BV OSCE Flashcards
Types of esotropia
- Primary
- Consecutive
- Secondary
Consecutive esotropia
Rarely develops spontaneously
. Constant/intermittent
. Most likely cause previously xot and has had surgery (over liberal surgery, deliberate to guard against re-divergence)
. If px has bsv try prisms
. Refer for surgery/btxa
Secondary esotropia
. The esotropia is secondary to a pathology such as (corneal opacity, macular lesions, glaucoma, optic atrophy, retinoblastoma)
. As children have a lot of accommodation, they tend to be esotropic when they get a pathology
. Surgery and/or btxa-adjustable sutures technique
. Leave slightly sot to guard against xot
Primary esotropia
- Constant – constant tropia (accommodative, non-accommodative)
- Intermittent – if patient has a phoria occasionally (related to accommodative effort, related to distance, related to time)
Constant Esotropia with an accommodative element
. Fully accommodative – deviation is totally corrected by correction of hypermetropia
. Partially accommodative- when there is a residual deviation president even with full hyperopic correction
Constant SOT with a partially accommodative element
. Partially accommodative esotropia
. Sot worse when accommodate – angle of esotropia larger at near
. Associated with hyperopia
. Size of sot decreases with hyperopic rx and in the distance
. Unilateral-amblyopia common
. Bsv present when fully corrected
Management: fully correct hypermetropia/leave if cosmesis good
-treat amblyopia
-refer- surgery/bxta in order to restore bsv/cosmesis
Infantile esotropia (congenital esotropia)
. Congenital esotropia
. Onset sot before 6 months
. Approx. 40% of children with neurological and developmental problems
. Cross fixation- uses le to look right and re to look left
. Angle usually greater than 30d so unlikely to gain bsv
. Usually alternating sot – no amblyopia
. May have small vertical deviation
. Look for dissociated vertical divergence (dvd) and manifest latent nystagmus (mln) and chp to reduce nystagmus, because of cross fixation (re turn to the re to adduct to re)
. Inferior oblique overaction common
Okn test in infantile esotropia: temporal to nasal (normal), nasal to temporal (weak)
Management: surgery (improve cosmesis, restore reduced bsv), consider age of surgery (functional vs cosmetic)
Dissociated vertical divergence (DVD):
-Presents before 2 years
-Eye drifts upwards spontaneously (fatigue) or after being covered
-Usually bilateral, often asymmetric
Nystagmus blockage esotropia
. Very rare
. Congenital, manifest (nystagmus present all the time), horizontal nystagmus
. Sot developed by trying to stop nystagmus
. Nystagmus amplitude increases on abduction
. Chp towards fixing eye to reduce nystagmus
. Sot variable angle
. Management: refer
Nystagmus (manifest latent):
-Nystagmus is present when both eyes open but nystagmus amplitude increases on dissociation (one eye covered)
-Amplitude increases on abduction
-Vision better on adduction
Non-accommodative esotropia
. Most common is infantile SOT
. Onset between 6 months- 2 years
. Refractive error insignificant
. Near deviation approximately equal distance deviation
. Amblyopia common
MANAGEMENT:
-amblyopia treatment
-surgery (improves cosmesis, restore reduced BSV)/BTXA
-consider age of surgery (functional vs cosmetic)
Late onset esotropia
. Usually after 4/5 years old
. Between 2-8 years olds
. Late onset means they have bsv
. May have been intermittent originally
. Diplopia present early stages rapidly moves to suppression if not corrected
. Normal retinal correspondence and sensory and motor fusion present
. Correcting refractive error has no effect
Management:
-Surgery once deviation stable
-Any signs of neurological problems, papilloedema, motility problems, nystagmus refer
-Refer hes for surgery/btxa
- Primary intermittent esotropia
They will have phoria in some positions
Fully accommodative esotropia
. Aetiology: uncorrected hyperopia
. Onset 2-3 years
. No SOT at all distances when fully corrected
. Associated with uncorrected hypermetropia (2D-7D), high AC/A
. Cover test (with full Rx- well controlled SOP all distances, without Rx-esotropia unilateral or alternating)
. BSV good with Rx
