Bilateral Refractive Amblyopia Clinical Trial
Official title:
Bilateral Refractive Amblyopia Treatment Study
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
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.
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Observational Model: Cohort, Time Perspective: Prospective