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Astigmatism Diagnosis 1
News
Astigmatism Diagnosis 1

Astigmatism Diagnosis 1

January 01, 2018

Equipments:

 

Phoroptor 1 set, Chart vision 1 set.

 

Example:

 

R: -3.00/-0.50 X 60, L: -250/-0.75 X 120   PD: 62 mm

 

Above power could obtain from the auto refractometer or the lens meter

 

Put above power to the phoroptor,

 

Remove all cylinder power, close left eye,

 

Right spherical power adjust to -2.50 (Means 0.50DS to fogging right eye and make examinee vision below 0.6)

 

Open radial chart, let examinee identify the clearest line

 

 (if no1 line most clear, then the initial axis is 30 degree= 1 X 30, if no 3 line most clear, then the axis is 90 degree= 3X 30, if all line clarity same, then examinee no astigmatism, in this example, examinee says no2 line most clear, then the initial axis is 60 degree)

 

After initial axis, add -0.25DC (cylinder power) each time till all line same clarity (no special line more clear, all same), in this example, all line same clarity when cylinder power add to -0.50DC, now the initial cylinder power is confirmed.

 

Open 0.8~1.0 chart, let examinee looks 1.0 and add -0.25DS (spherical power) till 1.0 chart clear. In the example, add to –-3.00 DS, examinee says could see 1.0 chart clearly. Now initial spherical power confirmed.

 

Open red-green chart, let examinee looks green fist, then red, to compare which part most clear, if red side clear, add -0.25DS till red and green in same clarity, if could not in same clarity, the final power make sure red part clear then green, in this example, examinee says red part clearer then green part, then add -0.25DS (-3.25 DS) examinee says green more clear then red, so the final spherical power is -3.00DS.

 

Close right eye, open left, operation same as right eye.

 

Open both eye, Red-Green test

 

 

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