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Ethnicity may play role in outcomes of strabismus surgery
Differences in extraocular muscle insertion sites may warrant different surgical guidelines for treating exotropia in two populations.
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Extraocular muscle insertion locations differ significantly between Western and Taiwanese populations, according to a study.
The findings support the trend toward customizing disease treatment, particularly for strabismus surgery, according to study co-author Yu-Hung Lai, MD.
“Treatment of diseases has become customized in many fields. For example, if two persons both had the same kind of cancer, their treatments could be different after analyzing DNA in their genomes and/or biochemical pathways in cancer cells,” Lai said in an email interview. “With more related studies and advanced technology in the future, we will be able to customize and personalize strabismus surgery too.”
The study
The retrospective study involved 183 Taiwanese patients: 123 consecutive patients with strabismus and a control group of 60 patients who had undergone an encircling scleral buckle procedure and had no previous diagnosis of strabismus.
A caliper was used to determine the distance between the anterior limbus and the midpoint of extraocular muscle insertion. Data were collected on age at surgery, gender, preoperative deviation and preoperative axial length. Postoperative data included residual deviation.
Insertion location data for the Taiwanese strabismus group were compared with data from an earlier study performed on a Western population of 47 Caucasians and three African-Americans. Surgical outcomes were compared with studies from Western and/or Asian populations.
The study was published in the British Journal of Ophthalmology.
Results
The lateral rectus insertion location was significantly connected to axial length in the right eye (P = .002) but not in the left eye. Insertions for the inferior rectus, superior rectus and lateral rectus correlated with other muscle insertion locations, but the medial rectus insertion did not, according to the study.
“The insertion of the [medial rectus] seems to be the most reliable and invariant of the rectus muscles in all patients regardless of their ethnic background,” the study authors said.
The study results demonstrated that the observed distances from insertion to the anterior limbus of the inferior rectus, lateral rectus and superior rectus were significantly longer in Western populations than in Taiwanese populations.
“We have observed that the [extraocular muscle] insertion locations in strabismus patients in Taiwan are more anterior than those reported in studies of Western populations,” the study authors said.
From the anterior limbus, mean inferior rectus distance was 6 mm, mean lateral rectus distance was 6.4 mm, and mean superior rectus distance was 6.8 mm in Taiwanese patients. In Western patients, the respective values were 6.8 mm, 6.9 mm and 7.9 mm. All distances other than that of the medial rectus were statistically significant (P < .001).
Due to globalization, physicians should review surgical data to improve outcomes.
“With globalization, ethnic analysis is not easy in some countries. However, in areas with relatively stable ethnic populations, to analyze with the patient’s ethnicity is important,” Lai said. – by Ashley Biro