What is fusional vergence Reserve?

What is fusional vergence Reserve?

The fusional reserves are the maximum amount the eyes can converge (positive fusional reserves, measured with base out prism) or diverge (negative fusional reserves, measured with base in prism) while still maintaining BSV. As the image doubles, the break point is reached.

What is the meaning of Fusional Reserve?

Fusional reserves are a measure of how much vergence a person has in reserve that can be used to overcome a heterophoria. The patient is instructed to fixate on a near target (usually at 33 cm) binocularly and a horizontal prism bar is placed before one eye starting with the weakest prism strength.

How is fusional convergence measured?

When measuring horizontal fusion ranges, base in prisms assess fusional divergence while base out prisms assess fusional convergence. The vertical fusional vergence amplitude can also be measured with base up and base down prisms although the horizontal PFR is typically the main focus when testing.

How is Fusional Reserve measured?

Fusional reserves are easy to assess using a prism bar, and with some keen observation can become an objective measure of your patient’s ability to maintain the correct balance of convergence and divergence at near.

How is vergence facility measured?

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.

How do you perform a vergence test?

To test step vergence using prism bars out of the phoropter, have the patient wear his correction (or use a trial frame) and sit facing an appropriate-sized near point target. Place the prism bar with the bases-in before one eye, and move it step by step as the patient attends to a distance or near target.

What is Sheard criterion?

Sheard’s criterion (1930) can be stated as a requirement that the. fusional reserve amount be twice the amount of the fusional demand. The. fusional reserve is the relative vergence in the opposite direction from the. heterophoria, and the fusional demand is the amount of heterophoria.

How do you balance NRA and PRA?

To determine the appropriate near correction for the patient, consider the negative relative accommodation (NRA) and the positive relative accommodation (PRA) findings. For example, if the NRA was +2.75D and the PRA was 0.75D, this would suggest an add of +1.00D to balance the NRA and PRA.

How do you test for vergence?

What is a flipper test?

The test measures how many words can a patient reads in one minute by flipping the flipper device in front of his eyes from plus lenses to minus lenses. By pressing the start, the test will begin measuring 60 seconds. You put flippers with plus lenses in front of his eyes and ask him to report a word written.

What is RAF ruler?

The RAF Rule provides a binocular gauge to measure objective and subjective convergence as well as accommodation in 1 mm increments. The RAF Rule is a 50 cm long rule with a slider holding a rotating four-sided cube, each side with a different target.

What is Percival’s criterion?

Percival’s criterion was that the orthophoria point of subject should be operating in the middle-third of the binocular vergence range. The values for Percival’s criterion were determined by calculating the value 1/3 greater of two fusional vergences minus 2/3 lesser of the two fusional vergences.

What does Maddox rod measure?

The Maddox rod test can be used to subjectively detect and measure a latent, manifest, horizontal or vertical strabismus for near and distance. The test is based on the principle of diplopic projection.

What is red glass test?

The red glass test is used to detect the presence and type of diplopia a patient has. It can also be used to detect suppression, determine retinal correspondence, and to confirm the type of diplopia a patient has (crossed or uncrossed). This is a moderately disassociating test.

What is Hirschberg test used for?

The Hirschberg test (also known as the corneal light reflex test) is a quick and simple way to check ocular alignment.

What is Maddox rod test?

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