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Related Experiment Video

Updated: Jul 23, 2025

Subjective Refraction Test Using a Smartphone for Vision Screening
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Comparison between wavefront-derived refraction and auto-refraction.

Konuralp Yakar1, Emrah Kan1, Mustafa Duran2

  • 1Department of Ophthalmology, Medicana International Hospital, Samsun, Turkey.

Photodiagnosis and Photodynamic Therapy
|July 17, 2023
PubMed
Summary

Refractive and keratometry measurements from the Nidek OPD-Scan II and Topcon KR 8900 autorefractokeratometer are not interchangeable. These differences persist even after cycloplegia in healthy adults, impacting clinical decisions.

Keywords:
AutorefractionCycloplegiaOcular refractionTopographyWavefront aberration

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Area of Science:

  • Ophthalmology
  • Optometry
  • Biomedical Engineering

Background:

  • Objective refractive errors and keratometry are crucial for eye care.
  • Accurate measurements are essential for refractive surgery planning.

Purpose of the Study:

  • To compare objective refractive errors and keratometry measurements between the Nidek OPD-Scan II and Topcon KR 8900.
  • To assess the interchangeability of these devices in healthy adults.

Main Methods:

  • 176 patients (18-35 years) undergoing refractive surgery evaluation had measurements taken.
  • Nidek OPD-Scan II and Topcon KR 8900 were used before and after cycloplegia.
  • Exclusion criteria included prior eye surgery and corneal pathologies.

Main Results:

  • Statistically significant differences (p<0.05) were found between devices for refractive and keratometry values.
  • Bland-Altman analysis showed mean differences in sphere, spherical equivalent, and keratometry readings.
  • These discrepancies were observed both before and after cycloplegia.

Conclusions:

  • The Nidek OPD-Scan II and Topcon KR 8900 provide non-interchangeable results.
  • Clinical decisions based on measurements from these devices require careful consideration.
  • Device choice may impact refractive surgery outcomes.