. Nil amblyopia
MANAGEMENT: if Rx fully corrects deviation surgical option not necessary especially when BSV is normal. If only a partially accommodative deviation, then surgery or prism may be required to correct)
Convergence excess esotropia
. Aetiology: high AC/A ratio greater than 6:1, every time they accommodate, they converge too much
. Onset 2-5 years
. Usually hyperopic, occasionally has emmetropia and rarely myopia
. Cover test
-no accommodation needed in distance so SOP (phoria) and BSV
-at near with light SOP as no accommodation with light
-SOT at near with accommodative target
-without hyperopic Rx SOT all distances
-MANAGEMENT: correct Rx fully if hypermetropic, under correct myopic
-bifocals- stops Px accommodation at near (minimum amount of plus to control near)/wear for 6 months and reduce by +0.50DS every 6 months
-exercises- improve negative fusional vergence
-surgery-bilateral medial rectus recession
Near esotropia
. With cover test (SOT at near, SOP and BSV at distance)
. Often nil significant refractive error
. Normal AC/A
. Normal ocular motility
. Often have equal VA as intermittent so might have amblyopia
-MANAGEMENT: surgery only (bilateral medial rectus recession)
Distance esotropia
. With cover test (SOT at distance, SOP or straight at near)
. Often no significant refractive error
. Normal AC/A
. Normal motility
. Often in elderly
. Exclude VI nerve palsy
MANAGEMENT: surgical only (asymmetrical lateral rectus resections,
Ipsilateral medial rectus recession)
Cyclic esotropia
. Rare- also known as alternate day squint
. Esotropia alternates day by day
. Constant esotropia on “squinting day” with no demonstrable binocular function
. Bsv with little or no esophoria on straight day
HISTORY of SOT
. Which eye?
. Direction of strabismus
. How often (constant/intermittent/regularity) constant=no bsv
. How long has it been there for (likelihood of amblyopia)
. When do parents notice (during a particular activity)
. Is vision good
. Birth history (premature/weight)- forceps damage lr
. Previous ocular history (any pathology), any treatment (surgery)
. Gh
. Fh (strabismus, amblyopia, refractive error)
Investigation of SOT
- VA- amblyopia common in constant except if alternating, uncommon intermittent
Consecutive esotropia – often have amblyopia
Secondary esotropia- vision likely to be poor
Infantile SOT – allow CHP to achieve best VA - Cover test- enable differentiation of different types of SOT
With and without Rx
Near and distance
With a light and accommodative target at near if SOT
Look for DVD and MLN - Ocular motility
IO and SO underaction with a V pattern, especially in constant esotropias - near point of convergence
Important indicator of control for near - measurement of angle
Consider age, level of vision – PCT best test to measure deviation
If poor vision, use krimsky- prism placed over fixing eye
Prism reflection test (PRT)- uncooperative and has SOT
Hirschberg’s test-babies (near and distance) - controlled binocular acuity test (CBA)
Patient looks target Snellen chart/budgie stick at near
Performed at distance using LogMAR
Point where they become manifest (double) – CBA is one before
Differential diagnosis using CBA
-In convergence excess SOT- near SOT will occur as patient accommodates to read further down the chart
-Near SOT- near SOT there all the time so not affected by accommodation
-fully accommodative SOT- near with Rx- No SOT patient remains SOP all the way down the chart
- measure AC/A ratio
Convergence excess esotropia has highest AC/A - measure binocular function
Sensory fusion (to assess diplopia, suppression, and ARC)
Motor fusion
Stereopsis - post-operative diplopia test
In patient with suppression this test must be performed to avoid diplopia
. measured with prisms
. prims placed before deviated eye
. base opposite the deviation then base in same direction
. prism increased until patient reports diplopia
. if complains of diplopia after small correction then not a good candidate for surgery - refraction
. refraction carried under cycloplegia
. >12months- use cyclopentolate 1%
. 6-12 months with light irides- use cyclopentolate 0.5%
. 6-12 months with dark irides- use cyclopentolate 1%
