Composition for hydrophilic lens blank and method of casting

• US 4,042,552 A
• Filed: 11/14/1975
• Issued: 08/16/1977
• Est. Priority Date: 09/19/1972
• Status: Expired due to Term

• Current Assignee: CIBA Vision Corporation (Novartis Ag)
• Original Assignee: Warner-Lambert Company (Pfizer Inc.)
• Inventors: Grucza, Bernard J.
• Primary Examiner(s): Welsh, M. J.
• Application Number:
  US05/631,997
• Time in Patent Office: 641 Days
• Field of Search: 260/29.6 RB, 260/29.6 WB, 260/29.6 RW, 260/29.6 E, 260/45.95 E, 260/885
• US Class Current: 523/108
• CPC Class Codes: B29D 11/00134 Curing of the contact lens material
• CPC Class Codes: C08F 220/20 of polyhydric alcohols or phenols , e.g. 2-hydroxyethyl (meth)acrylate or glycerol mono-(meth)acrylate
• CPC Class Codes: C08F 271/02 on to polymers of monomers containing heterocyclic nitrogen
• CPC Class Codes: C08L 2666/04 Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
• CPC Class Codes: C08L 51/003 grafted on to macromolecular compounds obtained by reactions only involving unsaturated carbon-to-carbon bonds C08L51/04, C08L51/06 take precedence
• CPC Class Codes: G02B 1/043 Contact lenses

Abstract

Improvements in the O'"'"'Driscoll et al. U.S. Pat. No. 3,700,761 composition consisting of regulating critical proportions of PVP, HEMA, MA, EDMA, Water and the first and second stage initiators for producing hydrophilic lens blanks from which reproducible and predictable hydrated lenses are obtained with ratios of acceptance of 95 - 98%, to dimensional standards between the grinding dry and hydrated wet states and with ratios of resisting dimensional change in wet storage of upwards of ninety five percent. Compositions lying outside of the critical ranges of proportions provide lenses which are unpredictable (90% rejection) drift in size and do not provide reproducibility between dry and wet states and thereby create fitting problems. Critical ratios of MA to EDMA lying between 2.5/3.2 at 15% PVP content down to 1/1 at 28% PVP content provide reproducibility and predictability dry-to-wet and the optimum ratio is 1.5/0.7 at 20% PVP (reagents containing less than 1% water). Further improvement is made in the method of casting and cutting of U.S. Pat. No. 3,700,761, in which there is used a disposable mold of Teflon, high-density polyethylene or of RTV Silicone material with break-away curved bottom which is discarded to provide a convex surface requiring no cutting thereby eliminating many cutting and grinding steps on the conventional hard-lens lathe. Water-soluble medicaments as in U.S. Pat. No. 3,700,761 can be added to precision-cut eye bandages by dissolving in H₂ O and adding a total of 5% H₂ O to HEMA or the medicament can be used in eye drops, the bandage with 5% added containing 65% H₂ O instead of 60%.

Claims

1. A contact lens composition which can be subjected to cutting and thereafter hydrated in a buffered saline solution to provide a dimensionally-stable contact lens and also suitable for medicament delivery to the eye having from 50 to 65% water after hydration, said composition in dry form consisting essentially of polymerized random graft copolymer containing:

1. from 67.2% to 79.3% hydroxy ethyl methacrylate;

2. 14.25% to 28% polyvinyl pyrrolidone;

3. from 0.1% to 4.04% ethylene glycol dimethacrylate;

4. from 0.1% to 2.5% methacrylic acid;

5. from about 0.1% up to 5.0% water, and

6. from 50 to 100 ppm of hydroquinone stabilizer;

said composition having been polymerized in two stages;

the first stage being carried out with a low temperature peroxide initiator effective at 40°

to 60°

C after an induction period modified by said hydroquinone stabilizer at 15°

to 30°

C for a period of 2.5 to 6 hours;

said second stage being carried out with a high temperature peroxide initiator effective at 90°

to 120°

C;

each of said low temperature initiator and high temperature initiators being present in concentrations of 0.05% to 0.15%; and

said two stages of polymerization being carried out for a total period of at least 4 hours or longer.