A) providing a mold for making a contact lens;

B) introduce a solution into the mold, wherein the solution comprises

(i) one or more crosslinkable prepolymers which are purified to be substantially free from monomeric, oligomeric or polymeric starting compounds used for preparing the prepolymers, and

(ii) one or more solvents selected from the group consisting of a C₁-C₆-alkanol, a glycol, a carboxylic acid amide, dimethyl sulfoxide, and water,

 wherein each of said one or more crosslinkable prepolymers is obtained by

(a) copolymerizing a mixture comprising at least one hydrophilic monomer having one first ethylenically unsaturated group and at least one crosslinker comprising two or more second ethylenically unsaturated groups in the presence of a chain transfer agent comprising a chain transfer group and a first reactive group to obtain a copolymerization product with first reactive groups, wherein the hydrophilic monomer is a monomer which, when polymerized, gives a homopolymer which is water-soluble or can absorb at least 10% by weight of water, and

(b) reacting an organic compound with the copolymerization product to form the crosslinkable or polymerizable prepolymer having third ethylenically unsaturated groups, wherein the organic compound comprises a third ethylenically unsaturated group and a second reactive group, wherein the second reactive group of the organic compound reacts with one of the first reactive groups of the copolymerization product,

 wherein said solution is substantially free of comonomers; and

C) crosslinking said one or more crosslinkable prepolymers in the mold to form a contact lens which forms a hydrogel when contacted with water,

wherein the process is characterized by that there is no need for subjecting the obtained contact lenses to subsequent extraction.