Clinical efficacy of intradermal type I collagen injections in treating skin photoaging in patients from high-altitude areas

Table 3 Comparison of skin thickness before and after intradermal injection of Col I (mm, mean ± SD)

	Baseline	1st	2nd	3rd	4th	5th	6th
Right cheek	1.65 ± 0.19	1.76 ± 0.22a	1.88 ± 0.19a	1.98 ± 0.16a	2.04 ± 0.15a	2.11 ± 0.17a	2.15 ± 0.20a
Left cheek	1.62 ± 0.21	1.69 ± 0.21	1.78 ± 0.19	1.90 ± 0.17a	1.99 ± 0.12a	2.06 ± 0.13a	2.12 ± 0.16a
Right zygomatic	1.57 ± 0.18	1.67 ± 0.20	1.79 ± 0.18a	1.89 ± 0.16a	1.96 ± 0.15a	2.02 ± 0.14a	2.08 ± 0.17a
Left zygomatic	1.56 ± 0.22	1.63 ± 0.24	1.75 ± 0.23	1.86 ± 0.20	1.94 ± 0.18a	2.01 ± 0.16a	2.05 ± 0.15a
Right temple	1.48 ± 0.25	1.54 ± 0.26	1.63 ± 0.24	1.75 ± 0.21	1.86 ± 0.18	1.96 ± 0.17a	2.00 ± 0.20a
Left temple	1.44 ± 0.24	1.52 ± 0.25	1.62 ± 0.26	1.73 ± 0.23	1.83 ± 0.20	1.94 ± 0.18a	1.99 ± 0.16a

^aP < 0.05, a statistically significant difference compared with before treatment.