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Agnes Wong, Herbert Goltz, Alan Blakeman, Linda Colpa; A prospective non-randomized study on early vs standard surgery for infantile esotropia in children: An interim report on optokinetic response. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5986.
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© ARVO (1962-2015); The Authors (2016-present)
Infantile esotropia is associated with nasotemporal asymmetry of optokinetic response (OKR) favoring nasalward movement during monocular viewing. This ongoing prospective non-randomized study is designed to determine whether early surgery (at ≤ 10 months) promotes the normal development of OKR in human infants, as compared to standard surgery (at 11-18 months). We hypothesize that early surgery promotes the normal development of OKR.
Forty-four children with a constant infantile esotropia of ≥ 30 prism diopters and onset before age 6 months have been enrolled prospectively. Early surgery was performed at age ≤ 10 months (n=17), and standard surgery at age 11-18 months (n=27). At age 5, OKR was recorded during monocular viewing using a Tobii X-50 remote eye tracker. Large field OKN (72° x 57°) was evoked using vertical black-and-white stripes (2.2° wide) moving horizontally at 15, 20 and 25 °/s. Cartoon character images were presented periodically to maintain subjects’ interest. OKR gain was calculated as the ratio of mean eye velocity to target velocity for nasalward (GN) and temporalward (GT) stripe motion separately. A nasal bias index (NBI) was calculated as (GN-GT)/(GN+GT). The NBI is positive for nasalward bias, negative for temporalward bias and zero for unbiased response. Kruskal-Wallis and post-hoc Dunn tests for ranked non-parametric data were performed with α = 0.05.
To date, 5 patients in the early surgery group, 9 in the standard surgery group and 8 age-matched controls have reached age 5 and completed OKR testing. There was a significant main effect among groups (H=10.977, df=2; p=0.004). Post-hoc testing indicated that the mean NBI (± standard error) in the standard surgery group (+0.10±0.02) was significantly higher than that in the control group (+0.01±0.01). There was no statistically significant difference between the early surgery (+0.04±0.03) and control groups.
The preliminary data from this ongoing prospective study suggest that early surgery may promote more normal development of OKR as compared to standard surgery. Further testing will be performed as more enrolled patients reach age 5 to confirm whether early repair is beneficial for cortical development in human infants.
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