Correlation of Levator-Muller's Complex Thickness on Ultrasound Biomicroscopy to Botulinum Toxin A Injection in Thyroid-Related Upper Eyelid Retraction.

[OBJECTIVES] To study the thickness of levator palpebra superioris-Muller's muscle complex (LMC) on ultrasound biomicroscopy (UBM) and to correlate with the clinical response to botulinum toxin A (BTA) injection in patients with inactive-stage of thyroid-related upper eyelid retraction (UER). We also studied the correlation of clinical parameters, preinjection with postinjection values.

[METHODS] This was a prospective, interventional study. Patients with thyroid-related UER who underwent subconjunctival injection of BTA were recruited. Demographic data and clinical details were evaluated. UBM (50 MHz) was done to measure the thickness of LMC. Patient's satisfaction was graded at each follow-up. Follow-up was done at 1 week, 1 month, and 3 months' time intervals.

[RESULTS] A total of 13 patients were recruited and 26 eyes were divided into two groups; group 1 included eyes with UER (n = 17), and group 2 included eyes without UER (n = 9). There was a statistically significant reduction in margin reflex distance 1 (MRD1) after BTA injection at 1-week, 1-month, and 3-months follow-up with maximum reduction at 1 month. The mean LMC thickness of 26 eyes was 0.96 mm which was found to be significantly more than normal controls. On comparison of mean LMC thickness with the amount of UER and reduction in MRD1, we did not find a significant difference.

[CONCLUSIONS] Patients with TED have significantly thicker LMC on UBM than controls. Further studies are needed with a larger sample size on the correlation of UBM features of levator aponeurosis with response to BTA injection.