Abstract
We compare the surgical outcomes of intermittent exotropia of the basic, pseudo-divergence excess (pseudo-DE) and true divergence excess (true DE) types. A study was performed with 342 patients who had undergone surgery for intermittent exotropia of the basic, pseudo-DE or true DE type with a postoperative follow-up period of 6 months or more. The main outcome measures were postoperative angles of deviation at distance and near, and surgical success rates. Surgical success was defined as alignment between exodeviation of 10 PD and esodeviation of 5 PD at distance and near. Additionally, survival curves of recurrence were analyzed by the Kaplan-Meier method. The postoperative angles of deviation at both distance and near in pseudo-DE type were significantly smaller than those in basic type at the final examination (p = 0.003, <0.001). The final surgical success rate in pseudo-DE (70.2%) was better than in basic (46.3%) or true DE (28.6%) (p = 0.003, 0.01). Reoperation for recurrent exotropia was performed in 27% of the basic, 17% of the pseudo-DE, and 35.7% of the true DE cases. According to a survival analysis for recurrence, patients with pseudo-DE showed lower incidence of recurrence than did patients with basic and true DE (p = 0.003, 0.02). In conclusion, the patients with intermittent exotropia of the pseudo-DE type showed better surgical outcomes than those with the basic or true DE type. Pseudo-DE also showed a lower recurrence rate than did the other 2 groups.
Highlights
Intermittent exotropia could be classified considering to the disparity of distance and near deviation
Based on the Burian’s classification, 1) patient in whom the distance deviation equals or less than 10PD of near is defined as basic type, 2) the distance deviation is more than 10PD larger than near deviation as true divergence excess type, 3) the near deviation increases within 10PD of distance after monocular occlusion as simulated divergence excess or pseudo-divergence excess type. 4) the near deviation is larger than distance as convergence-insufficiency [1,2,3,4]
The purpose of the present study was to compare the surgical outcomes of pseudo-DE and true divergence excess (true DE) type, and to compare them with basic type of intermittent exotropia
Summary
Intermittent exotropia could be classified considering to the disparity of distance and near deviation. 4) the near deviation is larger than distance as convergence-insufficiency [1,2,3,4]. In measurements of the deviation, monocular occlusion should be made to eliminate fusional impulses. Scobee[5] proposed 24 hours of monocular occlusion and Burian[1] suggested that only 30 to 45 minutes of monocular occlusion was enough to remove fusional stimuli. He classified such patients as having pseudo-DE, in which patients had equal deviations at near and distance after monocular occlusion test. Kushner[6, 7] used the term ‘‘tenacious proximal fusion” for such a persistent convergence innervation at near fixation
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