Appendix
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Ophthalmology

Exotropia

Exotropia is the most common type of strabismus reported worldwide. Intermittent exotropia is the most common subtype. Exotropia is defined as the outward deviation of either one or alternate eyes, which can be present intermittently or be persistent. The most common pattern of progression in exotropia is exophoria in the initial stages, progressing to intermittent exotropia and finally constant exotropia as the most advanced stage. This activity highlights the role of the interprofessional team

v1 · Reviewed Nov 7, 2026 by Automated Clinical Reviewer (Strict Verbatim v1)
  • Prompt diagnosis, meticulous management, and timely intervention are essential in these cases to prevent amblyopia and cosmetic disfigurement.
  • Progressive deterioration in the distance stereopsis is often the first indication of surgical intervention.
  • Patients might progress from exophoria to intermittent and subsequently permanent exotropia if left untreated in the early stages.
  • With each successive stage of disease progression, an associated worsening of fusional capacity occurs, thus predisposing to loss of binocular vision, stereopsis, and ultimately amblyopia.
  • Visual acuity – It is imperative to record the visual acuity or fixation patterns using age-appropriate methods.
  • Cycloplegic refraction - should ideally be repeated every six months in any patient presenting squinting eyes.
  • Corneal reflex/Hirschberg tes t should assess the ocular alignment at 1/3 meter, 6 meters, and far distance.
  • Cover test – should be done to assess eyes' alignment following breakage of fusion.
  • Prism cover test – prism bar cover test should be performed in all cardinal positions of gaze and for both near and distance.
  • Binocular single vision (BSV) – Should be assessed for distance and near separately with worth four dots test.
  • Stereopsis – Should be tested during the phoric phase.
  • An occlusion test is essential when the patient presents with an intermittent exotropia that is present only for distance or a distance deviation that exceeds near deviation by 15 prism diopters or more.
  • Fusional amplitudes – Convergence and divergence amplitudes should be measured.
New Castle scoring system
This is divided into scores for home control and clinic control for near and distance.
New Castle scoring system
Total score = Score for Home Control + Scores for Clinic Control for Near + Scores for Clinic Control for Distance
  • Amblyopia therapy should be started at the earliest possible.
  • Refractive error correction – Cycloplegic refraction should be done to assess any underlying myopia, hyperopia, astigmatism, or anisometropia.
  • Minus lenses, in particular, helps in regaining the fusion control.
  • Over minus therapy – Minus lenses work by stimulating the accommodative convergence.
  • Antisuppression exercises – In the form of part-time occlusion, are particularly beneficial for very young children who cannot perform active orthoptic exercises.
  • Orthoptics – Active anti-suppression exercises and diplopia awareness exercises like bar reading, cheiroscope, or synaptophore help make the patient aware whenever the deviation becomes manifest.
  • Surgical intervention might be needed when the exodeviation occurs for more than 50% of the waking hours, and there is a recorded gradual loss of fusional control, progressive increase of primary deviation, asthenopic symptoms not relieved by convergence, or fusional exercises, development of suppression or gradual deterioration of distance stereopsis.
  • The role of Botulinum toxin has also been evaluated in patients with intermittent exotropia.
  • Su et al. assessed the role of botulinum toxin type A versus strabismus surgery in children with intermittent exotropia.
  • In these cases, the alignment is mainly for cosmetic reasons and to help them improve their quality of life.
  • The usual choice of surgery in these patients will be a recession resection procedure in the amblyopic eye.
  • A super maximal recession of the range of 14mm of the lateral rectus and super maximal resection up to 11 mm of the medial rectus has been described in the literature for large-angle exotropia.
  • Ceylan et al., in their study, compared lateral rectus recession versus medial rectus advancement for the treatment of patients with consecutive exotropia.
  • Although there were no statistically significant differences, they found better results with medial rectus advancement than lateral rectus recession in treating consecutive exotropia.
  • The patient should be assessed for binocular sensory cooperation.
  • Normal retinal correspondence and bifoveal fusion – Exercises to overcome suppression, improve fusional convergence, and later planned for surgical correction.
  • No bifoveal fusion – Assess cosmetic appearance.
  • If good – observation alone with regular follow-ups can be advised.
  • If poor – plan for cosmetic surgical correction.
  • The postoperative care in patients who undergo surgical intervention should focus on alignment, any unexpected gross misalignment, conjunctival opposition.
  • Patients with exotropia might occasionally complain of double vision in the immediate postoperative period, which needs to be carefully observed with close follow-up.
  • For most patients, diplopia should settle down within six weeks.
  • If persistent, temporary use of prism glasses or occlusion glasses should be advised.
  • Most surgeons prefer using short-term topical steroids and antibiotics, with or without oral analgesics, on a case-to-case basis.
  • Younger children can be advised infusion dosage of analgesics if needed.
  • Follow-up visits should focus on assessing the alignment of eyes, ocular motility, and correction of any underlying refractive errors.
  • Patients might need to be maintained on orthoptic exercises to prevent recurrence of exodeviations.
  • Patient with sensory exotropia needs to be explained clearly about chances of recurrence over the years due to poor visual acuity in the exotropic eye.
  • review
    Exotropia. StatPearls [Internet] — Kirandeep Kaur, Bharat Gurnani — StatPearls Publishing, 2023

Decision support only. Verify against local protocols and current labeling. Source: www.ncbi.nlm.nih.gov