Elsevier

Ophthalmology

Volume 113, Issue 7, July 2006, Pages 1154-1158
Ophthalmology

Original Article
The Course of Intermittent Exotropia in a Population-Based Cohort

https://doi.org/10.1016/j.ophtha.2006.01.033Get rights and content

Purpose

To evaluate the change in the angle of deviation in an incidence cohort of pediatric patients diagnosed with intermittent exotropia during a 20-year period.

Design

Retrospective, population-based observational study.

Participants

All pediatric (<19 years old) residents of Olmsted County, Minnesota diagnosed with intermittent exotropia (≥10 prism diopters) from January 1, 1975 through December 31, 1994.

Methods

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

Main Outcome Measures

The change in the angle of deviation and its association with treatment were reviewed for each patient.

Results

A total of 184 pediatric patients were diagnosed during the study period, of which 138 patients (75.0%) had ≥2 examinations. The deviation resolved in 5 of the 138 patients (3.6%) during a median follow-up of 9.2 years, while the Kaplan–Meier rate of increasing by 10 or more prism diopters (PD) was 23.1% at 5 years and 52.8% at 20 years. The distance deviation increased by a median of 5 PD during the preoperative period in the 55 patients who underwent surgery during a mean follow-up of 3.2 years compared with a zero PD median change in the 83 patients who avoided surgery during a mean follow-up of 7.1 years. The Kaplan–Meier probability of undergoing surgery within 20 years after diagnosis was 74.0% in this population. We were unable to detect a significant association between nonsurgical treatments and a change in the angle of deviation.

Conclusions

In this population-based cohort of pediatric patients with intermittent exotropia, the deviation resolved in 4%, and more than half of the patients were expected to have an increase of 10 or more PD within 20 years of their diagnosis. Children who received surgery in this population were significantly more likely to have demonstrated an increase in their deviation during the preoperative period.

Section snippets

Subjects and Methods

The medical records of all patients younger than 19 years of age who were residing in Olmsted County, Minnesota when diagnosed by an ophthalmologist as having intermittent exotropia between January 1, 1975 and December 31, 1994 were retrospectively reviewed. Institutional review board approval was obtained for this study. Potential cases of intermittent exotropia were identified using the resources of the Rochester Epidemiology Project, a medical record linkage system designed to capture data

Results

During the 20-year study period, 184 new cases of childhood intermittent exotropia were diagnosed at a mean age of 6.3 years (range, 8.4 months to 18.6 years) in Olmsted County, Minnesota. Pertinent historical and clinical characteristics of the study patients are shown in Table 1. Two thirds of the patients were female, whereas 1 in 3 reported a family history of strabismus. A history of prematurity or diplopia was uncommon, and the ocular findings were otherwise unremarkable for this disorder

Discussion

The findings from this cohort of children with intermittent exotropia from Olmsted County, Minnesota suggest that the distance exodeviation of approximately one half of patients would increase by 10 or more PD after 20 years of follow-up. During a median follow-up of 5.6 years, the exotropia resolved in 3.6%, and children who received surgery in this cohort were significantly more likely to demonstrate an increase in their preoperative angle of deviation than those who did not undergo surgery.

References (15)

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Manuscript no. 2005-736.

This study was supported in part by an unrestricted grant from Research to Prevent Blindness, Inc., New York, New York.

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