FUN Examples

How do we lessen the convergence demand?

add base in prism

What is the PFV?

positive fusional vergence: what an exo patient uses to regain fusion

convergence

What is the equation for PFV?

prv-phoria

exo is -

eso is +

What is the NFV?

What the eso patient uses to regain fusion (divergence)

What is the equation for NFV?

nrv + phoria

exo is negative

eso is positive

If my patient is eso, what is the reserve?

the BI ranges aka the NRV. It is what is left over from the

How can you test vergence ranges out of a phoropter?

jump or step bar vergences

(start with BI prism bars with a target at 40 cm and increase prism amounts until you see a break, or alternating fixation.)

How do we create the conditions to disrupt fusion and measure a dissociated phoria?

1. exclusion = cover test

2. diplopia or displacement = von graefe

3. distortion = maddox rod or modified thorington

4. nonfusable (independent objects) = stereoscope phoria cards

What is the NRV?

BI blur

What is the PRV?

BO blur

What is the demand?

the phoria

If your patient is exo, what is the reserve?

exo=e+o for reserve

• its the PRV

What are the norms for accommodative facility?

11 cpm monocularly

8 cpm binocularly

• a difference of 4 cpm between the two eyes is concerning

How do we test accommodative facility?

test accommodative flexibility and stamina

• lens rock ± 2.00 D with a 20/30 letter for 1 minute

• monocularly and binocularly

For vergence facility what are the norms and how do you test it?

12 BO/3 BI is placed in front of the eye for 60 seconds

norms: 12-15 cpm

What could be the cause of someone having a high lag? >+0.75 D

• accommodative insufficiency

• ill-sustained accommodation

Is 4 BO an abnormal morgan norm?

Yes, at distance and at near we do not want to experience BO on a cover test. Eso is bad

What is the formula for a calculated AC/A?

PD(cm)+M(m)(near-far)

How would you treat an accommodative insufficiency?

• lenses

What is a normal MEM?

+0.25 to +0.50 D indicating a small lag. leads are bad!

When performing an alternative cover test, which eye do you look at?

the fixating eye (uncovered eye)

What does BO do to the eyes?

it converges the eyes

What is the monocular minimum?

15-0.25(age)

What accommodative test can differentiate between an accommodative and vergence problem?

accommodative facility

How do you treat a convergence insufficiency?

• VT 1st

• prism at near 2nd

How do you determine the amplitude of accommodation?

(100/NPA)+(RE-Lens)

How do you make sure a patient is not suppressing during phoropter testing?

• tell patient to keep the letters clear and single, if the letters move instead of break into two then they are suppressing

What accommodative test can differentiate between an accommodative and vergence problem?

accommodative facility

What is this called and used for?

A howell card

measures phorias at distance and near

What is the percent of school aged children that have an undiagnosed visual problem that affects school performance?

1 in 4 (25%)

What can a high lag of accommodation mean?

• eso at near with incompensating vergences

• accommodative dysfunction: insufficiency, fatigue, paresis, infacility

• a hyperope uncorrected

What if someone has a low lag or lead?

• exo at near

• spasm of accommodation

• uncorrected myope

When performing accommodative facility, why is the binocular value less than the monocular value?

• you have two lenses doing the work

• you introduced convergence

Your patient has a convergence excess that was treated with plus at near as a first choice. How do you determine the add?

Phoria/AC/A = add

PACA

What near ret test is purely a lag test?

MEM (monocular estimation method)

The saladins was distance phoria @ 8 BO distance ranges were x/4/2 prism needed was 8-2/2=3 BO or 1.5 OD/OS the new recovery should’ve been 5 because 8-3=5 BO (old recovery+ prism found) 2+3=5BO. she also to find the AC/A asked 65 mm pd, 40 cm wd and 8 BO and ortho at distance so

6.5cm+0.4m(8-0)=9.7/1 for the AC/A.

What percent of people over 18 had asthenopia after digital device usuage?

75%

What are prism prescriptions not a substitute for vision therapy in treating?

