Table 1. Physical Properties of Cross-linked Collagen and Collagen–HPMC Membranes^a.

		permeability
materials	water content (%)	glucose diffusivity (cm2/s)	tryptophan diffusivity (cm2/s)	NaCl diffusivity (cm2/s)	refractive index
collagen–HPMC	83.4	5.29 ± 0.3 × 10–6	1.86 ± 0.3 × 10–6	8.03 ± 0.4 × 10–6	1.3375
cross-linked collagen	76.5	3.88 ± 0.3 × 10–6	1.05 ± 0.3 × 10–5	1.22 ± 0.8 × 10–5	1.3350
human cornea	81b	2.4 × 10–6c	>10–6d	>10–6e	1.373–1.380f

^an = 3 samples for each measurement.

^bReference (38).

^cReference (40).

^dReference (41).

^eReference (42).

^fReference (34).