Purpose
To assess whether successful surgical intervention for intermittent exotropia, or the timing of intervention, has any effect on the development of mental illness.
Design
Retrospective, observational case series.
Methods
All patients (<19 years of age) diagnosed with intermittent exotropia in Olmsted County, Minnesota, from January 1, 1975, through December 31, 1994, were reviewed retrospectively. Potential cases were identified using the resources of the Rochester Epidemiology Project, a medical records database designed to capture data on any patient–physician encounter in Olmsted County, Minnesota. The main outcome measures were the occurrence and severity of mental illness among those who underwent strabismus surgery compared with those who did not.
Results
Ninety-six (52%) of the 184 children identified were diagnosed with a mental illness at a mean age of 23.3 years (range, 6 to 41 years). Thirty-five (36%) of the 96 children in whom mental illness developed underwent strabismus surgery. Success at surgery (<10 prism diopters) was not associated with a decreased occurrence of mental illness ( P = .30). Of the 88 patients in whom mental illness did not develop, strabismus surgery was not more commonly performed ( P = .54), nor was it performed at a younger age ( P = 1.0), when compared with the 96 patients in whom mental illness developed later.
Conclusions
Strabismus surgery for children with intermittent exotropia, regardless of success or age at surgery, did not alter the development of mental illness by early adulthood.
Intermittent exotropia affects 1% of children in the West and is the predominant form of ocular misalignment among Asians. Children with intermittent exotropia residing in Olmsted County, Minnesota, recently were found to be 3 times more likely than age- and gender-matched controls to have mental illness by early adulthood. A genetic link between constant exotropia and mental illness among adults has been reported, but environmental or other factors also likely play a role. The purpose of this study was to assess whether successful surgical intervention, or the timing of intervention, influences mental illness outcomes among a cohort of children diagnosed with intermittent exotropia as residents of Olmsted County, Minnesota, over a 20-year period.
Methods
This study was approved by the Institutional Review Board of Mayo Clinic, Rochester, Minnesota. It also conformed to the requirements of the United States Health Insurance Portability and Accountability Act. The medical records of all patients younger than 19 years and residing in Olmsted County, Minnesota, when diagnosed with intermittent exotropia by an ophthalmologist from January 1, 1975, through December 31, 1994, were reviewed retrospectively.
Intermittent exotropia was defined as an acquired, intermittent exodeviation of at least 10 prism diopters (PD) in an otherwise healthy child. Patients with underlying or associated developmental, neurologic, or sensory strabismus were excluded. The records of patients with intermittent exotropia also were reviewed for the use of psychotropic medication, mental health emergency department visits or hospitalizations, suicide attempts, suicidal or homicidal ideation, and diagnoses of mental illnesses included in the Diagnostic and Statistical Manual of Mental Disorders , Fourth Edition codes (specifically, attention deficit hyperactivity disorder [ADHD], adjustment disorder, learning disorder, substance abuse, and depression). Each mental illness diagnosis was confirmed by a psychiatrist. The psychotropic medications recorded include antidepressants, stimulants, antipsychotics, and mood stabilizers. The full criteria for inclusion of information indicative of mental health problems were described in a preceding study.
Potential cases were identified using the resources of the Rochester Epidemiology Project, a multicenter medical records database designed to capture data on any patient–physician encounter in Olmsted County, Minnesota. The racial distribution of Olmsted County residents in 1990 was 95.7% white, 3.0% Asian American, 0.7% black, and 0.3% each for Native American and other. The population of this county (106 470 in 1990) is relatively isolated from other urban areas, and virtually all medical care is provided to residents by a largely unified medical care system (Mayo Clinic, Mayo Medical Group, and their affiliated hospitals) that has accumulated comprehensive medical records for nearly a century.
A total of 184 children were diagnosed with intermittent exotropia during the 20-year study period. The ophthalmic findings and subsequent mental health characteristics of the 184 patients and their controls have been reported already. The medical records of each of the 184 children with intermittent exotropia were reviewed for any surgical intervention for strabismus, age at surgery, total number of surgeries, and postoperative motor and sensory results. Each of these factors was analyzed to determine correlation with the occurrence and severity of mental illness.
Continuous data are presented as a mean and range. Categorical data are presented as counts and percentages. The Fisher exact test was used to compare categorical variables between groups. The Wilcoxon rank-sum test was used for the comparison of continuous variables. All statistical tests were 2-sided, and the threshold of significance was set at α = 0.05.
