Method for manufacturing toric contact lenses

Patent metadata

Field	Value
Publication number	US-2019193350-A1
Application number	US-201816217707-A
Country	US
Kind code	A1
Filing date	Dec 12, 2018
Priority date	Dec 21, 2017
Publication date	Jun 27, 2019
Grant date	—

Abstract

A method of manufacturing of an astigmatic contact lens having a toric portion and a ballast portion such that said ballast portion causes the toric portion of the contact lens to properly orient in the eye of the wearer. The toric lenses are manufactured by an effective process control method for cylinder axis angle in toric lens production by modifying the target cylinder angle for mold rotation by eliminating the accumulative cylinder axis error from all previous steps including tool making, tool assembly, and molding. The amount modifying the target angle is determined by accurately determine the true cylinder axis on the corresponding mold by using a high-resolution interferometer, such as FISBA FS10M or equivalent models from Trioptics μShape® vertical series.

First claim

What is claimed is:

1 . A method for manufacturing a toric contact lens, the method comprising the steps of:
a. Injection molding to form an anterior mold section and a posterior mold section, wherein the posterior mold section or the anterior mold section has a toric portion and the other mold section has a prism ballast, wherein each mold has a tab or other locating features for facilitating a determination of orientation of the mold, b. measuring a cylinder axis angle error of the mold section having the toric portion by an interferometer apparatus, wherein the cylinder axis angle error is defined as a difference of measured cylinder axis angle by the interferometer apparatus and a reference cylinder axis angle defined by the tab position or other locating features, c. rotating one of the mold sections by an amount of a target axis angle subtracting the cylinder axis angle error, while the other molding section is not rotated, d. introducing a lens forming material into the lens shaped cavity after step c of rotating one of the mold, e. assembling the anterior mold section and the posterior mold section to form a lens shaped cavity there between, f. curing the lens forming material in the lens shape cavity to form the toric lens.

2 . The method of claim 1 , further comprising a step of repeating the steps c to f to consume all molds within a batch.

3 . The method of claim 1 , wherein the posterior mold section has a toric portion and anterior mold section has a prism ballast.

4 . The method of claim 1 , wherein the anterior mold section has a toric portion and posterior mold section has a prism ballast.

5 . The method of claim 1 , wherein the lens forming material comprises at least one member selected from the group consisting of a hydrophilic vinylic monomer, a silicone containing vinylic monomer, a silicone-containing crosslinker, a silicone-containing prepolymer, a hydrophilic prepolymer free of silicone, and combinations thereof.

6 . The method of claim 1 , wherein curing step is performed by an ultraviolet curing.

7 . The method of claim 1 , wherein curing step is performed by a thermal curing.

Assignees

• Novartis Ag

Inventors

• Gu Yeming
• Mckenney Curtis Dean
• Niculas Cornelius Daniel

Classifications

• B29K2083/00

  Use of polymers having silicon, with or without sulfur, nitrogen, oxygen, or carbon only, in the main chain, as moulding material · CPC title

• B29D11/00134

  Curing of the contact lens material · CPC title

• B29D11/00115

  made by rotational casting · CPC title

• B29D11/0048 Primary

  Moulds for lenses (moulds for plastic articles in general B29C33/00) · CPC title

• B29C33/3842

  Manufacturing moulds, e.g. shaping the mould surface by machining · CPC title