Bilateral Refractive Amblyopia Treatment Study
Condition: Bilateral Refractive Amblyopia
MeSH terms: Amblyopia
Study type: Observational

Summary: 
      The purpose of this study will be to:

        -  Determine the amount of visual acuity improvement with treatment of presumed bilateral
           refractive amblyopia

        -  Determine the time course of visual acuity improvement with treatment
    

Detailed description: 
      There is a paucity of literature on bilateral amblyopia that is due to a substantial amount
      of refractive error (hypermetropia or astigmatism), and it is limited principally to review
      articles and case reports. The incidence is not known, but in one study, 4 of 830 (0.5%)
      children examined at the time of entry into school had bilateral amblyopia. Schoenleber et al
      performed a retrospective review of office records and identified 184 children with > +4.00
      diopters of hypermetropia in both eyes, 12 of whom (6.5%) had bilateral amblyopia of 20/50 or
      worse. Ten of the 12 children (83%) improved to 20/40 or better in both eyes over a mean
      follow-up time of 22 months. Werner and Scott reported 6 cases of bilateral hypermetropic
      amblyopia with a spherical equivalent of at least +5.00 D and an initial visual acuity of
      20/40 or worse in both eyes. All 5 patients with follow up improved with glasses alone, and 2
      of these 5 had a most recent visual acuity worse than 20/40 in one eye with follow-up less
      than one year. Cavazos et al identified 218 eyes with hyperopia > +5.00 D or astigmatism
      >+2.00 D. Of these, 82 (38%) of the dominant eyes had an initial corrected visual acuity less
      than 20/25. Most improved to > 20/25, but many patients were lost to follow-up. In ongoing
      studies, bilateral refractive amblyopia is being evaluated in Native Americans.

        1. Patients will be enrolled who have bilateral refractive error with hyperopia >+4.00 D
           and/or astigmatism >2.00 D and have visual acuity in each eye, measured using best
           correction derived from cycloplegic refraction, meeting the following criteria:

             -  Using E-ETDRS testing for patients age 7 to <11 years: visual acuity 20 to 70
                letters (20/40 to 20/400)

             -  Using ATS HOTV testing for patients age 3 to <7 years visual acuity 20/50 to 20/400

        2. Enrolled patients will be prescribed spectacles, which will be paid for by the study.

        3. The patient will return for a Spectacle Baseline visit within 30 days, at which time the
           spectacles will be placed on the patient for the first time and binocular and monocular
           visual acuities will be measured.

             -  Patients whose monocular acuity at the Spectacle Baseline Visit is 20/25 or better
                in both eyes will end the study

             -  Patients whose monocular acuity at the Spectacle Baseline Visit is worse than 20/25
                in at least one eye will begin a one-year period of study follow up

        4. Follow-up visits are required at 5±:1 week, 13±:2 weeks, 26±:4 weeks, and 52±:4 weeks.

             -  If at any follow-up visit a patient's monocular acuity is 20/25 or better in both
                eyes, the patient should return for the 52-week visit only and may skip the interim
                follow-up visits.

      Sample size: The study plans to enroll 100 patients. At least 50 patients will be enrolled
      who have an interocular difference of less than 3 lines by ATS HOTV or less than 15 letters
      by E-ETDRS at the Spectacle Baseline visit.
    

Intervention name(s): Spectacles
Intervention type(s): Device
Intervention description(s): optimal spectacle correction
Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Community sample
      
Keywords: amblyopia; bilateral amblyopia; refractive error