(1a) Trial Frame vs Phoropter

Question 1

adjustments for trial frame

Answer 1

pupillary distance, temple length, pantascopic tilt, nose pad

Question 2

auxiliary lenses

Answer 2

pinhole, occluder, prisms, slits, maddox rods, red/green filters

Question 3

explain pinhole

Answer 3

used to determine whether reduced vision is caused by refractive error. if this is the case, pinhole will cause an improvement in visual acuity

Question 4

position of lens in trial frame

Answer 4

sphere first, cylinder in front of sphere. auxiliary anywhere

Question 5

advantages of trial frame

Answer 5

better for those with high rx (4D or higher) bc vertex distance can be maintained well (by placing lens closest to eye)

better for presbyopia px as frame similar to specs, can look down and simulates near reading vision better

Question 6

phoropter advantages

Answer 6

• faster, convenient for examiner
• comfortable for px, no weight on nose
• lenses not greased
• greater axis accuracy during cylindrical correction
• addividity errors reduced

Question 7

phoropter disadvantages

Answer 7

• hide patients face thus cannot observe px and their responses
• head tilt affects cylindrical axis
• difficult to control vertex distance
• need to check again with trial frame for px with high rx
• eff power at near different than in prescribed lens