constant strabismus
Constant strabismus is a manifest deviation that is present all the time and under all circumstances. Intermittent strabismus, by contrast, is present at some times and not at others.1 In constant strabismus the fusion mechanism cannot keep the eyes aligned under any circumstances, whereas in intermittent strabismus fusion holds in some situations and fails if the patient is tired, ill or under stress.2
An intermittent strabismus may become constant if left untreated, but others remain intermittent.1 Harmonious anomalous retinal correspondence is more likely to develop in constant strabismus, because an intermittent deviation would force correspondence to shift between normal and anomalous as the eyes straighten and deviate.3 Constant strabismus that begins before 1 year of age is most commonly infantile esotropia syndrome and requires referral.4
More detail
Cyclic strabismus is a rare intermittent form with a large convergent strabismus on alternate days only.1 Cyclic strabismus makes up less than 0.1% of all strabismus and usually becomes constant after a few months.1 Unilateral strabismus is also more likely than alternating strabismus to develop harmonious anomalous retinal correspondence.3
Sources (5)
- Pickwell's Binocular Vision Anomalies, ch. 1
- von Noorden and Campos, Binocular Vision and Ocular Motility, ch. 8
- Pickwell's Binocular Vision Anomalies, ch. 12
- Pickwell's Binocular Vision Anomalies, ch. 15
- Rutstein, R., Daum, K. (1997) Anomalies of Binocular Vision: Diagnosis & Management, Mosby, pp. 348.
Reviewed October 2026