A Pilot Clinical Trial of Overminus Spectacle Therapy for Intermittent Exotropia

Inclusion Criteria

• •The following criteria must be met for the child to be enrolled in the study:
• •Age 3 years to \< 7 years
• •Intermittent exotropia (manifest deviation) meeting all of the following criteria:
• •* Intermittent exotropia or constant exotropia at distance
• •* Mean distance control score of 2 points or more (mean of 3 assessments over the exam)
• •* Intermittent exotropia, exophoria, or orthophoria at near
• •* Subject cannot have a score of 5 points on all 3 near assessments of control
• •* Exodeviation at least 15∆ at distance measured by PACT
• •* Near deviation does not exceed distance deviation by more than 10∆ by PACT (convergence insufficiency type IXT excluded)
• •No previous non-surgical treatment for IXT (other than refractive correction), including vision therapy for IXT, within the past 6 months.
• •No previous substantial overminus treatment, defined as wearing spectacles that are overminused by 1.00D SE or more (treatment with lenses overminused by less than 1.00D SE is allowed at any time prior to enrollment).
• •No vision therapy, patching, atropine, or other penalization for amblyopia during the last 2 weeks
• •No prior strabismus, intraocular, or refractive surgery (including BOTOX injection)
• •Cycloplegic refraction within 7 months, but NOT on the day of enrollment
• •Spherical equivalent (SE) in both eyes between -6.00D and +1.00D inclusive
• •Distance visual acuity 0.3 logMAR (20/40) or better (by ATS-HOTV) in both eyes
• •No interocular difference of distance visual acuity more than 0.2 logMAR (2 lines)
• •Child must be wearing refractive correction (pre-study spectacles) for at least 1 week if refractive error (based on cycloplegic refraction performed within 7 months) meets any of the following:
• •* SE anisometropia ≥1.00 D
• •* Astigmatism ≥1.00 D in either eye
• •* SE myopia ≥-0.50 D in either eye
• •Refractive correction must meet the following criteria relative to the cycloplegic refraction:
• •* SE anisometropia must be within \<1.0D of the SE anisometropic difference
• •* Astigmatism must be within \<1.00D of full magnitude; axis must be within 10 degrees if ≤1.00D, and within 5 degrees if \>1.00D.
• •* The SE of the spectacles must be within \<1.00D of the full cycloplegic refraction SE.