Question | Answer |
Define what is meant by subjective refraction | Refraction result depending on patient's ability to discern changes in clarity |
Best Vision Sphere is part of subjective refraction | During subjective refraction - trying to find the best vision sphere (most +ve spherical lens that gives the best VA) * places Px far point close to optical infinity * must minimise Px accommodative response |
How to set up patient for subjective refraction including thinking about whether trial frame/phoropter would be better | Using phoropter pros: quicker, comfortable, cleaner leases, WOW factor Using trial frame: Pros: near addition, patients with low vision, patients with poor subjective responses, patients with high refractive error (change vertex distance), children Measure monocularly vision - want to relax accommodation so place +ve lenses first |
Understand the COLC concept and BVS equivalent findings to full prescription | For astigmatism - a point image does not exist for a point object, focal lines are formed along the two principle meridians and are separated by the interval of Sturm. Obtain BVS by finding sphere that would put the COLC on the retina (where both lines would be equal distances from the retina) |
How to determine BVS of patient using +/- method, +1.00 check and duochrome | . |
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