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The prism cover test ( PCT) is an objective measurement and the gold standard in measuring strabismus, i.e. ocular misalignment, or a deviation of the eye. [1] It is used by ophthalmologists and orthoptists in order to measure the vertical and horizontal deviation and includes both manifest and latent components. [1]
A gas-filled tube, also commonly known as a discharge tube or formerly as a Plücker tube, is an arrangement of electrodes in a gas within an insulating, temperature-resistant envelope. Gas-filled tubes exploit phenomena related to electric discharge in gases , and operate by ionizing the gas with an applied voltage sufficient to cause ...
Grade 4 anterior chamber angle. open angle between cornea and iris. AC 3/4. Grade 3 anterior chamber angle. AC 2/4. Grade 2 anterior chamber angle. AC 1/4. Grade 1 anterior chamber angle. AC 0/4.
Exophoria. Exophoria is a form of heterophoria in which there is a tendency of the eyes to deviate outward. [1] During examination, when the eyes are dissociated, the visual axes will appear to diverge away from one another. [2] The axis deviation in exophoria is usually mild compared with that of exotropia .
relevant position of the prism in front of the eye denoted by: base in “BI” or “-” for fusional divergence; base out “BO” or “+” for fusional convergence; base up “BU” or base down “BD” for vertical fusional vergence.
In a vacuum tube, conduction is dominated by free electrons because the distance between anode and cathode is small compared to the mean free path of electrons. A thyratron, on the other hand, is intentionally filled with gas so that the distance between anode and cathode is comparable with the mean free path of electrons.
Categories: Vacuum tubes. Glass applications. Electrical discharge in gases. Hidden category: Commons category link is on Wikidata.
In cold cathode tubes, the electric discharge in gas has three regions, with distinct current–voltage characteristics: I: Townsend discharge, below the breakdown voltage. At low voltages, the only current is that due to the generation of charge carriers in the gas by cosmic rays or other sources of ionizing radiation.
A Geissler tube is a precursor to modern gas discharge tubes, demonstrating the principles of electrical glow discharge, akin to contemporary neon lights, and central to the discovery of the electron.
Relaxation of accommodation can result in an increase in exophoria and a decrease in esophoria, leading to an inaccurate result. The examiner should check the function of the Maddox Wing Instrument before use; the septa can be easily bent, leading to the septa not covering the intended view.