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In Vitro Repeatability and Inter-Device Agreement of Higher-Order Aberration Measurements in Scleral Lenses Using Two
Francesco Viviano1,2, Marco Iovino2, Rute J Macedo-de-Araújo1,3
1Clinical and Experimental Optometry Research Lab (CEORLab), School of Science, University of Minho, 4710-057 Braga, Portugal.
Sensors (Basel, Switzerland)
|June 12, 2026
Summary
Hartmann-Shack metrology systems show excellent repeatability for scleral lens higher-order aberrations. However, spatial sampling density impacts accuracy at smaller apertures, necessitating standardized protocols for reliable quality control.
Area of Science:
- Ophthalmic optics and metrology
- Corneal and scleral lens design
- Higher-order aberration analysis
Background:
- Scleral lenses (SLs) increasingly feature complex optical designs for irregular corneas.
- Accurate optical verification of SLs relies on Hartmann-Shack (HS) metrology.
- Variations in HS device spatial sampling density raise concerns about quality control interchangeability.
Purpose of the Study:
- To evaluate the repeatability and inter-device agreement of higher-order aberration (HOA) measurements in SLs.
- To compare two HS metrology systems with different spatial sampling resolutions.
- To assess the influence of HS spatial sampling density on HOA measurement accuracy.
Main Methods:
- Sixteen scleral lenses with varying designs were measured three times each using two HS systems (Cito: 54x54, Prio: 157x157 lenslets).
- Sphere and Zernike coefficients (3rd-5th radial orders) were extracted for 3.00, 5.00, and 7.00 mm apertures.
- Measurements were analyzed as root-mean-square (RMS) values by radial order and Total HOA RMS.
Main Results:
- Both devices showed excellent within-device repeatability for Sphere, RMS4, and Total HOA RMS.
- Moderate repeatability was observed for RMS3 and RMS5.
- Excellent inter-device agreement was found at 5.00 and 7.00 mm apertures; however, significant bias was detected at 3.00 mm, with the Cito system underestimating HOA values.
Conclusions:
- Hartmann-Shack spatial sampling density significantly influences HOA measurement accuracy in scleral lenses, particularly at smaller apertures.
- Standardized high-resolution metrology protocols are essential for accurate HOA characterization and quality control of complex scleral lenses.
- Front surface eccentricity design did not significantly impact inter-device differences in HOA measurements.