Laser Eye Effects (1968) / Chapter Skim
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Laser Functional Effects
Laser Functional Effects
Pages 57-74
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From page 57... ...
INTR0DUCTI0N Little can be said directly of the effects of pulsed laser exposure on visual function because the unique combination of very narrow waveband and very brief, high energy flash has not often been studied. In addition to the few pulsed laser studies, there are a small number of experiments showing the effects of monochromatic light exposure on some aspects of visual function, which will be directly applicable to CW laser problems, and a fair-sized literature on the visual effects of flash exposure to stimulus fields of varying intensity.
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From page 58... ...
With consideration of seriousness of very brief loss of sight to a low-flying tactical aviator, more attention is also being paid to the study of visual response immediately after exposure. In order to predict laser effects on vision in various tactical military situations as well as those of accidental exposure in the laboratory, we would like to know what the recovery times are for various relevant visual tasks as a function of different physical stimulus parameters.
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From page 59... ...
E- Miller: 16.2' test letter; flash duration kept constant at 1.5 msec. 2.0 - 1.5 1.0 .5 28.2 0.0076mL OllmL 0.063mL O a O.lSmL n 0.43mL ..^ r»282mL 6.6 6.8 7.0 7.2 7.^ 7.6 7.8 8.0 Log Flash Energy (troland seconds)
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From page 60... ...
Brown7 hypothesizes the relationship of flash energy, target luminance, and recovery time over a broad range of values to be as shown in Figure 4. He shows the positively accelerating recovery times for the lower flash energies and the approximately linear relationship over the middle range to 1 x 107 troland-seconds, which levels off over a range of about one log unit of adapting intensity and then accelerates toward an asymptote representing irreversible injury.
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From page 61... ...
Log Recovery Time (seconds)
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From page 62... ...
Log Recovery Time (seconds)
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From page 63... ...
Recovery Time •n f 1 1 1 1 1 I I '"I • Q)
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From page 64... ...
Between these two extremes of threshold of seeing and burn threshold, little is known from psychophysical results. For purely photochemical results on the bleaching efficiency of different duration flashes, as summarized by Brown': Campbell and Rushton^3 found total energy determined amount of bleaching up to kS seconds.
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From page 65... ...
to aid in the comparison of the results with two spectral stimuli. Figure 5(a)
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From page 66... ...
This is the range of durations below which Hagins and Brindley found a reduction in the effectiveness of a given amount of stimulus energy for the bleaching of rhodopsin and for the production of an after image. WAVELENGTH SPECIFICITY 0F THE ADAPTING FLASH \ Little effort has been expended to study the adapting effects of intense narrow spectral bands in the visible spectrum, and no effort has been directed toward study of visual effects of adaptation to ultraviolet or infrared radiation.
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From page 67... ...
Apparently, also, intense blue light reveals a peak in the 570-90 nm region, which does not show under the white light plus red, white plus green conditions. The apparent difference between intense blue adaptation and red and green is discussed in a theoretical context by Sper 1 ing es£ a_K24 por our present purposes, these results demonstrate that the eye's sensitivity in other spectral regions may be relatively preserved after an intense narrow-band flash, whether it emanates from a laser or a filtered incoherent source.
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From page 68... ...
400 700 Figure 6. Relative spectral sensitivity of the fovea for different conditions of very narrow-band adaptation.
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From page 69... ...
Log relative spectral sensitivity for white-light and white-plus-spectral-light conditions for two monkeys. Intense narrow-band 650 -nm red added to white is compared with white alone (a,b)
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From page 70... ...
, the majority of noticeable reversible and irreversible changes may be expected from laser exposure in this region. When the chromatic adaptation is at a level sufficient to cause deviations from normal color vision, Brindley has found that there is also a degradation of visual acuity.
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From page 71... ...
Jones e_t a_l.^ have recently demonstrated that a single ruby laser pulse of large retinal subtense (approximately 1 cm2) at a retinal energy density of 0.2 J/cnr produces a significant decrease in the implicit time of the b wave and depresses the third oscillatory potential of the x wave in the Mangabey monkey.
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From page 72... ...
- - No study has been reported which provides a quantitative relationship between flash duration and adapting wavelength for a functional criterion such as threshold or supra-threshold light detection or threshold acuity. - - No work has been done on functional loss in the range of intensities between where photopigment bleaching approaches 100% and where gross burn lesions are observable.
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From page 73... ...
M Visual and Retinal Effects of Exposure to High Intensity Light Sources, AGARD Symposium 16-17 (March 1966)
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From page 74... ...
31. Yarczower, M., Wolbarsht, M
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