Process for manufacture of a thermochromic contact lens material

A process for manufacturing a photochromic contact lens consisting essentially of the steps of:

• selecting a photoinitiator which absorbs at a first wavelength within 420 nm to 480 nm;
• selecting a photochromic dye which displays substantial absorption at the first wavelength when the dye is at a temperature of 25° C. and but exhibits at least an 80% reduction in absorbance at the first wavelength when the dye is at a temperature of 70° C.;
• disposing a reaction mixture on a mold, the mixture including at least one polymerizable siloxane monomer, the photoinitiator and the photochromic dye;
• warming the reaction mixture to a temperature between 40° C. and 90° C., the warming causing the dye to reduce its molar absorbivity at the first wavelength;
• curing the warm reaction mixture to form a photochromic contact lens material by illuminating the mixture with light that includes the first wavelength, wherein the light is provided via a top light source and a bottom light source relative to the mold.

A process for manufacturing a photochromic contact lens material consisting essentially of the steps of:

• selecting a photoinitiator which absorbs at a first wavelength within 400 nm to 480 nm;
• selecting a polymerizable photochromic dye which displays substantial absorption at the first wavelength when the dye is at a temperature of 25° C. and but exhibits at least an 80% reduction in absorbance at the first wavelength when the dye is at a temperature of 80° C.;
• disposing a reaction mixture on a mold, the mixture including at least one polymerizable siloxane monomer, the photoinitiator and the photochromic dye;
• warming the reaction mixture to a temperature between 50° C. and 90° C., the warming causing the dye to reduce its molar absorbivity at the first wavelength;
• providing cure light that includes light of the first wavelength but omits at least a portion of the wavelengths that activate the dye when the dye is at a temperature of 80° C.;
• curing the warm reaction mixture to form a photochromic contact lens material by illuminating the mixture with the cure light, wherein the cure light is provided via a top light source and a bottom light source relative to the mold.

A process for manufacturing a contact lens comprising at least one thermochromic compound consisting essentially of the steps of:

• (a) selecting a photoinitiator which absorbs at a first wavelength;
• (b) selecting a thermochromic compound which displays substantial absorption at the first wavelength when the compound is at a first temperature and but exhibits at least an 80% reduction in absorbance at the first wavelength at a second temperature;
• (c) dispensing to a contact lens mold a thermochromic composition comprising at least one first thermochromic compound;
• (d) dispensing to the contact lens mold a reaction mixture comprising said photoinitiator and at least one polymerizable component;
• (e) equilibrating the reaction mixture to said second temperature, causing the thermochromic compound to reduce its molar absorbivity at the first wavelength;
• (f) curing the reaction mixture at said second temperature to form a thermochromic contact lens by exposing the mixture to radiation that includes the first wavelength, wherein the radiation is provided via a top light source and a bottom light source relative to the mold.