Transcript AMBLYOPIAx
KEHINDE, A. V.,
MB;BS, FWACS, FICS
Senior Ophthalmic Surgeon
Amblyopia refers to a
decrease of vision, either
unilaterally or bilaterally, for
which no anatomical cause
can be found.
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
Amblyopia
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.
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.
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.
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.
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.
OF AMBLYOPIA
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.
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.
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.
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-fixation
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.
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 eyes
CLASSIFICATION
Apparent Squint (Pseudostrabismus)
II. Latent squint (Heterophoria)
III. Manifest squint (Heterotropia)
a. Concomitant
b. Inconcomitant (paralytic, A &V patterns,
Restrictive squint)
I.
Pseudostrabismus
Pseudoexotropia
Hypertelorism
Pseudoesotropia
Prominent epicanthal
folds
HETEROPHORIAS
CAUSES
INVESTIGATION
ORBITAL
VA/REFRACTION
ASYMMETRY
ABNORMAL IPD
FAULTY INSERTION
OF EOM
EOM WEAKNESS
MALPOSITION OF
MACULA IN
RELATION TO THE
OPTICAL AXIS
INCREASED
ACCOMMODATION
COVER/UNCOVER TEST
PRISM COVER TEST
MADDOX ROD TEST
CONCOMITANT STRABISMUS
A manifest squint in which the
amount of deviation is constant in
all directions of gaze
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
deficiencies
TYPES
EXOTROPIA
HYPERTROPIA
ESOTROPIA
HYPOTROPIA
1. Infantile esotropias
2. Accommodative
3. NonEsotropia
accommodative
esotropia
Refractve
Stress-induced
Non-refractive
Sensory deprivation
CN VI palsy etc.
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
Surgery
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)
Fundoscopy
Exotropias
Intermittent
Convergence
Constant
insufficiency
Divergence Excess
Basic
TREATMENT
Spectacle correction
Orthoptic treatment
Occlusion therapy
Surgery/Referral
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