Related Experiment Video
Updated: Jul 31, 2026
05:40
Using an Automated Hirschberg Test App to Evaluate Ocular Alignment
Published on: March 24, 2020
Hartmann-Shack technique and refraction across the horizontal visual field
David A Atchison1, Dion H Scott, W Neil Charman
1Centre for Eye Research, School of Optometry, Queensland University of Technology, Victoria Park Road, Kelvin Grove, Q 4059 Australia. d.atchison@qut.edu.au
Summary
Analyzing wave aberrations with Hartmann-Shack instruments, this study found that objective refractions using either a 3mm pupil with second-order Zernike aberrations or a 6mm pupil with second- and fourth-order aberrations yield similar results, suggesting their utility for clinical applications.
Area of Science:
- Ophthalmic optics
- Visual science
- Optical engineering
Background:
- Wave aberrations, measured using instruments like the Hartmann-Shack, provide detailed information about an individual's refractive error.
- Analyzing these aberrations is crucial for understanding visual perception and developing accurate objective refraction methods.
Purpose of the Study:
- To compare different analytical approaches for determining ocular refractions from wave aberration data.
- To evaluate the impact of pupil size and Zernike aberration order on objective refraction accuracy.
Main Methods:
- Wave aberrations were measured for 6mm pupils in five subjects using a Hartmann-Shack instrument.
- These aberrations were converted into refractions using various combinations of pupil size (6mm, 3mm, 1mm) and Zernike aberration orders (second-order, second- and fourth-order).
- Refractive differences (mean sphere and cylinder) were calculated between the different analysis methods.
Main Results:
- Refractions derived from 3mm/2nd-order and 6mm/2nd-order analyses showed significant differences in mean sphere on-axis (up to 0.9 D) but smaller differences in the visual field periphery.
- Cylindrical differences were minimal centrally (<0.3 D) but increased peripherally (>1.0 D) between the 3mm/2nd-order and 6mm/2nd-order analyses.
- Minimal differences in mean sphere and cylinder were observed when comparing 3mm/2nd-order refractions with 1mm/2nd-order or 6mm/4th-order refractions.
Conclusions:
- Objective refractions derived from wave aberration data can be reliably obtained by either analyzing second-order Zernike aberrations with a smaller pupil (e.g., 3mm) or by including both second- and fourth-order aberrations with a larger pupil (e.g., 6mm).
- These findings suggest that objective refraction methods based on these approaches may be clinically useful, mirroring the pupil-size independence of subjective refraction under photopic conditions.
