Investigative ophthalmology & visual science
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Invest. Ophthalmol. Vis. Sci. · Nov 1980
The role of ambient lighting in circadian disc shedding in the rod outer segment of the rat retina.
Rats raised from birth on a 7 A. M.:7 P. M. light cycle exhibited a circadian burst of shedding 1 1/2 hr after the scheduled onset of light. ⋯ When animals were placed in altered lighting cycles, the shedding rhythm shifted accordingly, although the speed of this shift was greatest with large advances in the light cycle and slowest with small delays in the light cycle. Animals exposed to LL and then returned to the dark exhibited the original shedding rhythm, a phenomenon not affected when the optic nerves were severed. A shedding peak could be induced at a noncircadian time by exposing the animals to more than 20 hr of LL followed by 2 hr of darkness and 1 1/2 hr of light, although the magnitude of the shedding was related to the circadian time.
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Invest. Ophthalmol. Vis. Sci. · Jul 1979
Rapid assessment of visual function: an electronic sweep technique for the pattern visual evoked potential.
We have developed an electronic spatial frequency sweep technique for electrophysiological assessment of visual acuity and pattern vision. The technique allows an accurate and reliable measurement of VEPs to a full range of spatial frequencies in just 10 sec. ⋯ Sweeping spatial frequency linearly and extrapolating the high-frequency region of the VEP spatial-tuning function to zero voltage allows an estimate of acuity which correlates highly with psychophysical estimates of acuity. Variants of the procedure are appropriate for the assessment of refracture error, determination of equality of visual function for the two eyes and of binocular interactions, and for sequential assessment of therapeutic conditions.
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Invest. Ophthalmol. Vis. Sci. · Jun 1977
The effects of ketamine sedation and ketamine-pentobarbital anesthesia upon the intraocular pressure of the rabbit.
The effect of ketamine sedation and ketamine-pentobarbital anesthesia upon the intraocular pressure (IOP) of the rabbit was studied by applanation pneumatonography. Peak values of IOP during both ketamine sedation and ketamine-pentobarbital anesthesia were reached 3 to 5 minutes after administration of the drug(s). The peak IOP increase during ketamine sedation (10 mg./kg. ⋯ The peak IOP increase with ketamine-pentobarbital anesthesia (50 mg./kg. ketamine IM + 30 mg./kg. pentobarbital IM) was 7.1 +/- 0.8 mm. Hg. Atropine premedication did not prevent the increase in IOP seen with ketamine sedation or ketamine-pentobarbital anesthesia.