摘要:

Analysis of photographs of moiré images obtained with a modified biomicroscope and corneal toposcope reveals that the cone area in keratoconus is spherical and is delineated by a surrounding zone of aspherical curvature for most eyes. The cone appears to be symmetrical about the corneal apex but not about the visual axis.

ISSN:0002-9408    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

Longitudinal results obtained after four years show in a preliminary way the degree to which contact lenses affect the growth of the eye. as measured with ultrasound, and the development of myopia. Conclusions are based on comparison with a control group of spectacle-wearing myopes.

ISSN:0002-9408    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

The relation between duction break-recovery (B/R) ratios and localization error in a test of dynamic stereoacuity was examined in 73 young men. Positive (near) localization errors. esophoria, high negative spherical correction, high adductive and low abductive B/R ratios were found to be relaxed. Positive errors were associated with high adductive and low abductive B/R midpoints for esophores. but the relationship for exophores was not clear. The difference between adductive end abductive B/R ratios increased with increasing positive error. The difference between adductive and abductive B/R midpoints was greater for esophores than exophores and increased with increasing positive error. The magnitude of error was related to the magnitude of the spherical correction which the subject wore during the experiment. The direction and magnitude of the localization errors were not much more predictable from the duction measures than from the phorias.

ISSN:0002-9408    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

Two windshields with exaggerated prismatic characteristics were flight tested to determine their effect on a pilot's ability to land a four-engine jet aircraft while flying under Visual Flight Rules (VFR). One windshield contained a wedge of approximately 2.2Δ. Wedginess in the second windshield varied in direction and magnitude from approximately 0.1 to 1.0Δ. Generally, both windshields caused visual scenery to be displaced downward and to the left. Subjective and objective measures were used to record the performance of two senior test pilots during the approach and landing phase of flight. Analysis indicates that the variable prismatic windshield (0.1 to 1.0Δ) had greater negative effect on pilot performance than the linear prismatic one (2.2Δ).

ISSN:0002-9408    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

The investigation of Ball and Bartley (1967) on inducing and reducing errors of color defectives on saturation discrimination is extended to hue discrimination tasks. Twelve color defectives and two normals are tested on standard and specially designed pseudoisochromatic plates illuminated intermittently by a daylight source. A range of 2 to 12 cycles of light and dark per second is used and the lengths of the light pulse are varied from4/4to1/4the cycle duration. Errors on hue as well as saturation discrimination plates increase with short light pulses. The results complement those of the previous experiment except that instances of real improvement in color vision test performance at long pulses are difficult to establish with certainty.

ISSN:0002-9408    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

Subjective and objective tests of visual acuity were given using the same target, with the same luminance and at the same distance. Objective measurements were obtained by a method based on evoking and arresting a pendular eye movement in response to a grating moved sinusoidally to and fro. Eye movements were recorded by a very precise electronic apparatus including the CAT Computer. Objective and subjective measurements of acuity were found to be highly correlated. The absolute value of acuity was always higher when measured subjectively than when the objective measures were used. The correlation between the objective and subjective measurements are in good agreement with other investigations which differ greatly in mathod.

ISSN:0002-9408    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

A mathematical model describing the diffusion properties of truncated cone apariures for tear-dissolved oxygen across contact lenses is developed. Predictions of the model were tested by laboratory observation and the relative efficiencies of cone and cylinder configurations are discussed.

ISSN:0002-9408    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

By testing driving performance under binocular viewing conditions and under monocular viewing conditions, the authors make a comparison of the effectiveness of binocular and monocular clues.

ISSN:0002-9408    

出版商:OVID    

年代:1969

数据来源: OVID

ISSN:0002-9408    

出版商:OVID    

年代:1969

数据来源: OVID

ISSN:0002-9408    

出版商:OVID    

年代:1969

数据来源: OVID