Effect of Binocular Treatment Using a Dichoptic Reading Application in Children With Convergence Insufficiency.

Convergence insufficiency is a common disorder of binocular vision that can appear as early as childhood after visual effort, and is often associated with a variety of symptoms such as eyestrain, headaches, blurred vision and diplopia.

Treatment of symptomatic convergence insufficiency generally involves the intentional and controlled manipulation of a visual target's blur, conjugate and vergence movements around this target, with the aim of normalizing the accommodation and vergence systems and their mutual interactions.

Despite the effectiveness of this treatment, compliance is not optimal, ranging from 24% to 91% in the youngest patients. One of the main challenges is to keep patients focused and interested during the potentially tedious and repetitive periods of over-convergence. In order to stimulate the patient's active participation and stable, sustained attention, a dichoptic reading application on a digital tablet has been developed to provide sustained training in ocular alignment and coordination to reduce symptoms and restore binocular function in patients with symptomatic convergence insufficiency.

The dichoptic reading application on a digital tablet consists in reading, with red-green anaglyph glasses, a text composed of letters or words presented both binocularly and monocularly (black and red-green, respectively) from downloaded e-books. After centralized randomization, patients will undergo either reference orthoptic rehabilitation (control group) or dichoptic treatment on a digital tablet (experimental group). The control group will receive 12 training sessions (25 minutes twice a week for 6 weeks) as part of their regular treatment in the Ophthalmology Department of the CHU de Montpellier, while the experimental group will perform self-training at home (25 min/day, 5 days a week for 6 weeks). For all participants, an initial visit and two follow-up evaluation visits (visits 2 and 3) will be scheduled 3 and 6 weeks (+ 1 week) after the start of the intervention, and will be carried out by one of the 3 other orthoptists in the Ophthalmology Department of the CHU de Montpellier.

Eligibility Criteria:
Inclusion Criteria:

* Patients aged 8 to 17
* Minimum current schooling: CE2 class
* Availability of at least one legal guardian to supervise the child's training (strengthening exercises to be performed at home 15 min/day for the control group/ 25 min/day session at home for the experimental group) and complete the patient logbook.
* Ophthalmological check-up performed within 2 months prior to inclusion
* Convergence Insufficiency Symptom Survey (CISS) score ≥ 16
* Convergence punctum proximum ≥ 6 cm
* Amplitude of fusion in near convergence ≤ 15 prismatic dioptres or less than 2 times the phoria measured in near vision (Sheard's criterion).
* Best corrected distance and near visual acuity ≥ 20/25 (=8/10) and wearing appropriate refractive correction (glasses or contact lenses) for at least 2 weeks prior to study inclusion.
* See letters/words and be able to read 3 complete sentences on a predefined text presented dichoptically on the tablet with anaglyph glasses
* Availability of the patient to complete the training protocol over 6 weeks (or a maximum of 9 weeks in the event of temporary interruption of treatment).

Exclusion Criteria:

* Binocular vergence dysfunctions such as constant strabismus
* Prism (unless removed ≥ 2 weeks prior to inclusion)
* History of recent orthoptic rehabilitation (\< 6 months)
* History of intraocular or refractive surgery
* Current amblyopia treatment or treated amblyopia (isoacuity) \< 6 months
* Best corrected visual acuity of the worse eye \< 8/10
* Medication that may interfere with binocular vision and/or accommodation
* Accommodation paralysis
* Ocular comorbidity likely to reduce visual acuity
* History of vestibular migraines, vestibular disorders
* History of ocular or systemic disease, infections/congenital malformations
* Neurological history: stroke, head trauma, tumors, epilepsy or neurodegenerative disorders
* Specific learning disability
* Developmental delay (global, language, learning) likely to interfere with treatment or evaluation.
* Failure to obtain written informed consent after a period of reflection
* Not being affiliated to a French social security scheme or benefiting from such a scheme
* Pregnant or breast-feeding