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RESULTS
Among 12 patients of undercorrected group, one patient was lost in the sixmonth followup. No statistically significant differences were seen between both groups preoperatively in terms of hypermetropia, age, angle of deviation at far and near fixation with and without spectacle.
Six months after operation, 10 out of eleven patients in undercorrected group had surgical success (91%), and one patient (9%) was overcorrected. In standard group, 6months postoperatively, 7 patients (54%) were overcorrected, and 6 patients (46%) had surgical success. There was statistically significant difference between two groups in terms of overcorrection rate (P=0.027, fishers exact test).
Eight out of 12 patients with low to moderate hyperopia (<4D) preoperatively had surgical success, and 4 were overcorrected. In high hyperopic patients (≥4D) 8 patients were surgical successes and 4 were overcorrected. Difference between two groups was not statistically significant (P= 0.667).
There was no statistically significant correlation between surgical outcomes of both groups based on age, preoperative angle of strabismus (through full hyperopic correction at distant target) (Table 1).
DISCUSSION
Treatment of PAET consists of amblyopia management and prescription of full hyperopic correction. Strabismus surgery may be warranted for the nonaccommodative portion. Standard surgery for partially accommodative esotropia is based on the maximum nonaccommodative component of the deviation measured through the full cycloplegic prescription.
Song JH et al[10] reviewed the medical records of total 85 patients with PAET who underwent BMR surgery and were followed up for at least 6 months. The results were analyzed at 1 month, 1 year and 4 years after surgery and showed a tendency to become exotropic during the 4 years after surgery. They suggested in PAET, it is essential that orthotropia or minimal esotropia should be present in the early postoperative period in order to obtain a good binocular alignment as the long term result and also recommendedthat overcorrection be avoided in early postoperative exotropia. Table 1Results of analysis of standard group and undercorrected group patients（略）
Kushner[9] reviewed 382 patients who underwent surgery for PAET. He concluded that surgical overcorrection in patients with PAET with greater than +2.5 diopters of hyperopia may not be reversible by postoperative reduction in the hyperopic correction.
aruo et al[11] reviewed 956 patients under 15 years of age who underwent unilateral or bilateral recession of the medial rectus muscle during a 22year period. They comprised 521 cases of congenital/infantile esotropia (manifest before 6 months of age with no accommodative component) and 435 cases of acquired esotropia (manifest after 6 months of age with no accommodative component or with an accommodative component but excluding those with a high AC/A ratio). Both types of esotropia showed a slight tendency to become exotropic during the 4 years after surgery. They concluded that in infantile and acquired esotropia, it is essential that orthotropia or minimal esotropia be present at 1 month of surgery in order to obtain a binocular alignment within +/4 PD of orthotropia 4 years after surgery and strongly recommended to avoid overcorrection (consecutive exotropia) at 1 month after surgery for both congenital/infantile and acquired esotropia.
In our study, surgical overcorrection occurred in 54% of patients with PAET and normal AC/A who underwent standard BMR surgery in contrast to 9% in undercorrected BMR surgery. Our results seem to be the same as Arnoldi report[2] (i.e. 44% overcorrection with standard surgery).
This high overcorrection rate exceeds most published reports, possibly due to strict definition of overcorrection. Both in our study and Arnoldi study[2], high AC/A was an exclusion criteria, which could be a possible cause of such difference.
The relationship between refractive error and surgical outcome in PAET is unclear. Wright and BruceLyle[3] reported better surgical results in patients with lower refractive error while other reported opposite[2]. In our study there was no correlation between surgical outcomes and degree of hyperopia.
As mentioned previously, some authors suggested reducing hyperopic spectacle power in setting of consecutive exotropia , but others believed that this approach is not effective in long term, especially in hyperopia >+2.5[9] , and in normal AC/A[2]. In addition, some authors noted that in PAET, it is essential that orthophoria or minimal esotropia should be present in the early postoperative period to obtain good binocular alignment as the long term result and recommended that overcorrection must be avoided in early postoperative period.
According to above reports and this study, it seems that undercorrected method BMR surgery in patients with PAET and normal AC/A can be effective to reduce overcorrection rate and increase surgical success.
【参考文献】
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10 Song JH, Seong YS, Chang YH, Lee JB. The long term surgical outcome after bilateral medial rectus muscle recession in partially accommodative esotropia. J Korean Ophthalmol Soc2004;45(3):462468
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