I only found 1 link w/c used 半边脸. I suggest 面部分左右两侧 or 半边脸. Becase in this type of clinical study, one side is treated while the other side is not. After the study period, both side of the face will be compared.

random, split-face, double blind : 随机，面部分左右两侧，双盲

SPLIT-FACE模式观察新型强脉冲光治疗黄褐斑的疗效
http://d.wanfangdata.com.cn/Periodical_zgmryxzz200905030.asp...

A randomized, controlled, split-face clinical trial of 1320-nm Nd ... The study was a randomized, split-face, single-blind clinical trial. Patients were randomized to receive a series of 3 laser treatments to one half of the ...
linkinghub.elsevier.com/retrieve/pii/S0190962206040266 - Similar
by JS Orringer - 2007 - Cited by 14 - Related articles

585-nm脉冲染料激光及1064-nm Nd:YAG激光治疗痤疮疤痕的临床比较研究 ... - [ Translate this page ]... the treatment of acne scars: ...A randomized split-face clinical study[/url] ...本文为半边脸的随机-单盲试验，比较585-nm脉冲染料激光及1064-nm Nd:YAG激光对 ...
bbs.aesthetictimes.com/bbs/archiver/?tid-2177.html - Similar