ToF-SIMS and AFM Characterization of Brown Cosmetic Contact Lenses: From Structural Analysis to the Identification of Pigments

Table 2

Atomic force microscopic evaluation for root mean square roughness (R_rms) and average roughness (R_a) of the brown cosmetic contact lens at each area.

Samples	Position	Rrms (nm) (mean ± SD)	value^a for Rrms	Ra (nm) (mean ± SD)	value^a for Ra
CCL-A	(1) Central clear zone	3.57 ± 1.15	Clear: front	2.72 ± 0.82	Clear: front
			0.0015		0.0014
	(2) Front surface	26.19 ± 4.97	Front: back	21.03 ± 3.90	Front: back
			0.0017		0.0014
	(3) Back surface	3.75 ± 1.42	Back: clear	2.67 ± 1.02	Back: clear
			0.8702		0.9564
CCL-B	(1) Central clear zone	7.40 ± 0.22	Clear: front	5.40 ± 0.41	Clear: front
			0.0002		0.0002
	(2) Front surface	49.98 ± 5.64	Front: back	39.35 ± 4.52	Front: back
			0.0004		0.0003
	(3) Back surface	9.86 ± 2.66	Back: clear	7.05 ± 1.45	Back: clear
			0.1860		0.1308
CCL-C	(1) Central clear zone	5.12 ± 0.42	Clear: front	3.72 ± 0.54	Clear: front
			0.0001		0.0001
	(2) Front surface	43.17 ± 4.64	Front: back	33.44 ± 3.31	Front: back
			0.0002		0.0001
	(3) Back surface	8.34 ± 0.23	Back: clear	6.46 ± 0.19	Back: clear
			0.0003		0.0012

R_rms: root mean square roughness; R_a: average roughness; SD: standard deviation. ^aComparison of lens surface roughness between different sides using the unpaired t-test. At the colored parts, all lenses with the surface pigment had significant difference of roughness between the front and back surfaces ( indicates statistical significance).