Intermittent Exotropia - A Case Of Pseudo divergence Excess

Krishna Banjade Consultant optometrist in pediatrics and strabismus

ABBREVIATIONS

X’ - Exophoria XT - Exotropia X(T) - Intermittent Exotropia CT – Cover Test PD – Prism Dioptre IOP – Intra Ocular Pressure PACD – Peripheral Anterior Chamber Depth RAPD – Relative Afferent Pupillary Defect Sx – Surgery RTC – Return To the Clinic

PATIENTS DETAIL

Age : 10 Years/ Male

Profession - Student

Address- Lucknow, Uttar Pradesh, India

First visit - 05/07/2014

VISIT 1Visit 1

CHIEF COMPLAINTS

(OU) Gradual progressive painless blurring of vision for near and distance since 5 years

Occasional outward deviation of eyeballs noticed by parents since 4 years

Photophobia since 1 year

HISTORY

Recent ophthalmic consultation locally - diagnosed Alternate exotropia - referred to our hospital for further management

No h/o using glasses/contact lens/patching

No h/o head and ocular injury

No h/o seizures, Asthma and CAD

Normal pre, peri and postnatal birth history with normal physical , emotional and cognitive development

CONTD…

Family history- mother myopic

Not aware of any allergy

No h/o systemic diseases

No h/o past lasers, surgeries and medications

OD OS

Unaided Visual Acuity

20/60 20/100

With Pinhole 20/30 20/30

Near Vision N6 @ 30 cm with Snellens Chart in RI

N6 @ 30 cm with Snellens Chart in RI

Dry Retinoscopy -1.50/-0.75* 10 -2.00/-0.75 * 160

Dry Acceptance -1.50 DSph (20/30), N6 @ 30 cm

-2.00 DSph (20/30), N6 @30 cm

Cycloplegic Retinoscopy(cyclopentolate)

-1.50/-0.75 * 10 -1.50/-0.75*160

Refraction

Facial Asymmetry nil

Abnormal head posture nil

Nystagmus nil

EOM Movement Full, Free and Painless

Hirschberg's Test LXT 10 Degree

Cover Test 25-30 PD X(T) ( Distance) 12 PD X(T (Near)

Stereo Acuity using Random Dot Stereogram Test

80 sec of arc

External Examination

OD OS

Lids Flat Flat

Conjunctiva Quiet Quiet

Cornea Clear Clear

AC PACD > 1/2 CT, Quiet PACD > 1/2 CT, Quiet

Pupil R/R/R, No RAPD R/R/R

Iris Normal color and pattern

Normal color and pattern

Lens Clear Clear

IOP With GAT 13 mm of Hg @ 11:10am

14 mm of Hg @ 11:10am

Slit Lamp Examination

OD OS

Media Clear Clear

Retina On On

Macula Healthy Healthy

C/D 0.2 0.2

Fundus examination

DIAGNOSIS ?

DIAGNOSIS

(OU) Compound Myopic Astigmatism Intermittent Exotropia

PLAN OF RX

Glasses

Reassure

EOM Sx If Required

Patch Test next visit

RTC 3/12

INTERMITTENT EXOTROPIA

Obstracles to development or maintenance of BSV

Defective action of MR Muscles

Defective fusional convergence (1)

New born infants with transient exodeviation (2)

Refractive Errors, Anisomyopia and Anisoastigmatism (3)

Differs from Exophoria1. Worth C. Squint, its causes, pathology and treatment ed. 6. London 1929, Bailliere, Tyndall and Cox 2. 2. Archer SM, Helveston EM: Strabismus and Eye Movement Disorders. In Isenberg SJ (ed) The eye in Infancy

1994 Mosby, pg 255.3. Jampolsky A, Flom BC, Weymouth FS, Moster LE. Unequal corrected visual acuity as related to anisometropia Arch Ophthalmol. 1955;54:893

Tropia Phase of Intermittent exotropia observed when :

In Child - Tired, sick or day dreaming In Adults - Also after imbibing alcoholic beverages or taking

sedatives

PREVALENCE

Comprises 50-90% of cases of Exotropia

Affects 1 % of general population (1,2)

Nearer a country is to the equator the higher the prevalence of exodeviations (3)

1.Govindan M, Mohney BG, Diehl NN, Burke JP. Incidence and types of childhood exotropia: a population based study. Ophthalmology. 2005 Jan;112(1):104-8.

2. Noorden GK von. Exodeviations. In: Binocular Vision and Ocular Motility 5 th ed., 1996 Mosby, pg 343

3. Jenkins R. Demograhics: geographic variations in the prevalence and management of exotropia. Am. Orthopt. J. 1992,42:82.

NATURAL HISTORY

Remains obscure

Some cases

First at distance and then at near

Not all the cases are progressive, may be constant or even improve

ExophoriaIntermitte

nt exotropia

constant

Noorden GK von. Exodeviations. In: Binocular Vision and Ocular Motility 5 th ed., 1996 Mosby, pg 343

FACTORS TO BE RECORDED FOR PROGRESSION

Amount of Loss of fusional control with increasing strabismus

Development of a secondary convergence insufficiency

Increase in size of basic deviation

Development of Suppression

SYMPTOMS OF INT. XT

Transient Diplopia

Asthenopic symptoms

Photophobia (1)

Micropsia (2)

1. Manley DR. Classification of the exodeviations. In: Manley D ed.: Symposium on horizontal ocular deviations. St. Louis. 1971. Mosby-Year Book Inc. p128

2. Noorden GK von. Exodeviations. In: Binocular Vision and Ocular Motility 5 th ed., 1996 Mosby, pg 361

PATCH TEST

Noorden GK von: Atlas of Strabismus, ed 4. St Louis, Mosby–Year Book, 1983

Visit 2nd

1ST FOLLOW UP 10/09/2014

OD OS

VA with PGP

20/30 – NI with PHN6 @ 30 cm with Reduced Snellens chart

20/25 – NI with PHN6 @ 30 cm with Reduced Snellens chart

Stereopsis with PGP

60 Seconds of Arc With Random Dot Stereo Card

CT with PGP Dist. – 18 PD X(T)Near - 6 PD X(T)

Slit Lamp Examination

WNL

PROVISIONAL DIAGNOSIS

Basic Intermittent Exotropia

Divergence Excess

Convergence Insufficiency

Simulated or Pseudo-divergence Excess

Basic Intermittent Exotropia - Deviation for distance and near within 10∆

- Normal Accommodative, Fusional and

Proximal convergence

• Divergence Excess - Deviation for distance > 10∆ than near even after patch test

- High AC/A Ratio

Convergence Insufficiency - Near deviation > 10∆ than distance deviation

Simulated / Pseudo divergence Excess - Larger exotropia for distance than near but

near deviation increases within 10 PD

of distance deviation after Patch Test

Burian HM: Exodeviations: Their classification, diagnosis, and treatment. Am J Ophthalmol 62:1161, 1966

COVER TEST AFTER 1 HOUR PATCHING( WITH PGP)

Distance = 20-25 PD X(T)

Near = 20-25 PD X(T)

FINAL DIAGNOSIS

(OU) Compound Myopic Astigmatism

Intermittent Exotropia

(Pseudo divergence Type)

PLAN OF RX

Continue same glass

RTC 6-8 months

• Patch Test is the main criterion for differentiating true and pseudo divergence exotropia

• Nevertheless, not all intermittent exotropia are progressive nor do they need surgical interventions

• Proper clinical history with relation to classical symptoms plays vital role for the diagnosis

Thank you…