 1 week. A statistically significant (P < .05) portion of the subjects (76%) preferred the task-specific lenses overall. It also was preferred more frequently for each feature compared, although the difference was statistically significant (P < .05) only for utility of distance vision. Both of the task-specific designs contributed to symptomatic relief. The presence of a distance-clear zone and the absence of lens discontinuities most likely account for user preference for the task-specific lenses. That preference suggests improved performance for presbyopic computer users wearing task-specific progressive addition lenses.

Adult↗
PubMed1991

Assessment of cycloplegic effects on the vistech contrast sensitivity test in Army aviator candidates.

This study was designed to provide information regarding two aspects of contrast sensitivity testing of aviator candidates: first to determine whether contrast sensitivity functions (CSF's) obtained with the Vistech Visual Contrast Test System (VCTS) are affected by cycloplegia and second to determine whether the VCTS provides useful CSF's under clinical screening conditions in a timely and simple manner. Contrast sensitivity thresholds were obtained at 5 spatial frequencies from 106 aviator candidates before and after administering a cycloplegic. CSF's obtained under cycloplegia were reduced by about 20%. The VCTS provided useful CSF's under military screening conditions, and added about 6 min to the time required for the standard flight physical.

Adult↗
PubMed1991

Visual field restrictions with the M17 series protective mask.

The restrictions on the central and peripheral visual fields, resultant from wearing a M17 series mask, were measured on a subject with normal field of vision. The results showed a decrease in visual field in all meridians, with the nasal area being the most dramatically restricted.

Adult↗
PubMed1990

Evaluation of extended wear soft and rigid contact lens use by Army aviators.

Aviation systems incorporating sophisticated electro-optical displays frequently are designed without provision for use by spectacle-wearing pilots. Contact lenses offer a solution to the compatibility problems experienced by Army aviators, approximately 18% of whom wear corrective lenses. Under a waiver from The Surgeon General, 44 helicopter pilots performed flying duties while wearing extended-wear soft and rigid lenses. Pilots remained in the study for a minimum of 6 months and a maximum of 24 months. Six experienced temporary discontinuance of wear (4-19 days); and six withdrew from the study. An overall wearing success rate of 86% was achieved. No pilot was grounded due to contact lens-related problems. Subjectively, extended wear contact lenses favorably affected job performance. This is the first major field evaluation of contact lens use by U.S. Army aviators while flying military aircraft.

Adult↗
PubMed1987

The effect of cycloplegia on the visual contrast sensitivity function.

Contrast sensitivity assessment is one of several emergent techniques being considered for inclusion in a visual standards test battery for the Army, particularly for the evaluation of Army aviators. Since a cycloplegic refraction is required for initial selection of candidates for Class I and Class IA flying duty, it is important to determine what effect, if any, cycloplegia has on the contrast sensitivity function. There were 12 subjects tested, all officers in preparation for flight training who had passed a recent Class I flight physical. Contrast sensitivity functions were obtained under normal ambient conditions and in the presence of a glare source both under manifest and cycloplegic conditions. Cycloplegia produced a small reduction in contrast sensitivity under normal ambient conditions, and a greater reduction under glare conditions. For both conditions, the cycloplegia effect was greater for the higher spatial frequency gratings than for the lower.

Aerospace Medicine↗
PubMed1985

Essential ions for maintenance of the corneal epithelial surface.

It is generally believed that tears are required to furnish only oxygen to the corneal epithelium. However, as tears are a very complicated solution, it is likely that other factors are essential to the cells of the corneal surface. The amount of light scattered from the epithelial surface of the excised rabbit cornea was examined with the in vitro specular microscope while the epithelium was bathed in different solutions. It was shown that the epithelial surface was maintained best with a buffered solution containing potassium, calcium, magnesium, phosphate and bicarbonate, in addition to sodium chloride. The solution was named Basic Tear Solution (BTS). The effect was not due to osmolarity. Potassium was particularly important, as corneas bathed with sodium chloride and potassium chloride were maintained better than corneas bathed with sodium chloride only. The appearance of the epithelial surface was different in these bathing solutions. In sodium chloride the surface scattered more light and more cells were sloughed. Least light was scattered in BTS, and cell-sloughing was at a minimum. Thus, the rate at which cells were sloughed from the epithelial surface and the quality of the surface were dependent on the bathing solution.

Animals↗