Combining test results to diagnose

decompensated heterophoria DISSOCIATED HETEROPHORIA

Prof Bruce Evans BSc (Hons) PhD FCOptom DipCLP DipOrth FAAO FBCLA

fusional reserves

Director of Research Institute of Optometry Visiting Professor City University Visiting Professor London South Bank University Private practice Cole Martin Tregaskis, Brentwood, Essex © 1990-2015 Bruce Evans

motor fusion

sensory fusion

fusion lock

COMPENSATED or NOT

Reference: Pickwell’s Binocular Vision Anomalies, 5th Edition, Elsevier, 2007 Handout from www.bruce-evans.co.uk

for regular tweets on optometric research

DEFINITION OF DECOMP. PHORIA A heterophoria that produces symptoms “symptomatic heterophoria”

KEY SIGNS OF DECOMP. PHORIA Symptoms Poor cover test recovery

A heterophoria that produces signs Depends on tests used A heterophoria that requires treatment

Aligning prism Low fusional reserve opposing phoria Sheard’s criterion Particularly useful for exophorias For esophorias, size and imbalanced fusional reserves are relevant For hyperphorias, size matters

Q: Which of the following is not a symptom of decompensated phoria?

SYMPTOMS OF DECOMP. PHORIA

1. Dyslexia 2. Blurred vision 3. Double vision 4. Headaches 5. Aching eyes

1. Blurred vision 2. Diplopia 3. Distorted vision 4. Difficulty with stereopsis 5. Monocular comfort 6. Difficulty changing focus 7. Headache 8. Aching eyes 9. Sore eyes 10.General irritation

1

KEY SIGNS OF DECOMP. PHORIA

KEY SIGNS OF DECOMP. PHORIA Grade 1 2 3 4

Symptoms

Symptoms Convergence insufficiency symptom survey (CISS) Validated & reliable for CI in children aged 9-18y (Borsting et al., 2003) Used in 14 other studies Criticised for non-ocular questions & found to have low sensitivity for detecting CI (Horwood et al., 2014)

Poor cover test recovery

Description rapid and smooth slightly slow/jerky definitely slow/jerky but not breaking down slow/jerky and breaks down with repeat covering, or only recovers after a blink breaks down readily after 1-3 covers

5

Scale

3.00

2.0 1.8 1.6 1.4

1st appt. difference (TP-BE)

2.00

1.2 1.0

orthophoria

hyperphoria

esophoria

exophoria

1.00

0.00

-1.00

-2.00

-3.00

0.00

Panesar & Evans, in preparation

Q: What does the Mallett fixation disparity test measure (more than 1 may be correct)?

1.00

2.00

3.00

4.00

5.00

1st appt. mean (TP & BE)

KEY SIGNS OF DECOMP. PHORIA Symptoms

1. Fixation disparity

Poor cover test recovery

2. Aligning prism

Aligning prism (FD test)

3. Associated heterophoria

Low fusional reserve opposing phoria Sheard’s criterion Particularly useful for exophorias

4. Decompensated heterophoria

For esophorias, size and imbalanced fusional reserves are relevant

5. Suppression

For hyperphorias, size matters

ALIGNING PRISM: Mallett Unit

ALIGNING PRISM: Mallett Unit •

aligning prisms/spheres to eliminate FD

•

good foveal and peripheral fusion lock

•

question set is important

• Maintain normal binocular vision • Increase lighting, full field of view • Use hand held loose prisms • Minimum prism for alignment

• ask if a line ever moves

• Re-normalise BV between prisms

• Karania & Evans (2006)

•

for symptomatic phoria:

• Prism dioptre steps: 0.5, 1.0, 2.0, 4.0 1.0

1.0 ∆

1∆+

1+

• sensitivity 75%

.8

• specificity 78%

.6

• Jenkins, Pickwell, & Yekta (1989)

1∆+

1∆+

.8

2∆+

2∆+

.6

.4

.4

2∆+

2∆+

3∆+ aged 40 years and over

.2 ∆

under the age of 40 years

3+

0.0 0.0

.2

.4

.6

1-SPECIFICITY

.8

1.0

3∆+ aged 40 years and over

.2 ∆

under the age of 40 years

3+

0.0 0.0

.2

.4

.6

.8

1.0

1-SPECIFICITY

2

KEY SIGNS OF DECOMP. PHORIA Poor cover test recovery

FUSIONAL RESERVES Can be measured with:

loose prisms

prism bar

Aligning prism Low fusional reserve opposing phoria Sheard’s criterion Particularly useful for exophorias For esophorias, size and imbalanced fusional reserves are relevant rotary prisms

For hyperphorias, size matters

Q: Which fusional reserve should you measure first? 1. Divergent at distance, convergent at near 2. The fusional reserve that opposes the phoria

FUSIONAL RESERVES Measure the reserve that opposes the phoria first Rosenfield Often the blur point cannot be measured (Horwood & Toor, 2014)

3. Divergent 4. Convergent 5. Base up 6. Base down

KEY SIGNS OF DECOMP. PHORIA

MALLETT FOVEAL SUPPRESSION TEST Tang & Evans (2007)

Poor cover test recovery

R

L

Aligning prism Low fusional reserve opposing phoria Sheard’s criterion Particularly useful for exophorias For esophorias, size and imbalanced fusional reserves are relevant For hyperphorias, size matters

1. Only show patient test with visor on 2. Have patient read down test binocularly 3. You are assessing monocular acuities under binocular conditions

3

MALLETT FOVEAL SUPPRESSION TEST R

L

MALLETT FOVEAL SUPPRESSION TEST

Binocular R L

R

L

Binocular Occluded R L R L

x

x

x 1. 2. 3.