. 3-6 months – use cyclopentolate 0.5%
. atropine 1% to achieve full cycloplegia in patients with darkly pigmented irides
-glasses prescribed when indicated and worn full time for at least 1 month to enable accurate diagnosis - fundus and media examination
Management of esotropia (SOT) stage 1
. Refraction
. Fundus and media examination
. Correction of ametropia
. Even when you refer give hyperopic rx
. Amblyopia therapy particularly if they under 7 years of age if has sot and suppression> 5 years old must have sbisa before treating as can cause tractable diplopia
Management of esotropia (SOT) stage 2
Improve alignment of visual axis
. restore BSV
. enhance ARC
. no potential for BSV consider surgery (self-esteem, mood, quality of life)
Management options
1. conservative
Observe-monitor
Optical (prisms, manipulation Rx)
Orthoptic exercises
- non-conservative- refer to HES
Surgery
Botulinum Toxin
Conservative optical management
- Hyperopic glasses
-relax accommodation and therefore convergence
-order full plus in all accommodative SOT - Prisms
-Base out prisms
-resolve diplopia
-investigate BSV before surgery
-assess risk of diplopia post-op - Exercises
-improve negative relative convergence (look through the cats by cutting holes in the cats tummy)
-used in intermittent SOT
-lend prism bar- Base IN exercise - Surgery
-angle > near (both medial rectus recessions)
-angle>at distance (both lateral rectus recessions)
-near angle=distance angle (MR recession and LR resection on one eye) - Botox
-neurotoxin which paralyses muscle into which it is injected
-paralyzes the muscle within 5-7 days, recovery of muscle function up to 3 months
-injected into medial rectus for esotropia
-antagonist (lateral rectus) has the advantage
-eye moves out
Advantages: useful as results are temporary:
-consecutive SOT- as already had surgery
-residual SOT-reducing deviation might allow patients to regain control
-secondary deviation-when vision poor
-useful to confirm is post-op diplopia suggests intractable diplopia
Secondary exotropia
-XOT follows visual impairment from a pathology
-nil fusion causes eye to drift
-usually constant, unilateral
-more likely in older patients
-Management: treat amblyopia, refer HES, treat underlying condition
Consecutive exotropia
-XOT follows previous esotropia/phoria
-often constant
-may occur spontaneously (no BSV & amblyopia)
-often after surgery for eso deviation (over correction by surgeon)
-management: under 8 years (refer) to prevent loss of BSV or amblyopia
Primary exotropia
-Initial defect was the XOT
-Constant or intermittent
Primary constant exotropia
-XOT under all viewing conditions
-ensure nil pathology or neurological disease particularly <2 years
-consider refer to HES
-amblyopia may develop if occur early
MANAGEMENT:
-treat amblyopia
-BOTOX-into lateral rectus muscle
-surgery- MR AND LR in affected eye, adjustable sutures in px with diplopia
Intermittent near XOT
more common in adults than children
-more likely to complain of diplopia
-may complain of problems for near work (headaches, diplopia, asthenopia symptoms)
-cover test (near xot, distance controlled (phoria)
Management:
-under correct hyperopic rx
-prism- base in
-surgery-bilateral medial rectus resection
Intermittent non-specific XOT
-intermittent XOT/BSV at any distance of viewing
-can present in any age group
-diplopia unlikely-usually suppression occurs
-Management- refer for surgery
Intermittent distance XOT
-near=BSV
-distance-intermittent or constant XOT
-most common in children
-suppression normally occurs when manifest-diplopia rare
-may close one eye in bright light
Distance XOT split into
1. True distance XOT
-near BSV
-distance XOT
- simulated distance XOT
-want to break into XOT at near but controlled by accommodation (high AC/A Ratio), which is eliminated by +3.00DS causing them to become manifest at near
-controlled at near by fusion which is eliminated using patching
Differential diagnosis- carry CT after 45 minutes of occlusion if deviation controlled at near after occlusion, then true, if near manifest after occlusion than simulated
Management:
-prism- base in relieving
-minus lenses-particularly those with high AC/A
-surgery
