Abstract
To introduce and evaluate a refraction-based method for calculating the correct power of the intraocular lens (IOL) in eyes with corneal refractive surgery and to compare the results here to previously published methods. Retrospective review of medical records was done. Group 1 was used to derive two formulas. From the relevant IOL calculation and postoperative refractive data, the refraction-derived K values (Krd) were calculated using a linear regression analysis. The values obtained with the two formulas were compared to previously published methods in group 2 to validate the results. The following methods were evaluated: Haigis-L, Barrett True-K (no history), Potvin-Hill, BESSt 2, Scheimpflug total corneal refractive power (TCRP) 4 mm (Haigis), Scheimpflug total refractive power (TRP) 4 mm (Haigis), modified Scheimpflug TCRP 4 mm (Haigis), and modified Scheimpflug TRP 4 mm (Haigis). The modified TCRP 4 mm Krd (Haigis) had good outcomes, with 60% and 90% of eyes within ±0.50 D and ±1.00 D of the refractive target, respectively. A new method using modified Scheimpflug total corneal refractive power in the 4.0 mm zone appeared to be an accurate method for determining IOL power in eyes with corneal refractive surgery.
Highlights
As significantly increased number of laser refractive surgery, it is common to face the patient with cataract after refractive surgery
We found that the Scheimpflug total corneal refractive power (TCRP) 4 mm K (Haigis) and total refractive power (TRP) 4 mm K (Haigis) formulas had comparable accuracies to the Haigis-L6, Barret True K (No History)[8,9,10], and Potvin-Hill[11] formulas
To establish a formula, the measured values ofScheimpflug TCRP 4.0 mm zone K (KTCRP), KTRP,back-calculated Krd.TCRP, and back-calculated Krd.TRP were plotted on a scattergram
Summary
As significantly increased number of laser refractive surgery, it is common to face the patient with cataract after refractive surgery. Groups without the clinical history has popular methods including the Haigis-L6, Barrett True-K (no history)[8,9,10], Potvin-Hill[11] and BESSt13 they showed improved accuracy than the traditional clinical history methods These methods do not require historical information but rather indices such as current biometry, keratometer index change, and keratometric correction factor. It is very important to accurately measure the actual corneal power after laser refractive surgery for IOL calculation without previous clinical historic data. Our previous study[14] reported that formulas using the Scheimpflug total corneal refractive power (TCRP) and the total refractive power (TRP) with the Haigis formula had comparable results to previously published methods (Haigis-L, Shammas, Barrett True-K (no history), and WKM). By comparing the results seen in our study to previously published methods, we sought to provide new post-refractive IOL calucation methods
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