What is vergence testing?
Background: Testing of vergence ranges is a routine clinical procedure providing valuable information about the patient’s binocular status. Unfortunately, obtaining this information from non-verbal or very young patients has proven difficult or impossible in many situations, due to lack of subjective response.
How do you test a vergence facility?
Testing Procedure: The test is performed at 40 cm as the patient views a vertical 20/30 target or similar. Twelve diopter base out (BO) and three diopter base in (BI) prism is alternately placed before one eye; the patient is asked to report when the target becomes single and clear.
What is vergence in vision?
Vergence refers to the simultaneous movement of both eyes in opposite directions to obtain single binocular vision. When the eyes rotate towards each other (convergence) the angle of eye increases and when the eyes rotate away from each other (divergence) the angle becomes smaller (Figure 1).
What is smooth vergence testing?
Purpose Smooth vergence testing is designed to assess the fusional vergence amplitude and recovery at both distance and near.
What is vergence facility?
Vergence facility, defined as the number of cycles per minute that a stimulus can be fused through alternating base-in and base-out prisms, attempts to capture the ability of the fusional vergence system to respond rapidly and accurately to changing vergence demands over time.
How is vergence measured?
The magnitude of the demand on the fusional vergence system is assessed by measuring heterophoria (phoria), which is the misalignment of the visual axes when disparity information is removed, by covering one eye for example.
What is light vergence?
Vergence is the angle formed by rays of light that are not perfectly parallel to one another. Rays that move closer to the optical axis as they propagate are said to be converging, while rays that move away from the axis are diverging.
How do you perform a mem?
The retinoscope beam should be oriented vertically. Ask the patient to watch the animation. While the patient is watching, quickly guide the streak across the patient´s left and right eye and try to evaluate the reflex for WITH or AGAINST motion or for neutrality. Do the test a few times on both eyes to be sure,.
What is fusional vergence dysfunction?
Fusional vergence dysfunction (FVD) is a binocular vision disorder with an unknown etiology.1 In this condition, accommodative convergence/accommodation (AC/A) ratio is normal, distance and near heterophorias are within the expected values, and accommodative function is intact, but fusional vergence findings are …