Color discrimination in heterozygous deutan carriers.

PURPOSE: The color discrimination abilities of heterozygous deutan female carriers were measured using color mixture thresholds and compared with those of suspected nonheterozygous normal subjects. METHODS: Eight test subjects and 26 control subjects were run on a computer-controlled color test (color mixture thresholds) that presented 1 degree diameter spots on a color television monitor for 1/60 of a second. A QUEST procedure was used to determine visual thresholds for spots varying in brightness and/or color. Individual data points were graphed on an X/Y plot and fitted with an ellipse. The major and minor diameters of the ellipse represent the color and brightness thresholds, respectively. RESULTS: The mean axis angle of the ellipse for the heterozygous carriers did not differ from that for the controls (15.75 degrees vs. 14.93 degrees, p = 0.428, Mann-Whitney test). The carriers did show, however, a larger mean major axis length (68.79 vs. 46.78, p = 0.0218, Mann-Whitney test). Additionally, the length-to-width ratios for the carriers were higher than the controls (9.34 vs. 6.80, p = 0.0403, Mann-Whitney test). CONCLUSIONS: Deutan-carriers do show reduced color purity discrimination as measured using color mixture thresholds compared with nonheterozygous, color vision normals.

On determining the relationship between blood alcohol concentration and smooth pursuit eye movements.

Residual impairment after alcohol consumption implies that the relationship between blood alcohol concentration (BAC) and deficits in performance of some task is not the same when becoming intoxicated as it is when returning to sobriety. A pilot study was performed to determine the feasibility of and the appropriate methodology for studies on residual impairment of smooth pursuit performance. Four subjects consumed alcohol for 2 h. Measurements of BAC and smooth pursuit eye movements were made every 30 min during drinking and for 4 h after drinking. Pursuits were elicited by having subjects track a sinusoidal target (0.40 Hz and 0.60 Hz) for 10 s. Impairment of smooth pursuit was quantified with frequency analysis scores. Frequency analysis scores declined as BAC increased. As BAC decreased, frequency analysis scores tended to increase toward pre-drink levels. The relationship between BAC and frequency analysis score was not significantly different on the ascending and descending limbs of the blood alcohol curve. However, the idea that residual impairment does not occur could not be conclusively demonstrated for several reasons. First, as BAC returned to pre-drink levels, frequency analysis scores were inconsistent for each subject perhaps because of boredom and fatigue. Second, the relationship between BAC and frequency analysis score varied between subjects. Finally, because the recording periods were short, the effect of alcohol on sustained attention could not be assessed. In this paper, potential artifacts in studies of residual impairment of pursuits are discussed and potential solutions to the methodological problems encountered in the pilot study are provided.

Motorist vision policy.

BACKGROUND: The primary purpose of public policy requiring vision testing for driver license renewal is to identify individuals with functional vision impairments and, when necessary, to restrict their driving. This is based on the presumption that poor vision is causally related to poor driving and traffic crashes. METHODS: The AOA Environmental and Occupational Vision Committee performed a synthesis of relevant empirical literature on policy-based research and developed potential options for enhancing traffic safety. RESULTS: Presently, some states require vision testing for driver's license renewal and some do not. Regional and nationwide studies report that vision-related license renewal policies are associated with enhanced traffic safety. However, contemporary vision screening tests may be of limited value in identifying individuals with functional vision impairments. CONCLUSION: The most cost-effective and valid method for identifying, treating and counseling visually impaired drivers is to require a comprehensive eye examination as a condition for driver license renewal for those with a high prevalence or high probability of vision impairment.

Setting an uncorrected visual acuity standard for police officer applicants.

Government agencies have used uncorrected visual acuity (UVA) standards for many years for police officer applicants. With the passage of the Americans With Disabilities Act of 1990, public employers have concern about the validity of these standards. This report shows how data can be used to set a reasonable standard. The report includes a description of a survey of incumbents, acuity testing of a sample of incumbents, collection of essential task information, and experimentation based on the essential tasks. A series of focus group meetings resulted in agreement that 2 essential tasks officers must be able to perform when visually incapacitated are identifying a weapon in a typical room and finding spectacles that have been dislodged. The experimentation showed that a noticeable performance decrement begins to appear at 20/125 level of acuity. As a result of the research, the City of Columbus, Ohio, changed the UVA standard from 20/40 to 20/125.

Determination and application of vision standards in industry.

Job-related vision standards benefit both employee and employer. By comparing employees' vision to specific job requirements, workers can be better placed into positions commensurate with their visual abilities. For a company without a vision care program, a project was undertaken to determine visual standards, and the need for vision care services for employees to better meet these standards. The critical factors for performing specific visual tasks for 40 job classifications were identified through direct observation and measurement, and through worker interviews. Additionally, a sample of employees was screened to determine plant population characteristics, and to determine what percentage of employees met the newly formed standards. This study can serve as a model for the application of visual standards to the workplace and is pertinent, as "reduced vision" is increasingly defined by government as a disability.

Ophthalmic lens retention in safety frames.

