ET Flashcards
amblyopia
reduction in vision (20/30 or worse) in a healthy eye. The reduced vision is a result of changes at the cortical level due to suppression
types of amblyopia
form deprivation
refractive amblyopia
strabismic amblyopia
form deprivation amblyopia
occurs when there is an obstruction of a clear image to the retina before the age of 6-8 years of age
critical period
7-9yo
refractive amblyopia
occurs when there is a large amount of anismetropia between the two eyes (anisometropic amblyopia) or a large amount of refractive error is present in both eyes (isometropic amblyopia)
strabismic amblyopia
occurs when the visual axes of each eye are misaligned under binocular conditions, resulting in diplopia and confusion due to a lack of fusion. The patient may eventually develop suppression, which occurs when the image from one eye is filtered out at the cortical level.
types of ET
infant
acquired
secondary
micro
types of acquired ET
accommodative
acute
mechanical
all occur after 6m of age
types of secondary ET
sensory
consecutive
infantile ET
large angle (40-60), constant ET that occurs prior to 6m of age and is usually idiopathic in nature. Additional associated include DOL (DVD, OIO, Latent nystagmus). Because of the large angle of deviation within the cortical period, non-accommodative infantile ET is often treated with surgery
accommodative ET
acquired
secondary to accommodation and is due to either s high amount go uncorrected hyperopia and/or a high AC/A ratio. Initially, the deviation may be intermittent, but it may become constant If not prompts treated. Treatment is typically with corrective lenses (bifocals may be necessary). Prism, VY, and/or surgery may be considered if glasses do not help to avoid suppression, amblyopia, and ARC
treatment for someone with a high AC/A
lenses
infantile ET is the same as
congenital ET
acute ET
acquired
has a sudden onset and is secondary to a neurological problem (CN6 palsy) or a decompensated phoria. Although some cases resolve over time, treatment with patching or surgery may be necessary
mechanical ET
acquired
secondary to a physical restriction of an EOM (type 1 Duanes)
neuro vs decompensated phoria
test for comitancy
- comitant=decompensated phoria
- noncomitant=neuro
things about Duanes
left eye
female
adduction=globe retraction and fissure narrowing
sensory ET
secondary
occurs after the age of 5 and is a result of reduced VA in one eye from trauma, disease, etc
consecutive ET
secondary
is iatrogenic and is usually due to overcorrection of an XT during strabismic surgery. Treatment includes prism, VT, lenses
micro ET
constant unilateral eso less than 10PD before age 3 small central suppression scotoma use 4BO to confirm leads to intractable diplopia treat with VT or prism
best way to check VAs in amblyopia
one letter at a time due to the crowding effect
W4D
evaluates flat fusion ability and the presence of suppression when stereopsis is worse than 40 seconds of arc. The patient wears RG glasses with the red lens over the right eye while viewing a flashlight with 4 dots (1 white, 1 red, 2 green) at distance and near. the right eye will see a white and red dot (2 dots), the left eye will see a white dot and 2 green dots (3 dots)
W4D: 2 red dots seen
OS suppression
W4D: three green dots seen
OD suppression
W4D: 4 dots
flat fusion without suppression
W4D: 5 dots seen
diplopia
W4D and suppressing at distance vs near and light vs dark
patients who suppress at distance only and only with the room lights on have a shallow and small suppression scotoma. If the patient also suppresses at near and with the room lights dim, he has a large and deep suppression scotoma
spectacle correction and amblyopia
according to PEDIG ATS, spec correction alone will resolve amblyopia in 1/3 of patients with moderate anisometropic amblyopia (BCVA 20/40-20/80). A bifocal may be necessary at near in order to decrease the patient’s accommodative demand, particularly if the patient has a high AC/A
PEDIG amblyopia treatment guidelines
consider adding one treatment at a time
- correction of refractive error
- occlusion therapy with patching or atropine
- structured near activities and/or VT
PEDIG: patching ages 3-6: moderate amblyopia
2 hr/day
PEDIG: patching ages 3-6: severe amblyopia
6hr/day
PEDIG: atropine ages 3-6: moderate amblyopia
2 days/week
PEDIG: atropine ages 3-6: severe amblyopia
2 days/week
when would you use atropine vs patching
if the patient is not compliant with patching to patching results in only a minimal improvement in BCVA
moderate amblyopia
20/40-20/80
severe amblyopia
20/100-20/400
ATS-3
treating amblyopia in older children ages 7-17 with moderate and severe amblyopia
results of ATS-3
- over 50% of patients had 2 or more lines of improvement in BCVA when treated with patching or atropine
- almost 50% of patients ages 13-17 who received no prior amblyopia treatment improved with patching or atropine
when to d/c amblyopia treatment in older kids
if the patient is compliant with treatment and the initial gain in VA stabilizes
atropine vs patching: PEDIG
demonstrated that atropine and patching result in similar improvements in BCVA for patients with moderate amblyopia. After 6 months, the amblyopic eye was 20/30 or better, and/or improved 3 or more lines from baseline BCVA in approximately 75% of patients in both study groups. the recommended treatment duration is 6 months, with follow up exams every 4-6 weeks
adverse effects of atropine
increased blood pressure, mental confusion, increased pulse, dryness of mouth and throat, and loss of neuromuscular coordination
- hot as a hare, dry as a bone, red as a beat, mad as a hatter.
- RX homatropine 5% if side effects occur
epicentral folds
most often seen in asian infants and infants with Down syndrome. They are prominent vertical nasal skin folds that may cause the eyes to appear as if they are in esophaguses position when they are actually ortho. they do not increase the risk of strabismus
risk factors for strabismus
downs syndrome famhx cerebral palsy diabetes head trauma