Results
The historical and clinical characteristics of the 184 subjects are summarized in Table 1 . Sixty-three (34%) of the 184 children underwent surgery. The prevalence of a positive psychiatric family history between patients who underwent surgery and those who did not was similar. Similarly, the difference in the prevalence of a history of chemical dependency between patients in the surgical and nonsurgical group was not statistically significant.
| Variable | Total (n = 184) | No Surgery (n = 121) | Surgery (n = 63) | P Value a |
|---|---|---|---|---|
| Male (%) | 66 (36) | 46 (38) | 20 (32) | .42 |
| Family history of strabismus (%) | 58 (51) | 36 (52) | 22 (49) | .85 |
| Family history of chemical dependency (%) | 32 (27) | 21 (32) | 11 (21) | .21 |
| Premature birth (<37 wks) | 10 (7) | 6 (7) | 4 (7) | 1.00 |
| Difficult birth | 104 (60) | 68 (61) | 36 (58) | .75 |
| Median birth weight (g) | 3395 | 3395 | 3395 | .67 |
| Range | 2970 to 3790 | 2970 to 3638 | 3088 to 3790 | |
| Median age at exotropia onset (y) | 2.8 | 3.2 | 2.0 | .04 |
| Range | 1.6 to 4.9 | 1.9 to 6.1 | 1.3 to 3.2 | |
| Median age at exotropia diagnosis (y) | 5.4 | 6.9 | 3.4 | <.001 |
| Range | 3.3 to 8.7 | 3.9 to 9.9 | 2.2 to 5.3 |
Ninety-six (52%) of the 184 study patients, followed up to a median age of 21.8 years (range, 1 to 41 years), were diagnosed with a mental illness at a median age of 13.3 years (range, 7.9 to 17.5 years; Table 2 ). Seven (7.3%) were diagnosed with a mental illness before they were diagnosed with intermittent exotropia, 1 (1.0%) was diagnosed with both on the same day, and the remaining 88 (91.7%) were diagnosed with intermittent exotropia before being diagnosed with a mental illness. Thirty-five (36%) of the 96 children in whom a mental illness developed underwent strabismus surgery at a median age of 6 years (range, 3 to 29 years). A similar proportion, 28 (32%) of the 88 children who did not have a mental illness, also underwent strabismus surgery at a median age of 6 years (range, 3 to 23 years). There was no statistically significant difference in the number of patients undergoing strabismus surgery, or the age at surgery, between those who had mental illness and those who did not. There was also no statistically significant difference in either the number of patients in whom mental illness developed, or the total number of mental illness disorders, between those who underwent surgery and those who did not. The type and severity of mental health disorders also were similar between the 2 groups ( Tables 3 and 4 ).
| Variable | Total (n = 184) | No Surgery (n = 121) | Surgery (n = 63) | P Value a |
|---|---|---|---|---|
| No. with psychiatric disorders (%) | 96 (52) | 61 (50) | 35 (56) | .54 |
| Median age at psychiatric diagnosis (y) | 13.3 | 12.3 | 13.6 | .85 |
| Range | 7.9 to 17.5 | 7.9 to 18.6 | 7.9 to 17.3 | |
| No. of psychiatric disorders per patient | 2.0 | 2.0 | 2.0 | .85 |
| Range | 1.0 to 4.0 | 1.0 to 3.0 | 1.0 to 4.0 |
| Variable | Total (n = 184) | No Surgery (n = 121) | Surgery (n = 63) | P Value a | Surgery at 6 Years of Age or Younger (n = 32) | Surgery at Older than 6 Years (n = 31) | P Value a |
|---|---|---|---|---|---|---|---|
| Psychiatric disease | 96 (52) | 61 (50) | 35 (56) | .54 | 11 (58) | 24 (55) | 1.0 |
| ADHD | 28 (15) | 15 (12) | 13 (21) | .19 | 7 (22) | 6 (19) | 1.0 |
| Adjustment disorder | 29 (16) | 20 (17) | 9 (14) | .83 | 4 (13) | 5 (16) | .73 |
| Learning disorder | 12 (7) | 5 (4) | 7 (11) | .11 | 4 (13) | 3 (10) | 1.0 |
| Substance abuse | 19 (10) | 12 (10) | 7 (11) | .80 | 2 (6) | 5 (16) | .26 |
| Major depression | 24 (13) | 15 (12) | 9 (14) | .82 | 4 (13) | 5 (16) | .73 |
| Variable | Total (n = 184) | No Surgery (n = 121) | Surgery (n = 63) | P Value a | Surgery at 6 Years of Age or Younger (n = 32) | Surgery at Older than 6 Years (n = 31) | P Value a |
|---|---|---|---|---|---|---|---|
| Using psychiatric medication | 57 (31) | 37 (31) | 19 (30) | 1.0 | 9 (28) | 10 (32) | .78 |
| Psychiatric ED visit | 36 (20) | 25 (21) | 11 (17) | .70 | 5 (16) | 6 (19) | .75 |
| Suicide ideation | 31 (17) | 23 (19) | 8 (13) | .31 | 2 (6) | 6 (19) | .15 |
| Suicide attempt | 17 (9) | 14 (12) | 3 (5) | .18 | 0 (0) | 3 (10) | .11 |
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
