| dysjunctive nystagmus | A nystagmus in which the movements of the two eyes are dissimilar in direction, amplitude, and periodicity. Synonym: dysjunctive nystagmus, incongruent nystagmus, irregular nystagmus. (05 Mar 2000) |
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| incongruent nystagmus | A nystagmus in which the movements of the two eyes are dissimilar in direction, amplitude, and periodicity. Synonym: dysjunctive nystagmus, incongruent nystagmus, irregular nystagmus. (05 Mar 2000) |
| irregular nystagmus | A nystagmus in which the movements of the two eyes are dissimilar in direction, amplitude, and periodicity. Synonym: dysjunctive nystagmus, incongruent nystagmus, irregular nystagmus. (05 Mar 2000) |
| ocular nystagmus | The pendular or, rarely, jerky nystagmus seen in severely reduced vision. Synonym: amaurotic nystagmus. (05 Mar 2000) |
| opticokinetic nystagmus | Nystagmus induced by looking at moving visual stimuli. Synonym: opticokinetic nystagmus, railroad nystagmus. (05 Mar 2000) |
| optokinetic nystagmus | Nystagmus induced by looking at moving visual stimuli. Synonym: opticokinetic nystagmus, railroad nystagmus. (05 Mar 2000) |
| end-point nystagmus | A jerky, physiologic nystagmus occurring in a normal individual when attempts are made to fixate a point at the limits of the field of fixation. Synonym: deviational nystagmus. (05 Mar 2000) |
| jerky nystagmus | Nystagmus in which there is a slow drift of the eyes in one direction, followed by a rapid recovery movement, always described in the direction of the recovery movement; it usually arises from labyrinthine or neurologic lesions or stimuli. (05 Mar 2000) |
| upbeat nystagmus | A vertical jerky nystagmus with a rapid component upward, occurring with brainstem lesions. (05 Mar 2000) |
| fixation nystagmus | Nystagmus aggravated or induced by ocular fixation, arising as optokinetic nystagmus, or resulting from midbrain lesions. (05 Mar 2000) |
| labyrinthine nystagmus | Nystagmus resulting from physiological stimuli to the labyrinth that may be rotatory, caloric, compressive, or galvanic, or due to labyrinthal lesions. See: Barany's sign. Synonym: labyrinthine nystagmus. (05 Mar 2000) |
| latent nystagmus | Jerky nystagmus that is brought out by covering one eye. The fast phase is always away from the covered eye. (05 Mar 2000) |
| Abbe test plate | <equipment> A long, wedge-shaped coverslip about 0.20 mm thick at one end and 0.10 to 0.12 mm at the other end coated chemically with a silver film on which are ruled horizontal lines. at each variation in thickness of 0.01 mm there are vertical lines. By means of oblique illumination and by focusing on different portions of the plate, it is possible to determine the optimum coverslip thickness for any objective and also, for microscopes with drawtubes, the tube length for best objective performance. The approximate freedom from spherical and chromatic aberrations can also be estimated. Small isolated bits of silver near the edges of the lines form good objects for the star test (05 Aug 1998) |
| acetone test | A test for ketonuria; the suspected urine is shaken up with a few drops of sodium nitroprusside, and strong ammonia water is then gently poured over the mixture; if acetone is present, a magenta ring forms at the line of contact; tablets containing sodium nitroprusside and alkali are now more commonly used. (05 Mar 2000) |
| achievement test | A standardised test used to measure acquired learning, e.g., competence in a specific subject area such as reading or arithmetic, in contrast to an intelligence test which is a useful index of potential ability or learning. (05 Mar 2000) |