Clinical Features and the Risk Factors of Infantile Exotropia Recurrence




Purpose


To evaluate the clinical features and the risk factors of recurrence in infantile exotropia.


Design


Retrospective, observational case series.


Methods


The clinical records of 20 infantile exotropia patients who underwent exotropia surgery were reviewed retrospectively. Patients were divided into 2 groups according to the amount of exodeviation present at 1 year after surgery. Preoperative patient characteristics and postoperative alignments were evaluated at 1 day and 1, 3, 6, and 12 months after surgery.


Results


The successful group was composed of 12 patients with an alignment of less than 10 prism diopters (PD) of exodeviation, and the recurrent group was composed of 8 patients with an alignment of 10 PD or more of exodeviation (range, 10 to 18 PD) at 1 year after surgery. The incidences of dissociated vertical deviation, inferior oblique overaction, and rates of constancy before operation were not significantly different in the 2 groups ( P = .603, P = .158, and P = .347, respectively), and postoperative deviations were not significantly different at 1 day after surgery. However, postoperative deviations were significantly different in the 2 groups at 1 month ( P = .069) and 3 months ( P < .001) after surgery, and this difference was maintained at 12 months after surgery. Furthermore, correlation between initial alignments at 1 month after surgery and final alignments was significant in successful group ( P = .012).


Conclusions


No single factor affecting the surgical outcome was identified in infantile exotropia, but the recurrence of infantile exotropia was apparent from the first postoperative month.


Patients with intermittent exotropia tend to show an exotropic drift over time. Furthermore, it has been reported that overcorrection of exotropia in the early postoperative period may be associated with improved long-term results in intermittent exotropia. Scott and associates and Raab and Parks reported that initial postoperative alignment of 4 to 14 prism diopters (PD) and 11 to 20 PD esodeviation remains satisfactory in the long term after surgery, whereas Oh and Hwang found that early postoperative overcorrection is the only predictor of a successful long-term outcome after surgery for intermittent exotropia.


However, infantile exotropia is a rare motility disorder characterized by divergent strabismus that is apparent in infancy and persists beyond age 6 months. Hunter and associates and Biglan and associates reported that approximately equal numbers of infantile exotropia patients have intermittent or constant exotropia at presentation and that clinical outcomes are similar regardless of presentation.


Reported long-term alignment results after surgery for infantile exotropia have been disappointing. Reoperations are needed by up to 50% of patients, and most are undertaken to treat recurrence. Furthermore, it is probably best to aim for slight overcorrection during the immediate postoperative period to overcome the high rate of undercorrection reported for this condition, because even small angles of esotropia after surgery in infantile exotropia may create the risk of amblyopia with monofixation syndrome. However, no controlled study has been undertaken on the relationship between initial alignment and long-term outcome or on the factors that affect the recurrence of infantile exotropia. The aim of this study was to evaluate the clinical features and risk factors associated with recurrence of infantile exotropia.


Methods


The records of 20 patients diagnosed with exotropia before 12 months of age and who underwent surgery at the Korea University Medical Center from 2003 through 2008 were extracted. Patients with exotropia caused by previous eye muscle surgery and those with any other ocular or systemic disease were excluded, as were patients who were uncooperative during alternate prism cover testing. The following information was recorded when available: age at onset and at visit, sex, preoperative and postoperative angles of strabismus, intermittent versus constant phase before surgery, age at surgery, associated ocular motility disturbance, and binocular sensory status. Age at onset was defined the age at which a parent or relative first observed ocular misalignment, and recalled values were checked using old patients’ photographs.


Alternate prism cover testing for fixation at 1/3 and 6 m was conducted on all patients. All patients underwent bilateral lateral rectus muscle recession. Surgery was performed when stable exodeviation, stabilization of the angle over 2 or 3 consecutive visits, exceeded 25 PD. All surgeries involved bilateral lateral rectus muscle recession and were performed by 1 surgeon (S.-H.K.). Surgical dosages were applied using standard tables.


All patients were managed by alternate patching for 1 to 4 weeks after surgery (each eye for 8 hours/8 hours daily) on an individual basis. If the patients had obtained orthophoria, we stopped patching. The Titmus stereoacuity test (Stereo Optical, Chicago, Illinois, USA) was used in cooperative patients to assess binocular sensory status.


Postoperative alignments at distance and near were measured at 1 day and 1, 3, 6, and 12 months after surgery. Those with less than 10 PD of exotropia for distant deviation at 1 year after surgery were allocated to the successful group, and those with 10 PD or more of exotropia were allocated to the recurrent group. Reoperation for recurrence was performed if exotropia exceeded 20 PD at distance after primary surgery.


