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Ray tracing enhances aspheric IOL calculations
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Ray tracing was effective in enhancing power calculations for aspheric IOLs in eyes with good postoperative visual acuity, according to a study.
“The results of this study show that ray tracing utilizing additional measurements of the crystalline lens was able to improve overall accuracy, a result that was expected,” the study authors said.
The prospective study included 591 eyes of 396 patients; 363 eyes were implanted with spherical IOLs, and 228 eyes were implanted with aspheric aberration-correcting IOLs. Patients had a median age of 74 years.
For spherical IOLs, the SA60AT (Alcon) was implanted in 320 eyes and the Y-60H (Hoya) was implanted in 43 eyes. For aspheric IOLs, the SN60WF (Alcon) was implanted in 57 eyes, the Tecnis ZCB00 (Abbott Medical Optics) in 112 eyes, the CT Asphina 404 (Carl Zeiss Meditec) in 21 eyes and the iMics1 (Hoya) in 38 eyes.
The Lenstar (Haag-Streit) with Okulix ray tracing software (Tedics) was used to measure axial length, corneal radius, central corneal thickness, and position and thickness of the crystalline lens.
The primary outcome measure was a mean absolute prediction error based on the variation between calculated refraction and manifest refraction spherical equivalent 1 month after surgery.
Study results showed that mean absolute error was 0.27 D for aspheric IOLs and 0.36 for spherical IOLs. Mean absolute error was 0.26 D in eyes with corrected distance visual acuity of 1.0 or better and 0.38 D in eyes with corrected distance visual acuity worse than 1.0.
All between-group differences in postoperative values were statistically significant (P < .05), the authors said.
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