refractive error

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refractive error

Ametropia, myopic shift Ophthalmology The inability of images to focus properly on the retina, often corrected by glasses contact lenses, or refractive surgery. See Astigmatism, Farsightedness, Myopia, Presbyopia.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.

refractive error 

The dioptric power (K) of the ametropia of the eye. It is equal to 1/k in dioptres, where k is the distance between the far point and either the spectacle plane (spectacle refraction), or the principal point of the eye, or the refracting surface of the reduced eye (ocular refraction), in metres. Thus
K = 1/k
when the eye is situated in air. Syn. ametropia (although this is not strictly so as ametropia is the anomaly); refraction of the eye; refractive status; static refraction. See far point of accommodation; Scheiner's experiment.
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann
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At age 10 years his spectacle refraction was R -2.00/-0.75 x 90 and L -2.50/-1.25 x 90.
The myope up close
(1) The effective treatment calculated at the corneal plane (taking into account the preoperative and postoperative spectacle refraction, converted at the corneal plane with the formula [23] SE corneal plane = SE spectacle plane/[1 - (0.012 x SE spectacle plane)]) was added to the Kpost.
Calculation of Unknown Preoperative K Readings in Postrefractive Surgery Patients
If the lens sits in a stable position then a compensation can be made to the lens order to account for this clockwise rotation and 30[degrees] should be added to the spectacle refraction axis
A back-to-basics approach to soft toric contact lenses
Simply enter the spectacle refraction (without BVD) for right and left eyes, including reading add and dominant eye, and the app gives an initial lens power recommendation.
Multifocal
Users select the lens type they want, enter the spectacle refraction and the recommended trial lens power is shown in a bar below.
Contact Lens Toric
SAUFLON HAS launched an online calculator which is designed to assist practitioners in accurate contact lens selection for its core or XR toric prescriptions by simply inputting spectacle refraction and back vertex distance values.
Contact lens update
Most laboratories will need to be provided with spectacle refraction, along with the back vertex distance (BVD), as well as the K readings (to two decimal places).
Terminology Explanation Spectacle refraction The spherical and cylindrical combination required, at a stated vertex distance, to correct the patient's ametropia Ocular refraction The spectacle refraction adjusted by compensating for the back vertex distance (BVD) Spectacle astigmatism Can occur either from corneal and/or lenticular astigmatism.
The soft approach to RGPs: part 3: don't let torics put you in a spin
A restriction will also apply if the refractive correction exceeds -8.00DS (-8.75DS spectacle refraction if contact lenses are worn), and the uncorrected vision must be at least 6/20 (0.3 decimal).
Vision standards for driving--the evidence base: course code C-16307 O/D
A 54-year-old patient has the spectacle refraction shown in Image C.
If the patient in Question 5 and with the spectacle refraction shown in Image C decides to opt for monovision correction, which of the following would be the MOST appropriate lens powers to select initially?
Presbyopia & ageing eyes: Course Code: C-16279 O/D/CL
RGP fittings are usually done from a trial set or ordering empirically from the "K" readings (keratometer reading) along with the spectacle refraction and back vertex distance (BVD).
Contact lens options for keratoconus

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