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Biomedical subjects

A C Kothe

Publications and source records attributed to A C Kothe.

22 records · Page 2Linked to original sources
PubMed1988

Neural effects of body inversion: photopic oscillatory potentials.

The effect of alterations in retinal and choroidal circulation resulting from changes in body orientation were examined in 10 subjects with normal systemic and intraocular pressures. Body inversion resulted in an increase in the intraocular pressure with a concomitant increase in the ocular perfusion pressure. The effect of these pressure elevations was assessed by photopic oscillatory potentials (OPs). The trends in the change in OP amplitude with experimentally elevated ocular perfusion pressure varied across OP wavelets. OP-1 and the OP index exhibited a statistically significant decrease with an increase in ocular perfusion pressure, with OP-2 to OP-5 showing statistically insignificant reductions. Only OP-5 showed a significant decrease in implicit time with increased perfusion pressure. The magnitude of these changes were quite small despite a greater than 70% increase in the ocular perfusion pressure. Vascular autoregulatory mechanisms are hypothesized to be responsible for maintaining the OPs to within clinically normal levels.

Adult↗
PubMed1987

Variation of dark focus of accommodation with laser speckle exposure duration.

Dark focus of accommodation (DFA) was measured in 10 subjects using a computer-aided He-Ne Badal laser optometer having high temporal and amplitude resolution. Accommodative responses were tracked during 5 min sessions for 10 speckle exposure durations ranging from 100 to 1000 ms. DFA-speckle exposure functions fell into four distinct groups. This identifies the laser speckle exposure time as a possible contaminant in measures of DFA made by laser optometers if individual variability across exposure times is ignored. Group averaging of accommodative responses for laser exposure times obfuscates the reported individual variability.

Accommodation, Ocular↗
PubMed1987

The influence of letter size on the focusing response of the eye.

The monocular and binocular steady state accommodation responses in 10 normal subjects were measured for different letter sizes presented at 6m and 0.4m observation distances. A computer-aided Badal laser speckle optometer system was used to measure accommodative responses. For each subject, and group-averaged data, accommodative responses were independent of letter limb subtense. Binocular and monocular responses averaged across subjects did not differ significantly. The magnitude of accommodative responses was related to the resting focus of accommodation and was independent of subjects' accommodative amplitude, refractive error and pupil size. The implications of these findings for clinical and human factor methods for examining visual performance are discussed.

Accommodation, Ocular↗