Contact lens molds and systems and methods for producing same
View Patent ↗Contact lens molds and systems and methods for producing contact lens molds are described. The contact lens mold sections include two optical quality surfaces, a flange circumscribing at least a portion of the two optical quality surfaces, and an elongate member extending from the flange. Two mold sections can contact one another to form a mold assembly having a contact lens shaped cavity. The mold sections are structured to form a contact lens having an edge that does not require further physical modification before placement on an eye. Systems and methods are described which direct a molten polymeric material into cavities corresponding to the mold sections.
1. A method of producing a contact lens, comprising:
directing a molten thermoplastic material into a mold cavity, thereby forming a first contact lens mold section comprising the thermoplastic material in the mold cavity, wherein
the mold cavity comprises a first optical quality insert surface; an opposing second surface; a mold flange-defining region circumscribing the first optical quality insert surface and the second surface, the first optical quality insert surface and the second surface defining a first lens-defining surface and a second substantially opposing surface of a contact lens mold section; and an elongated channel extending substantially radially outwardly from the mold flange-defining region, the elongated channel including a first portion having a substantially uniform width and a second portion having a divergent width, the second portion being adjacent the flange-defining region and being thinner than the first portion of the elongated channel;
providing a complementary second contact lens mold section;
placing a polymerizable composition onto a concave lens defining surface of one of the first mold section or the second mold section;
placing the other one of the first mold section or the second mold section on top of the one of the first mold section or the second mold section to enclose the composition within a lens shaped region defined therebetween;
coupling together the first and second mold sections which define the lens-shaped region and contain the enclosed composition to form a mold assembly; and
subjecting the mold assembly to polymerizing conditions to produce a polymer article in the shape of a contact lens.
2. The method of claim 1 , further comprising providing first and second discrete regions along the elongated channel that have different roughnesses, and the first and second discrete regions are effective in forming indicia on the mold section.
3. The method of claim 2 , wherein the first and second discrete regions are effective in forming machine readable indicia on the mold section.
4. The method of claim 1 , wherein the first optical quality insert surface is a surface of an insert located in a first plate of a removable change plate assembly.
5. The method of claim 4 , further comprising retaining the mold section formed in the mold cavity on one change plate when the first plate and second plate are separated from each other.
6. The method of claim 4 , further comprising cooling the change plate assembly.
7. The method of claim 4 , wherein the removable change plate assembly includes generally conical locator parts for facilitating positioning of the removable change plate assembly.
8. The method of claim 4 , further comprising measuring the temperature of the removable change plate assembly.
9. The method of claim 1 , wherein the first optical quality insert surface is a surface of a single piece insert.
10. The method of claim 1 , wherein the second surface is a surface of a single piece insert.
11. The method of claim 1 , further comprising causing the formed contact lens mold section to be retained on one of the first optical quality insert surface or the second surface.
12. The method of claim 11 , wherein the causing step comprises using a retaining structure or mechanisms.
13. The method of claim 1 , wherein the elongated channel has a length extending substantially radially outwardly from the mold flange-defining region which is at least as great as a diameter of the first optical quality insert surface.
14. The method of claim 13 , wherein the length of the elongated channel is between 30 mm and 35 mm.
15. The method of claim 1 , wherein the second surface comprises a second optical quality insert surface, and the second surface defines a second lens-defining surface substantially opposing the first lens-defining surface of the contact lens mold section.
16. The method of claim 15 , wherein the second optical quality surface is a surface of an insert located in a second plate of the removable change plate assembly.
17. The method of claim 1 , further comprising separating the complementary sections of the mold assembly to reveal the polymerized lens shaped article on the first mold section or the second mold section.
18. The method of claim 17 , further comprising removing the polymerized lens shaped article from the first mold section or the second mold section.
19. The method of claim 1 , wherein the elongated channel has a length to depth ratio of between 22:1 to 44:1.