CONCOMITANT STRABISMUS

SITI MARIAM BINTI MOHD HAMZAH

A type of manifest squint in which the

amount of deviation in the squinting eye

remains constant in all directions of gaze; and there is no associated

limitation of ocular movements

ETIOLOGY

• Binocular vision and coordination of ocular movements are not present since birth but are acquired in the early childhood.

• The process starts by the age of 3-6 months and is completed up to 5-6 years. Therefore, any obstacle to the development of these processes may result in concomitant squint.

ETIOLOGY

Sensory obstacles• Refractive errors• Prolonged use of

incorrect spectacles • Anisometropia• Corneal opacities• Lenticular opacities• Diseases of macula• Optic atrophy• Obstruction in the

pupillary area due to congenital ptosis

Motor obstacles• Congenital

abnormalities of the shape and size of the orbit

• Abnormalities of extraocular muscles

• Abnormalities of accommodation, convergence and AC/A ratio

Central obstacles• Deficient

development of fusion faculty

• Abnormalities of cortical control of ocular movements, and hyperexcitability of the CNS during teething

1. OCULAR DEVIATION• Unilateral or alternating• Inward deviation or outward deviation or vertical

deviation• Primary deviation is equal to secondary deviation • Ocular deviation is equal in all directions of gaze

CLINICAL FEATURESIN GENERAL

2. OCULAR MOVEMENT• Not limited in any direction

3. REFRACTIVE ERROR• May or may not be associated

4. SUPPRESSION AND AMBLYOPIA• May be develop as sensory adaptation to strabismus• Amblyopia develops in monocular strabismus only and is

responsible for poor visual acuity

5. A-V PATTERNS• May be observed in horizontal strabismus.• when this patterns associated, the horizontal concomitant

strabismus becomes vertically incomitant

V esotropia

A esotropia

Convergent squint (esotropia)

Divergent squint

(exotropia)

Vertical squint

(hypertropia)

TYPES

• Denotes inward deviation of one eye and is the most common type of squint in children.

• Unilateral or alternating

COVERGENT SQUINT

1. INFANTILE ESOTROPIA• Age of onset, usually 1-2 months, but may occur during

first 6 months of life• Angle of deviation is constant and fairly large (>30 degree)• Fixation pattern

• Binocular vision does not develop and there is alternate fixation in primary gaze and cross fixation in the lateral gaze

• Amblyopia in 25-40% cases

• Treatment• Amblyopia treatment by patching the normal eye should

always be done before performing surgery• Recession of both medial recti is preferred over

unilateral recess-resect procedure• Surgery should be done between 6 months – 2 years;

preferably <1 year

2. ACCOMMODATIVE ESOTROPIA• Occurs due to overaction of convergence associated with

accommodation reflex

• 3 types• Refractive accommodative esotropia

• Associated with high hypermetropia (+4 to +7D)• Fully correctable by use of spectacles

• Non-refractive accommodative esotropia• Caused by AC/A ratio• Esotropia is greater for near than that for distance• Fully corrected by bifocal glasses with add +3DS for near vision

• Mixed accommodative esotropia• Caused by combination of hypermetropia and high AC/A ratio• Esotropia for distance is corrected by correction of

hypermetropia; and the residual esotropia for near is corrected by addition of +3DS lens

3. ACQUIRED NON-ACCOMMODATIVE ESOTROPIAS

• Includes all those acquired primary esodeviations in which amount of deviation is not affected by the state of accommodation

4. SENSORY ESOTROPIA• Results from monocular lesions in childhood which either

prevent the development of normal binocular vision or interfere with its maintenance

5. CONSECUTIVE ESOTROPIA• Result from surgical overcorrection of exotropia

• Characterised by outward deviation of one eye while the other eye fixates

DIVERGENT SQUINT

Types– Congenital exotropia– Primary exotropia– Secondary exotropia– Consecutive exotropia

Rare, almost present at birthMay be unilateral or alternating and may be intermittent or constant exotropia

Constant unilateral deviation which results from long-standing monocular lesions associated with low vision in the affected eye

Constant unilateral exotropia which results either due to surgical overcorrection of esotropia, or spontaneous conversion of small degree esotropia with amblyopia into exotropia

EVALUATION• History• Examination:

- inspection- ocular movements- pupillary reactions- media & fundus examination- testing of vision & refractive error- cover tests (direct and alternate)- estimation of angle of deviation - tests for grade of binocular vision and sensory functions

• Direct Cover Test• confirms the

presence of manifest squint

• Alternate Cover Test• Reveals whether the

squint is unilateral or alternate

• Differentiates concomitant squint from incomitant squint

i. Hirschberg corneal reflex test

ii. The prism and cover test

iii. Krimsky corneal reflex test

iv. Measurement of deviation with synoptophore

TREATMENT• Goals of treatments:

- To achieve good cosmetic correction- To improve visual acuity- To maintain binocular single vision

• Treatment modalities:- spectacles with full correction of refractive error- occlusion therapy- preoperative orthoptic exercises- squint surgery- postoperative orthoptic exercises

• Squint surgery– Should always be instituted after the

correction of refractive error, treatment of amblyopia and orthoptic exercises.

Basic principles: These are to weaken the strong

muscle by recession (shifting the insertion posteriorly) or to strengthen the weak muscle by resection (shortening the muscle).

thank you