Statistical Analysis


Statistical analysis was performed using SPSS for Windows version 12.0 (SPSS, Inc, Chicago, Illinois, USA). Mean postoperative exodeviation was used for the primary outcome variable. Postoperative exodeviation amounts during follow-up between the 2 groups were compared using the Mann–Whitney U test. The Fisher exact text was used to compare categorical variables, such as associated features or constant deviation, between the 2 groups. The Spearman rank correlation analysis was used to investigate the correlation between postoperative alignment and final outcome. Statistical significance was accepted for P values of less than .05.




Results


The mean follow-up after primary surgery was 28 months (range, 12 to 81 months). The 20 patients enrolled were assigned to 2 groups according to the amount of exodeviation present at 1 year after surgery; that is, 12 patients with less than 10 PD of exodeviation were assigned to the successful group (range, orthophoria to 8 PD), and 8 patients with 10 PD or more to the recurrent group (range, 10 to 18 PD). The preoperative characteristics of patients were not significantly different between the 2 groups ( Table 1 ). Furthermore, no significant intergroup differences were found for age at presentation, age at primary surgery, or preoperative exodeviation ( P = .384, P = .270, and P = .678, respectively). The incidences of dissociated vertical deviation and inferior oblique overaction were higher in the successful group, but not significantly ( P = .603 and P = .158, respectively, Fisher exact test), and similarly, rates of constancy were not significantly different ( P = .347, Fisher exact test). Binocular sensory status was checked in 8 of the 20 patients, and 3 achieved 100 seconds of arc of stereopsis ( Table 1 ).



TABLE 1

Comparison of Variables between Successful and Recurrent Groups in Infantile Exotropia Recurrence
































































Successful Group (n = 12) Recurrent Group (n = 8) P Value
Mean age at visit (mos) 25.92 ± 9.02 (15 to 40) 29.88 ± 10.86 (13 to 46) .384 a
Mean age at surgery (mos) 32.75 ± 8.73 (20 to 43) 37.38 ± 8.30 (24 to 47) .270 a
Preoperative deviation
Distance (PD) 32.08 ± 6.56 (25 to 45) 33.13 ± 5.94 (25 to 40) .678 a
Near (PD) 30.50 ± 6.97 (18 to 40) 33.75 ± 6.41 (25 to 40) .343 a
Associated features
DVD 4 (33.3%) 1 (12.5%) .603 b
Inferior oblique overaction 6 (50.0%) 1 (12.5%) .158 b
Constant deviation 2 (16.7%) 3 (37.5%) .347 b
Follow-up (mos) 22.10 ± 15.18 (12 to 51) 36.77 ± 25.91 (12 to 67) .098 a
Stereopsis 3 c (0 to 400 sec) 5 c (0 to 100 sec)

DVD = dissociated vertical deviation; mos = months; PD = prism diopters.

a Mann–Whitney U test.


b Fisher exact test.


c Mean number of patients who were able to perform stereopsis testing.



Alignments at 1 day and 1, 3, 6, and 12 months after surgery are shown in Table 2 . All patents underwent bilateral lateral rectus muscle recession, and no intraoperative surgical complications were encountered. Furthermore, no patient needed surgery for dissociated vertical deviation or inferior oblique overaction.



TABLE 2

Postoperative Alignments in the Successful and Recurrent Groups in Infantile Exotropia Recurrence


































Successful Group (n = 12) a Recurrent Group (n = 8) a P Value
Postoperative day 1 deviation (PD) −5.08 ± 3.56 (−10 to 2) −4.75 ± 3.85 (−10 to 0) .571 b
Postoperative month 1 deviation (PD) 1.75 ± 2.90 (−2 to 8) 5.75 ± 4.83 (0 to 12) .069 a
Postoperative month 3 deviation (PD) 0.67 ± 1.78 (0 to 6) 7.00 ± 3.55 (4 to 12) <.001 b
Postoperative month 6 deviation (PD) 0.67 ± 2.31 (0 to 8) 8.50 ± 5.53 (0 to 16) .002 b
Postoperative year 1 deviation (PD) 1.50 ± 2.84 (0 to 8) 13.25 ± 2.82 (10 to 18) <.001 b

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Jan 17, 2017 | Posted by in OPHTHALMOLOGY | Comments Off on Clinical Features and the Risk Factors of Infantile Exotropia Recurrence
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