Purpose of Visual Tests

— Subjective Refraction

Determine the refractive status from the patient’s responses, giving the prescription or a starting point for one.

VT7

— Habitual Phoria At Far

Measure the distance deviation with the habitual correction.

VT3

— Induced Phoria At Far

Measure the deviation with the new correction (VT7) and check that accommodation and convergence are balanced.

VT8

— Vertical Phoria And Duction At Far

Find vertical imbalance when fusion is broken and measure SR/IR strength.

VT12

— Habitual Phoria At Near

Measure the near deviation with the habitual correction.

VT13A

— Induced Phoria At Near

Measure the near deviation with VT7 and check the accommodation–convergence balance at near.

VT13B

— Induced Phoria Through Unfused Cross Cylinder

Find the effect of phoria on the dissociated cross-cylinder result and support the tentative ADD.

VT15A

— Vertical Phoria And Duction At Near

Same purpose as VT12, but at near.

VT18

— True Adduction At Far

Measure available convergence at distance without accommodation (compensates exophoria).

VT9

— Convergence At Far

Measure fusion/vergence amplitude (break/recovery) with accommodation involved (compensates exophoria).

VT10

— Abduction At Far

Measure the limit of negative vergence (compensates esophoria).

VT11

— Positive Relative Convergence

Measure convergence tolerance with accommodation fixed, and compensate near exophoria.

VT16A

— Positive Fusional Reserve

Measure the extra fusional movement that maintains single binocular vision (break/recovery).

VT16B

— Negative Relative Convergence

Find the limit of fusional convergence at near, i.e. tolerance for the eyes diverging.

VT17A

— Negative Fusional Reserve

Measure the tolerance range where single binocular vision is still maintained.

VT17B

— Dissociated Cross Cylinder

Check for accommodative lag, recheck the cylinder, check binocular balance, and help determine the add.

VT14A

— Fused Cross Cylinder

Find the tentative add and evaluate accommodative posture under binocular conditions.

VT14B

— Amplitude Of Accommodation

Measure the total accommodation available (aging/presbyopia) and help determine the ADD.

VT19

— Positive Relative Accommodation

Measure how much accommodation can be stimulated with convergence held constant.Measure how much accommodation can be stimulated with convergence held constant.

VT20

— Negative Relative Accommodation

Measure how much accommodation can be relaxed with convergence held constant.

VT21