Abstract
Purpose: :
To determine the prevalence of hypermetropia and propose a theory for its predominance in children with myotonic dystrophy (MD).
Methods: :
Six boys and six girls were included in the case series. Age range was 4 months to 7 years. Cycloplegic refraction, slit lamp biomicroscopy, and ocular motility evaluation were performed on all subjects. Some patients had molecular confirmation of the clinical diagnosis and the number of trinucleotide repeats in the myotonic dystrophy protein kinase gene was available for review. A literature search was conducted to compare results with previously published reports.
Results: :
All subjects except one were hypermetropic. Spherical equivalent refractive error ranged from –1.50 to +12.50D with a mean of +6.60 OU. Six patients had esotropia, 4 had ptosis, 4 had amblyopia, and 2 had the characteristic Christmas tree cataracts. Two patients underwent strabismus surgery and one had ptosis repair. We could not correlate the degree of hypermetropia to the number of trinucleotide repeats in those patients in whom this information was available.
Conclusions: :
Hypermetropia is present in more than 90% of children with MD. In many cases, hyperopic refractive error is accompanied by esotropia. Patients also have a significant risk of amblyopia. The tendency toward high hyperopic refractive error may result from the low intraocular pressure which is prevalent in MD patients.
Keywords: hyperopia • refractive error development • strabismus