| 摘要 |
A highly water-absorptive ophthalmic lens which is formed of a macromolecular material including vinyl alcohol unit as a major component and whose water content is in a range of 50-90 %, characterized in that: the macromolecular material is a cross-linked vinyl alcohol-allyl alcohol/halogenated-alkyl ethylene copolymer which includes allyl alcohol unit and/or halogenated-alkyl ethylene unit, together with the vinyl alcohol unit; and the ophthalmic lens has a ratio of a dimensional change of less than +/-2 % and being free from whitening after (A) the ophthalmic lens has been subjected to three cycles of a freezing-thawing operation wherein the ophthalmic lens formed of the macromolecular material is left at a temperature of not higher than -10 DEG C for not less than twelve hours, and is subsequently left at a temperature in a range from 15 DEG C to 30 DEG C for not less than six hours, and/or (B) the ophthalmic lens has been kept at a temperature in a range from 1 DEG C to 9 DEG C for three months. |
