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Clinical Accuracy of the Nidek ARK-1 Autorefractor

Paudel, Nabin, PhD1,2*; Adhikari, Sameep, BOptom1; Thakur, Ajit, MOptom1; Shrestha, Bhairaja, MD1; Loughman, James, PhD2

Optometry and Vision Science: June 2019 - Volume 96 - Issue 6 - p 407–413
doi: 10.1097/OPX.0000000000001386
ORIGINAL INVESTIGATIONS
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SIGNIFICANCE Autorefractors are commonly used by eye care practitioners worldwide as a starting point for clinical prescribing and by researchers as an instrument to study development of refractive errors and accommodation. This study demonstrates that the Nidek ARK-1 provides a reasonable and repeatable estimate of refractive error.

PURPOSE The purposes of this study were (a) to compare refraction measurements of the Nidek ARK-1 (2016 release) autorefractor with that of subjective refraction and retinoscopy performed by an experienced clinician and (b) to determine the intratest and intertest variability of autorefraction measures taken using the ARK-1 autorefractor.

METHODS Sixty-seven adult patients aged 18 to 69 years underwent retinoscopy, subjective refraction, and ARK-1 autorefraction on a same day by a single clinician. A separate subset of 14 participants was invited for the repeatability and reproducibility study. Both eyes of each participant were included in the analysis.

RESULTS A statistically significant (but not clinically significant) positive spherical difference was observed between the ARK-1 and subjective refraction (P = .003). Spherical equivalent refractive errors were statistically similar between the ARK-1 and subjective refraction (P = .20). A statistically and clinically significant difference was observed in the cylindrical component between the ARK and subjective refraction (P < .01). No statistically significant difference was observed between the ARK and subjective refraction in both the horizontal (J0; P = .08) and oblique cylindrical vector (J45; P = .96). Bland-Altman analysis revealed that the 95% limits of agreement were widest between the ARK and subjective refraction in all of the refractive components (−0.60 to 0.89 diopter for spherical component, −0.80 to 0.69 diopter for spherical equivalent, and −0.98 to 0.30 diopter for cylindrical component). The intertest and intratest variability of the ARK-1 was small.

CONCLUSIONS The Nidek ARK-1 autorefractor is a useful clinical tool that provides a reasonable and repeatable estimation of refractive error in adults.

1Drishti Eye Care Centre, Kalanki, Kathmandu, Nepal

2Centre for Eye Research Ireland, Technological University Dublin, Dublin, Ireland *nabin.paudel@dit.ie

Submitted: July 11, 2018

Accepted: February 28, 2019

Funding/Support: None of the authors have reported funding/support.

Conflict of Interest Disclosure: None of the authors have reported a financial conflict of interest.

Author Contributions and Acknowledgments: Conceptualization: NP; Data Curation: NP, SA; Formal Analysis: NP; Investigation: NP, SA, AT; Methodology: NP; Supervision: BS, JL; Visualization: NP; Writing – Original Draft: NP; Writing – Review & Editing: SA, AT, BS, JL.

We would like to thank Dr. Mark Bullimore, MCOptom, PhD, FAAO, for his contributions to the early development of the article.

Online date: May 20, 2019

© 2019 American Academy of Optometry