AMBLYOPIA/STRABISMUS - PowerPoint Presentation

Slide1

AMBLYOPIA/STRABISMUS

KEHINDE, A. V.,

MB;BS, FWACS, FICS

Senior Ophthalmic SurgeonSlide2

Amblyopia refers to a decrease of vision, either unilaterally or bilaterally, for which no

anatomical cause

can be

found.Slide3

TERMINOLOGIES

Functional amblyopia often is used to describe amblyopia, which is potentially reversible by occlusion therapy.

Organic

amblyopia refers to irreversible amblyopia.

Amblyopia-ex-

anopsia

AmblyopiaSlide4

Pathophysiology

Amblyopia

is believed to result from

‘disuse atrophy’ from

inadequate foveal or peripheral retinal stimulation, (typically due to refractive errors) and/or abnormal binocular interaction that causes different visual input from the foveae

.

Slide5

SENSITIVE PERIODS

The development of visual acuity from the 20/200 range to 20/20, which occurs from birth to age 3-5 years.

The period of the highest risk of deprivation amblyopia, from a few months to 7 or 8 years.

The period during which recovery from amblyopia can be obtained

, is

from the time of deprivation up to the teenage years or even sometimes the adult years. Slide6

EPIDEMIOLOGY

Range from 1-3.5% in normal children to 4-5.3% with ophthalmic problems. Most data show that about 2% of the general population has amblyopia.

It is the leading cause of monocular vision loss in adults aged 20-70 years or older. Slide7

EPIDEMIOLOGY (Contd.)

Mortality/Morbidity

Amblyopia is an important socioeconomic problem. Studies have shown that it is the number one cause of monocular vision loss in adults. Persons with amblyopia have a higher risk of becoming blind because of potential loss to the sound eye from other causes.

Race/Sex

No racial /gender preference is known.

Age

Amblyopia occurs during the critical periods of visual development. An increased risk exists in those children who are developmentally delayed, were premature, and/or have a positive family history. Slide8

CAUSES OF AMBLYOPIA

Anisometropia

Small amounts of hyperopic

anisometropia

, such as 1-2

diopters

, can induce amblyopia. In myopia, mild myopic

anisometropia

up to -3.00

diopters

usually does not cause amblyopia.

Strabismus

Incidence of amblyopia is greater in

esotropic

patients than in

exotropic

patients.

Visual deprivation

Amblyopia results from disuse or

understimulation

of the retina. This condition may be unilateral or bilateral. Examples include

cataract,

corneal opacities,

ptosis

, etc.

Organic

Structural abnormalities of the retina or the optic nerve may be present. Slide9

MANAGEMENT

OF AMBLYOPIASlide10

HISTORY

Elicit any previous history of patching or eye drops as well as past compliance with these therapies.

Document previous ocular surgery or disease.

In addition to the routine information, obtaining a family history of strabismus or other ocular problems is important because the presence of these ocular problems may predispose a child to amblyopia. Slide11

DIAGNOSIS

Visual acuity

Usually requires a 2-line difference of visual acuity between the eyes.

Crowding phenomenon

There is difficulty in distinguishing

optotypes

that are close together. VA is better when the patient is presented with single letters rather than a line of letters. Slide12

DIAGNOSIS (Contd.)

Contrast sensitivity

Strabismic and anisometropic amblyopic eyes have marked losses of threshold contrast sensitivity; this loss increases with the severity of amblyopia.

Neutral density filters

Patients with strabismic amblyopia may have better visual acuity or less of a decline of visual acuity when tested with neutral density filters compared to the normal eye.

Binocular function

Amblyopia usually is associated with changes in binocular function or stereopsis.

Eccentric fixation

Some patients with amblyopia may consistently fixate with a nonfoveal area of the retina under monocular use of the amblyopic eye, the mechanism of which is unknown. This can be diagnosed by holding a fixation light in the midline in front of the patient and asking them to fixate on it while the normal eye is covered. The reflection of the light will not be centred. Slide13

Testing in preverbal children

Cover/Uncover test.

Fixation preference may be assessed, especially when strabismus is present.

Induced

tropia

test may be performed by holding a 10-prism

diopter

before one eye in cases of an

orthophoria

or a

microtropia

.

Cross-fixationSlide14

TREATMENT

Refraction

Cycloplegic

refraction must be performed on all patients, using

retinoscopy

to obtain an objective refraction.

Occlusion therapy/Patching

Rule-One week/Year of age

Full time

Part time

Referral

Perform a full eye examination to rule out ocular pathology. Slide15

STRABISMUS

(DEFN.)

A visual defect in which one eye cannot focus with the other on an object because of imbalance of the eye muscles.

A mis-alignment of the visual axes of the two eyesSlide16

CLASSIFICATION

Apparent Squint (

Pseudostrabismus

)

Latent squint (

Heterophoria

)

Manifest squint (

Heterotropia

)

a. Concomitant

b.

Inconcomitant

(paralytic, A &V patterns, Restrictive squint)Slide17

Pseudostrabismus

Pseudoexotropia

Hypertelorism

Pseudoesotropia

Prominent

epicanthal

foldsSlide18

HETEROPHORIAS

CAUSES

ORBITAL

ASYMMETRY

ABNORMAL IPD

FAULTY INSERTION OF EOM

EOM WEAKNESS

MALPOSITION OF MACULA IN RELATION TO THE OPTICAL AXIS

INCREASED ACCOMMODATION

INVESTIGATION

VA/REFRACTION

COVER/UNCOVER TEST

PRISM COVER TEST

MADDOX ROD TESTSlide19

CONCOMITANT STRABISMUS

A manifest squint in which the amount of deviation is constant in all directions of gazeSlide20

CAUSES OF CONCOMITANT STRABISMUS

Sensory causes:

Refractory errors, prolonged use of incorrect spectacles, media opacities,

neuroretinal

dxs

.

Motor causes:

Malformed orbits, EOM disorders

Central causes:

Fusional deficiencies, Cortical deficienciesSlide21

TYPES

EXOTROPIA

ESOTROPIA

HYPERTROPIA

HYPOTROPIASlide22

1. Infantile

esotropias

2. Accommodative

Esotropia

Refractve

Non-refractive

3. Non-accommodative

esotropia

Stress-induced

Sensory deprivation

CN VI palsy etc. Slide23

Infantile esotropia

Presents usually within first 6mos of life

Usually alternating

Error is usually normal for the age of patient, +1 -+1.50.00DS

Correct significant refractive errors and amblyopia

SurgerySlide24

Accommodative Esotropia

Refractive : 6mos-7yrs.

Hypermetrope

, +3 - +7. correct deviation with specs

Non-refractive: Esotrop

ia

for near. Correct with +3.00

Mixed AE

Esotropia

for far, worse for near. Correct

Hypermetropia

with a plus add, (Bifocals)

FundoscopySlide25

Exotropias

Intermittent

Constant

Convergence insufficiency

Divergence Excess

BasicSlide26

TREATMENT

Spectacle correction

Orthoptic

treatment

Occlusion therapySurgery/ReferralSlide27

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