Refractometey Flashcards
What is an important factor when preparing a patient for a refraction?
Explain to the patient to choose the lens that provides the clearest vision.
What are three appropriate starting points for refracting a patient?
Retinoscopy, auto refractometry, or patient’s current spectacle are rX.
What is a common mistake made by the refraction its?
Flipping the lenses to quickly.
In what order should refinement of a refraction be performed?
Sphere, axis then cylinder.
What accessory phoropter lens is utilized to refine cylinder axis and power?
Jackson cross cylinder
Name two methods of refractometry?
Objective and subjective
When is the spherical equivalent best used in a spectacle RX?
If patient is an adult and has never worn glasses and requires a large astigmatic correction.
Name of test to determine best myopic correction using red/ green filter on the projector?
Duochrome test
What normally determines the strength of an add power for near correction?
The age of the patient
Distance from back surfaces of lens to front surface of the eye called?
Vertex distance
Explain how explain how to transpose a sphere ocylinder from plus to minus cylinder form or from to minus to plus cylinder?
Algebraically add the sphere and cylinder powers- retain the cylinder power but change the cylinder sign, and change cylinder axis by 90 degrees.
Which color vision test consist of pseudo isochromatic plates that determine red green color and Anomalies and deficiencies?
Ishihara
Which color defects may be distinguished by the ishihara test?
Red and green
A -scan biometry measures the distance between_____ ______ _____
Internal ocular surfaces
Spherical equivalent obtained by
Take half of the cylinder and algebraically add it to the sphere
