Constant Esotropia Flashcards
What are the 4 non-paralytic forms of esotropia?
1) Primary
2) Consecutive
3) Secondary (Sensory)
4) Residual
What is non-paralytic esotropia?
Not an issue with the nerve
What is Primary Non-Paralytic esotropia?
No other reason for it
What is Consecutive non-paralytic esotropia?
After the eye has been in a different position i.e. was an Exo but became an Eso post-surgery
Spontaneous conversion from initial large-angle exotropia to esotropia or orthophoria can be encountered (Voide and Robert, 2018)
What is Secondary/Sensory non-paralytic esotropia?
E.g. lost vision in one eye/blindness in one eye so it begins to turn in
What is Residual non-paralytic esotropia?
What is left in prism dioptres after surgery or botox
What is a primary constant esotropia?
Esotropia is the initial defect and is present under all conditions (including Nr and Dist & in 9 positions of gaze)
Primary = Origin
Constant = Presence
Esotropia = Direction
After surgery want PD do we want the patient to be in to orthophoria?
Ideally want the patient within 10PD of orthophoria. With an adjustable suture you can adjust the eye to fine-tune the angle you want the eye to be at.
What is the incidence of esotropia?
More common than exotropia in childhood in Western populations.
In school children - 0.3-3.6%
Or 111 per 100,000 <19yo
Cumulative prevalence 2% children <6yo
What did Bruce and Santorelli find in Bradford children aged 4-5yo?
Ratio of Eso to Exo was 1:7. Have a high Pakistani background in Bradford.
What did Greenberg et al (2007) find?
Prevalence of esotropia 2% before 5yo and accommodative types made up nearly half of the study
Peaks further at 12-14yo and 18yo due to educational demands = more reading - need to converge and accommodate more (26.7% with constant esotropia, most common are intermittent)
What are the risk factors associated with constant esotropia (Torp-Pedersen et al, 2010)?
- Normal paediatric pop. 0.1 - 6%
- Low birth weight <3kg (strabismus prevalence of 12-36%)
- Premature birth before 37 gestational weeks (more premature = higher deviation)
- Large head circumference
- Children with chromosomal abnormalities or syndromes
What are the genetics associated with strabismus?
- Primary esotropia
- Linkage to chromosome 7 for ET and XT, locus STBMS 1
How can Primary Constant Esotropia be split?
- With accommodative element (partially accommodative)
- Without accommodative element
What is a primary constant esotropia with an accommodative element?
The esotropia is affected by accommodative effort. Previously know as Partially Accommodative Esotropia. Relaxed accommodation will help (+ve lens/convex lens)
What is a primary constant esotropia without accommodative element?
The esotropia is unaffected by accommodation and the size of the deviation is approximately the same with and without refractive correction. However significant refractive error is unlikely to be present.
What might accommodative esotropia result from?
- Uncorrected refractive error
- High AC/A ratio
What is accommodative esotropia sensitive to?
Blur.
Horwood and Riddel (2013, 2014) have shown that accommodative esotropia is sensitive to blur and excessive accommodation is exerted to see clearly. So driven by clarity to see clearly so would rather have clarity than binocularity = breakdown of BSV and esotropia develops
What is the age of onset for constant esotropia with accommodative element? Why?
1 - 3 years old
This type of esotropia mostly arises from a small early onset esotropia which later develop an accommodative element causing an increase in the size of the deviation. These patients generally have poor potential for BSV. Or it may arise from the decompensation of an intermittent esotropia and these patients usually have good potential for BSV.
How can refractive error assist with a constant esotropia with accommodative element?
- ET increases significantly on accommodation without glasses
- ET decreases with hypermetropic correction but not eliminated
Uncorrected hypermetropia – may result in the esotropia increasing on accommodation but reducing in size by wearing the hypermetropic correction, although the esotropia is not eliminated and remains manifest convergent deviation for near and distance fixation.
Previously know as Partially Accommodative Esotropia.
How may a constant esotropia with accommodative element by affected be a high AC/A ratio?
- ET for near more than 10∆ greater than for distance
- ET reduces for near with +3.00DS, but not eliminated
The size of the deviation will be greater for near (at least 10Δ) than distance fixation. The deviation for near fixation will decrease with additional +3.00DS (example bifocals) but will never be eliminated.
How might a constant esotropia with accommodative element be affected by both refraction and high AC/A ratio?
Example with high AC/A ratio:
s/gls N 45 ET
s/gls D 20 ET
= Near angle is higher than distance angle by more than 10PD so may have a combo of refractive and a higher AC/A ratio. A larger deviation for near persists after refractive correction but reduces with +3.00DS.
BUT a high hypermetropia can decrease the esotropia by a significant amount in the presence of a normal AC/A ratio and may not have an abnormal accommodative component
How might a constant ET WITHOUT an accommodative element be broken down into?
Acquired ET with myopia
Nystagmus block syndrome
Micro-ET
Acquired non-accommodative ET (late-onset called normosensorial and early-onset which is 6mo - 2yo)
Infantile ET (<6mo)
What are the features of acquired non-accommodative esotropia that’s early onset?
Onset 6mo - 2yo
Common to have amblyopia
Poor prognosis for restoring BSV due to age of onset
Deviation may increase with time
Often require surgery to improve cosmesis of the ET
