What is frame effective diameter? - Sage-Answer The alternate method for calculating the minimum blank size is to measure the frame while on the wearer. Insight has been the leading industry publication in Australia for more than 40 years. Although the magnitude is correct, according to this . Hb```f`` @Q9?e_:Qat]"T8P"uHyeQz-JLXzbbf[TNU'Vl2_PIIIg Relation with focal length: A lens of less focal length produces more converging or diverging and is said to have more power. The nominal lens formula gives us the total power of the lens by adding the power of the front surface(s) to the power of . From here we can get the correct ED measurement. In a hypothetical example, let's assume the height of the original image is 8 cm. The effective diameter is the inside diameter of the objective lens frame. Why? Providing accurate frame measurements along with the shape number that most closely matches the patient's frame should help drastically cut down remakes for cut-out issues. Accuracy of intraocular lens power calculation formulas for highly myopic eyes. A three-part system for refining intraocular lens power calculations Jack T. Holladay, M. D. Thomas C. Prager, Ph.D. Thomas Y. Chandler, M. D. Kathryn H. Musgrove, M.D. An improved universal theoretical formula for intraocular lens power prediction. Vert DEC = OC HT - (B/2)