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Subjective Refraction is a technique to determine the combination of lenses that will provide the best corrected visual acuity (BCVA). [1] It is a clinical examination used by orthoptists , optometrists and ophthalmologists to determine a patient's need for refractive correction, in the form of glasses or contact lenses.
A subjective refraction requires responses from the patient. Typically, the patient will sit behind a phoropter or wear a trial frame and look at an eye chart. The eye care professional will change lenses and other settings while asking the patient for feedback on which set of lenses give the best vision.
Following that "objective refraction" the clinician typically shows the person lenses of progressively higher or weaker powers in a process known as subjective refraction. Cycloplegic agents are frequently used to more accurately determine the amount of refractive error, particularly in children [23]
In some offices, this process is used to provide the starting point for the ophthalmologist or optometrist in subjective refraction tests. Here, lenses are switched in and out of a phoropter and the patient is asked "which looks better" while looking at a chart. This feedback refines the prescription to one which provides the patient with the ...
[1] [3] Diagnosis is by an eye examination called autorefractor keratometry (objective, allows to see lens and cornea components of astigmatism) and subjective refraction. Three treatment options are available: glasses, contact lenses, and surgery. [1] Glasses are the simplest. [1]
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In 1909, Nathan Shigon of New York City invented [3] a monocular optometer with a range of +0.25 to +6.00 diopters, consisting of a mechanism where a disc of low-powered lenses advanced a second disc of higher power lenses automatically with each rotation, as in a modern phoropter.
Low vision visual acuity examinations are done using the LogMAR chart. The advantage that this presents with is that it allows for more accurate measures of the individual's vision to be recorded. Other tests done and their significance are as follows: Amsler's grid test - to locate scotomas on the visual field of the individual