Abstract
Subjective ocular refractions performed by an optometrist are usually considered the criterion or ‘gold standard’ for measurement and prescription of spectacle or contact lenses for compensation of refractive errors. The method is subjective in that the patient is closely involved in making decisions during the procedure. Whilst many clinicians are of the view that results produced by subjective refractions are more valid and repeatable than those from automated objective refractors (instruments to measure refractive state), others report less satisfactory reliability and precision for repeated subjective refractions. With objective methods patients are generally not required to make any decisions during the refractive process, although they are required to fixate on a target within the instrument. Sometimes ophthalmic pharmaceutical agents (cycloplegics) are used with these clinical refractive methods to prevent unintended influences from the eye’s focusing (accommodative) system...
D.Phil. (Optometry)