AIM:To investigate the clinical effect of rectus muscle release and recession combined with orbital fat resection on restrictive strabismus of thyroid associated ophthalmopathy.

METHODS: From March 2018 to June 2019, 27 cases of restrictive strabismus with thyroid associated ophthalmopathy were retrospectively analyzed, 34 eyes in total. Under general anesthesia, all patients underwent rectus muscle release and orbital fat resection. The range of orbital fat resection was selected according to the degree of the ophthalmologic process in the subnasal, subtemporal, superior nasal, or superior temporal quadrants.Inferior rectus recession was performed in 25 eyes, medial rectus recession in 5 eyes and superior rectus recession in 4 eyes. According to the degree of exophthalmos, he internal and external fat of inferior nasal, infratemporal, Supranasal or supratemporal quadrant muscles were excised respectively during the operation. According to the preoperative strabismus degree and the degree of contraction of external rectus muscle, the recession amount of rectus operation was designed,and the strength of passive rotation test was estimated intraoperatively. The amount of fat removed during the operation was designed according to the degree of protrusion before operation, and it was designed to remove about 1mL fat and retract the eyeball by 1mm.The postoperative follow-up time was once a week, once a month after 1mo, and irregular follow-up after 3mo. All patients were followed up for more than 6mo.

RESULTS: The amount of fat removed was 2.1-3.4mL, with an average of 2.6mL.The visual(LogMAR)acuity was 0-0.2 in the 1mo after operation, with an average of 0.11±0.16. The visual acuity was 0-0.3 in the 6mo after operation, with an average of 0.12±0.17.There was no significant difference in visual acuity before and after operation(P>0.05). The degree of eyeball protrusion was 13-16mm, with an average of 14.4±0.8mm, and the degree of corrected eyeball protrusion was 2-4mm, with an average of 2.4mm(q=10.737, P<0.01). The degree of eyeball protrusion at 6mo after surgery was 13-15.5mm, with an average of 14.5±0.6mm, showing no significant difference from 1mo after surgery(q=0.624, P=0.173). 1mo after surgery, the strabismus was 2^△-10^△, with an average of 6.7^△±2.3^△, all of which were under correction(q=18.068, P<0.01). Before surgery, all the patients had diplopia at the first sight, and the first diplopia disappeared one month after surgery. All patients showed significant improvement in compensatory head position. The strabismus(undercorrection)of the patients at 6mo after surgery was 0^△-7^△, with an average of 3.4^△±1.2^△, and the difference was statistically significant compared with 1mo after surgery(q=5.385, P=0.015). The patient had no diplopia at the first and lower transitory position. The mean intraocular pressure after surgery(17.12±1.89mmHg)was lower than that before surgery, and the difference between preoperative and postoperative intraocular pressure was statistically significant(q=4.258, P=0.018).The mean intraocular pressure at 6mo after surgery was 17.53±1.67mmHg, with no significant difference from 1mo after surgery(q=0.729, P=0.154).

CONCLUSION: Orbital fat resection can improve the protrusion of the eyeball, but has no significant influence on the surgical design and effect of restrictive strabismus. It is a kind of controllable operation scheme to treat the limited strabismus with exophthalmos of thyroid associated ophthalmopathy with rectus muscle release and recession combined with orbital fat resection.