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Prentice's rule, named so after the optician Charles F. Prentice, is a formula used to determine the amount of induced prism in a lens: = where: P is the amount of prism correction (in prism dioptres) c is decentration (the distance between the pupil centre and the lens's optical centre, in millimetres)
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.
Optometry Ophthalmology. Heterophoria is an eye condition in which the directions that the eyes are pointing at rest position, when not performing binocular fusion, are not the same as each other, or, "not straight".
The usual recommendation for those needing iseikonic correction is to wear contact lenses. The effect of vertex distance is removed and the effect of center thickness is also almost removed, meaning there is minimal and likely unnoticeable image size difference.
Incomitant strabismus cannot be fully corrected by prism glasses, because the eyes would require different degrees of prismatic correction dependent on the direction of the gaze. Incomitant strabismus of the eso- or exo-type are classified as "alphabet patterns": they are denoted as A- or V- or more rarely λ -, Y- or X-pattern depending on the ...
Treatment options for esotropia include glasses to correct refractive errors (see accommodative esotropia below), the use of prisms, orthoptic exercises, or eye muscle surgery. The term is from Greek eso meaning "inward" and trope meaning "a turning".
Cyclotropia cannot be corrected with prism spectacles in the way other eye position disorders are corrected. Nonetheless two Dove prisms can be employed to rotate the visual field in experimental settings.)
In geophysics, the free-air gravity anomaly, often simply called the free-air anomaly, is the measured gravity anomaly after a free-air correction is applied to account for the elevation at which a measurement is made.
It can be used to establish whether a patient has the ability for the eyes to fuse the light that is received from each eye into 4 lights. The test is indicated with the use of a presence of a prism in individuals with a strabismus and fusion is considered present if 4 lights are maintained, with or without the use of a prism. The W4LT can also ...
The K-correction can be defined as follows M = m − 5 ( log 10 D L − 1 ) − K C o r r {\displaystyle M=m-5(\log _{10}{D_{L}}-1)-K_{Corr}\!\,} I.E. the adjustment to the standard relationship between absolute and apparent magnitude required to correct for the redshift effect. [4]