SOVA

suppression

oculomotor dysfunctions

vergence facility dysfunctions

accommodative issues

Why do we give prism?

reduce fusional vergence demand and relieve symptoms

What phoria test is the most reliable and repeatable between clinicians?

modified thorington

What is special about a saladin card?

it can give you dissociated and associated phoria measurements but only at near

Find the AC/A with a pd of 65 mm, 40 cm working distance, and 8 BO at near and ortho at distance.

AC/A is 6.5cm+0.4m(8-0)=9.7/1

AC/A= pd(cm)+M(m)(near-far)

What is the rule for sheards?

fusional reserve should be twice the demand

• for exos greater than 4 BI

(2XP- BO to Blur)/3 = total BI prism

use absolute values!

Find the total prism needed for

distance = ortho near = 16 XP

Near BO range: 8/22/10 ; Near BI ranges: 15/30/20

use sheards

(2*16XP-8)/3= 8 BI total or 4 BI OD/OS

The ANSI tolerance for prism is 0.5 meaning,

do not split 1 diopter of prism between two eyes

Why is percivals for everyone?

• it doesn’t take the phoria into account

• better for laterals tho!

What does fixation disparity measure?

vergence adaptation

For a type 1 fixation disparity curve, what is the prism needed? Associated phoria? Fixation disparity?

all are zero, the patient is asymptomatic

What is Percival’s equation?

(greater- 2 * lesser)/3

if the number is negative —> they don’t need prism 🙂

compare BI and BO BLUR (can use break next if no blur) at distance or near

Example: ortho at distance 12 exo at near (+1.00 also 12 XP at near)

distance: BI x/16/8; BO 4/8/2

near: BI 24/32/20; BO 6/12/10. do percivals.

percivals at distance: (16-2(4))/3 = 2.67 BI

percivals at near: (24-2(6))/3 = 4 BI (trial 2 BI OD/OS)

Who can you use saladins for?

• basic esophoria

• divergence insufficiency

How do you know how much prism you should prescribe with saladins?

• prescribe enough BO prism to make the EP equal the BI recovery

• BO prism = (EP-BI recovery)/2

Distance phoria : 8 BO

Distance BI range: x/4/2

what is the prism using saladins?

BO prism = (EP-BI recovery)/2

prism = (8-2)/2 = 3 BO or 1.50 in front of each eye

How do you recheck the prism, what should the new phoria and recovery be?

old phoria - new prism

8-3=5 BO

and the new recovery should increase to 5.

What is the percent of people in the world with myopia?

42%

What are the degrees of myopia?

• Degree of Myopia

  • Mild/Low: up to -3.00D

  • Moderate: -3.25 to -5.75D

  • Severe/High: >-6.00

How can you get a kid to prevent myopia?

spend more time outdoors

• visual hygiene (less device usuage)

If someone has two myopic parents, what are the odds of them progressing into myopia vs one myopic parent?

6-7x more for two myopic parents vs 3x more for one

Name the risk calculators for myopia?

• ocumetra

• lens star myopia

What is the average rate of myopia progression?

-0.50 D per year

Is there a benefit to undercorrecting myopia?

No, myopic kids need 1 annual exam a year due to rapid progression

What are some myopic treatment options?

• MFCL (misight 1 day)

• ortho K/CRT

• low dose atropine (0.05%) superior tx after 2 years

• special specs: Stellest!

What is the goal of myopia management?

• slow or stop the progression of axial length and refractive error

• axial length should be <26mm

• refractive error should be <-6.00D to prevent disease

What is involved in a myopic eval?

history, pupils check, pentacam, topos, refraction, etc

What is anisometropia?

refractive error differs between the two eyes by >1.00 D

severe is >3.00 D which can lead to amblyopia

How many americans have an astigmatism?

1 in 3 (look at K’s w AR or topo)

How many hyperopes are in the US?

approximately 10% (33 million)

Which vergence syndromes need plus at near as a first treatment option?

Convergence Excess

Pseudo-CI (its an accommodative issue solely)