When the convergence and divergence of both eyes remain unchanged, the accommodation of the eye is increased or decreased separately, and the fusional convergence and divergence compensates for the accommodative convergence and divergence to maintain binocular monovision, which is called relative accommodation.

Look at a fixed near target with both eyes.The maximum amount of regulation that can be relaxed when the convergence and divergence remain unchanged is called negative relative accommodation (NRA).
Look at a fixed near target with both eyes.The maximum amount of regulation that can be increased when the convergence and divergence remain unchanged is called positive relative accommodation (PRA).

Positive and Negative Relative Accommodation Inspection

1.Operation Steps On Comprehensive Refractometer：
Steps:
(1)Correct the refractive error of both eyes completely and adjust the pupil distance.
(2)Turn on the light and place the vision chart at 40cm from eye,which is above the row of chart with best vision on near vision card.Ask the patient to look.
(3)Gradually increases the degree of the convex lens until the first blurred point appears.The vision chart can be read at this time, but the definition is different from the beginning one.Now, the increased degree of the convex lens is the negative relative accommodation of the measured eyes(NRA).
(4)Adjust the optical aperture luminosity back to the original prescription.
(5)Gradually increase the degree of the concave lens until the vision chart is continuously blurred .The increased degree of the concave lens is the positive relative accommodation of the measured eyes(PRA).

2.Operation Steps On Adjustable Multifunctional Retinoscopy Rack Set：
Adjustable multifunctional retinoscopy rack set is composed of two sets, one with concave(-) lens and the other with convex(+) lens. The luminosity of the two rows is the same. The sphere lens can be superimposed and the optical center distance can be adjusted through the adjustment of optical center distance. The degree of single row is 0.50D, 1.00D, 1.50D, 2.00D, 2.50D, 3.00D, 3.50D, 4.00D and 5.00D. If superimposed, it will form a new retinoscopy rack set combination with the degree of 1.00D, 2.00D, 3.00D, 4.00D, 5.00D, 6.00D, 7.00D, 8.00D and 10.00D.

Steps:
(1)Correct the refractive error of both eyes completely and adjust the pupil distance on the retinoscopy rack set.
(2)Turn on the light and place the vision chart at 40cm from eye,which is above the row of chart with best vision on near vision card.
(3)The patient holds the retinoscopy rack set with convex lens and gradually increases the degree of the convex lens until the first blurred point appears.The vision chart can be read at this time, but the definition is different from the beginning one.Now, the increased degree of the convex lens is the negative relative accommodation of the measured eyes(NRA).
(4)Change the retinoscopy rack set to the red one with concave lens and gradually increase the degree of the concave lens until the blurred point appears.The increased degree of the concave lens is the positive relative accommodation of the measured eyes(PRA).