Comprehensive Refractometer Test Presbyopia
Comprehensive Refractometer test presbyopia
First, the steps:
Fusion cross - cylinder (FCC) preliminary determination of presbyopia
Negative Relativity Regulation / Positive Relativity Regulation (NRA / PRA)
Measure the precise adjustment of presbyopia
Finally determine the old view attached
1, fusion cross-cylinder (FCC) preliminary to determine the old view attached:
In the completion of long-distance refractive correction on the basis of the near pupil distance, eyes placed ± 0.50D cross-cylinder, 40 cm place the grid as standard, suitable lighting. Refractometer Ask the tester which line is brighter and clearer, if there is presbyopia, the tester will report the horizontal line than the vertical line clear to each time + 0.25D in front of the eyes gradually increase the positive mirror, until the test v. Level And the vertical line is also clear, near the increase in the amount of presbyopia as the initial prescription
2, negative relative adjustment / positive relative adjustment (NRA / PRA), Refractometer measurement of precision adjustment
The purpose of the NRA / PRA measurement is to examine the ability of the subject to increase and decrease the adjustment in the case of total vertebral fixation. The absolute value of the NRA / PRA should be equal.
NRA / PRA measurements were made on the basis of initial addition of presbyopia, with eyes in the "O"
Near vision of the meter placed at 40 cm, watching the best near vision on one or two lines of the visual standard, first measured NRA: plus positive lens, each + 0.25D until the first continuous fuzzy. Refractometer The first persistence of ambiguity refers to the initial sight of the clear view is no longer so clear, but may still be able to read, record the total amount of light, return to the initial value, re-determine the target is clear.
Measured PRA plus negative mirror, each time -0.25D until the first occurrence of persistent blur, record the total amount of light.
Appropriate precise adjustment of presbyopia:
(NRA + PRA) / 2 + presbyopia append = presbyopia
Finally determine the old view attached: according to the habit of the subject to adjust the ± 0.25D, Refractometer and try to try to wear the audition to complete the fitting test.