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18 Cards in this Set
- Front
- Back
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How far do we rotate (CYL) the axis dial?
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It depends on starting cyl power. Larger the cyl power ===smaller the axis changes should be. If the starting cyl power is only .25 or .5 D, then first rotate the dial by 15 degrees. If starting cyl power is .75 to 1.25 D, then rotate the dial 10 degrees. If starting cyl power is above 1.25 D, then only rotate the dial 5 degrees. Get final results few "trys" as poss.
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Spherical Equivalent
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If using a plus cyl , check the sphere power in the minus direction. If using minus cyl phoropter, check the sphere power in the plus direction (make a .25 D change in the sphere power for every .5 D change in the cylinder power).
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Refine the Sphere Power
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Re-check sphere power using same procedure used with initial sphere power check . Pt. sees good use .25 diopter moves instead of .50 diopter steps
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One final check can be done with?
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the red-green test
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Everyone with cylinder power over 1.00 D should be checked with?
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spherical equivalent comparisons
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plus cyl chase white dot
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The patient again indicates that the vision is best on flip 2, with the white dot to the right of the"straddle", so move the axis dial 10 degrees in the clockwise direction, from axis 1 to 2 (finally move in 5 degrees)
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Keratometry and astigmatism
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Calculating the corneal cylinder and axis. 44.50 X 180 and 42.50 X 90. Take the difference between the two diopter powers, in this case 44.50 minus 42.50 equals 2.00 In plus cyl, the axis is the axis of the higher diopter power, 44.50, Therefore the cylinder axis is 180. If working in minus cylinder, the axis is the axis of the lower diopter power, 42.50, so the minus cylinder axis is 90.
You are 2/3 done. If + plus cyl you have: ? + 2.00X180. |
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Phoroptor Steps
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Sphere power, the cylinder power, and the cylinder axis, the add power
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Vertex Distance and Face: Always be sure auxiliary lens wheel set to O “(open)” on the eye being checked, and OC “(occlude)” on the other eye.
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Tell PT never mash face or eyeballs into surface, or they will have to mash glasses into face to ever see perfect.
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Step 1) Start Refractometry:
~Put Pt. in chair, with phoroptor leveled (or leveled to Pt.) INCLUDE pd CHECK AND VERTEX DISTANCE CHECK ~Put Rx or % known into phoroptor ~Occlude OD |
Put up an entire screen of letters, with the 20/20 line at the bottom
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2nd chart step ESTABLISH Sphere
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Read the smallest line of letters Pt. can clearly see (Fog for accommodation)
Ask Pt. to read the lowest line Pt. can "TRY HARD and Read the chart . Now "isolate" the line of letters just above the line that patient had some trouble reading. ..ie: patient missed two letters on 20/30 line, isolate 20/40 line. Going for most plus or least minus that gives best "visual acuity". |
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Continue ESTABLISHING Sphere
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Make a lens change: Starting first with + ... which flip choice gives the better vision. Near the end point: "or about the same"
Myopic is it better or just smaller and darker. Have Pt. |
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Tell Pt:
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"tell me which way is better, one, or two” (just prior to saying “two” the lens power or axis is changed)
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First sphere check, present the patient with a choice of powers at least .50 diopters apart (two clicks on the sphere wheel) . If the initial vision check was not good (e.g. 20/50 to 20/80), you can use .75 diopter changes, or even 1.00 diopter changes if the patient's vision was worse than 20/80.
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First sphere check, present the patient with a choice of powers at least .50 diopters apart (two clicks on the sphere wheel) . If the initial vision check was not good (e.g. 20/50 to 20/80), you can use .75 diopter changes, or even 1.00 diopter changes if the patient's vision was worse than 20/80.
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3) REFINE CYLINDER AXIS (look for astigmatism) :Add JCC
not sure? Check for cyl, by 90,180 then 45,135 |
one line above line patient has trouble reading.NOT below the 20/30 line. (addition of JCC produces blur)
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Start JCC "STRADLING" (45 degrees from principal meridians of correcting cylinder)
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Start JCC "STRADLING" (45 degrees from principal meridians of correcting cylinder)
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How long so you repeat flips with the JCC?
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Until the two flip choices appear "about the same" or equal.
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Use JCC to refine Cyl. POWER
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Change the straddle to align with principal meridians of correcting Cyl.
AGAIN: 1, 2 or about the same. Remember to click to add half as much sphere (equivalent) in the opposite direction |