Lens retention in metal and zyl safety frames was tested using both a high mass (500 g), low velocity impact (HM-LV), and a low mass (1.04 g), high velocity impact (LM-HV) for plano polycarbonate lenses of various thicknesses. The results showed that the metal safety frames retained lenses better than the zyl (p < 0.01) after a HM-LV impact. For the LM-HV impact, metal and zyl frames performed equally (p = 1.00). Lens thickness was not a factor in lens in frame retention for the HM-LV impact (p = 0.958). However, for the LM-HV impact, 1.6-mm thick lenses were more easily displaced than lenses with thicknesses of 2.0, 2.4, and 3.2 mm (p = 0.003).

Role of optometrists in combatting high blood pressure.

To determine the contribution made by optometrists in blood pressure measurement and comanagement, a short survey was sent to all the optometrists licensed in Ohio. Of those responding, over 90% reported to routinely question their patients concerning blood pressure, while 72% reported to have blood pressure measuring equipment in their offices. Optometrists can continue to be strong members of the primary health care team by adhering to the recommendations delineated in the 1988 Report of the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure. Practitioners should measure blood pressure at each patient visit, provide feedback to the patient concerning the findings, and follow the recommended follow-up criteria.

Chronic solar radiation exposure and endothelial polymegethism.

Acute exposure of ultraviolet radiation to the cornea has previously been shown to produce endothelial pleomorphism and polymegethism. The reciprocity of exposure intensity and duration typically seen with the photochemical effects of ultraviolet radiation on biological tissue predicts a similar effect with chronic exposure. This was tested by comparing the regularity of the hexagonal endothelial mosaic for a group of workers (n = 9) chronically exposed to solar radiation to that for an age-matched control group (n = 18). Although the mean cell area of the endothelium was similar between groups (p greater than 0.10), a significant difference (p less than 0.01) was demonstrated in the degree of polymegethism. This supports the contention that chronic ultraviolet radiation exposure may contribute to increased polymegethism seen with age.

The use of progressive addition multifocals with video display terminals.

Consideration must be given to a number of factors when designing spectacles for the presbyopic VDT worker. Video terminals are routinely positioned high within the working field, usually at an intermediate distance. It is often difficult for a practitioner to design a single pair of multifocals to satisfy the visual needs of these workers. In this investigation, different fitting designs of progressive addition multifocals were subjectively compared for 24 presbyopic VDT operators. The results were correlated with measurements taken at the workstations for each of the participants.

Use of horizontal gaze nystagmus as a part of roadside sobriety testing.

Alcohol is a central nervous system depressant that can affect eye movement control. Even at low blood alcohol concentrations (BAC's) smooth pursuit eye tracking can be lost and horizontal nystagmoid movements become apparent at relatively small angles of lateral gaze. Law enforcement officers across the nation are being taught evaluation techniques to use these eye movement signs as an indicator of alcohol intoxication. Information obtained at the Ohio State Highway Patrol (OSHP) course on the Advanced Detection, Apprehension, and Prosecution of subjects suspected of driving a vehicle while intoxicated is presented here including the testing and scoring techniques of the horizontal gaze nystagmus sobriety test.

Hypertension: an optometric problem for the 80s.

As primary health care providers, optometrists can make a significant contribution to the overall health of our patients by routinely measuring blood pressure, referring those individuals with elevated blood pressures for evaluation and/or treatment, and supporting previously diagnosed hypertensives to maintain their treatment regimen. The 1984 Report of the Joint National Committee on Detection, Evaluation and Treatment of High Blood Pressure gives optometrists an up-to-date synopsis of blood pressure management. It includes referral procedures, blood pressure classifications, the revised stepped-care treatment approach and patient-professional interaction suggestions for improving long-term treatment compliance. It is imperative that optometrists reinforce the importance of regular hypertension evaluation to our patients and answer questions concerning blood pressure and its related follow-up care.

Component evaluation of cup/disk ratio estimation.

Cup/disk (C/D) ratio estimation is frequently used to evaluate cupping within the optic nerve head. Two components are involved in the determination of this value: (1) the cup and disk margin determination, and subsequently (2) the magnitude estimation of the cup size relative to the disk size. This study investigated the magnitude estimation component by asking fourth year optometry students to estimate C/D ratios on optic nerve head photographs and drawings. The importance of the magnitude estimation was demonstrated by the high degree of variability among subjects on the nerve head drawings upon which cup and disk margins were presented unambiguously. A subsequent survey of faculty clinicians indicated a large percentage of practitioners (41%) have no method they consciously use to help determine their C/D ratio estimate. A specific method is presented which allows clinicians to simply and logically deduce this magnitude estimation.

Eikonic lens design for minus prescriptions.

Designing size lenses for aniseikonia correction usually involves considering only the shape factor of the total spectacle magnification. However, for minus prescriptions, an increase in the shape magnification of a lens does not always result in total lens magnification. As the front curve of a lens is steepened (which increases the shape magnification), the sagittal depth of the lens is increased, which effectively increases the vertex distance. For a minus lens, an increased vertex distance means decreased power magnification; depending upon the lens power, the decrease in power magnification can totally offset the increase in shape magnification. The shape factor-power factor relationship of high minus size lenses is presented, along with general guidelines for proper design of size lenses.