APR 30, 2009
This study's authors retrospectively reviewed the medical records of all patients diagnosed with infantile esotropia in one Minnesota county over a 30-year period and found that the condition's incidence did not significantly change. The surgical intervention rate for the diagnosis also remained similar. The authors speculated that the possible decrease in infantile esotropia incidence perceived by some ophthalmologists may have been due to a disproportionate increase in the number of practicing ophthalmologists compared with the number of live births in the United States during the study period of 1965 to 1994.
New infantile esotropia cases were diagnosed in Olmsted County during the study period at a rate of 25 per 10,000 or 1 in 403 live births. The prevalence remained similar over time, with 45 cases diagnosed from 1965 and 1974, 51 from 1975 to 1984 and 34 from 1985 to 1994. This translated to a rate of 1 in 392, 1 in 323 and 1 in 483, respectively. Surgery incidence was a mean of 1.8 per patient diagnosed from 1965 to 1974 during a mean 16.9 years of follow-up, 1.9 per patient diagnosed from 1975 to 1984 during 13.5 years of follow-up and 1.6 per patient diagnosed from 1985 to 1994 during 9.1 years of follow-up.
While live births in the United States rose 3.7 percent from 3.76 million in 1965 to 3.9 million in 1994, the number of practicing ophthalmologists in the country increased 108 percent from 8397 to 17,464. This means that there were 448 children born for each practicing ophthalmologist in 1965 but only 223 in 1994. Each ophthalmologist would have diagnosed an average of 1.11 new infantile esotropia cases annually in 1965 compared with only 0.55 in 1994.