clinical history method. When the preoperative K value is unknown, 44.0 D is considered as the preoperative value and the effective refractive power (EffRP) of the Holladay Diagnostic Sum- mary–EyeSys Corneal Analysis System (Dallas, Texas) as the postoperative value.
Aramberri26 published the double K method using the SRK/T formula. The SRK/T formula was modified to use the preoperative K value to estimate the ELP and the post refractive surgery K value (clinical history method) to calculate IOL power by the vergence formula. The Holladay 2 formula contains the double K entry for post refractive surgery cases. If the preoperative K value is unknown, the formula suggests the 43.86 D value.
Post radial keratotomy and cataract surgery
Special attention should be given to patients with previous RK who undergo cataract surgery. Transient hyperopia is commonly observed in the immediate postoperative period.27,28 The stromal edema around the radial incisions and even the opening of the incisions flatten the center of the cornea. The hyperopic shift may need on average 8 to 12 weeks to complete resolution. Any hasty decision, such as IOL exchange or laser corrections, should not be taken during this period.
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