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Background Hyaluronic acid fillers can be manufactured using various processes. They have multiple properties, including their concentration, degree of modification, and rheological data. Cohesion is one such property to evaluate gel integrity; however, there is no standardized method for calculating this parameter. This study aimed to evaluate different tests for calculating hyaluronic acid cohesion and discuss the importance of hyaluronic acid cohesion as a consideration when selecting fillers. Methods The cohesion levels of five different hyaluronic acid fillers with different rheological properties were evaluated and compared using the drop weight, compression, tack, and dispersion time tests. Results The cohesion tests yielded different results in the samples. Samples 2 and 4 showed approximately two times the number of droplets when compared with Sample 5 in drop weight test. Samples 1, 2, 3, and 4 were superior to Sample 5 in tack test. Samples 1, 2, and 3 showed cohesive appearances at 95 seconds in most cases in dispersion test. Rheological test results did not reflect the measures of cohesion. Conclusion Although there are no definite standardized tests to evaluate the cohesion of hyaluronic acid fillers, our proposed tests showed similar results for different hyaluronic acid filler products. Further studies are needed to evaluate the cohesion of hyaluronic acid fillers and determine the clinical use of this distinguishing characteristic for clinicians selecting the product of choice. Level of evidence statement: These data are Level IV evidence.
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BACKGROUND: Mild to moderate blepharoptosis, or ptosis, is relatively common among Asians, and it is not uncommon to offer ptosis correction at the time of double-eyelid surgery in this patient population. The traditional open approaches to ptosis correction are subject to scarring and prolonged recovery time, whereas the newer nonincisional approaches are marred by issues of incomplete correction or recurrence. This study describes a new nonincisional technique that overcomes the limitations of current methods by using conjoint fascial sheath (CFS) for suspension. METHODS: From January 2014 to April 2015, a retrospective review was conducted on 21 patients (41 eyelids) who underwent simultaneous nonincisional ptosis correction and double-eyelid surgery. All patients had either mild or moderate ptosis without excess skin hooding and excellent or good levator palpebrae function. RESULTS: Mild ptosis correction (1-loop CFS suspension) was performed in 25 eyelids, and moderate ptosis correction (2-loop CFS suspension) was performed in 16 eyelids. At 6 months of follow-up, 23 eyelids (56.1 %) improved to "normal" with overall improvement seen in 33 eyelids (80.0%). The mean marginal reflex distance 1 increased from 3.16 ± 0.61 mm preoperatively to 4.11 ± 0.61 mm postoperatively, which was statistically significant (P < 0.001). CONCLUSIONS: Mild to moderate ptosis correction with nonincisional CFS suspension technique is a safe and effective method that combines the benefits of nonincisional procedure with longevity and precision seen in the traditional open approaches. The procedure is easy to perform with minimal recovery time and high patient satisfaction and can be combined with nonincisional double-eyelid surgery.
