Correlation Between Age and Insertional Distance Between the Nasal Limbus and the Insertion of the Medial Rectus Muscle Measured in Surgery
Takashi Negishi, MD, PhD
Juntendo University Faculty of Medicine, Department of Ophthalmology
Introduction: The distance between the nasal limbus and the insertion of the medial rectus muscle (insertional distance) is sometimes observed shortly especially in early surgical treatment of congenital esotropia. We investigated basic characteristics of insertional distance in esotropia patients.
Methods: Retrospective research. All the patients underwent eye muscle surgery under 15-year-old and Asian population. Main outcome measures are correlations of the insertional distance, the onset of esotropia, angle of esotropia, refractive errors and age at the surgery. A single surgeon measured the distance using standard calipers at the surgery. All research was conducted under the tenets of the Declaration of Helsinki.
Results: 147 eyes of 80 patients (47 males) were investigated. Average age at the surgery was 3.9±2.9 (0.7~14.6). Average distance was 4.4mm±0.5mm (3.0mm~5mm). The correlation coefficient between insertional distance and the onset of esotropia(0.0027), age at the surgery(<.0001) was significantly high. Otherwise, correlations between insertional distance and refractive errors(0.06), angle of esotropia(0.053) was lower. (Spearman’s rank correlation coefficient, JMP 8).
Discussion: Recently, a lot of group reported insertional distances using optical coherence tomography. However, non-invasive measurement is very difficult for infantile esotropia. Mild correlation between insertional distance and refractive errors might represent that axial length and insertional distance increase differently. Age at the surgery was strongly correlated with insertional distance, although we haven’t experienced infants less than 6 months.
Conclusion: The insertional distance and the age at the surgery were strongly correlated. Average insertional distance was overall shorter than previously reported normal control.
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2. Swan KC, Wilkins JH. Extraocular muscle surgery in early infancy–anatomical factors. J Pediatr Ophthalmol Strabismus. 1984;21(2):44-9.
3. Barsoum-homsy M. Medial rectus insertion site in congenital esotropia. Can J Ophthalmol. 1981;16(4):181-6.