Is vision training still needed after strabismus surgery?

By Crystal Wong 王水晶, Registered Optometrist (Part I), Hong Kong | July 2026

What do surgery and vision training each address?

A useful way to think about it: surgery fixes the hardware; vision training retrains the software.

Surgery repositions or adjusts the tension of the extraocular muscles to improve alignment. But "both eyes pointing the same way" and "the brain knowing how to use both eyes together" are different things. Binocular vision is a brain function — fusing two images into a single three-dimensional percept. A child with long-standing strabismus may have learned to suppress one eye's signal to avoid double vision, and that habit does not automatically disappear once the eyes are aligned.

Vision training, after alignment has improved, uses structured exercises to rebuild fusion, reduce suppression and develop stereopsis.

Which children may need a post-operative assessment?

• Still reporting double vision after surgery, or tiring quickly during near work
• Still tilting the head or closing one eye to see comfortably
• Long-standing strabismus before surgery, or a history of amblyopia
• Intermittent strabismus that drifts out again when tired or unwell
• Weak performance on stereopsis tests

Can vision training replace surgery?

The honest answer: usually not — they address different problems. Large-angle constant strabismus generally needs surgical correction; training cannot "straighten" a clearly deviated eye. The strongest evidence for vision training is in convergence insufficiency: the large randomised Convergence Insufficiency Treatment Trial (CITT) showed office-based training with home reinforcement is effective in children¹. For post-surgical binocular rehabilitation, training aims to consolidate the surgical result and build fusion — the two are complementary, not interchangeable.

When to assess?

Usually after the ophthalmologist confirms the post-operative alignment is stable and healing is complete (weeks to months after surgery, per the surgeon's advice). The assessment covers alignment measurement, suppression testing, fusional ranges, stereopsis and accommodation, after which the ophthalmologist and optometrist jointly decide whether training is indicated, its goals and a rough timeline.

Signs parents should watch for

1. Frequently closing one eye or tilting the head during homework or reading
2. Complaining that words "move around", skipping lines or words, unusually slow reading
3. Poor distance judgement on stairs or when catching a ball
4. Reports of double vision, or an eye "drifting out" when tired

Any of these warrants a comprehensive binocular vision assessment.

Crystal Wong 王水晶

Registered Optometrist (Part I, Optometrists Board, Hong Kong), BSc (Hons) in Optometry (The Hong Kong Polytechnic University), PhD researcher in vision neuroscience. Seven years of clinical and research experience in paediatric vision, binocular vision and myopia management. Full professional profile →