Intraocular Lens Power Calculation by Ray-Tracing after Myopic Excimer Laser Surgery

Intraocular Lens Power Calculation after Small Incision Lenticule Extraction

“…As of today, however, these clinical data are lacking. Hence, considering that ray tracing has been proven to be highly efficacious in estimating corneal power changes 9 and calculating IOL power after LASIK and PRK by numerous clinical reports 7,8,10 , we believe that ray tracing represents the currently best available benchmark for IOL power calculation in post-SMILE eyes. A plethora of empirically optimized formulas is available in the ASCRS online calculator to accurately predict IOL power after excimer-based keratorefractive surgery (i.e.…”

“…First and foremost, ray tracing was considered as the gold standard method. Even though it has been clearly demonstrated that this technique enables accurate IOL power calculation in treatment-naïve eyes 17,18 and post-photoablation eyes 7,8,10 , its applicability in post-SMILE eyes is still not ultimately proven. A methodological limitation to the ray tracing method itself is that exact IOL design information such as physical curvatures, thickness and refractive index is required.…”

“…Conveniently, a range of these formulas is readily accessible in the American Society of Cataract and Refractive Surgeons (ASCRS) post-keratorefractive surgery IOL power online calculator. Avoiding any empirical optimization, ray tracing represents a purely physical approach for IOL power calculation particularly attractive in eyes with previous LASIK or PRK [6][7][8][9][10] . This method involves direct measurement of the posterior corneal curvature (e.g.…”

Assessing the corneal power change after refractive surgery using Scheimpflug imaging

“…Potentially, IOL calculation in the future could be performed with the corneal power assessed through ray tracing, regardless of any previous corneal surgery. A few studies have reported promising results using ray tracing for assessment of IOL power prior to cataract surgery. Based on our results, ray tracing has the potential to overcome the problems associated with the traditional methods assessing power measurements from the anterior surface alone.…”

Accuracy of the Barrett True-K formula for intraocular lens power prediction after laser in situ keratomileusis or photorefractive keratectomy for myopia

“…A third limitation of our study is that it was confined to formulas and methods available on the ASCRS online calculator. Further studies that compare the Barrett True-K formula with and without a change in manifest refraction information with additional formulas and methods including ray tracing 15 and intraoperative aberrometry 4,14 are warranted. Finally, no subgroup prediction analysis was performed for eyes with different axial lengths and mean K values.…”