Refractive Precision of Ray Tracing IOL Calculations Based on OCT Data versus Traditional IOL Calculation Formulas Based on Reflectometry in Patients with a History of Laser Vision Correction for Myopia

Abstract

Purpose To compare the refractive predictability of ray tracing IOL calculations based on OCT data versus traditional IOL calculation formulas based on reflectometry in patients with a history of previous myopic laser vision correction (LVC). Patients and Methods This was a prospective interventional single-arm study of IOL calculations for cataract and refractive lens exchange (RLE) patients with a history of myopic LVC. Preoperative biometric data were collected using an optical low coherence reflectometry (OLCR) device (Haag-Streit Lenstar 900) and two optical coherence tomography (OCT) devices (Tomey Casia SS-1000 and Heidelberg Engineering Anterion). Traditional post LVC formulas (Barret True-K no-history and Haigis-L) with reflectometry data, and ray tracing IOL calculation software (OKULIX, Panopsis GmbH, Mainz, Germany) with OCT data were used to calculate IOL power. Follow-up examination was 2 to 3 months after surgery. The main outcome measure, refractive prediction error (RPE), was calculated as the achieved postoperative refraction minus the predicted refraction. Results We found that the best ray tracing combination (Anterion-OKULIX) resulted in an arithmetic prediction error statistically significantly lower than that achieved with the best formula calculation (Barret True-K no-history) (−0.13 D and −0.32 D, respectively, adjusted p = 0.01), while the Barret TK NH had the lowest SD. The absolute prediction error was 0.26 D and 0.35 D for Anterion-OKULIX and Barret TK NH, respectively, but this was not statistically significantly different. The Anterion-OKULIX calculation also had the highest percentage of eyes within ± 0.25, compared to both formulas and within ±0.50 and ±0.75 compared to the Haigis-L ( p = 0.03). Conclusion Ray tracing calculation based on OCT data from the Anterion device can yield similar or better results than traditional post LVC formulas. Ray tracing calculations are based on individual measurements and do not rely on the ocular history of the patient and are therefore applicable for any patient, also without previous refractive surgery.

Biometry and Intraocular Lens Power Calculation in Eyes with Prior Laser Vision Correction (LVC) – A Review

“…A direct comparison of the same eyes (paired samples) would have been of interest. The reported results of Anterion-based OKULIX were comparable to results of IOL calculation studies on eyes without prior surgery 23 , 25 , 30 , 31 . In the larger cohort, Casia-based OKULIX and Barrett True-K NH both showed similar outcomes, and the Haigis-L formula achieved fewer eyes within an absPE of 0.50 dpt ( Table 1 and 2 ) 30 .…”

“…The reported results of Anterion-based OKULIX were comparable to results of IOL calculation studies on eyes without prior surgery 23 , 25 , 30 , 31 . In the larger cohort, Casia-based OKULIX and Barrett True-K NH both showed similar outcomes, and the Haigis-L formula achieved fewer eyes within an absPE of 0.50 dpt ( Table 1 and 2 ) 30 . There are very few other studies on raytracing in eyes after LVC.…”

“…Gjerdrum et al reported results of a small cohort of patients with prior myopic LVC. The calculation was performed with either a low-coherence reflectometry (OLCR) biometer and no history (NH) formulae, or a combination of OKULIX and two different anterior segment OCT tomographs [30]. Unfortunately, the study reported different case numbers for Anterion-based (Heidelberg Engineering GmbH, Heidelberg, Germany) OKULIX calculations compared to Casia SS-1000-based (Tomey Corporation, Nagoya, Japan) OKULIX calculations and OLCR biometry-based NH-formulae [30].…”

Intraocular lens power calculation with ray tracing based on AS-OCT and adjusted axial length after myopic excimer laser surgery

“…6,8 Recently, Gjerdrum et al reported similar results using Okulix software with AS-OCT measurements by the Anterion (Heidelberg Engineering GmbH) and optical biometry by the Lenstar (Haag-Streit, Switzerland); the mean PE in their series (À0.13 D) is close to the mean PE obtained with the polynomial AL adjustment for the Holladay 2 formula (0.08 D) and the percentage of eyes with a PE within ±0.50 D was even higher (88%). 9 However, their results cannot be directly compared with this study results because they calculated the MedAE after zeroing out the mean PE and the mean AL in their series (25.3 ± 1.2) was much lower than the mean AL in this study (27.79 ± 1.97 mm). A comparison with studies evaluating traditional formulas in postmyopic refractive surgery eyes reveals that the outcomes of our study are more accurate than those obtained with any history or no-history method.…”

Effect of Implantable Collamer Lens on Anterior Segment Measurement and Intraocular Lens Power Calculation Based on IOLMaster 700 and Sirius

“…In addition, the Scheimpflug/Placido imaging system represented by Sirius and Pentacam AXL has clinical advantages and is widely used. As for IOL calculation, despite the theoretical formulas are commonly used in calculations of IOL power, the accuracy of the ray-tracing technique has been reported previously [ 11 ]. It remains unknown whether the new apparatus and technology are affected by ICL implantation.…”