NRA (Negative Relative Adjustment) and PRA (Positive Relative Adjustment) are two important items in the binocular vision function examination, and both of them need to be examined on the basis of distant refractive correction.
1.NRA: It refers to the ability to relax binocular accommodation under the condition of unchanged collection.
(1) Adjust the refractive correction on the comprehensive optometrist.
(2) Place the NRA card 40 cm in front of both eyes, and ask the patient to look at the line on the smallest scale that he or she can see clearly.
(3) Add corrective lenses in front of both eyes at the same time, increasing +25 degrees each time, until the patient sees persistent blurring of the near visual field.
(4) The sum of the added positive lens degrees was recorded. This is the patient’s NRA value.
2. PRA: This refers to the ability of both eyes to adjust the tension in both eyes with the collection unchanged.
(1) Adjust the distance refractive correction on the comprehensive optometrist.
(2) Place a near-refractive scale card in front of both eyes at a distance of 40 cm from each eye, and ask the patient to look at the smallest scale that he or she can see on the top line of the scale.
(3) Negative lenses were added in front of both eyes at the same time, increasing by +25 degrees each time, until the patient observed persistent blurring of the near visual field.
(4) The sum of the degrees of negative lenses added was recorded as the patient’s PRA value.
Teenagers are recommended to check NRA optometry and PRA optometry in specialized eye hospitals when they are prescribed lenses or have symptoms of visual fatigue.