Intraocular Lens Power Calculations After Laser In Situ Keratomileusis

Abstract

Significant refractive errors occurred with each of the methods investigated for determining IOL power after LASIK. RH, CL, or AVG 2 provided the most accurate results.

Accurate intraocular lens power calculation after myopic laser in situ keratomileusis, bypassing corneal power

“…Our cornea bypass method compares favorably with the results of Randleman et al 1 and Wang et al, 10 who also showed their methods with a similar patient series. Randleman et al 1 used preoperative information with the clinical history method, the contact lens method, or the mean of these 2 methods; the postoperative SE was similar to that in our study (C0.21 D) but the range (ÿ2.25 to C2.25 D) and standard deviation (1.54 D) were much higher. Since their study, the contact lens method has been reported to be unreliable.…”

“…2 The inaccuracy of the IOL calculation is caused by inability to accurately measure the corneal power with standard keratometry or videokeratography. 3 Techniques to determine the corneal power include the clinical history and the contact lens methods, as well as the mean of these 2 as described by Randleman et al 1 There have also been more recent techniques such as the modified Maloney method (Maloney RK, personal communication, October 2002) and the topographic central corneal power adjustment method (EffRP adj ) described by Wang et al 3 In this study, a new method to calculate IOL power for patients having cataract surgery after myopic LASIK was developed that ''bypasses'' the need to determine the corneal power. This method is described by Ladas and Stark.…”

“…This presents a challenge because the intraocular (IOL) power calculations after refractive surgery are notoriously inaccurate. 1 It is common to have a ''hyperopic surprise'' in a postmyopic laser in situ keratomileusis (LASIK) eye owing to inaccurate IOL calculations. 2 The inaccuracy of the IOL calculation is caused by inability to accurately measure the corneal power with standard keratometry or videokeratography.…”

Intraocular lens power calculation using ray tracing following excimer laser surgery

“…[6][7][8] Several reports have been published indicating the high accuracy of this method. Gimbel et al, 4 and Randleman et al, 23 also support the good outcomes for CHM.…”

“…3,4,[19][20][21][22][23] The spherical equivalent change is subtracted from the original corneal refractive power. However, accurate pre-refractive data as well as a stable postoperative refraction are necessary.…”