Objective To observe the therapeutic effect of poly tetrahydrofurfuryl-co-lactic acid (copolymer C 4) as the biodegradable vitreous substitutes on rhegmatogenous retinal detachment. Methods Vitreoretinal surgery with copolymer C 4 tamponades was performed on 32 pigmented rabbits (64 eyes) with rhegmatogenous retinal detachment. The rate of reattached retina and the post-operative complications were observed. Results Three months after the operation, reattached retina was found in 96.4%, glaucoma in 5.5%, cataract in 10.9%, and copolymer emulsion in 10.2% of all the eyes. Conclusion copolymer C 4 may withstand the retinal tear effectively for 3 months, and can be a valuable vitreous substitutes.

Objective:To explore the application value of ultrasound in the early noninvasive monitoring of acute compartment syndrome model, and to provide reference for further clinical applications.Methods:This was a prospective self-controlled study. A model of healthy volunteers with acute compartment syndrome was established by cuff compression. The random method was used to determine the experimental side and the control side. The experimental side cuff was given 0, 20, 30, 40, 50, 60, 70, and 80 mmHg pressure in sequence, while the control side cuff was kept uncompressed at all times. Each pressure on the experimental side lasted for 5 min, during which the ultrasound was used to measure the blood flow waveform and vascular structure of the bilateral popliteal artery, popliteal vein and dorsal plantar artery. Statistical analysis was performed using repeated measures analysis of variance and multivariate analysis of variance.Results:The study included 25 healthy volunteers. There was no statistically significant difference in calf circumference and anterior tibial compartment thickness ( P = 0.314 and 0.678). During compression, the volunteers' heart rate and blood pressure were stable ( P = 0.235 and 0.358). On the experimental side, the maximum blood flow velocity of the popliteal artery during systole increased with the increase of pressure ( P<0.001), and the minimum blood flow velocity of the popliteal artery increased with the increase of pressure ( P<0.001). When pressurized by 30 mmHg, the maximum blood flow velocity of the popliteal artery on the experimental side was significantly higher than that on the control side [(73 ± 19) cm/s vs (59 ± 14) cm/s, P=0.023)]. When pressurized by 20 mmHg, the minimum blood flow velocity of the popliteal artery on the experimental side was significantly higher than that on the control side [(-28 ± 8) cm/s vs (-22 ± 6) cm/s, P=0.012)]. With the increase of pressure, the diastolic retrograde arterial flow ratio of the experimental side gradually increased ( P <0.001), and when the pressure was increased by 20 mmHg, the diastolic retrograde arterial flow ratio of the experimental side of the popliteal artery increased significantly [(0.42 ± 0.14) cm/s vs (0.30 ± 0.12) cm/s, P=0.009)]. The systolic prograde arterial flow ratio of the dorsal artery in the experimental side decreased with the increase of pressure ( P = 0.024). Conclusions:Increased limb compartment pressure can significantly change the arterial flow waveform of the proximal and distal arteries, and ultrasound can be used as an early monitoring tool for acute compartment syndrome.