Clinical Findings of Constant Exotropia Developed from Intermittent Exotropia

PURPOSE: To investigate clinical characteristics of constant exotropia patients with a previous history of intermittent exotropia. METHODS: Constant exotropia patients (CXT) with a previous history of intermittency, and intermittent exotropia patients (X [T]) who had undergone surgery for exotropia were included in the present study. Patching therapy of the fixating eye was performed for all patients. Surgical results, the effect of patching, lateral incomitancy, and suppression were retrospectively reviewed and compared between the 2 groups. RESULTS: The number of CXT was 51 and X (T) was 84. The angles of deviation at the initial visit and at surgery were significantly larger in CXT. After 3 months of patching therapy, there was no difference between the 2 groups in the reduction of distant angle of deviation. However, the reduction of near angle of deviation was 0.29 +/- 5.44 in CXT and 4.42 +/- 6.26 Delta in X (T), which was significantly different (p = 0.04). Lateral incomitancy was observed in 7.8% of CXT and 34.5% of X (T) (p < 0.001). The angles of deviation at the final visit and surgical success rate were not different between the groups. Preoperative suppression at distant was found in 100% of CXT and 88.7% of X (T), and postoperative suppression was in 17.6% and 18.3%, respectively. CONCLUSIONS: The surgical success rate and postoperative suppression were not different between constant exotropia and intermittent exotropia. However, the frequency of lateral incomitancy and the response to the patching therapy was lower in constant exotropia.

Consecutive Esotropia in Intermittent Exotropia Patients with Immediate Postoperative Overcorrection More Than 17 Prism Diopters

PURPOSE: To report the incidence and the factors of consecutive esotropia (ET) in patients with immediate postoperative overcorrection of at least 17 prism diopters (PD) after surgery for intermittent exotropia (X(T)). METHODS: Four-hundred-five patients under the age of 18 were included in this study. They underwent bilateral lateral rectus recession (LROU-rec) or unilateral recession-resection (R&R) for X(T). On postoperative day one, the patients with at least 17 PD overcorrection were classified as group 1 and those with less than 17 PD as group 2. Age, refractive error, type of surgery, lateral incomitancy, and the incidence of consecutive ET were analyzed for each group. RESULTS: Group 1 consisted of 116 patients (28.6%) and group 2 consisted of 289 (71.4%). At the six-month follow-up visit, consecutive ET had developed in 16 patients (13.8%) in group 1, and in five patients (1.7%) in group 2 (p<0.001). The occurrence of consecutive ET was not related to age at the time of surgery (p=0.46 in group 1 ; p=0.54 in group 2), refractive error (p=0.18 in group 1 ; p=0.08 in group 2), or the type of surgery (p=0.69 in group 1 ; p=1.00 in group 2). The incidence in group 1 was 23.8% in patients with lateral incomitancy and 8.1% in patients without lateral incomitancy (p<0.05). In group 2, the incidence was 4.4% in patients with lateral incomitancy and 0.5% in patients without lateral incomitancy (p=0.04). CONCLUSIONS: Consecutive ET developed in 13.8% of patients with immediate overcorrection of at least 17 PD. Lateral incomitancy was the most important risk factor.

The position of eye and head for measurement of lateral incomitancy in intermittent exotropes

PURPOSE: To determine proper position of lateral gazes and angle of head turn for the measuring lateral incomitancy in intermittent exotropia. METHODS: Twenty-five Korean intermittent exotropes with exoangle more than 25 prism diopters (PD) and 25 orthophoric people were taken. Three lateral gazes were proposed: position A, when the lateral limbus of the abducted eye was off the lateral canthus; position B, when touched the lateral canthus; and position C when was hidden behind the lateral canthus. The angle of deviation and head turn were measured at each position. In the most comfortable position which subjects selected, the length from lateral canthus to lateral limbus (lateral cantho-limbal distance) of the abducted eye was measured. RESULTS: 23 patients of each group selected that position A was the most comfortable. At position A, the mean of cantho-limbal distance in exotropes was 1.19mm at the right lateral gaze and 1.04 mm at left, people with orthophoria showed larger values in both gazes. The average amount of head turn was 24.1 degrees at the right lateral gaze and 24.3 degrees at the left at position A, 27.5 degrees and 34.1 degrees at position B, 27.6 degrees and 33.7degrees at position C. The average angle of exodeviation was 27.4 PD in the primary gaze. It was 21.7 PD in the right lateral gaze and 20.3 PD in the left lateral gaze at position A, 17.9 PD and 17.5 PD at position B, and 9.0 PD and 8.6 PD at position C. CONCLUSIONS: In the measurement of lateral exo-angle to evaluate lateral incomitancy in intermittent exotropia, the most appropriate position of eye and head turn turned to be when the lateral limbus of the abducted eye is about 1mm apart from the lateral canthus with head turn of 25degrees laterally.

Consecutive Esotropia after Surgical Correction of Intermittent Exotropia

Intentional overcorrection is recommended immediately after surgery of intermittent exotropia for its superior long-term prognosis. However, esotropia can develop in 6~15%, especially in children less than 4 years of age, and bring about the problems such as diplopia, suppression, decreased vision and impaired binocular single vision. The purpose of this study is to evaluate the factors possibly associated with its occurrence. A retrospective study was conducted on the 22 patients with consecutive esotropia, which had developed after surgical correction of intermittent exotropia. They underwent unilateral or bilateral medial rectus muscle recession for correction of esotropia. The mean angle of exodeviation before intermittent exotropia surgery was 30.0+/-5.2 PD(prism diopters)(23~40 PD). The mean angle of esodeviation at surgery for consecutive esotropia was 24.1+/-10.3 PD(10~55 PD). Before surgery of intermittent exotropia, 13 of the 16 patients(81.3%)had showed lateral incomitancy. No significant difference was found between age at surgery and consecutive esotropia. High AC/A ratio had been present preoperatively in only one patient. No patient showed A-V pattern preoperatively. Out of the 17 patients who had undergone bilateral lateral rectus recessions for intermittent exotropia, 10(58.8%) patients had either lateral rectus muscle recessed by 7.5 mm or more. Four of the 5 patients(80%)had a medial rectus resected by 5 mm or more. This study suggests that consecutive esotropia after intermittent exotropia surgery can develop more likely in the patients who have had lateral incomitancy, excessive recession of lateral rectus muscle by 7.5 mm or more, or excessive resection of medial rectus muscle by 5 mm or more.