Incidence and types of childhood hypertropia: a population-based study.
OBJECTIVE
To determine the incidence and types of childhood hypertropia in a defined population.


METHODS
Retrospective population-based cohort.


METHODS
All pediatric (<19 years of age) residents of Olmsted County, Minnesota, diagnosed with vertical strabismus from January 1, 1985, through December 31, 1994.


METHODS
The medical records of all potential patients identified by the resources of the Rochester Epidemiology Project were reviewed.


METHODS
Incidence and types of childhood hypertropia.


RESULTS
Forty-two cases of childhood hypertropia were identified during the 10-year period, yielding an annual age- and gender-adjusted incidence of 12.9 (95% confidence interval, 9.0-16.9) per 100000 patients younger than 19 years of age. This rate corresponds to a prevalence of approximately 0.26%, or 1 in 391, of all children younger than 19 years of age. Nearly three fourths (71.4%) of the children had a IVth cranial nerve palsy, primary inferior oblique overaction, Brown syndrome, or a vertical tropia in the setting of an abnormal central nervous system.


CONCLUSIONS
The incidence rates for childhood hypertropia in this population-based study are higher than published reports of prevalence. Fourth cranial nerve palsy and primary dysfunction of the inferior oblique muscle were the most common forms of vertical strabismus in this population.
Tollefson
Megha M
MM
Department of Pediatric & Adolescent Medicine, Mayo Clinic and Mayo Foundation, Rochester, Minnesota 55905, USA.
Mohney
Brian G
BG
Diehl
Nancy N
NN
Burke
James P
JP
D000293:Adolescent; D017677:Age Distribution; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D008910:Minnesota / Q000453:epidemiology; D015835:Ocular Motility Disorders / Q000453:epidemiology; D009886:Ophthalmoplegia / Q000453:epidemiology; D015995:Prevalence; D012189:Retrospective Studies; D017678:Sex Distribution; D013285:Strabismus / Q000145:classification* / Q000453:epidemiology*; D020432:Trochlear Nerve Diseases / Q000151:congenital / Q000453:epidemiology