RE reads to 5 mins of arc, LE only to 10 mins of arc Is the reason for the poor acuity in the LE foveal suppression or poor VA? To find out, keep visor in place and occlude RE, re-measuring LE

FOVEAL SUPPRESSION TEST: norms

x 1. 2. 3.

x

RE near VA 5 mins arc LE near VA 7 mins arc Under binocular viewing conditions, LE has 3 min arc foveal suppression

STEREOTESTS www.bernell.com

R

L

For 95% of the population, the VAs under binocular viewing conditions should be within one line of the VAs obtained under monocular viewing conditions Tang & Evans (2007)

BINOCULAR INSTABILITY: (FUSIONAL VERGENCE DYSFUNCTION) DIFFERENTIAL DIAGNOSIS SIGN

B.I.

DECOMP. PHORIA

phoria variability of phoria cover test recovery fusional reserves

may/may not be present > ±1.75 ∆ may/may not be abnormal convergent & divergent usually low, worse as tires unstable FD, may be aligned "on average" significant correlate

must be present < ±1.75 ∆ usually slow & hesitant low reserve opposing phoria

aligning prism dyslexia

misaligned, may/may not be unstable non-significant correlate

Optometric correlates of dyslexia: Meares-Irlen Syndrome/Visual Stress (MISViS) PREVALENCE:

30% of people with dyslexia

AETIOLOGY:

cortical hyperexcitability causing pattern glare from text

SYMPTOMS:

asthenopia, headaches, perceptual distortions

SIGNS:

coloured overlays alleviate symptoms and improve rate of reading

TREATMENT:

Precision Tinted lenses

Allen, Evans, Wilkins (2010) Vision & Reading Difficulties

4

Differential diagnosis: Binocular vision anomaly or MISViS Sign

Binocular vision anomaly

Meares-Irlen Syndrome

Significant phoria

May be present (not if binocular instability)

Unlikely

Low fusional reserves

Present

May be present

Symptoms alleviated by occlusion Pattern glare

Yes

Unlikely

Unlikely

Present

Photophobia

Yes, but not colour specific

Yes, colour specific

Symptoms alleviated by coloured filters

Unlikely

Yes

SUMMARY:

DIAGNOSIS

Sign or symptom one or more of the symptoms of decompensated heterophoria cover test: heterophoria detected cover test: absence of rapid and smooth recovery (+1 if quality of recovery 'border-line') aligning prism (Mallett): 1∆+ for under 40 years or 2∆+ for over 40 years aligning prism (Mallett): 3', or diplopia during foveal suppression test if score: 5 treat, 4-5 continue down table adding to score so far Sheard's criterion: failed Percival's criterion: failed dissociated heterophoria unstable so that result is over a range 3∆ (i.e., phoria ±2∆) fusional amplitude (divergent break point + convergent break point) < 20∆ if total score: 8 cm jump convergence (see next slide)

amplitude of accommodation heterophoria tests for near vision fixation disparity tests at reduced distance

PRACTICAL SESSION GOALS Test 3 people with Mallett-type unit Evans units are a copy of Mallett made by a different person called Evans, not the presenter! Genuine Mallett units from www.ioosales.co.uk Be careful to detect any movement Use loose prisms to find minimum prism to align strips

Other tests: fusional reserves Randot stereotest

Q: With the Mallett fixation disparity test, which of the following is recommended?

ALIGNING PRISM: Mallett Unit • Maintain normal binocular vision

1. Use a prism bar leaving in place all the time 2. Carry out in the dark 3. Use 5 prism dioptre steps

• Increase lighting, full field of view • Use hand held loose prisms • Minimum prism for alignment • Re-normalise BV between prisms • Prism dioptre steps: 0.5, 1.0, 2.0, 4.0 1.0

1∆+

4. Allow binocular vision to re-normalise between prisms

1∆+

.8

2∆+

.6

.4

2∆+

3∆+ aged 40 years and over

.2 ∆

under the age of 40 years

3+

0.0 0.0

.2

.4

.6

.8

1.0

1-SPECIFICITY

5

Some famous people who were dyslexic Thomas Edison, Albert Einstein, Michael Faraday, Willem Hollenbach, Orlando Bloom, Tom Cruise, Danny Glover, Whoopi Goldberg, Keanu Reeves, Oliver Reed, David Bailey, Leonardo da Vinci, Tommy Hilfiger, Pablo Picaso, Auguste Rodin, Andy Warhol, Duncan Goodhew, Cher, John Lennon, King Carl Gustav, Winston Churchill, Michael Heseltine, John F Kennedy, Nelson Rockefeller, George Washington, Hans Christian Anderson, Agatha Christie, F. Scott Fitzgerald, Richard Branson, F.W. Woolworth, Walt Disney, W.B. Yeats.

“We find comfort among those who agree with us – growth among those who don’t.” Frank A. Clark

Handout from www.bruce-evans.co.uk

for regular tweets on optometric research

6