Nanavaty Mayank A, Safir Margarita, Alwindi Muhanned
J Refract Surg. 2025 Apr;41(4):e310-e317. doi: 10.3928/1081597X-20250207-01. Epub 2025 Mar 1.
To develop a method for quantifying objective depth of focus (DOF) from the visual Strehl ratio based on the optical transfer function (VSOTF), measured on a ray-tracing aberrometer (iTrace; Tracey Technologies) and to compare it to the subjective clinical DOF in two groups of pseudophakic eyes with varying asphericity of the intraocular lenses (IOLs).
In this cross-sectional study, two groups with negatively aspheric (Eyhance; Johnson & Johnson) and aspherically neutral (RayOne; Rayner) IOLs were assessed 3 to 9 months postoperatively. The patient assessments included: logarithm of the minimum angle of resolution visual acuity, refraction, defocus curves, and iTrace assessments. The primary outcome was to determine the threshold of VSOTF (%) corresponding to subjective DOF. Secondary outcomes were uncorrected (UDVA) and corrected (CDVA) distance visual acuities, manifest refraction, keratometry, and wavefront aberrometry. The specific threshold of VSOTF matching the subjective DOF was determined.
Forty-two eyes (21 patients in each IOL group) were analyzed. For the primary outcome, in the Eyhance versus the RayOne IOL group and all eyes together there was no significant difference between 25% ( = .10 vs .28; = .07) and 30% ( = .55 vs .73; = .58) VSOTF and subjective DOF, respectively. For secondary outcomes, UDVA was better in the Eyhance group ( = .02). There was no difference in CDVA, manifest refraction, and keratometry. There was a significant difference in total and internal spherical aberration between the two groups, although it was not clinically significant.
This study showed that a 25% to 30% threshold of VSOTF values on iTrace measurements (Nanavaty Threshold) gives an objective DOF estimate, equivalent to clinical DOF derived from the defocus curve irrespective of the IOL's optical profiles. .
