Intermittent exotropia: facts, opinions, and unknowns

Schielen oder nicht Schielen? – Strabismus divergens intermittens, eine besondere Schielform

Hintergrund

Schielen tritt bei ca. 5–7 % der gesunden Kinder auf. Außenschielen ist mit 1,24 % weltweit seltener als Innenschielen. Der Strabismus divergens intermittens stellt mit 40–90 % die häufigste divergente Schielform dar. Das klinische Bild wurde von vielen AutorInnen beschrieben. Dennoch stellt es durch die Variabilität der Befunde eine therapeutische Herausforderung dar.

Material und Methode

Es wurden im Rahmen einer Literaturrecherche die Ergebnisse von Studien zum Strabismus divergens intermittens mit Fokus auf klinisches Bild, Untersuchungskriterien und Therapieansätze gesammelt und die Ergebnisse dargestellt.

Resultate

Der Strabismus divergens intermittens zeichnet sich durch eine besondere Binokularsituation und bisher ursächlich nicht vollends geklärte Symptome (Photophobie, Kneifen) aus. Konservative Therapien dienen der Entlastung des visuellen Systems, in vielen Fällen ist aber eine Schieloperation nötig. In der präoperativen Beurteilung ist der Stabilität des Schielwinkels besonderes Augenmerk zu schenken, als Entscheidungshilfe hinsichtlich Schieloperation hat sich der New Castle Control Score bewährt.

Schlussfolgerung

Die klinischen Charakteristika des Strabismus divergens intermittens sind klar beschrieben. Hinsichtlich therapeutischer Ansätze zeigen sich im internationalen Vergleich Unterschiede. Die Bedeutung der Einbeziehung der Eltern („shared decision making“) bei der Beurteilung der Schielhäufigkeit und bei der Operationsentscheidung ist zu betonen.

Comparison of surgery versus observation for small angle intermittent exotropia

In young children with small angle exotropia, making decisions for the individual patient whether to perform surgery or not, and choosing the optimal time for surgical intervention are quite difficult. We aimed to compare the long-term outcomes of small angle intermittent exotropia of 20 prism diopters (PD) or less after observation versus strabismus surgery. A retrospective study was performed on 164 patients aged 3 to 13 who underwent surgical intervention or observation with or without conservative management for intermittent exotropia of 14 to 20 PD. The minimum follow-up period was 2 years. The average follow-up period was 3.9 ± 2.2 years in the observation group and 4.5 ± 2.3 years in the surgery group. At the final examination, the mean angle of deviation at distance was 11.1 ± 8.9 PD in the observation group and 9.0 ± 7.5 PD in the surgery group, which was not significantly different (P = 0.121). Changes in sensory outcome and fusional control were not significantly different between both groups (P = 0.748 and P = 0.968). Subgroup analysis including patients with poor fusional control also showed similar results. By multivariate analysis, the type of surgery, unilateral recess-resect procedure, was the only predictive factor of good motor outcome in the surgery group. In conclusion, long-term surgical outcomes in small angle exotropia did not appear to be more satisfying than observation in terms of motor and sensory outcomes.

Clinical study of the effect of refractive status on stereopsis in children with intermittent exotropia

Background

Many studies have shown that patients with intermittent exotropia have different degrees of damage to their stereopsis function. The purpose of this study is to explore the effect of different refractive status on stereopsis in children with intermittent exotropia(IXT).

Methods

We assessed 90 children of ages 4~ 16 years with intermittent exotropia at the Second Affiliated Hospital of Dalian Medical University during the years 2016–2017. According to their refractive status, the patients were divided into hyperopia group(spherical equivalent > or = − 1.00 diopters), myopia group(spherical equivalent < or = − 1.00 diopters), emmetropia group (spherical equivalent diopter: within ±1.00DS) and anisometropia group(binocular equivalent spherical difference > or = 1.50 diopter). The distant stereopsis of the patient was checked by the synoptophore, and the near stereopsis of the patients was checked by the Titmus stereogram. Then, we compared the difference between distant stereopsis and near stereopsis in the four groups.

Results

(1)The retention rates of distant stereopsis in the hyperopia group, emmetropia group, myopia group and anisometropia group were 33.3, 45.2, 34.6, and 33.3%, respectively. There was no significant difference between the groups with different refractive status. (2)The retention rates of near stereopsis in the hyperopia group, emmetropia group, myopia group and anisometropia group were 66.7, 83.9, 80.8, and 55.6%, respectively. There were statistically significant differences between the emmetropia group and the anisometropia group (P = 0.030). (3)The retention rate of distant stereopsis in children with intermittent exotropia was 37.8%, and the retention rate of near stereopsis was 74.4%. The difference between the two groups was statistically significant (P = 0.019).

Conclusions

The damage to distant stereopsis in children with intermittent exotropia is more serious than that to near stereopsis. The damage to near stereopsis in children with intermittent exotropia and anisometropiais more serious.