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Prism dioptres. Prism correction is commonly specified in prism dioptres, a unit of angular measurement that is loosely related to the dioptre. Prism dioptres are represented by the Greek symbol delta (Δ) in superscript. A prism of power 1 Δ would produce 1 unit of displacement for an object held 100 units from the prism. [2]
Convergence insufficiency. Convergence Insufficiency. Other names. Convergence disorder. Specialty. Ophthalmology, optometry. Convergence insufficiency is a sensory and neuromuscular anomaly of the binocular vision system, characterized by a reduced ability of the eyes to turn towards each other, or sustain convergence .
Esophoria is an eye condition involving inward deviation of the eye, usually due to extra-ocular muscle imbalance. It is a type of heterophoria. Cause. Causes include: Refractive errors; Divergence insufficiency; Convergence excess; this can be due to nerve, muscle, congenital or mechanical anomalies.
Enamel prism. An enamel prism, or enamel rod, is the basic unit of tooth enamel. Measuring 3-6 μm in diameter in primates, [1] enamel prism are tightly packed hydroxyapatite crystals structures. The hydroxyapatite crystals are hexagonal in shape, providing rigidity to the prism and strengthening the enamel.
the x-intercept gives the amount of a prism (P 0) that compensates a naturally occurring fixation disparity. This x-intercept is also referred to as aligning prism or – in earlier times – as associated phoria when the subjective nonius method was used (sP 0) the slope of the curve near zero prism load
IPR is an irreversible procedure and can be an alternative to dental extraction. Indications for the procedure include mild to moderate crowding (4 - 8mm), [7] black triangles in anterior teeth, enhancing retention and stability after orthodontic treatment, and correction of the Curve of Spee.
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]
Roof prism. A roof pentaprism used in Single-lens reflex cameras; the lower right face is the roof ( dach ). A roof prism, also called a Dachkanten prism or Dach prism (from German: Dachkante, lit. "roof edge"), is a reflective prism containing a section where two faces meet at a 90° angle, resembling the roof of a building and thus the name.
The system could be both more manageable for admins and more democratic for contributors by simply dropping noteworthiness as a requirement. Once this is done, there could be a streamlined process requiring less discussion to quickly delete articles that have been submitted in bad faith, such as libels, nonsense, and misinformation.
Advantages and disadvantages. Advantages of air abrasion include that it preserves more healthy tooth tissue (which can increase the strength and longevity of restorations), and has less risk of fracturing or chipping a tooth when compared to a traditional pneumatic dental drill.