CYCLICAL ESOTROPIA

Question 1

What is cyclical SOT + aetiology?

Answer 1

• ET at near and distance at regular intervals, alternate day strabismus’
• Aetiology: ? Related to biological clock mechanism and abnormality in superior colliculi, oculomotor nuclei or other nuclei

Question 2

Characteristics of cyclical sot?

Answer 2

• Characteristics: : Normally alternate day cycle (48h), 24h manifest N & D then 24h straight with BSV, No sig refraction, Suppression when manifest, Orthophoria or E on straight day, Generally becomes constant 4-11 months
• Age of Onset: 4-6 yrs

Question 3

Investigation of cyclical sot?

Answer 3

• Case history
• Review on ET and straight day
• Diary of when changes
• Refraction
• VA
• CT; light, accom target, dist, c & s gls
• BSV – vary depending on day
• PCT
• OM
• Accommodation
• Convergence
• AC/A ratio

Question 4

What are aim of management in cyclical sot?

Answer 4

• Equal VA (Correct any refractive error, Correct any refractive error)
• Determine cycle (Manifest phase normally increases until constant ET)
• Restore NBSV

Question 5

Surgery in cyclical sot?

Answer 5

• Timing of surgery important – early whilst still intermittent otherwise could reoccur
• Unilateral MR recession / LR resection
• Bilateral MR recession
• Weakening of both IO (if bilateral IO o/a & significant V-pattern
• Sx and bilateral BT based on the largest manifest deviation on an ET day are associated with excellent surgical outcomes. Hennein & Moore (2020)

Question 6

Botulinum toxin in cyclical sot?

Answer 6

• Success in some patients
• Prisms also successfully used and Sx avoided
• Sx and bilateral BT based on the largest manifest deviation on an ET day are associated with excellent surgical outcomes. Hennein & Moore (2020)