Water Properties of Soft Contact Lenses: A Comparative Near-Infrared Study of Two Hydrogel Materials

Table 1

Soft contact lens materials used in this research (specifics provided by Vista Optics, England).

Material	VSO38	VSO50
British approved name	pHEMA Filcon I 1	Copolymer of HEMA and VP Filcon II 1
Water content	38.1% ± 2	48% ± 2
Average measured Dk (fatt)	9	15
Expansion ratio radial	1.163 ± 0.04	1.270 ± 0.04
Expansion ratio diametric	1.2041 ± 0.04	1.270 ± 0.04
Refractive index wet	1.4351 ± 0.001	1.420 ± 0.001
Refractive index dry	1.5178 ± 0.003	1.524 ± −0.003