BVS 2

cover-uncover

alternating - done to observe phoria

prism cover test - measures magnitude

Quantify latent deviations

Small misalignment of visual axes during binocular viewing conditions that doesn't result in loss of sensory fusion.

• test for cyclo deviations

  1. put maddox rod on both eyes, different colours with linesgoing vertical = 1 horizontal line

  2. add 6 base DOWN prism on RE to dissociate = 2 horizontal lines seen

  3. ask px if both lines are straight. If not, change axis of MR until both straight

Tests crossed

Hold test upside-down or reversing filters swaps disparity to uncrossed

60” = normal

Lag- under accomodate, usually for near

Lead- over accomodate, usually for distance

Myopes - accomodate less, converge less so more exo. We fix that by adding base in prism, which helps convergence = NPC overestimated

Hyperopes- accomodate more, converge more so more eso. We add base out prism to fix eso which makes accommodation difficult = NPC overestimated

Total- red green filters,

• TNO

• Maddox rod

• occluder

• Worths light

Partial- polarising filters

• Bagolini

• Titmus

• Mallet OXO

Difficulty maintaining adequate motor and sensory fusion = decompensating phoria ( px becomes symptomatic)

Will see this as slow recovery on CT

• Astenopia, headache, sore swollen eyelids, general irritation intermittent dip, blur

• Heterotropia = dip or suppression

1. Task conditions- size, contrast, colour, lighting, distance

2. Health- phoria may decompensate during ill health, fatigue, anxiety, meds reduce accom

3. Rx- uncorrected rx affects accom, affects convergence via AC/A ratio

4. Fusional range- fusional vergence used to overcome latent dev to maintain BSV

1. Prisms - dont correct whole phoria!

1. Rx- undercorrect hyperopic exo and myopic esos ( for horizontal)

2. Additional power to change accomodation = change convergence (for horizontal)

   • Plus addition relaxes accom = reduced eso at near bz blurred DV. Works well with high AC/A

   • Minus addition stimulates accom= reduces exo at distance and near. May be uncomfortable

3. Surgery- with large deviations and Symptomatic and other management options have failed

4. Orthoptic exercises- used for horizontal phoria

1. Physiological dip- hold 2 pens 20cm apart. Look at further pen, nearer one should appear double. Vice versa

2. Free space stereograms- 3 cats. Bring them closer or further to fuse into 1 cat

Repeat little time and often, once or twice 5x daily

Review every 6 weeks

Myopes reading without specs

New presbyopes with near specs

Newly corrected low hyperopes

Unilateral amblyopia

Excessive close work

Wide pd

1. Pen to nose- try to maintain single target, aim to get closer each time.

   • Several times a day, 5 to 10mi s

   • Review after 1 month

2. Jump- 2 pens one distance and near. Fixate on further then jump to near. Repeat and bring near target closer till dip reported

1. Full rx, max plus, worn DV NV

2. Exercises- push up, flipper lenses +2, 2-6 x a day, for 5 mins

Any tilt means problem with obliques

Max seperation means dev in that area

Lower line means higher eye

Can be crossed or uncrossed ( see which eye has which colour goggles )