ISSN:0093-7002    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Air traffic controllers perform a variety of tasks which require them to identify, discriminate, and name colors. Qualification standards for this occupation require applicants and incumbents to have normal color vision. The validity of this standard has been questioned and is currently under review. In this study, 22 deutans and 78 normals were tested on a set of tasks which simulated critical tasks performed daily by air traffic controllers. The four tasks included discriminating red from black pencil marks on flight progress strips, color-naming of 1° and 0.1° discs, and identification of colored line segments embedded in a multicolored background. Deutans classified as mild were found to perform all tasks as well as normals. Moderate deutans performed only the large disc color-naming task as well as normals, whereas severe deutans performed none of the tasks as well as normals. Different methods for scoring the color vision tests were explored to determine their value as predictors of task performance. The D-15 relative error score was found to be the single best predictor of performance on the tasks (r-square = 0.602). It is concluded that mild deutan color defectives have adequate color vision for safe performance of several critical air traffic control tasks. Moderate and severe deutans do not. In addition, the results of several methods for scoring color vision tests can be used to predict group, but not individual, performance with high reliability.

ISSN:0093-7002    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

In vitro [UV absorption, fluorescence, phosphorescence, and nuclear magnetic resonance (NMR)] spectroscopic studies on the normal human lens demonstrate age-related changes which can be correlated with biochemical and photobiologic mechanisms occurring during our lifetime. Chronic cumulative UV exposure results in an age-related increase of photochemically induced chromophores and in color of the lens nucleus. This enables the lens to filter the incident UV radiation, thereby protecting the underlying aging retina from UV photodamage. We have measured the age-related increase in lens fluorescencein vivoon more than 300 normal subjects (1st to 9th decade) by UV slitlamp densitography. These data show a good correlation with the in vitro lens fluorescence studies reported previously and demonstrate that molecular photodamage can be monitored in the lens. In vitro NMR (human and animal lenses) andin vivoexperiments currently in progress are rapidly elucidating the physiocochemical basis for transparency and the development of light scattering areas. Surface scanning NMR can monitor organophosphate metabolism in the ocular lensin vivoas well asin vitro. These studies demonstrate the feasibility of using biophysical methods (optical spectroscopy and NMR analyses) to delineate age-related parameters in the lens,in vivoas well asin vitro.

ISSN:0093-7002    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Six male and seven female English-speaking university students, with corrected vision of 20/20 (6/6), were trained using the closed circuit television system (CCTV) as a reading aid. This was an attempt to identify the essential factors in CCTV-aided reading. Active and passive observers were trained in pairs, with the passive observer being the yoked control of the active observer. The control participants were trained alone using the same reading material without the use of a CCTV. All participants used material from the Thurstone Reading Kit throughout the five training sessions and were given a pre- and postreading test to assess the increase in reading speed measured in words per minute (WPM). The active observers increased their reading speed to a greater extent than the passive observers, and the passive observers to a greater extent than the control participants. Suggestions are made pertaining to future experimentation and use of the CCTV.

ISSN:0093-7002    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Selective loss of sensitivity to blue light, when it is detected by the short wavelength-sensitive cones (B cones), is a common early sign of many retinal and visual pathway disorders. A reliable clinical test is needed to allow detection of this defect. We describe a new, simple forced-choice clinical test of B cone function which is brief, reliable, and free of patient criteria for seeing. Test results are relatively unaltered by up to 2 D of uncorrected refractive error and the usual small fixation changes the patient makes during the test. A comparison of three different test results, all obtained within 5 min, allows measurement of R and/or G cone function free of age and individual differences caused by yellowing of the ocular media in the B cone test result. The test has been used to demonstrate B cone sensitivity losses related to the severity of retinopathy in 60 diabetics, as well as selective B cone loss in glaucoma and ocular hypertension.

ISSN:0093-7002    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

The visual fields of 10 healthy myopic patients were compared using hydrogel lenses with a clear pupil and an opaque colored portion covering the iris and clear hydrogel lenses. Significant (>10°) field loss was found in all cases when the midperipherally colored lenses were worn. Patients interested in these lenses should be advised of this slight reduction of peripheral vision before fitting.

ISSN:0093-7002    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Several lines of evidence suggest that the processes of excitation and inhibition associated with good stereoacuity may also underlie binocular rivalry, implying that performance on these two tasks could be related. To test this possibility, we measured stereoacuity and rivalry under similar stimulus conditions in 40 observers. To estimate stereoacuity, a two-alternative, forced-choice procedure was used, wherein observers determined which of two sinusoidal grating patterns appeared displaced in depth. To measure rivalry, observers reported the occurrences of exclusive right-and left-eye dominance; dominance durations and alternation rates were recorded. The results showed that stereoacuity was significantly correlated with binocular rivalry, suggesting that stereoacuity and rivalry may share, at least in part, common neural mechanisms.

ISSN:0093-7002    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

An infrared optometer was used to investigate the relation between cognitive induced shifts in tonic accommodation (TA) and ciliary muscle innervation. Twenty emmetropic men volunteers took part in a double-masked protocol which involved high (a reverse counting task) and low levels of mental load and blocking of sympathetic innervation of the ciliary muscle with the nonselective β receptor antagonist timolol maleate (0.5%). The high level of cognitive demand induced shifts in TA of up to +1 D. There was no clear reason why large differences in intersubject susceptibility to these shifts occurred. The effect of β-antagonism on these shifts was insignificant for subjects having initial TA values <1.2 D. However, sympathetic antagonism induced significant increases in cognitive shifts for the remaining subjects. The inference is that cognitive induced shifts in TA are predominantly parasympathetic mediated although a sympathetic attenuation may occur at higher levels of TA.

ISSN:0093-7002    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

The corneal endothelium in nine cases of keratoconus (18 eyes) was analyzed quantitatively for mean cell area and standard deviation (SD) of cell area to determine the presence of polymegathism. Four of the subjects were veteran wearers of rigid contact lenses and five of the subjects had not worn contact lenses previously. The subjects were matched for age, sex, and contact lens history with a group of normals. The endothelium in eyes with keratoconus did not show a significant increase in the extent of polymegathism as compared with controls. There was no significant difference in mean cell area between the study group and the control group. These results suggest that polymegathism in keratoconic patients may be related to contact lens wear.

ISSN:0093-7002    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Intraocular pressure (IOP) was recorded regularly over a 24-h period in 13 normal subjects. All subjects showed a dramatic rise in IOP after sleep, ranging from 37 to 248%. In a second experiment, IOP decreased when 15 subjects remained upright and awake through-out the night. When sleep was not permitted IOP was lowest at 3:00 a.m. (0300); when six of these subjects were permitted to sleep from 0600 to 0800, they showed a rapid and significant increase in IOP of up to 150%, whereas the remaining nine subjects showed (posturally induced) increases of up to 38%.

ISSN:0093-7002    

出版商:OVID    

年代:1987

数据来源: OVID