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By Thomas R. Collins
Medscape Medical News
April 19, 2010 (Orlando, Florida) — Contrary to conventional thought, acquired nonaccommodative esotropia (ANAET) is common and not associated with the presence of intracranial lesions, according to a new retrospective study that followed up almost 200 patients diagnosed as having the disorder for an average of 11 years.
The results were presented here at the American Association for Pediatric Ophthalmology and Strabismus (AAPOS) 36th Annual Meeting.
"There have been no other long-term outcome studies of this form of esotropia in the literature," reported lead study author Sarah Jacobs, a 4-year medical student at Mayo Medical School in Rochester, Minnesota, during her presentation — which was named by the AAPOS as one of the top 10 "Best of Show" posters at the event.
"There have been short-term follow-up studies and smaller cohort studies, but this is the largest study of its type that has been done for this condition," added Ms. Jacobs.
Long-Term Results
The investigators evaluated the medical records of all pediatric patients between the ages of 6 months and 19 years who were diagnosed as having ANAET at the Mayo Clinic between January 1965 and December 1994 (n = 176, 61% male).
"This represented an incidence of 1 in 284 live births," said Ms. Jacobs.
"It was an interesting patient group that 10 or 15 years ago very few people really understood or knew much about," added principal investigator Brian G. Mohney, MD, professor of ophthalmology at the Mayo Clinic.
Diagnosis of ANAET was given at a median age of 4.3 years (range, 11 months to 18.2 years). Although 11% were diplopic at initial presentation, "none of the study patients were subsequently diagnosed with an intracranial malignancy," report the study authors.
A total of 73% of the patients (n = 129) underwent at least 1 strabismus surgery, 16.5% had a second surgery, and 2.8% had a third.
During a mean follow-up of 10.8 years (range, 0 days to 37 years), 70.3% of the postoperative patients had 10 or less prism diopters of deviation on final examination. In addition, 64% of all study patients regained some stereoacuity (median, 800 seconds of arc) and 7.4% regained normal stereopsis.
"Our study showed that 1 decade after a single surgery, two-thirds of these patients were within 10 prism diopters of orthotropia and 1 in 13 of all patients had normal stereopsis," said Ms. Jacobs. "So there were good outcomes, especially with surgical intervention."
"In summary, our findings show that ANAET is a lot more common than conventionally thought and that the incidence of intracranial lesion is a lot less common than typically thought," she added.
For clinicians who wonder whether they should perform magnetic resonance imaging (MRI) when a child comes in with an ANAET, "I'd say that, looking at our numbers, where none of the patients in our series had an intracranial lesion, it's really not cost-effective or clinically warranted to reflexively do an MRI in these kids unless there's a systemic neurologic abnormality present," said Ms. Jacobs.
"In this day and age where you're trying to wisely use healthcare dollars, you just don't need to scan every child who comes in with this condition unless there are other signs," reiterated Dr. Mohney.
Real Value From an Important Study
"I think this is an important study because it looked at kids with crossed eyes who don't have any obvious reason for having crossed eyes, which we call [ANAET]," said poster session comoderator Stephen Christiansen, MD, pediatric ophthalmologist and chair of the Ophthalmology Department at Boston University in Massachusetts and member of the AAPOS Program Committee.
"These are kids that we've always worried about because they don't need glasses and weren't born with esotropia. So why did they get it? The worry is that they have a central nervous system tumor," said Dr. Christiansen, who was not involved with this study.
"To have this cohort of patients, where a substantial number had diplopia (double vision), and be able to follow them for a very long period of time and find that they don't have tumors seems quite important."
He noted that he had some concerns with the investigators' inclusion and exclusion criteria, which may affect their data in the long term. "However, I still think that this is a substantial study and follows up well on some of the work that Dr. Mohney has done in the past. There's a lot of real value here and a lot that we'll learn from it."
"I'd say the key takeaway is that many of these children with [ANAET] ultimately are healthy children who can have very good outcomes," concluded Dr. Christiansen.
Ms. Jacobs, Dr. Mohney, and Dr. Christiansen disclosed no relevant financial relationships.
American Association for Pediatric Ophthalmology (AAPOS) 36th Annual Meeting: Abstract 74/Poster 10. Presented April 15, 2010.
