Patent ID: 8764822

Claim:
A method of calculating the required power of a toric ophthalmic lens, comprising the steps of: determining an optimum cylindrical refraction needed to correct sphero-cylindrical refractive errors in a patient's eye; calculating a predicted surgically induced refractive change to the patient's eye; analyzing the optimum cylindrical refraction needed to correct sphero-cylindrical refractive errors in the patient's eye in combination with the predicted surgically induced refractive change to the patient's eye to determine the required power of the toric ophthalmic lens implant at a corneal plane, comprising describing the corneal-astigmatism and the surgically-induced astigmatism in vector terms; calculating a predicted post-op corneal astigmatism with a vector analysis; and converting the vector analysis results back to conventional sphero-cylindrical format wherein the step of calculating the predicted post-op corneal astigmatism with the vector analysis comprises using the following equation: Rx Cornea =( M,J 0 ,J 45 ); Rx SIRC ′=( M′,J 0 ′,J 45 ′) Rx Xcyl =Rx Cornea +Rx SIRC ′=( M+M′,J 0 +J 0 ′,J 45 +J 45 ′) wherein M=S+0.5 C, J 0 =−0.5C*cos (2α), J 45 =−0.5C*sin(2α), S=the spherical power of the implant at the corneal plane, C=the cylindrical power of the implant at the corneal plane, and α=an angle of the cylindrical correction from vertical; and and wherein the step of converting the vector analysis results back to conventional sphero-cylindrical format comprises using the following equation: C = - 2 ⁢ J 0 2 + J 45 2 ; S = M - C 2 ; α = { 1 2 ⁢ tan - 1 ⁡ ( J 45 J 0 ) J 0 ≥ 0 & ⁢ ⁢ tan - 1 ⁡ ( J 45 J 0 ) ≥ 0 1 2 ⁢ tan - 1 ⁡ ( J 45 J 0 ) + 180 ° J 0 ≥ 0 & ⁢ ⁢ tan - 1 ⁡ ( J 45 J 0 ) < 0 1 2 ⁢ tan - 1 ⁡ ( J 45 J 0 ) + 90 ° J 0 < 0 & ⁢ ⁢ tan - 1 ⁡ ( J 45 J 0 ) ≥ 0 1 2 ⁢ tan - 1 ⁡ ( J 45 J 0 ) + 90 ° J 0 < 0 & ⁢ ⁢ tan - 1 ⁡ ( J 45 J 0 ) < 0 wherein S=the spherical power of the implant at the corneal plane, C=the cylindrical power of the implant at the corneal plane, and α=an angle of the cylindrical correction from vertical; and reporting a selection of a toric lens implant based on the conversion to sphero-cylindrical format, wherein the steps of the method are implemented by a computer through software.