Objective Versus Subjective Depth of Focus Correlation in Pseudophakic Eyes

Area of Science:

• Ophthalmology
• Optical Engineering
• Visual Optics

Background:

• Accurate depth of focus (DOF) assessment is crucial for pseudophakic patients.
• Current methods for DOF evaluation often rely on subjective clinical measures.
• Objective quantification of DOF can enhance the understanding of visual performance after intraocular lens (IOL) implantation.

Purpose of the Study:

• To develop a method for quantifying objective depth of focus (DOF) using the visual Strehl ratio based on the optical transfer function (VSOTF).
• To compare this objective DOF measurement with subjective clinical DOF in pseudophakic eyes.
• To evaluate the influence of intraocular lens (IOL) asphericity on objective and subjective DOF.

Main Methods:

• A cross-sectional study involving two groups of pseudophakic eyes with different IOLs (negatively aspheric vs. aspherically neutral).
• Measurements included visual acuity, refraction, defocus curves, and iTrace aberrometry to obtain VSOTF.
• The primary outcome was determining the VSOTF threshold corresponding to subjective DOF.

Main Results:

• No significant difference was found between 25% or 30% VSOTF thresholds and subjective DOF across both IOL groups.
• Uncorrected distance visual acuity (UDVA) was significantly better in the negatively aspheric IOL group.
• No significant differences were observed in corrected distance visual acuity (CDVA), manifest refraction, or keratometry.

Conclusions:

• A 25% to 30% VSOTF threshold on iTrace measurements provides an objective DOF estimate.
• This objective DOF estimation is equivalent to clinical DOF derived from defocus curves.
• The method is effective irrespective of the intraocular lens's optical profiles.