Visual function examination is one of the important professional skills in optometry and glasses fitting, and it is also one of the professional skills that middle and senior optometrists and ophthalmologists must possess.
Since visual function examination is of great significance to the diagnosis of consumers' vision health, the methods of visual function examination have been enriched and developed. Hereby, several visual function examination methods are summarized for your reference.
NO.1 Accommodation amplitude test
1. Approach method
The approach method is to stimulate the human eye's accommodation by gradually moving the indicator closer to cause the divergence of light. It is a subjective method to measure the accommodation amplitude.
Operation steps:
① The refractive error of the tested eye is completely corrected
② Cover the left eye and measure the accommodation amplitude of the right eye.
③ Place the near cross sight mark or the upper line sight mark of the best vision on the near vision chart at 40cm, and ask the tested eye to look at the sight mark.
④ Move the near sight mark card closer to the tested eye at a speed of 1cm/second until the sight mark is continuously blurred. If the person being tested reports that the sight mark is blurred and then becomes clear, continue to move forward until the sight mark is completely blurred.
⑤ Record the distance from the near sight mark card to the main point in front of the eye, and convert it into the accommodation amplitude. If the distance from the sight mark card to the main point in front of the eye is 10cm, its accommodation amplitude = 1/0.1 = 100 (D)
⑥ Cover the right eye and test the left eye according to the above steps.
⑦ Open both eyes and test both eyes according to the above steps.
2. Negative lens method
The negative lens method is a method of stimulating accommodation by adding a negative lens in front of the eyes, thereby measuring the accommodation amplitude.
Operation steps:
① The refractive error of the tested eye is completely corrected
② Cover the left eye and measure the accommodation amplitude of the right eye.
③ Place the near cross sight mark or the upper line sight mark of the best vision on the near vision chart at 40cm, and ask the tested eye to look at the sight mark.
④ Slowly add negative lenses in a step of -0.25D in front of the tested person (the interval is 5~10 seconds) until the sight mark is continuously blurred.
⑤ Record the increased negative lens degree, and the accommodation amplitude is the absolute value of the increased negative lens degree plus 2.5D (the accommodation force generated by the near sight mark at 40cm).
⑥ Cover the right eye and test the left eye according to the above steps.
⑦ Open both eyes and test both eyes according to the above steps.
NO.2 Positive and negative relative accommodation inspection
Operation steps for positive and negative relative accommodation on the comprehensive ophthalmometer:
① Place both eyes at the far refractive correction degree and adjust the near pupil distance.
② Turn on the near light, set the near cross sight mark or the upper row sight mark of the best near vision at 40cm, and ask the tested eye to look at the sight mark.
③ Gradually increase the positive spherical lens until the tested eye reports the initial point of continuous blurring of the sight mark, that is, the sight mark can be read, but the first value is different from the clarity seen at the beginning. The added positive spherical lens light is the negative relative accommodation (NRA) of the tested eye.
④ Return the aperture light to the initial prescription
⑤ Gradually increase the negative spherical lens until the tested eye reports continuous blurring of the sight mark. The added negative spherical lens light is the positive relative accommodation (PRA) of the tested eye.
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Post time: Jun-14-2024